GLOBAL WATER CYCLE:
EXTENSION ACROSS THE EARTH SCIENCES
Progress Report on the Work Plan
NASA Earth Observing System
NAGW-2686
November, 1993
The Pennsylvania State University
EARTH SYSTEM SCIENCE CENTER
and
MARSHALL SPACEFLIGHT CENTER
INTRODUCTION
This document describes the progress of our research under NASA Grant NAGW-
2686, "Global Water Cycle : Extension Across the Earth Sciences" during the period
December, 1992 - November, 1993. The "Near Term Objectives" of the original Work
Plan (p. 67-87) and the key tasks listed in the "Near Term Research Priorities, Supplement
to the Work Plan for Confirmation" (February, 1991) describe FY91, FY92, and FY93
research plans. We have keyed the sections in this document to the detailed research
objectives listed below. The Susquehanna River Basin Experiment focuses four of our
original objectives in a regional experiment. Progress on this element of our research
program is reported in a combined section.
OBJECTIVES
Objective 1. Evaluation of GCM capability to simulate hydrologic cycle components
Objective 2. Development of standardized model products
Objective 3. Evaluate GCM sensitivity to lower boundary forcing
Objective 4. Generation of global data sets for documentation of global change,
specifically for hydrologic variables, and for global model validation
and verification
Objective 5. Development and testing of components of an atmospheric model of the
regional hydrologic cycle
Objective 6. Testing the adaptability of hydrologic models for sensitivity to spatial
and topographic scales
Objective 7. Test methodologies for indirect measurement of soil water content and
integrate results into mesoscale model simulations
Objective 8. Development of a comprehensive database and GIS for the
Susquehanna River Basin to facilitate the development and evaluation of
the nested model approach to regional prediction
Objective 9. Development of a comprehensive database and GIS for the Cape Region
in E. Central Florida in order to better understand process coupling
between the land and atmosphere in a subtropical summer environment.
Objective 10. Determination of ice sheet mass balance
Objective 11. Development of a landscape evolution model
Objective 12. Climate - Agriculture Modeling
RESEARCH ELEMENTS
Global Circulation Modeling (Objectives 1, 2, 3, 4)
(E. Barron, R. Crane, F. Robertson, J. Christy, and D. Fitzjarrald)
GENESIS
The archived results of a ten-year integration with an R15 version of GENESIS
have served as a very interesting database in evaluating GENESIS capabilities. Results
were presented at the Annual Meetings of the American Meteorological Society in January
(Robertson, et al., 1993) and at the first GENESIS Workshop at NCAR in September. At
R15 GENESIS has some difficulty in reproducing tropical precipitation structure. For
some purposes (zonal averages) this is not a problem. However, with regard to interannual
variability in the Indian Monsoon, or the configuration of mid-latitude planetary waves
which are to some extent forced by tropical divergence, this resolution is important. This is
in part the motivation for porting the GENESIS model to the MSFC XMP system so that
additional resources can be used in making higher resolution runs (see below). We are
anticipating moving to T31 resolution as a standard mesh size.
Our analysis has also indicated that high cloudiness in the model is somewhat
deficient over tropical convective areas. Although one could adjust the cloud diagnostic
parameters in the model, much more understanding could be gained by formulating a
predictive equation for condensate that makes the physics behind the water mass and
radiative energy balance more realistic. We have obtained the convective code from
GENESIS and are beginning to look at how this might be done.
Preparations have been made to run the GENESIS model on the MSFC SSL Cray.
With diligent work by Bill Peterson at ESSC and Jayanthi Srikishen at MSFC, all the files
and the makefiles are in place and procedures for archiving and analyzing the data are being
developed. We are currently waiting for the MSFC system administrator to reconfigure the
XMP file structure to enable it to use long Unix file names, so that the file and directory
structure matches the ESSC Cray YMP. As soon as the reconfiguraton is accomplished the
model can be integrated. Data transfer over slow networks has been a significant constraint
in working on the ESSC Cray from MSFC. The ability to run the model and analyze the
results in-house will enable more efficient studies of interannual variability of moisture
processes, since these studies will entail the generation, transfer, and analysis of large
quantities of data by the model.
(Note: Please refer to Susquehanna River Basin Experiment section for a complete
listing of experiments completed)
GENESIS Sensitivity to SST Anomalies
In tandem with the 10-year baseline integrations of GENESIS using a slab ocean
model, integrations were made using fixed annual cycle sea surface temperatures (SST's)
and Atmospheric Modeling Intercomparison Project (AMIP) CAC observed SST's as
lower boundary forcing. An analysis of the precipitation variance amplitude shows that the
model forced with the observed SST's has considerably more variability than does the
climatological varying SST's. Tropical response to this forcing is fairly robust. 1983 minus
1982 precipitation in the GENESIS model and from MSU show quite good agreement
(evidence of the strong ENSO forcing). In middle latitudes over North America and over
Asia, the model response in terms of precipitation anomalies, hydrology and tropospheric
mean temperatures matches poorly with observations. Nevertheless, some events seem to
be reproduced qualitatively, most notable among these being the 1988 drought over North
America which coincided with anomalously cool equatorial eastern Pacific SST's.
Motivated by questions of intermodel variability and signal to noise ratio, we have
begun experiments with the GSFC/GLA 17-layer, 4 by 5 degree gridpoint climate model.
This model has evolved over many years from the UCLA gridpoint model and incorporates
a number of improvements in the surface, moisture, and cumulus parameterizations that are
appropriate to this EOS study. As a start, we have begun to repeat the AMIP prescribed
SST integration (years 1979 to 1988) using an improved parameterization of rainfall
evaporation. With the AMIP decade-long run as control, we have commenced a series of
experiments to investigate the influence of end-of-season snow cover on the subsequent
development of spring and summer precipitation patterns. For example, were the midwest
floods of 1993 due to a greater than normal snowpack in the west that preserved late spring
soil moisture? The first few years of this integration suggest that indeed the resulting
changes in the surface energy balance due to altered Bowen ratio can impact equivalent
barotropic atmospheric thermal structure and, hence, storm track position.
It is important in this study to do enough cases to get an idea of the inherent chaotic
variability of the model simulation and the sensitivity of this variation to changes in snow
cover. To this end, we will use the 10 spring seasons of the AMIP control run as different
realizations to apply the enhanced snow cover, then compare the subsequent precipitation
patterns to each unaltered control run. Initial results indicate that the snow cover forcing is
adequate to significantly alter subsequent precipitation, and that the soil moisture field must
have equilibrated before the experiment is started. The first 2 years of the AMIP control run
appear to retain too much of the arbitrary soil moisture initial conditions.
Global Data Sets for Earth System Change Documentation
Having completed the initial study in early FY93 with Special Sensor for
Microwave/Imaging (SSM/I) F8 retrievals of integrated liquid water and water vapor, we
have devoted efforts this year to increasing the data base which now extends through mid-
calendar year 1993. It was felt that more than the original three years was necessary in
order to produce accurate statistics, even for intraseasonal variability (20-90 days). In
FY94 we expect to complete statistical analysis on a 5-yr climatology which will document
synoptic through interannual time scales.
We have undertaken a pilot study to assess the feasibility of forcing moisture
conservations with SSM/I data (F. Robertson). The objective of this work is to produce a
climatology which is based heavily on remotely-sensed water vapor (SSM/I, High
Resolution Infrared Radiation Sounder (HIRS-2), SSMT/2) and which uses additional
constraints from global gridded analyses. A unique aspect of this study is a semi-
prognostic approach whereby remotely-sensed moisture data are assimilated into an
evolving analysis. Wind and temperature fields from global gridded analyses (e.g. GSFC,
National Meteorological Center (NMC) or European Centre for Medium Range Forecasting
(ECMWF) reanalyses) are used to drive predictive equations for water vapor, condensate,
and precipitation. In addition to transport processes, parameterized bulk microphysics and
moist convection affect the distribution of water substance. The incorporation of remotely-
sensed water vapor is accomplished by a nudging procedure which updates the evolving
water vapor field and constrains it to observations. This semi-prognostic approach differs
from four dimensional data assimilation (FDDA) in several ways: (1) only these moisture
fields are prognosed, (2) it is much less computationally expensive, so many experiments
with differing moist physics can be done. In fact it can serve as a testbed for future FDDA
model convective and cloud parameterizations and (3) current reanalysis efforts do not
include explicit simulation of cloud water or ice.
This year we have focused on testing of convective parameterizations that will allow
us to diagnose the effect that closure assumptions have on estimates of mass flux. This
strongly affects the production of upper-tropospheric condensate. We have been
diagnosing the TOGA-COARE period of Nov. 1992-Jan. 1993 (Robertson and McCaul,
1993) and have been able to reproduce the observed upper-level cloudiness field which has
such a strong effect on cloud radiative forcing in the western Pacific.
In 1994 we will be folding in MSU precipitation estimates, Tim Liu's oceanic
evaporation estimates, and assessing the differences in analysis results arising from
differences in the ECMWF and GSFC analyses. We expect the results of this effort ( a
global analysis of vapor, precipitation and cloud condensate) to be very useful in two ways:
First, it will help in interpreting moisture relationships to kinematic, bulk microphysical and
convective processes. This will facilitate comparison of the International Satellite Cloud
Climatology Program (ISCCP) cloud climatology and Earth Radiation Budget (ERB) cloud
radiative forcing estimates to global distributions of water vapor. Second, it will assist in
improving parameterizations for convection and cloudiness that could be used in the GSFC
EROS assimilation model.
Work on the analysis of heating rates from global gridded analyses, partitioned into
latent heat release, radiative flux convergence, sensible heat flux and eddy heat transports
has focused, in the last half of FY93, on gearing up codes to use the GSFC reanalysis
products, now estimated to be available in Dec. 1993. We have coordinated with Sig
Schubert and Richy Rood at GSFC regarding current strengths and issues with the analysis
system and anticipate diagnostic studies to resume in 1994. In addition we have explored
with Prashant Sardeshmukh, NOAA ERL CRD, the possibility of comparing his divergent
circulation estimates, derived from vorticity balance considerations, to the divergent
circulation in the GSFC assimilated products. Because these two methods are largely
independent of each other, an intercomparison will strengthen understanding of the
uncertainties in diabatic heating estimates and the moisture diagnostics noted in this task.
Research in 1993 by Christy continued to focus on the determination of lower
stratospheric temperature. A paper (Spencer and Christy, 1993) documents the high
precision of channel 4 in the Microwave Sounding Unit (MSU) data. In another paper,
Christy and Drouilhet (1993) we have added more information on the precision issue and
have studied the daily variability of the zonal mean anomalies. We found daily zonal mean
anomalies of lower stratospheric temperature are known to within 0.01 deg C near the
equator and within 0.07 near the poles. Signal to noise ratios are generally above 100 and
approach 1000 near the equator and poles.
