Lambert azimuthal projection for U.S.

The Lambert azimuthal projection which is widely used by the USGS and other agencies for the 48 conterminous states is defined as follows:

    Projection:                       Lambert azimuthal
    Datum:                            none
    Units:                            meters
    Radius of sphere of reference:    6370997.0
    Longitude of projection center:   -100 0 0 (100° W)
    Latitude of projection center:      45 0 0 (45° N)
    False easting (meters):           0.0
    False northing (meters):          0.0

Relative to this cooordinate system, the polygon version of the dataset has the following bounding coordinates (in meters):

        Xmin = -2031854.125        Xmax = 2516407.500
        Ymin = -2116675.500        Ymax = 732416.375

For the 1-km grid version, the bounding coordinates were extended outwards to match the coverage of the 1-km landcover and digital elevation datasets from the USGS EROS Data Center, giving

        Xmin =  -2050500           Xmax = 2536500
        Ymin =  -2136500           Ymax =  752500
        nrow =      2889           ncol =    4587
        cellsize =  1000

For most image processing software packages, the coordinates of the center of the upper left (northwest) cell should be entered as

        x = -2050000, y = 752000

Last change: 2001 April 6, R. A. White / raw@essc.psu.edu