Data Retrieval and Manipulation Tools

Objectives

The various SRBEX models produce output datasets, and require input data, which encompass a wide range of spatial and temporal extents and represent a variety of data formats and map projections. A smooth flow of data between SRBEX components and effective support for analyzing and disseminating results are essential. To this end, we require

Facilities for documenting and storing datasets and then retrieving them using arbitrary combinations of spatial, temporal, and data-type search criteria.
Standard GIS (Geographic Information System) and image processing tools for displaying and analyzing the data and converting them between different formats, computer platforms, and map projections.
Easy access to results and data by other members of the physical climate and hydrology research community.

Current Activities

We are addressing the data management requirements in two ways. First, we have created a geographcially nested hierarchical database which assigns datasets to database levels on the basis of geographic extent. Users are currently offered three search options: by geographic hierarchy, starting with The World; via an alphabetical listing of names of geographic subregions; and by specifying the latitude and longitude of a point and the types of data desired.

Second, we are attempting to overcome the problems inherent in applying spatially based GIS to multitemporal data by developing a prototype database which gives equal emphasis to the temporal, spatial, and content attributes of the data. The temporally based component of this prototype is in place (Peuquet and Wentz, 1994), and implementation of the second, location-based, component is underway. We have also undertaken a broader study of spatiotemporal representations of information with the realization that addressing complex human and environmental issues such as global warming and human impact on the environment requires not only sophisticated, multidimensional tools for handling and analyzing empirical data, but also an integrated, interdisciplinary representational framework from the conceptual (human) viewpoint (Peuquet, 1994).

To support data analysis and manipulation, we are supporting several standard GIS and image processing packages, including Arc/Info and GRASS GIS software and ERDAS Imagine and LAS (Land Analysis System) image processing facilities. We are exploiting the AML (Arc Macro Language) component of Arc/Info and the availability of source code and support libraries for the public-domain LAS to add additional capabilites to these packages as needed to meet SRBEX science requirements.

Achievements

A number of data retrieval and manipulation tools are now in place. Tools and facilities that have been created as part of the EOS/SRBEX effort include

A geographically nested hierarchical database which supports searches initiated via World Wide Web (WWW) servers; this has been integrated into the set of WWW pages which describe the Penn State/MFSC EOS interdisciplinary study on the global water cycle.
LAS modules for aggregating GIS data to the grids required by various models, moving model outputs into standard GIS and image formats, and converting data between LAS and Arc/Info formats.
An initial version of a prototype database designed around the triad of temporal, spatial, and content attributes of the datasets.

Last change: 10 May 1995, R. A. White / raw@essc.psu.edu