By calculating the meridional curvature (second derivative) near the equator, an
index for the QBO was determined. However, the typical relationships reported by others
for QBO versus polar anomalies was not found in the MSU data. Ozone concentrations
during October over the South Polar region were will correlated with MSU 4 prior to the
effects of Mt. Pinatubo in 1991.
The global lower tropospheric temperature trend since 1979 shows the atmosphere
cooling at a 0.03 deg C per decade rate. Much of this can be attributed to the cooling due to
Pinatubo. The effects of Pinatubo, El Chichon and El Ninos have been calculated in the
lower troposphere. Once removed they show a decadal trend of +0.09 deg C. This may be
the warming, however slight, due to enhanced greenhouse gases.
We continued to work in 1993 on the creation of an optimal climatological
precipitation and streamflow data set. The Navy Cal/Val operational SSM/I rainfall
algorithm was submitted for the WETNET PIP-1 precipitation intercomparison project to
assess a possible baseline global rainfall scheme. It was learned that the surface calibration
data set used to develop this algorithm was inadequate. Comparison with the GPCP rainfall
climatology, ECMWF model, and other independent "truth" sets show that the operational
algorithm underestimates instantaneous rainrate by a factor of two. The ECMWF 12-h
forecast is calibrated with GPCP raingage data, and therefore agreed best with the GPCP
climatology. Further studies are planned as part of the PIP-2 case study experiments.
Synoptic-Scale Validation
The methodologies have been developed for synoptic-scale validation through
translation across scales, from the synoptic-scale circulation to the regional climate. The
focus for this work in 1993 has been on precipitation: tropical rainfall in southern Mexico
and, in contrast, snowfall in the Colorado Rockies. The approach used is to apply neural
nets to develop empirical relationships between the large-scale circulation and the regional
precipitation. A simple feed-foward net architecture has proved very effective in both
locations (Colorado and Mexico).
Colorado Basin Snowfall
The results of the analysis of snowfall in the Colorado Basin show that the neural
net demonstrates that the synoptic circulation (as represented by the 700 mb height field)
exerts a strong control on snowfall. The relationship between circulation and snowfall
varies as a function of geographic region which reflects largely individual sub-drainage
basins. The circulation accounts for approximately 70% of the day-to-day variability in
snowfall. This relationship is highly non-linear. Traditional linear regression methods
explain only 34% of the variance between circulation and snowfall (McGinnis, 1993).
Mexican Precipitation
Previous work in this part of the EOS research project found that neural nets could
be used to relate the surface and 500 mb circulations to precipitation over Chiapas, southern
Mexico. The neural net was able to predict the onset of the summer rainy season, as well as
the phase of individual rain events. The present work extends these earlier results by de-
composing the net and establishing the sensitivity of the rainfall to individual features of the
500 mb and surface pressure fields. Different features of the circulation are important for
explaining rainfall variability during different parts of the season. The Inter-Trpocial
Convergence Zone (ITCZ) controls rainfall during the onset of the rains and during their
dissipation at the end of the season. In the middle of the season the rainfall variability is
controlled in part by upper level divergence (easterly waves), and in part by the extension
of the Bermuda High, which affects moisture supply to the region (Hewitson and Crane,
1993).
Mesoscale Modeling (Objective 5)
(T. Ackerman, B. Albrecht, D. Lamb, T. Warner)
Improved Treatment of Cloud Processes in a Mesoscale Model
Cirrus clouds are an important but poorly understood component of the climate
system. Due to their large spatial extent and cold temperatures, cirrus clouds have a large
impact on the planetary radiation budget by reducing outgoing longwave radiation and
increasing the downward longwave flux at the surface. In addition, radiative heating in the
cloud deck can be a significant factor. Despite the importance of cirrus, however, current
cloud parameterization schemes used in general circulation models are clearly inadequate in
their prediction of cirrus occurrence and diagnosis of cirrus radiative processes, while most
mesoscale models contain no cirrus parameterizations at all.
The objective of our current activity is to improve the treatment of cirrus formation
and life cycle, and radiative impacts in the MM4 and MM5 versions of the Penn State
University/National Center for Atmospheric Research mesoscale model. Our approach may
be outlined briefly as follows:
1) Collect a data set of cirrus cloud characteristics (such as frequency of
occurrence, height, ice water content, and optical properties), associated radiative
fluxes, and environmental variables (such as temperature, humidity, and wind);
2) Use the data to produce diagnostic 4-D fields of the environmental variables;
3) Use a mesoscale model to simulate these same 4-D fields and compare them
to simulated and observed fields;
4) Incorporate a cloud parameterization scheme into the mesoscale model and use it
to predict the occurrence of cirrus cloud and associated radiative properties;
5) Compare the predicted and observed cirrus characteristics and computed and
observed radiative fluxes.
The data which we are using was collected during the First ISCCP Regional
Experiment (FIRE) Cirrus II campaign in Coffeyville, Kansas, in 1991. The hub site of
this experiment was located within the area covered by the National Weather Service
(NWS) wind profiler demonstration array. The wind profilers measure hourly-averaged
profiles of the horizontal wind speed and direction from about 1 km to the tropopause. In
principle, the complete 4-D wind field can be diagnosed from these profilers by
interpolating the observations to a uniform 3-D grid, calculating the horizontal divergence,
and then applying continuity to obtain the vertical velocity. In practice, due to the spatial
scale of the profilers and instrument errors, it proved to be difficult to obtain realistic
results. However, during the past year, we have completed a diagnostic package that
allows us to produce 4-D wind fields from the profilers, as well as the divergence and
vorticity (Mace et al., 1993). In order to test the method for consistency, we have applied it
to several case studies (Mace et al., 1993a,b).
Producing 4-D thermodynamic fields (temperature and absolute humidity) for the
experiment period is much more challenging because the only available data is from
radiosonde releases. We have developed a technique to use the radiosonde-measured
temperatures and humidities in conjunction with the 4-D wind field to produce 4-D
thermodynamic fields.
During the past year, we have also completed a month-long series of overlapping
model runs for the FIRE II campaign using MM5, the non-hydrostatic version of the
PSU/NCAR mesoscale model at 1 km resolution. The model was run from initial
conditions for 48 hours with a 12 hour overlap at the beginning of each run and the end of
the previous run. By averaging the two runs during the 12 hour overlap, a virtually
seamless mesoscale model simulation for the entire experiment period has been produced.
During the past year, we have also completed a study of the effect of non-spherical
ice crystals on solar and infrared radiative fluxes. This work defines the needed precision
of optical property measurements in ice clouds in order to achieve computed accuracies of 5
W/m2 or better in surface fluxes. The purpose is to determine how well cirrus cloud
parameterizations need to specify cloud optical properties in order to achieve the requisite
accuracy in flux computations.
Over the course of the next year, we intend to publish the results of these diagnostic
studies. (Both studies are nearing completion as Ph. D. dissertations.) The next step is to
intercompare the diagnostic fields, the MM5 results, and an FDDA product from the NWS.
From this intercomparison, we will be able to ascertain whether the model captures the
thermodynamics and dynamics necessary for cirrus formation. If the answer is positive, we
will incorporate a cloud parameterization scheme and begin evaluation and modification of
that scheme.
Regional Modeling of Boundary Layer Clouds
Collaboration with Shouping Wang at NASA Huntsville on the development and
improvement of parameterizations of boundary layer clouds has continued during this
funding period. This collaboration resulted in the development of a regional boundary
layer model that simulates conditions associated with both fair-weather cumulus and
stratocumulus and predicts inversion height and the thermodynamic structure below the
inversion. The regional model has been tested and evaluated using ECMWF analyses to
define boundary conditions for the stratocumulus regime off the coast of California (Wang
et al., 1993). This regional model is now being used to simulate cloud and boundary layer
structure over the central Atlantic during the Atlantic Stratocumulus Transition Experiment
1993 (ASTEX). Further evaluation of the effects of drizzle on the thermodynamic
structure of the trade wind boundary layer was made using a one-dimensional model
(Albrecht, 1993).
The Atlantic Stratocumulus Transition -- ASTEX
A unique data set was collected during the summer of 1992 as part of ASTEX. The
study area for this experiment was over the eastern Atlantic in the vicinity of the Azores and
the Madeiras. During this experiment Penn State deployed an extensive suite of remote
sensing systems to monitor cloud characteristics continuously from the island of Santa
Maria. A 94 GHz cloud radar was used to define cloud-top variations and the internal
structure of the stratocumulus decks (Ackerman, et al., 1993). A microwave radiometer
provided estimates of cloud liquid water path and integrated water vapor. Cloud base
height was defined from a laser ceilometer and cloud base temperature was estimated from
an IR radiometer. Broadband radiometers provided fluxes of shortwave and longwave
radiation at the surface. Upper-air soundings (4-8 per day) from Santa Maria, Porto Santo,
and four ships were placed on the Global Telecommunications System (GTS) and were
assimilated into ECMWF and NMC analyses. These analyses provide the thermodynamic,
wind, and divergence fields needed to drive the regional model described previously.
Initial simulations of the boundary layer and cloud characteristics of the ASTEX study area
have been made by Shouping Wang using the regional model. In addition, the detailed
measurements from the surface-based remote sensors and the aircraft data that were
collected during ASTEX have been used to develop data sets that will be used to test and
further develop the parameterizations used in the model. Patrick Minnis, of NASA
Langley, is comparing cloud statistics from the Santa Maria measurements with those he
retrieves from satellites. Once this verification is completed, the satellite cloud
characteristics from Minnis's analyses for the entire ASTEX study area will be compared
with characteristics simulated by the regional boundary layer model.
Future tasks include:
1) Refine ASTEX regional boundary layer simulations and compare with satellite
and surface-based observations.
2) Develop a method for using the regional model with precipitable water estimates
from satellite observations with the Scanning Multichannel Microwave
Radiometer (SMMR) to improve specification of the water vapor content above
the inversion in the subtropics. We will use ASTEX surface-based radiometers
as ground-truth for SSMR retrievals.
3) Test the sensitivity of the regional boundary layer model to the large-scale
forcing obtained from the output of several GCM's. This will first be done
using different versions of NCAR GCM's. The large-scale parameters (vertical
velocity, above-inversion moisture, etc.) most critical to the prediction of low
cloud will be identified. Cloud distributions will be compared with those from
ISSCP.
4) Define how EOS observations will be used to further refine and develop the
regional model and define how EOS observations can be used to test the
parameterizations used in the regional model. Evaluate the merit of using adjoint
techniques to assist with this evaluation.
Cloud Microphysics Process Studies
The primary goal of the cloud microphysical studies has been to find ways to
improve the representation of clouds in atmospheric models over various scales. While the
dynamic and thermodynamic setting for cloud formation is established via mesoscale
forcing of the atmosphere, the utilization of the excess water is dictated by the phase
transformation processes that occur on the microscale. The scales interact in complicated
ways, thus necessitating the use of detailed numerical modeling.
The approach taken to investigate the role of microphyscial processes in cloud
formation, precipitation evolution and cloud persistence has been to develop a process-
oriented model from which physically-based parameterizations can be devised and
implemented in three-dimensional mesoscale models. Phase 1 of the investigation,
completed early in the year, involved the formulation and testing of computer code for the
microphysical model, a one-dimensional kinematic framework in which the cloud particles
are categorized simultaneously by water mass and solute content (Chen, 1992; Chen and
Lamb, 1993a). Ice particles are additionally categorized according to their shape, as
indicated by the ratio of lengths along the principal crystallographic axes. Such a
multicomponent framework permits the study of a variety of aerosol-clod interaction
phenomena not otherwise amenable to investigation.
Phase 2 of the investigation has been using the microphysical model to perform
sensitivity studies to gain a deeper understanding of the processes involved in cloud
formation. One study (Zahn, 1993) looked at the interactive roles played by the
atmospheric aerosol during the formation and dissipation of boundary-layer stratocumulus
clouds. Even though the boundary layer itself was idealized, it became apparent that the
large end of the aerosol size distribution plays an important role in determining the cloud
microstructure. Giant cloud nuclei significantly help to destabilize the cloud by initiating the
collision-coalescence process that leads to rain formation. At the same time, the coalescence
of cloud drops serves as a mechanism to generate additional giant nuclei and to a
perpetuation of the rainout process. This mechanism also enhances the atmospheric
removal of trace substances and so impacts the chemistry of the atmosphere (Zahn et al.,
1993). Such nonlinear processes can only be studied with a model of suitable complexity,
in particular one that can track more than one component at a time.
The ice phase can be an important initiator of precipitation from cold clouds, as well
as the dominant particle type cirriform clouds. A traditionally used parameterization of the
crystal habit (shape or form), derived originally from observation, was shown this year to
be explainable in terms of fundamental surface-kinetic and vapor-transport mechanisms
(Chen and Lamb, 1993b). From this new understanding of the physics of habit formation,
the parameterization has been extended to permit calculations of shape changes with time
and in repsonse to varying environmental conditions. Our new "adaptive" parameterization
scheme should eventually help improve the treatment of ice and precipitation formation in
mesoscale models with prognostic water capabilities.
Susquehanna River Basin Experiment (Objectives 5,6,7,8)
(E. Barron, T. Carlson, T. Gardner, L. Kump, A. Miller, G. Petersen,
D. Peuquet, T. Warner, B.Yarnal)
Introduction
The Susquehanna River Basin (SRB) Experiment (SRBEX) continued to evolve
during 1993. SRBEX is the first of several planned regional experiments which are to be
undertaken in our EOS research program. The SRB is a 62,419 km2 watershed covering
portions of New York, Pennsylvania, and Maryland (Figure 1). Our project seeks to
integrate a wide range of observations on climate, hydrology, topography and land
resources, with a suite of numerical simulation models for the purpose of studying the
elements of the global water cycle (Figures 2 and 3). These models include: the GENESIS
global circulation model (GCM), the Penn State/National Center for Atmospheric Research
(NCAR) mesoscale model (MM), the Soil Hydrology Model (SHM), the Penn State
University Biosphere-Atmosphere Model Scheme (PSUBAMS), the Terrestrial Hydrologic
Model (THM), and the Water Quality Model (WQM). Ultimately our results will provide
valuable information for evaluating the human dimensions of global change in the SRB.
In 1993 the SRBEX research group, which consists of approximately 15 faculty,
staff and graduate students, met on a regular basis (approximately every 2 weeks) and
continued to build the model linkages and support infrastructure required to carry our
research effort through the EOS launch date. As a group, we focused on establishing a
sequence of simulation scenarios that will allow us to test, refine, and validate the model
linkages. We have established a timeline to guide our interactions through mid-1995
(Figure 4). This evolutionary process has opened new areas of interaction and synergism
within our team. The following discussion of the SRBEX research elements elaborates on
the relationships shown in Figures 3 and 4.
Global Circulation Model
The primary objective of the GCM research is to evaluate the capability of the global
models to simulate hydrologic cycle components and to execute the simulations which can
be nested with the MM to produce high resolution regional predictions. Last year we
adopted a new GCM (GENESIS, developed by Starley Thompson and David Pollard at
NCAR) and we have now completed extensive testing of this model and we have produced
a series of simulations designed for the nesting experiments and SRBEX.
These experiments include:
1) R15 control run with a mixed layer ocean (typical of controls for doubled CO2
experiments)
2) R15 run similar to (1) with increased ocean heat transport (designed to evaluate
a new capability)
3) R15 run similar to (1) with zero ocean heat transport (designed to evaluate a
new model capability)
4) R15 run similar to (1) with uniform ocean heat transport (designed to evaluate
cases where the actual distribution of ocean currents is not certain)
5) R15 control run to evaluate lupanov exponents
6) R15 run with 10 years of fixed annually varying sea surface temperatures
derived from observations (the best possible case for knowledge of the ocean
surface and also a contribution to the AMIP).
7) R15 run with fixed climatological sea surface temperatures (annually varying
sea surface temperatures but with the climatologic average rather than
interannual variations).
8) R15 control run repeated with doubled atmospheric carbon dioxide
9) T42 control run with a mixed layer ocean (experiment 1 repeated for 8x higher
horizontal resolution)
10) T42 run similar to (9) but with doubled atmospheric carbon dioxide
11) T42 run with 10 years of fixed annually varying sea surface temperature (in
progress - high resolution version of (6)).
These experiments provide important tests of model capability, evaluate the
importance of spatial resolution of the GCM in driving the MM, provide the best possible
cases of specified conditions for the GCM in driving the mesoscale model, allow direct
comparison of the nested model simulations with observations, and plan for future CO2
nested model predictions at a regional scale.
The first case studies of nesting the GCM with MM have also been completed
(Guerrero, 1992). This work has established the procedures for model nesting.
We have also continued our efforts at validation of the GCM climates and exploring
the capability of GENESIS to simulate components of the hydrologic cycle. For example,
we have been processing the history tapes to derive daily data from the GENESIS present
day run using the ten years of observed sea surface temperatures, and the 2xCO2
simulation. Once the daily data are extracted, the plan will be to examine the synoptic-scale
circulation in the GENESIS climate. This will be a validation exercise similar to our
previous work using the Goddard Institute for Space Studies (GISS) model. We will also
look at circulation and temperature/precipitation relationships over the SRBEX region using
the neural net approach, and conduct a similar analysis using the GENESIS data. The
objective will be to determine whether the same large-scale versus local control is present in
the GCM climate as is observed in the NMC data.
Synoptic Climatology of the SRB
Work through 1992 focused on developing general theory and methods in synoptic
climatology (Yarnal, 1993a). This year that research shifted to the specific needs of
SRBEX and synoptic climatologyÕs role in that experiment. ManabeÕs (1991) ÒtriadÓ
strategy for climate prediction clarifies the place of synoptic climatology in SRBEX
(Figure 5). The first activity involves development and application of individual and linked
models. The second incorporates in-depth comparison of model output with observations.
The third concerns monitoring of the climate system by in-situ and remote observations.
Together, the three activities make up the climate-prediction triad, which is informed by
process studies and contributes to the human dimensions.
Figure 5. The triad strategy for improving climate prediction (modified
from Manabe, 1991).
Synoptic climatology in SRBEX fits two of these boxes. First, process studies are
underway that relate the atmospheric circulation on daily and longer time scales to
precipitation, evapotranspiration, runoff, soil moisture and water quality. Of these
variables, precipitation is critical because it is a principal output of the GCM and the MM
and a necessary input to the remaining SRBEX models (Figure 3). Present process studies
are directed to improving the initial synoptic classifications (Yarnal, 1993b; Yarnal et al.,
1993) and to relating the atmospheric circulation to varying scales of surface climate. The
latter involves conducting synoptic climatologies on watersheds of various sizes, ranging
from WE-38 (the intensive study area in the Mahantango Creek watershed) to the SRB
itself. Preliminary findings for the SRBÕs Leading Ridge One watershed show how
wintertime migratory cyclonic systems control precipitation, runoff and high-sulfate events,
while stationary fronts dominate summer hydrology (Yarnal and Draves, 1993).
The second box of Figure 5 to which synoptic climatology relates is model
validation through diagnostic study. By definition, synoptic climatology is the study of
relationships between the atmospheric circulation and the surface environment. Thus, the
synoptic climatologies of precipitation, evapotranspiration, runoff, soil moisture and water
quality provide diagnostics of model linkages between the large-scale atmospheric models
(GENESIS and MM) and the smaller-scale models of the surface environment (THM,
PSUBAMS, SHM and WQM). These model-linkage validations Ð when compared to
conventional validations that relate model output to simple variables Ð are a unique feature
of SRBEX. Initial model-linkage validations by synoptic climatology will follow each
linked-model experiment. Through an iterative process, these diagnostics will improve the
models, while the models will suggest the most appropriate future remote sensing and
diagnostic activities (Figure 5).
Penn State/NCAR Mesoscale Model
The Penn State/NCAR mesoscale model (MM) is a versatile three-dimensional,
limited-area meteorological numerical model. The MM uses a high-resolution planetary
boundary layer (PBL) model developed by Blackadar, and described by Zhang and Anthes
(1982). This PBL model uses a modified version of BATS, the Biosphere-Atmosphere-
Transfer Scheme, (Lakhtakia and Warner, 1993) as a sophisticated surface-physics/soil-
hydrology parameterization module.
During the last year, a number of model-development efforts have been underway
that will enable the MM to be used as a more effective tool for studies of regional climate
change. The major effort involved the evaluation of the 5th generation of the PSU/NCAR
mesoscale model (MM5) for a variety of meteorological situations. This model differs
significantly from the previous version (MM4), which has been utilized for about the last
eight years, in that it is nonhydrostatic and it has a more sophisticated atmospheric
hydrologic cycle, an improved atmospheric radiation scheme, and more efficient numerics
to make longer-range simulations more tractable. MM5 has been tested on a number of
meteorological cases over a wide range of scales, where the emphasis has been on the
hydrologic cycle and surface forcing. For example, the surface energy budget has been
evaluated through comparison of the predicted surface-layer temperatures and special field
program surface temperatures in the San Joaquin Valley; the tests showed that the surface
energy-budget equation in MM4/5 produced good quality simulations of the diurnal
variation of surface temperature, provided that the surface conditions were specified
accurately. As soon as MM5 Version 1 is released for public use (before the end of 1993)
the Biosphere-Atmosphere Transfer Scheme (BATS) will be incorporated into MM5, and
that model will then be used as part of the SRBEX suite of models (Figure 3). In the
interim, testing of BATS in a non-hydrostatic version of MM4 continues.
The domain to be used in the regional simulations for the Susquehanna River Basin
is shown in Figure 6. A coarse-grid mesh of 61 x 61 grid points in the horizontal and 36
km grid spacing is used, with 2 nested grids of 12 and 4 km grid spacing. All three grids
are centered over the Mahantango Creek watershed.
Detailed land-surface-process parameterization schemes like BATS require accurate
information on land-surface and soil properties. To address these requirements, the USGS-
EROS Data Center (EDC) Land-Surface Characteristics Database has been acquired for
SRBEX studies. This database includes 159 land-cover classes at a 1 km resolution for the
entire 48 conterminous United States. The land-cover classes in this database were reduced
to the 18 vegetation/surface-cover types used in BATS. The data were transformed to meet
the cartographic requirements of the mesoscale-model grid, and were then aggregated
(using a modal aggregation technique) from the 1 km original resolution to all three model
grids (36, 12 and 4 km) (Smith, 1993).
The USDA-SCS STATSGO soil database provides the most useful resource for
characterizing the nature of the soils found at scales represented by mesoscale model
domains. Through a cooperative agreement with the USDA-SCS National Soil Survey
Center we have recently obtained STATSGO soils information for the eastern two-thirds of
the conterminous United States.
The linkage of the MM with the THM and the SHM is a central element within
SRBEX (Figure 3). This linkage consists of the SHM providing initial values of soil-water
content to the MM and the THM. In turn, the MM provides the simulated precipitation data
to the THM. This process is depicted in Figures 7 and 8 (Lakhtakia et al., 1993). In Step 1,
the GIS is used to register the data obtained from a particular database (e.g., the USGS-
EDC land-surface-characteristics, the USDA-SCS soils and the USGS 3 arc-second digital
elevation model (DEM) data) to a specific model grid. In this particular case there are two
different types of horizontal grids involved (i.e., the SHM-MM grids and the THM grids).
The GIS provides the means for model grid registration. Step 2 represents the execution of
the SHM for the particular experiment. The output from the SHM is regridded in the GIS
(Step 3) in order to provide part of the initial conditions for the MM and the THM. The
MM is executed in Step 4. The precipitation fields simulated by the MM are piped into the
GIS environment, where they are regridded (Step 5) for use by the THM as a forcing term
in the surface hydrology balance. The THM is executed in Step 6 and its output is placed
in the GIS (Step 7). A series of experiments with these models is planned, as shown in the
timeline diagram (Figure 4). The first of these simulations, a storm event, has been chosen
and the initial conditions for the MM created.
Soil-Vegetation-Atmosphere (SVAT) Model/Remote Sensing
Soil Hydrology Model (SHM) link with Mesoscale Model (MM)
The use of a sophisticated scheme like BATS within the MM requires the
initialization, among other variables, of the soil-water-content profile at each of the MM
grid-point locations. Chris Smith demonstrated in his M.S. thesis (Smith, 1993) that a soil
hydrology model could be used to provide the MM with a field of initial soil-water content.
The soil hydrology model used in that work is the SHM, a one-dimensional, diffusion-
gravitation soil-hydrology model driven by conventional meteorological, soil and
vegetation information (Capehart and Carlson, 1993a).
The data used in Chris Smith's work was obtained from the NCAR archives and
the USGS-EDC Land-Surface-Characteristics data. The SHM was executed over the MM
grid domains (Figure 6) for a four-month period in 1990 (March-July) to produce the soil-
water-content profile for each of the grid-point locations. This information was then used
as part of the initial conditions for a 12 hour simulation with the MM at the end of the four-
month period (mid-July 1990 - coincident with the NASA MAC-HYDRO mission). In the
process of linking the SHM to the MM, it was found that only two months of input
meteorological data (rather than four) are required to achieve a stable initial soil-water-
content field for the MM. A paper, co-authored by Smith, Lakhtakia, Capehart and Carlson
(Smith et al., 1993b), on this subject has been submitted to the Bulletin of the American
Meteorological Society. We have also prepared -- with the aid of William Jester, an
engineering student -- an animated film showing the time evolution of the soil-water-
content fields as generated by the SHM for the aforementioned four months of 1990. This
film will soon be available for demonstration (copy available for loan).
Steve DiRienzo, an M.S. candidate in meteorology, plans to conduct another pilot
study with the SHM. He will execute the SHM for different land-cover conditions using
operational weather data available in the Penn State Department of Meteorology rather than
relying on archived data. One goal in this work is to allow the SHM to be used as a
pedagogical tool and another goal is to investigate the possibility of using more than one
land-cover category at a given grid point in the MM grid. Eventually, however, we plan to
execute the SHM for an arbitrary grid of points over the entire United States, Canada and
Mexico using the Penn State weather data.
Penn State University Biosphere Atmosphere Model Scheme -- PSUBAMS
The Penn State University Biosphere Atmosphere Model Scheme (PSUBAMS) is
our principal tool for interpretation of satellite (visible and infrared temperature) imagery.
For the past two years we have been working on a new method that allows determination
of the surface soil-water content, the surface energy balance and the fractional vegetation
cover over partially vegetated surfaces.
To date, one paper (coauthored by Carlson, Gillies and Perry) has been accepted
for publication in Remote Sensing Reviews (Carlson et al., 1993). A second paper, based
in part on the Ph.D. thesis of Robert Gillies (Gillies, 1993) is about to be submitted to the
Journal of Applied Meteorology (Gillies and Carlson, 1993a). One of the unique aspects of
the technique we describe in these two papers is the recovery of the surface soil-water
content, as opposed to a bulk value, which neglects the presence of vegetation and so, has
far less physical meaning.
We are working on an additional paper in which the surface soil-water-content
measurements reduced from C-130 NS001 radiometric measurements from the 1990 MAC-
HYDRO mission are to be collated with surface soil-water-content estimates obtained from
the Push Broom Microwave Radiometer measurements made at the same time. This paper,
by Carlson, Gillies and Schmugge will be submitted to Agricultural and Forest
Meteorology as part of a dedicated volume of papers associated with the recent workshop
on Thermal Remote Sensing of the Energy and Water Balance over Vegetation, held in La
Londe, France, in September 1993 (Gillies, et al., 1993). This workshop constitutes an
ESSC initiative and was organized by Toby Carlson. Robert Gillies is organizing the
proceedings for that workshop.
Although we have not yet subjected the method to rigorous analysis, we anticipate
making some verification using the datasets available from International Satellite Land
Surface Climatology's (ISLSCP) First Field Experiment (FIFE). Several case studies will
be made using coincident NOAA-AVHRR and C-130 NS001 radiometer data from the
intensive field phases of FIFE in 1987 and 1989.
A way of linking PSUBAMS to the SHM (Figure 3) constitutes the focus of Bill
Capehart's Ph.D research. Capehart is adapting the method of systematically inserting
remotely determined estimates of surface soil-water content and fractional vegetation cover
in the SHM. He plans to develop a technique for nudging the continual series of estimates
provided by the SHM with intermittent estimates as determined from satellite observations
(Capehart and Carlson, 1993b).
Two other related projects involving PSUBAMS are planned. First, we are
contemplating a study of deforestation/urbanization. We will use archived AVHRR data for
a couple of rapidly growing urban areas and two forests, one in Mexico and one in the
United States or Canada. We propose to develop a new type of deforestation/urbanization
index based on two parameters -- surface soil-water content and fractional vegetation cover
(Gillies and Carlson, 1993b). These parameters are highly descriptive of land use and are
also required as input to climate models. Consequently, the deforestation/urbanization
index can also be used to study climatological effects of land-use changes with the aid of
climate models. A second aspect of PSUBAMS will be, in part, pedagogical. We plan to
develop a version of PSUBAMS with a sophisticated user interface and a "book" (or
training manual) that will allow the model to be used to teach and assist persons not trained
in boundary layer meteorology (such as architects, agronomists, engineers, etc.) to address
problems in their own discipline. To foster this use of the model, we plan to conduct
workshops through ESSC starting sometime in 1995.
Watershed Modeling Studies
Terrestrial Hydrologic Model (THM)
The THM is a multi-layer, multi-level, raster-based model for distributed-parameter
modeling of the terrestrial hydrologic system. During 1993 we focused on continued model
component development, improvement, and validation.
Figure 9 illustrates the basic components of the current model. Initially, the model
requires a DEM. The drainage network is delineated and all cells are initialized. Cell
accumulation, flow direction, overland flow-routed, and channel flow routed files are
generated by the program. Because the model was written without arrays, dataset size is,
effectively, unlimited. Many other models of a similar nature have limited study area
capabilities due to the sizing of the arrays and hardware memory restrictions.
Figure 9. Terrestrial Hydrologic Model components
Current hydrologic-abstraction options include a phi index, a constant loss
regardless of item and soil conditions and a curve number, linked to time only through
rainfall patterns and almost entirely dependent on the soil characteristics. Efforts to utilize
the Green-Ampt infiltration scheme employed by the SHM have proven very fruitful and it
is intended that the full integration of the Green-Ampt routine and the THM will be
completed by the end of the year.
To date the model has received limited testing on a few sample DEM's. Simulated
data has been used for testing of many of the model routines. One of the goals for the
immediate future is test the model with the data represented in Table 1. Calibration of the
model with actual storm events and comparison of the model with other hydrologic
prediction models is planned for early 1994. Other research objectives include the
investigation of data scale on the hydrologic parameterization and the eventual effect on the
outfall hydrograph and overall mass balance.
Data Description 30m Resolution 100m Resolution 1 km Resolution
DEM Mahantango Mahantango &
Susquehanna Mahantango &
Susquehanna
Land Use /
Land Cover Mahantango Mahantango &
Susquehanna Mahantango &
Susquehanna
Sat. Hyd.
Conductivity
(STATSGO)
Mahantango Mahantango &
Susquehanna Mahantango &
Susquehanna
Matrix Potential
(STATSGO) Mahantango Mahantango &
Susquehanna Mahantango &
Susquehanna
Field Capacity
(STATSGO) Mahantango Mahantango &
Susquehanna Mahantango &
Susquehanna
Hydrologic Soil
Grouping A,B,C,
etc
(STATSGO)
Mahantango
Mahantango &
Susquehanna
Mahantango &
Susquehanna
SSURGO Mahantango Mahantango Mahantango
Table 1. Data for terrestrial hydrologic model testing and calibration
In 1993 our research was presented and published in the Proceedings of the
American Society of Civil Engineers - 1993 Intenational Symposium on Engineering
Hydrology in San Francisco (Miller and Johnson, 1993). An abstract has been accepted for
oral presentation and publication at the 1994 American Water Resources Association,
Annual Summer Symposiium (Johnson and Miller, 1993).
Initialization of the SCS TR-55 Hydrologic Model with Spatial Information
Egide Nizeyimana, under the supervision of Thomas Gardner, has just begun an
M.S. program in Geosciences. His research will focus on the use of DEM's, soils
information and remotely sensed data to generate input parameters for the SCS TR-55
hydrologic model for 3 watersheds of different sizes and cell resolutions. Comparisons will
be performed between the USDA-SCS State Soil Geographic (SSURGO) data and the
more generalized USDA-SCS STATSGO soils data, aerial photographs and Landsat
Thematic Mapper (TM) images, as well as Landsat TM and Advanced Very High
Resolution Radiometer (AVHRR) data. The TR-55 model, which is written in Basic, will
be translated into the C language in order to interface to the GRASS GIS. Precipitation
input data will be a series of rainfall events of 24-hour duration with a return period of 10
years estimated from rainfall-frequency distribution maps. The streamflow discharge will
be estimated for type II storm rainfall distribution. The degree of accuracy of runoff curve
numbers from the above sources in predicting runoff depth and peak discharge will be
determined by comparing predicted to observed data for the same rainfall events. Statistical
analyses will be performed using linear regression.
Synthetic Aperature Radar Studies at Mahantango Creek Watershed
The NASA-sponsored MAC-HYDRO mission in July 1990 acquired a range of
multi-temporal SAR data, including like and cross polarized data in three frequencies, over
the Mahantango Creek watershed. During the mission a range of soil-moisture conditions
existed, providing an opportunity to test the sensitivity of the SAR data to soil-moisture
variations.
Eric Warner, a Ph.D. candidate in Soil Science under the supervision of Gary
Petersen, is evaluating the MAC-HYDRO SAR data to determine the extent of the relative
impacts of soil moisture, crop cover and terrain on SAR backscatter, to normalize crop and
terrain influences on SAR backscatter, to predict soil-moisture content, and to examine the
effectiveness of slant to ground range conversion and reflector-based calibration on the
sensitivity of SAR backscatter.
Terrain influences are examined as the product of multi-scale interactions. Previous
research has noted these interactions as occurring at pixel and supra-pixel levels. However,
a limited range of terrain variables were examined, resulting in an incomplete understanding
of terrain influences on SAR backscatter. The use of DEM's will allow for the
determination of a more complete set of terrain variables, improving insight concerning the
relationship between SAR backscatter and terrain.
Approaching SAR image studies through ground and instrument variables allows
for a more complete exploration of the limitations of the instrument. The results obtained
from this study will provide other researchers with increased insight about SAR as a data-
collection tool. For those specifically involved in modeling, this insight will include an
understanding of which SAR frequency and polarization combination allow for collection
of desired data and the impact of calibration and terrain on the data-collection process. The
increased understanding will also be valuable in initializing models and conducting
sensitivity and error analyses.
Water Quality Modeling
Introduction
Our goals in 1993 were to compile an extensive chemistry and hydrological dataset
with which to test the SRBEX hydrology and water quality model parameterizations, to use
this dataset to assess the environmental factors (rainfall, temperature, hydrological flow
path) which control rates of chemical weathering, to determine how the effect of these
factors vary as a function of catchment size, and to use this information to develop
empirical relationships for water quality which can be used within the SHM and THM to
estimate chemical fluxes. In addition, we have been analyzing a number of rock cores
recovered from the Mahantango Creek watershed for mineralogy, bulk chemistry, and
fracture density and orientation. The latter analysis is proving quite useful in our modeling
of flowpaths within the watershed, and indicating that the bulk of flow is confined to the
upper 5 m of the fractured bedrock layer. The following describes our achievements over
the last project year, grouped in terms of the types of models being developed.
Watershed Mass Balance Model
We now have nearly a year of observations of weekly surface-water and monthly
well-water chemistries for watershed WE-38 (a Mahantango Creek sub-basin) (Figure 10)
and for two subwatersheds within WE-38, WD-38 and W.2 (Figure 10). Watershed W.2
is located at the top of the watershed on forested colluvium, and receives little agricultural
impact. WD-38 is located in a hilly region at the bottom of the watershed, and is
extensively impacted by agricultural activity. WE-38 itself includes a variety of surficial
environments, with forested ridges, farmed and wooded valleys; it is thought to be
representative of typical, non-carbonate Ridge and Valley watersheds within the
Susquehanna Drainage Basin.
Surface-water, well-water, and rain-water samples have been analyzed for a variety
of dissolved constituents, including both major and trace elements, and the nutrient
elements (Figure 11). We will soon complete the year-long sampling campaign, and will
then be carrying out individual mass-balance calculations for each element in each
subwatershed. Part of these calculations requires realistic estimates of the mineralogy and
thickness of soils throughout each watershed.
Figure 11. Major cation concentration and discharge versus time for weir
WE-38.
We are using the USDA-SCS SSURGO soils data in a GIS format to aid in this
process. Figure 12 shows one of these layers: the distribution of soil types and sampling
locations within the watershed.
Recharge Model
One of our research goals is to utilize the output from the (SHM) (Figure 3) to
determine the rates of chemical weathering as a function of depth within a soil column. As a
step in this direction, we have developed a recharge model to estimate recharge fluxes
below the soil zone, based primarily on observed water table fluctuations.
Yearly recharge cycles calculated with the model are comparable to those calculated
in the standard way, using a water budget. A cumulative recharge plot (Figure 13)
demonstrates that most of the recharge of groundwaters in this watershed occurs during the
10 largest recharge events. We are working with Brent Yarnal to relate these events to
patterns in the watershed's climatology using synpotic climatologic techniques. The
implication for us is that the contribution of dissolved ions from the soil zone to the
groundwaters occurs during infrequent, large events, and should lead to temporal
variability in groundwater quality. Our well-water chemistry observations substantiate this
prediction. Our next steps include a comparison of our recharge estimates to those from the
SHM, and a field test of the models on a small hillslope in WE-38.
Figure 13. Cumulative recharge versus number of recharge events for 1983
- 1987.
Chemical Weathering Model
In conjunction with the recharge modeling effort, we have developed a leaching
model which calculates the rates of mineral dissolution as a function of soil-moisture
content, soil- water chemistry, temperature, reactive mineral surface area, and recharge
frequency. We have run the model for the ideal case of quartz dissolution, and have found
that both temperature and rainfall recurrence interval have large effects on the rate of
mineral dissolution (Figure 14). These are factors that have not been well considered in
discussions concerning the discrepancy between laboratory and field determinations of the
rates of chemical weathering. Given that previous watershed mass balance calculations
have typically assumed uniform temperatures and water-saturated soil conditions, we may
now explain these discrepancies quite readily, given the orders of magnitude sensitivity to
these factors we calculate.
Figure 14. Effective leaching rate as a function of rainfall recurrence
interval and temperature. Calculation is for the dissolution of
quartz in a silt loam.
Human Dimensions of Environmental Change in the SRB
Research on the human dimensions of environmental change has been added to
SRBEX. Physical studies are not sufficient to understand the SRBÕs hydrology;
hydrologic change can only be understood as a complex function of physical and social
forces. Preliminary investigation (Yarnal, 1993b) has shown that several sectors of human
activity Ð agriculture, forestry, mining, industry and energy, urbanization, and
transportation Ð have had direct impacts on basin hydrology. Furthermore, these activities
are driven by several interacting social forces, i.e., population change, economic growth,
technological innovation, socio-political institutions, and culture and beliefs (National
Research Council, 1992). To predict future hydrologic change, these social driving forces
must be understood. Therefore, the scientific objectives of the human-dimensions research
are:
1) To distinguish the human-induced changes in basin hydrology over time;
2) To identify the human activities that caused those changes;
3) To understand the social forces driving those activities.
The ultimate goal is to understand how human systems interact with physical processes to
produce the observed hydrology of the SRB. Understanding this interaction will guide
monitoring efforts and suggest policy for mitigating and adapting to environmental change.
The human dimensions program of SRBEX just got underway in 1993. Initial
activities included surveys of human-induced hydrologic change in the SRB (Yarnal,
1992/93, Kasper et al., 1993) and GIS-based studies of land use in one sub-watershed
(Chamberlain, 1993; Kasper, 1993). Work in progress spotlights the human dimensions
of land-use/land-cover change.
SRBEX GIS and Data Management System
Activities as part of the SRBEX GIS and Data Management System have focused
on obtaining additional geographic data needed to support SRBEX modeling activities,
augmenting existing software for preprocessing the geographic data and remotely sensed
imagery, and enhancing facilities for cataloging and archiving these data.
New geographic data acquired during the year include 25 meter resolution land-use
data for the entire Chesapeake Basin, derived from Landsat Thematic Mapper imagery as
part of the EPA EMAP program; soils information (USDA-SCS STATSGO) for the eastern
two-thirds of the U.S.; additional USGS 3-arc second digital elevation data (DEM) to
complete coverage for the Cheseapeake Basin; and 90-meter DEM data for a number of 7.5
minute map quads in the SRB.
Because these data are in a variety of formats, generated by diverse image
processing and GIS packages, we have continued to acquire and, when necessary, develop
additional software for preprocessing and format conversion. Newly acquired software
includes the SUN workstation versions of the ARC/Info GIS software, and the LAS and
ERDAS Imagine raster image processing packages. These packages are being installed both
on workstations attached to the ESSC network and on two new SUN SPARCstation Model
10/30 computers, acquired with non-NASA funding, located at the Office for Remote
Sensing of Earth Resources (ORSER) at Penn State.
Software written by SRBEX team members during the past year includes ARC/Info
Arc Macro Language (AML) routines for extracting properties from the STATSGO and
converting LAS images between VAX and SUN SPARCstation data formats. Work in
progress includes additional software modules for regridding and rescaling rasterized
geographic data into formats and map projections needed for model ingest. Data structures
have been defined to facilitate catalog searches and retrievals of data at all scales of
SRBEX analysis. These data structures are being implemented to facilitate access from the
ESSC workstation network with automatic migration of data to and from a large tape
archive using the Cray Data Migration software on the Cray supercomputer. We have
begun the process of transferring existing GIS data from offline magnetic tape and cartridge
disk archives located at ORSER to the ESSC archival system.
Because of the importance of complete documentation of all data, (e.g. remotely
sensed imagery and ancillary spatial data, as well as model outputs) we have started
development of an interactive system for entering, editing, and retrieving data
documentation and other metadata. We will attempt to implement the draft "Content
Standards for Spatial Metadata" being developed by the Federal Geographic Data
Committee, although the initial version may support only a subset of these standards. We
are attempting to keep informed about similar efforts elsewhere, in the hope that we will be
able to incorporate features and modules from other systems into our own design, thereby
minimizing duplication of effort.
Advanced Techniques for the Representation of Geographic Information
Temporal representation in geographic information systems has long been
conceptually and structurally deficient. In the past year the temporally-based component of
a database design has been successfully implemented in a demonstration prototype called
TGIS (Temporal Geographic Information System). This data model, in its current form,
incorporates locational information with a temporal context. Presently, TGIS also includes
the following elements as operational capabilities: a specialized graphics interface, a facility
for converting digital data from several other formats for input into TGIS, and an initial
suite of manipulation and display algorithms. The initial testing phase of TGIS has been
completed, showing very favorable results in terms of both storage compactness of the data
model and efficiency of the initial manipulation and display algorithms.
Cape Experiment (Objective 9)
(S. Goodman)
Research activities for this period have been directed toward modeling surface
energy and hydrologic processes utilizing data collected during the Convection
and Precipitation/Electrification Experiment (CaPE) held in east central Florida in 1991.
The objectives of this project are to establish and apply methodologies for the diagnosis
of land and atmospheric water budget components for the CaPE region (approximately
25000 km2). The underlying philosophy guiding this study is that these techniques can be
applied on scales consistent with Global Energy and Water Cycle (GEWEX) Contiental
International Project (GCIP) activities such as the CART ARM experiment and ultimately
the Mississippi basin.
The surface energy and water flux component of this investigation is
being carried out using a land surface model based on BATS, in conjunction with data
from a wide array of measurement systems. The model has been tested using data from
the two Florida State University flux sites. These stations were used because of the
availability of model input variables - wind, temperature, humidity, pressure,
precipitation and solar and longwave downwelling radiation, as well as flux measurements
necessary for model validation. Results from these simulations indicate that the model,
using soil and vegetation parameter values appropriate for the local conditions, is capable
of accurately estimating surface energy and moisture fluxes. Model simulations are
currently being performed for each of the 38 PAM sites within our study area, with the
aim of producing an initial estimate of areal heat and moisture fluxes. Thirteen of the
PAM stations measured incident shortwave radiation; 4 of these also collected reflected
shortwave, emitted longwave and net radiation, and soil temperatures. Model
sensitivity to radiation input will be tested using a variety of methods for specifying solar
and longwave fluxes using the point measurements. For example, what is the impact on
model-diagnosed fluxes of using spatially uniform radiative input, as compared with
values measured at each site?
A more sophisticated modeling scheme for estimating areal fluxes for the CaPE
domain has been designed. This method incorporates BATS, geographic information
(landcover classes and soil properties), and statistical distributions of surface
properties (such as leaf area index, albedo and fractional vegetation cover) based on
high-resolution remotely sensed data. Distributions of normalized difference vegetation
index (NDVI) and spectral albedo have been derived from 20 m resolution SPOT
imagery for each of the 18 land cover classes in the study area. The BATS model will
be run at grid points for the CaPE domain; each grid cell will be treated as a mixture
of landcover types. To add further realism to the model, the statistical distributions of
surface properties within each landcover 'patch' will be represented via a discrete
probability density function inferred from the observed distributions of NDVI and
albedo. Scale issues will be addressed with a series of model runs in which the
resolution of remotely sensed data, used to establish the nature of surface variability, is
degraded. Preliminary analyses have shown that degradation of SPOT data from 20 mup
to 1 km resolution (simulating AVHRR footprints) results in large changes in both mean
and variance of surface properties.
Ice Sheet Mass Balance (Objective 10)
(R. Alley)
Our research related to the determination of ice sheet mass balance is proceeding
smoothly. One of the main assumptions in projections of future sea level is that much of the
water released by melting of low-latitude glaciers and of low-altitude regions of polar ice
caps will be transferred to high-altitude regions of ice caps because of increased
precipitation in the warmed world. We have tested this relation against data from the
Greenland Ice Sheet II (GISP2) deep ice core from the central region of the Greenland ice
sheet, and we find that it is not well-supported in Greenland.
The usual expectation (precipitation proportional to the temperature gradient of the
saturation vapor pressure) is not realized in the recent (Holocene) or in the the Younger
Dryas cold event or the main ice age (Oldest Dryas). This relation predicts an increase of
about 11% in precipitation per degree warming, but the ice core records less than 1%
increase in accumulation per degree warming.
Transitions between glacial and interglacial conditions (warming at the end of the
ice age, cooling into the Younger Dryas, warming from the Younger Dryas) show slightly
more than 11% change in accumulation per degree change in temperature, but this almost
certainly is caused by changes in strom tracks (which were far south of Greenland in cold
periods but near Greenland in warm periods). These data suggest that temperature has little
to do with precipitation in central Greenland, and that atmospheric dynamics dominate.
This forms the M.S. research for Wanda Kapsner and will be presented to the Union
Session at the Fall, 1993 meeting of the American Geophysical Union and subsequently
prepared for publication (Kapsner, et al., 1993).
Chris Shuman has advanced his demonstration that changes in near-surface snow
conditions on ice sheets over days to weeks can be detected using Special Sensor for
Microwave Imaging (SSM/I) polarization data. He is conducting spatial and temporal
mapping of events that affect the paleoclimatic record archived in ice cores, and that affect
sublimational moisture fluxes from the ice sheet to the atmosphere. A report of this work
was just published (Shuman, 1993) and a second manuscript is in press in Geophysical
Research Letters.
Landscape Evolution Modeling (Objective 11)
(R. Slingerland, G. Tucker)
As presented at the December 1992 NASA EOS site visit, our research is focused
on the general question, "How do erosion, transportation, and deposition of earth's surface
materials reflect climate change? We are posing two more specific questions:
1) How do catchment morphometrics and sediment yields evolve in response to
changing climate?
2) What are the interactions among climate, tectonics, and topography at the
regional scale?
To answer these questions we have developed a Geophysical Landscape Evolution
Model (GOLEM), using various geomorphic parameters such as drainage density and relief
from a variety of settings. This has been accomplished and the results presented in a paper
at the Third International Geomorphology Conference in August 1993 (Tucker and
Slingerland, 1993). A paper has also been accepted for publication in the Journal of
Geophysical Research (Tucker and Slingerland, 1993)
REFERENCES
Ackerman, T.P., B.A. Albrecht, M.A. Miller, E. Clothiaux, R. Peters, and W. Syrett.
1993. Remote sensing of cloud properties using a 94 GHz radar. In: Topical
Symp. on Combined Optical-Microwave Earth and Atmosphere Sensing. March
22-25. Albuquerque, NM. pp. 211-214.
Albrecht, B.A. 1993. Effects of precipitation on the thermodynamic structure of the trrade
wind boundary layer. J. Geophys. Res. 98:7327-7337.
Bluth, G.J.S. and L.R. Kump. 1993. Lithologic and climatologic controls of river
chemistry. Geochim. et. Cosmochim. Acta. (In Press)
Capehart, W.J and T.N. Carlson. 1993a. Estimating near-surface soil moisture availability
using a meteorologically driven soil water profile model. J. Hydrology. (Accepted
for Publication)
Capehart, W.J. and T.N. Carlson. 1993b. Estimation of surface moisture availability using
a hydrology budget model aided by surface satellite observations and a soil-
vegetation atmosphere transfer scheme (SVAT). 21st Con. on Ag. and Forest Met.
San Diego, CA. (Abstract Submitted)
Carlson, T.N., R.R. Gillies, and E.M. Perry. 1993. A method to make use of thermal
infrared temperature and NDVI measurements to infer surface soil water content
and fractional vegetation cover. Remote Sensing Reviews -- Special Issue on
Recent Advances in Remote Sensing Science. (Accepted for Publication)
Chamberlain, R. 1993. Fragipans and land use in the Mahantango Creek Intensive Study
Area. Unpublished working paper. Dept. of Geography. The Pennsylvania State
University.
Chen, J.P. 1992. Numerical simulations of the redistribution of atmospheric trace
chemicals through cloud processes. Unpublished Ph.D. dissertation. Dept. of
Meteorology, The Pennsylvania State University. 342 p.
Chen, J.P. and D. Lamb. 1993a. Simulation of cloud microphysical and chemical
processes using a multicomponent framework. Part I: Description of the
microphysical model. J. Atmos. Sci. (In Press)
Chen, J.P. and D. Lamb. 1993b. The theoretical basis for the parameterization of ice
crystal habits: Growth by vapor deposition. J. Atmos. Sci. (In Press)
Christy, J.R. and S.J. Drouilhet. 1993. Variability in daily, lower zonal mean lower
stratospheric temperatures. J. Climate. (In press)
Christy, J.R. 1992. Monitoring global temperature changes from satellites (Chapter 11).
Global Climate Change: Implications, Challenges and Mitigation Measures. S.K.
Majumdar et al. eds. The Pennsylvania Academy of Science. 566 pp.
Dutton, E.G. and J.R. Christy, 1992. Solar radiative forcing at selected locations and
evidence for global lower tropospheric cooling following the eruptions of El
Chichon and Pinatubo. Geophys. Res. Lett. 19:2313-2316.
Gillies, R.R. 1993. A physically based land-use classification scheme using remote solar
and thermal infrared measurements suitable for describing urbanization.
Unpublished Ph.D. dissertation. Dept. of Architecture. University of Newcastle,
UK.
Gillies, R.R and T.N. Carlson. 1993. Thermal remote sensing of surface soil water content
with partial vegetation cover for incorporation into mesoscale prediction models.
(Submitted to J. Appl. Met.)
Gillies, R.R and T.N. Carlson. 1993b. A physically based modeling approach for
including remotely derived measurements in the study of land use change. Effects
of Human-Induced Changes on Hydrological Systems. American Water Resources
Association (AWRA) Summer Symposium. (Abstract Submitted)
Gillies, R.R., A. Olioso, and K. Humes. 1993. (Ed's). Proc. Workshop on Thermal
Remote Sensing of the Energy and Water Balance over Vegetation in Conjunction
with Other Sensors. (In Preparation)
Guerrero, T. 1992. Linking a general circulation model and a mesoscale model to examine
the effects of model resolution on a simulated last glacial maximum storm in the
western North Atlantic Ocean. Unpublished M.S. thesis. Department of
Geosciences, The Pennsylvania State University. 233p.
Hewitson, B.C. and R.G. Crane. 1993. Precipitation controls in southern Mexico. In:
Hewitson, B.C. and R.G. Crane (Eds.). Neural Nets: Applications for Geography.
Kluwer Academic Pub. Dordrecht, Holland. (In Press)
Johnson, D.L. and A.C. Miller. 1993. A hydrologic model for use with raster data. Effects
of Human-Induced Changes on Hydrological Systems. American Water Resources
Association (AWRA) Summer Symposium. (Abstract Submitted)
Kapsner, W.R. 1993. Response of snow accumulation to temperature variations in Central
Greenland. Trans. Amer. Geophys. Union, San Fransisco, CA. (Abstract
Submitted)
Kasper, W.J. 1993. Modeling Spatio-Temporal Patterns of Nitrous Oxide and Methane
Soil-Gas Fluxes on a Farmstead. Unpublished M.S. thesis. Dept. of Geography.
The Pennsylvania State University.
Kasper, W.J., E.P. Arabas, C.J. Rosin, L.L. Diamond, R.A. Heidl, and A.S. Hertz.
1993. The human dimensions of water-quality changes in the Susquehanna River
Basin. Unpublished working paper. Dept. of Geography. The Pennsylvania State
University.
Lakhtakia, M.N. and T.T. Warner. 1993. A comparison of simple and complex
treatments of surface hydrology and thermodynamics suitable for mesoscale
atmospheric models. Mon. Wea. Rev. (Accepted for Publication)
Lakhtakia, M.N., D.A. Miller, R.A. White, and C.B. Smith. 1993. GIS as an integrative
tool in climatologic and hydrologic modeling. Second Int. Con./Workshop on
Integrating Geographic Information Systems and Environmental Modeling,
September 26-30. Breckenridge, CO.
Mace, G.G., T.P. Ackerman, and E. Clothiaux. 1993. Mesoscale diagnostic quantities
from arrays of doppler wind profilers and radiosondes. In: Preprints of the Fourth
Symposium on Global Change Studies. January 17-22. Anaheim, CA. pp. 232-
234.
Mace, G.G. and T.P. Ackerman. 1993a. Cirrus cloud development in a mobile upper
tropospheric trough: The November 26th FIRE cirrus case study. Proc. of the
FIRE Cirrus Science Con. June 14-17, 1993. Breckenridge, CO.
Mace, G.G. and T.P. Ackerman. 1993b. Examination of the observed synoptic scale
Cirrus cloud environment: The December 4-6 FIRE Cirrus case study. Proc. of the
FIRE Cirrus Science Con. June 14-17, 1993. Breckenridge, CO.
Manabe, S. 1991. Triad strategy for improving climate prediction. In: Confronting
Climate Change: Risks, Implications and Responses, edited by Irving M. Mintzer,
New York: Cambridge University Press. p. 51.
McGinnis, D. 1993. Predicting snowfall from synoptic circulation: A comparison of linear
regression and neural network methodologies. In: Hewitson, B.C. and R.G. Crane
(Eds.). Neural Nets: Applications for Geography. Kluwer Academic Pub.,
Dordrecht, Holland. (In Press)
Miller, A.C. and D.L. Johnson. 1993. Formulation of a hydrologic model for use with
remotely sensed data. Proc. Amer. Soc. Civ. Eng. - 1993 Int. Symp. on Eng.
Hydro., San Francisco, CA.
National Research Council, 1992: Global Environmental Change: Understanding the
Human Dimensions. Washington, DC: National Academy Press.
Robertson, F.R. and E.W. McCaul. 1994. Large scale structure of water vapor and
condensate over the TOGA COARE Region. 6th Amer. Met. Soc. Con. on Climate
Variations. January 23-28, 1994 Nashville, TN. (Abstract Submitted)
Robertson, F.R., E.J. Barron, S. Goodman, D. Fitzgerald, B. Bishop, J. Christy, S.
Thompson, and D. Pollard. 1993. GENESIS climate model: Intercomparsions with
multiple climate data bases. In: Preprints Fourth Symp. on Global Change Stud.
Jan. 17-22, 1993 Anaheim, CA. Amer. Met. Soc. pp. 3-8.
Shuman, R.B. Alley, and S. Anadakrishnan. 1993. Characterization of a hoar-
development episode using SSM/I brightness temperatures in the vicinity of the
GISP2 site, Greenland. Ann. Glaciol. 17:183-188.
Shuman, C.A. and R.B. Alley. 1993. Spatial and temporal characterization of hoar
formation in Central Greenland using SSM/I brightness temperatures. Geophys.
Res. Letters. (In Press)
Smith, C.B. 1993. Initialization of soil-water-content for regional-scale atmospheric
prediction models. Unpublished M.S. thesis. Dept. of Meteorology. The
Pennsylvania State University. 87 p.
Smith, C.B., M.N. Lakhtakia, W.J. Capehart, and T.N. Carlson. 1993b. Initialization of
soil-water content in regional-scale atmospheric prediction models. Bull. of Amer.
Met. Soc. (Paper Submitted)
Spencer, R.W. and J.R. Christy. 1993. Precision lower stratopsheric temperature
monitoring with the MSU: Validation and results 1979-91. J. Climate 6: 1194-
1204.
Tucker, G.E. and R.L. Slingerland. 1993. Erosional dynamics, flexural isostasy and long-
lived escarpments: A numerical modeling study. J. Geophys Res. (Paper
Submitted)
Tucker, G.E. and R. Slingerland. 1993. A model of regional-scale denudation: Results
from verification studies. In: Third Int. Geomorphology Con. Program with
Abstracts. Aug. 23-28, 1993. Hamilton, Ontario. p. 262.
Wang, S., B.A. Albrecht, and P. Minnis. 1993. A regional simulation of marine
boundary-layer clouds. J. Atmos. Sci. 50:4022-4043.
Yarnal, B. 1993a. Synoptic Climatology in Environmental Analysis. London: Belhaven
Press.
Yarnal, B. 1993b. Human dimensions of global environmental changes in the
Susquehanna River Basin: A call for research. Pennsylvania Geographer XXX
(2):19-34.
Yarnal, B. and J.D. Draves. 1993 A synoptic climatology of stream flow and acidity.
Climate Research 2:193-202.
Yarnal, B., A.C. Comrie, M. Dilley, J.D. Draves, B.C. Hewitson,and K.B.Yelsey.
1993. On choosing the ÒbestÓ classification procedure in synoptic climatology.
International Journal of Climatology. (Paper Submitted)
Zahn, S.G. 1993. An investigation of warm-wloud microphysics using a multi-component
cloud model: Interactive effects of the aerosol spectrum. Unpublished M.S. thesis.
Dept. of Meteorology. The Pennsylvania State University. 107 p.
Zahn, S.G., D. Lamb, and J.P. Chen. 1993. A modeling study of cloud drop coalescence
and its impact on in-cloud chemistry and deposition. Paper A248, 87th Annual
Mtg. Air and Waste Mgmt. Assoc. 19-24 June, 1994. Cincinnati, OH. (In
Preparation)
Zhang, D. and R.A. Anthes. 1982. A high resolution model of the planetary boundary
layer - sensitivity tests and comparisons with SESAME-79 data. J. Appl. Met.
21:1594-1609.
EOS CONTRIBUTIONS
1992-1993
Ackerman, T.P., B.A. Albrecht, M.A. Miller, E. Clothiaux, R. Peters, and W. Syrett.
1993. Remote sensing of cloud properties using a 94 GHz radar. In: Topical
Symp. on Combined Optical-Microwave Earth and Atmosphere Sensing. March
22-25. Albuquerque, NM. pp. 211-214.
Albrecht, B.A. 1993. Effects of precipitation on the thermodynamic structure of the trrade
wind boundary layer. J. Geophys. Res. 98:7327-7337.
Barron, E.J. 1993. Water and global change. Presentation at Ann. Meet. Amer. Met. Soc.,
Anaheim , CA.
Barron, E.J. 1993. Addressing critical issues of climate and hydrology from space. Trans.
Am. Geophys. Union, San Francisco, CA. (Abstract Submitted)
Bluth, G.J.S. and L.R. Kump. 1993. Lithologic and climatologic controls of river
chemistry. Geochim. et. Cosmochim. Acta. (In Press)
Capehart, W.J and T.N. Carlson. 1993a. Estimating near-surface soil moisture availability
using a meteorologically driven soil water profile model. J. Hydrology. (Accepted
for Publication)
Capehart, W.J. and T.N. Carlson. 1993b. Estimation of surface moisture availability using
a hydrology budget model aided by surface satellite observations and a soil-
vegetation atmosphere transfer scheme (SVAT). 21st Con. on Ag. and Forest Met.
San Diego, CA. (Abstract Submitted)
Carlson, T.N. and R.R. Gillies. 1993. A physical approach for inverting vegetation index
with surface radiometric temperature to estimate surface soil water content. Proc.
Workshop on Thermal Remote Sensing of the Energy and Water Balance over
Vegetation in Conjunction with Other Sensors. (In Preparation)
Carlson, T.N., R.R. Gillies, and E.M. Perry. 1993. A method to make use of thermal
infrared temperature and NDVI measurements to infer surface soil water content
and fractional vegetation cover. Remote Sensing Reviews -- Special Issue on
Recent Advances in Remote Sensing Science. (Accepted for Publication)
Carlson, T.N. and A.Olioso.1993. Radiometric temperature response of soybean and corn
leaves to water stress. Proc. Workshop on Thermal Remote Sensing of the Energy
and Water Balance over Vegetation in Conjunction with Other Sensors. (In
Preparation)
Chamberlain, R. 1993. Fragipans and land use in the Mahantango Creek Intensive Study
Area. Unpublished working paper. Dept. of Geography. The Pennsylvania State
University.
Chen, J.P. 1992. Numerical simulations of the redistribution of atmospheric trace
chemicals through cloud processes. Unpublished Ph.D. dissertation. Dept. of
Meteorology, The Pennsylvania State University. 342 p.
Chen, J.P. and D. Lamb. 1993. Simulation of cloud microphysical and chemical processes
using a multicomponent framework. Part I: Description of the microphysical model.
J. Atmos. Sci. (In Press)
Chen, J.P. and D. Lamb. 1993. The theoretical basis for the parameterization of ice crystal
habits: Growth by vapor deposition. J. Atmos. Sci. (In Press)
Christy, J.R. and S.J. Drouilhet. 1993. Variability in daily, lower zonal mean lower
stratospheric temperatures. J. Climate. (In press)
Christy, J.R. and R.W. Spencer. 1993. Monitoring global temperature from satellites.
Storm 1: 18-24.
Christy, J.R. 1992. Monitoring global temperature changes from satellites (Chapter 11).
Global Climate Change: Implications, Challenges and Mitigation Measures. S.K.
Majumdar et al. eds. The Pennsylvania Academy of Science. 566 pp.
Dutton, E.G. and J.R. Christy. 1992. Solar radiative forcing at selected locations and
evidence for global lower tropospheric cooling following the eruptions of El
Chichon and Pinatubo. Geophys. Res. Lett. 19:2313-2316.
Fitzjarrald, D., F. Robertson, E. Barron, S. Thompson, and D. Pollard. 1994. Simulated
interannual variability in the hydrologic cycle over North America. Ann. Meet. Am.
Met. Soc., Nashville, TN. (Abstract Submitted).
Gillies, R.R. 1993. A physically based land-use classification scheme using remote solar
and thermal infrared measurements suitable for describing urbanization.
Unpublished Ph.D. dissertation. Dept. of Architecture. University of Newcastle,
UK.
Gillies, R.R. and T.N. Carlson. 1993a. Thermal remote sensing of surface soil water
content with partial vegetation cover for incorporation into mesoscale prediction
models. (Submitted to J. Appl. Met.)
Gillies, R.R. and T.N. Carlson. 1993b. Translation of satellite measurements to land
surface parameters. Proc. ERDAS Northern Regional User's Group Meeting.
Gillies, R.R. and T.N. Carlson. 1993c. A physically based modeling approach for
including remotely derived measurements in the study of land use change. Effects
of Human-Induced Changes on Hydrological Systems. American Water Resources
Association (AWRA) Summer Symposium. (Abstract Submitted)
Gillies, R.R., A. Olioso, and K. Humes. 1993. (Ed's). Proc. Workshop on Thermal
Remote Sensing of the Energy and Water Balance over Vegetation in Conjunction
with Other Sensors. (In Preparation)
Guerrero, T. 1992. Linking a general circulation model and a mesoscale model to examine
the effects of model resolution on a simulated last glacial maximum storm in the
western North Atlantic Ocean. Unpublished M.S. thesis. Department of
Geosciences, The Pennsylvania State University. 233p.
Hewitson, B.C. and R.G. Crane. 1993. Precipitation controls in southern Mexico. In:
Hewitson, B.C. and R.G. Crane (Eds.). Neural Nets: Applications for Geography.
Kluwer Academic Pub., Dordrecht, Holland. (In Press).
Johnson, D.L. and A.C. Miller. 1993. A hydrologic model for use with raster data. Effects
of Human-Induced Changes on Hydrological Systems. American Water Resources
Association (AWRA) Summer Symposium. (Abstract Submitted)
Kapsner, W.R. 1993. Response of snow accumulation to temperature variations in Central
Greenland. Trans. Amer. Geophys. Union, San Fransisco, CA. (Abstract
Submitted)
Kasper, W.J. 1993. Modeling Spatio-Temporal Patterns of Nitrous Oxide and Methane
Soil-Gas Fluxes on a Farmstead. Unpublished M.S. thesis. Dept. of Geography.
The Pennsylvania State University.
Kasper, W.J., E.P. Arabas, C.J. Rosin, L.L. Diamond, R.A. Heidl, and A.S. Hertz.
1993. The human dimensions of water-quality changes in the Susquehanna River
Basin. Unpublished working paper. Dept. of Geography. The Pennsylvania State
University.
Lakhtakia, M.N. and T.T. Warner. 1993. A comparison of simple and complex
treatments of surface hydrology and thermodynamics suitable for mesoscale
atmospheric models. Mon. Wea. Rev. (Accepted for Publication)
Lakhtakia, M.N. 1993. The use of a complex treatment of surface hydrology and
thermodynamics within a mesoscale model and some related issues. Colloquium
and Workshop on Multiscale Coupled Modeling. NASA. February 22-25.
Calverton, MD.
Lakhtakia, M.N., D.A. Miller, R.A. White, and C.B. Smith. 1993. GIS as an integrative
tool in climatologic and hydrologic modeling. Second Int. Con./Workshop on
Integrating Geographic Information Systems and Environmental Modeling,
September 26-30. Breckenridge, CO.
Lakhtakia, M.N.1992. BATS in the MM4 model and a procedure to obtain initial soil-
water content for the model when BATS is used. The Second Penn State / NCAR
Mesoscale Model User's Workshop. October 20-22. Boulder, CO.
Mace, G.G., T.P. Ackerman, and E. Clothiaux. 1993. Mesoscale diagnostic quantities
from arrays of doppler wind profilers and radiosondes. In: Preprints of the Fourth
Symposium on Global Change Studies. January 17-22. Anaheim, CA. pp. 232-
234.
Mace, G.G. and T.P. Ackerman. 1993a. Cirrus cloud development in a mobile upper
tropospheric trough: The November 26th FIRE cirrus case study. Proc. of the
FIRE Cirrus Science Con. June 14-17, 1993. Breckenridge, CO.
Mace, G.G. and T.P. Ackerman. 1993b. Examination of the observed synoptic scale
Cirrus cloud environment: The December 4-6 FIRE Cirrus case study. Proc. of the
FIRE Cirrus Science Con. June 14-17, 1993. Breckenridge, CO.
McGinnis, D. 1993. Predicting snowfall from synoptic circulation: A comparison of linear
regression and neural network methodologies. In: Hewitson, B.C. and R.G. Crane
(Eds.). Neural Nets: Applications for Geography. Kluwer Academic Pub.,
Dordrecht, Holland. (In Press)
Miller, A.C. and D.L. Johnson. 1993. Formulation of a hydrologic model for use with
remotely sensed data. Proc. Amer. Soc. Civ. Eng. - 1993 Int. Symp. on Eng.
Hydro., San Francisco, CA.
Robertson, F.R. and E.W. McCaul. 1993. Large scale structure of water vapor and
condensate over the TOGA COARE Region. 6th Amer. Met. Soc. Con. on Climate
Variations. January 23-28, 1994 Nashville, TN. (Abstract Submitted)
Robertson, F.R., E.J. Barron, S. Goodman, D. Fitzgerald, B. Bishop, J. Christy, S.
Thompson, and D. Pollard. 1993. GENESIS climate model: Intercomparsions with
multiple climate data bases. In: Preprints Fourth Symp. on Global Change Stud.
Jan. 17-22, 1993 Anaheim, CA. Amer. Met. Soc. pp. 3-8.
Shuman, R.B. Alley, and S. Anadakrishnan. 1993. Characterization of a hoar-
development episode using SSM/I brightness temperatures in the vicinity of the
GISP2 site, Greenland. Ann. Glaciol. 17:183-188.
Shuman, C.A. and R.B. Alley. 1993. Spatial and temporal characterization of hoar
formation in Central Greenland using SSM/I brightness temperatures. Geophys.
Res. Letters. (In Press)
Smith, C.B. 1993. Initialization of soil-water-content for regional-scale atmospheric
prediction models. Unpublished M.S. thesis. Dept. of Meteorology. The
Pennsylvania State University. 87 p.
Smith, C.B., M.N. Lakhtakia, W.J. Capehart , and T.N. Carlson. 1993a. Initialization of
soil-water content for regional-scale atmospheric prediction models. Con. on
Hydroclimatology: Land-Surface/Atmosphere Intereactions on Global and Regional
Scales. Amer.Met. Soc. January 17-22. Anaheim, CA. pp.24 - 27.
Smith, C.B., M.N. Lakhtakia, W.J. Capehart, and T.N. Carlson. 1993b. Initialization of
soil-water content in regional-scale atmospheric prediction models. Bull. of Amer.
Met. Soc. (Paper Submitted)
Spencer, R.W. and J.R. Christy. 1993. Precision lower stratopsheric temperature
monitoring with the MSU: Validation and results 1979-91. J. Climate 6: 1194-
1204.
Tucker, G.E. and R.L. Slingerland. 1993. Erosional dynamics, flexural isostasy and long-
lived escarpments: A numerical modeling study. J. Geophys Res. (Paper
Submitted)
Tucker, G.E. and R. Slingerland. 1993. A model of regional-scale denudation: Results
from verification studies. In: Third Int. Geomorphology Con. Program with
Abstracts. Aug. 23-28, 1993. Hamilton, Ontario. p. 262.
Uttal, T., S.M. Shaver, E.E. Clothiaux, and T.P. Ackerman. 1993. Cloud boundaries
during FIRE II. In: Proc. 26th Int. Con. on Radar Met. Amer. Met. Soc. May 24-
28. Norman, OK. pp. 573-575.
Wang, S., B.A. Albrecht, and P. Minnis. 1993. A regional simulation of marine
boundary-layer clouds. J. Atmos. Sci. 50:4022-4043.
Wang, S. and Q. Wang. 1993. Roles of drizzle in a third-order turbulence closure model
of the nocturnal stratus-topped marine boundary layer. J. Atmos. Sci. (In Press)
Wang, S. 1993. Regional simulations of marine boundary layer clouds during ASTEX.
Ann. Mtg. Amer. Geophys. Union. Baltimore, MD.
Wang, S. 1993. Comparison of clouds derived from a regional boundary layer model,
satellite data and ECMWF analysis for ASTEX period. Eighth Con. on
Atmospheric Radiation, 23-28 January 1994. Nashville, TN.
Warner, T.T., Y.-H. Kuo, J.D. Doyle, J. Dudhia, D.R. Stauffer, and N.L. Seaman.
1992. Nonhydrostatic, mesobeta-scale, real data simulations with the Penn State
University/National Center for Atmospheric Research Mesoscale Model. Met. and
Atmos. Phys. 49:209-227.
Warner, T.T. and M.N. Lakhtakia. 1993. Simulation of mesoclimate with regional
meteorological models. Directory of CRAY Sponsored University Research &
Development Grants. CRAY Research, Inc.
Yarnal, B., 1993a. Synoptic Climatology in Environmental Analysis. London: Belhaven
Press.
Yarnal, B. 1993b. Human dimensions of global environmental changes in the
Susquehanna River Basin: A call for research. Pennsylvania Geographer XXX
(2):19-34.
Yarnal, B. and J.D. Draves. 1993 A synoptic climatology of stream flow and acidity.
Climate Research 2:193-202.
Yarnal, B., A.C. Comrie, M. Dilley, J.D. Draves, B.C. Hewitson,and K.B.Yelsey.
1993. On choosing the ÒbestÓ classification procedure in synoptic climatology.
International Journal of Climatology. (Paper Submitted)
Zahn, S.G. 1993. An investigation of warm-wloud microphysics using a multi-component
cloud model: Interactive effects of the aerosol spectrum. Unpublished M.S. thesis.
Dept. of Meteorology. The Pennsylvania State University. 107 p.
Zahn, S.G., D. Lamb, and J.P. Chen. 1993. A modeling study of cloud drop coalescence
and its impact on in-cloud chemistry and deposition. Paper A248, 87th Annual
Mtg. Air and Waste Mgmt. Assoc. 19-24 June, 1994. Cincinnati, OH. (In
Preparation)