USGS

Venus Mapping White Paper

Open-File Report 95-519


Appendix 2

Calculating Average Values of Ancillary Data with the ANC_DATA Program

The Fortran program anc_data will provide average values and ranges for elevation, rms slope, emissivity, and Fresnel reflectivity. Smooth and rough-surface dielectric constants, discussed in the text, are also calculated. The only inputs to the program are latitude and longitude coordinates for a sample box. Data values are taken from cylindrical projection files of the maps on GxDR Volume 2 (a mosaic of the Mercator and polar stereo maps in each directory), which you need to copy from the public ftp account on ceps.nasm.edu. File names are emis.cyl, rms.cyl, refl.cyl, and topo.cyl, which in total occupy 200 Mbytes of disk space. The program should be run in whatever directory you place these data files. The resolution of the reprojected maps is 0.044o per pixel. A sample run and output are shown below.

/home/campbell/guide: 236>anc_data

Output log file name?

'logfile2'

Lat Range (S, N), Long Range (W, E)?

30.863,30.999,43.502,43.666

Would you like another box (y or n)?

y

Lat Range (S, N), Long Range (W, E)?

30.418,30.465,43.495,43.568

Would you like another box (y or n)?

y

Lat Range (S, N), Long Range (W, E)?

30.637,30.746,43.842,44.030

Would you like another box (y or n)?

n


OUTPUT FILE:

Lat, Long Box: [( 30.863, 30.999), ( 43.502, 43.666)]

Mean and Range (min, max) of Physical Properties:

Elevation (km): 6051.540 (6051.508, 6051.551)

RMS slope (deg): 1.57 ( 1.40, 1.90)

Fresnel Reflectivity: .114 (.085, .145)

Emissivity: .828 (.819, .840)

Incidence angle (deg): 42.

Smooth and Rough-Surface Diel. Values: 3.7, 5.6

Lat, Long Box: [( 30.418, 30.465), ( 43.495, 43.568)]

Mean and Range (min, max) of Physical Properties:

Elevation (km): 6051.421 (6051.399, 6051.452)

RMS slope (deg): 4.28 ( 3.60, 4.90)

Fresnel Reflectivity: .093 (.080, .100)

Emissivity: .856 (.849, .864)

Incidence angle (deg): 42.

Smooth and Rough-Surface Diel. Values: 3.2, 4.7

Lat, Long Box: [( 30.637, 30.746), ( 43.842, 44.030)]

Mean and Range (min, max) of Physical Properties:

Elevation (km): 6051.493 (6051.484, 6051.504)

RMS slope (deg): 4.62 ( 3.00, 7.40)

Fresnel Reflectivity: .100 (.085, .120)

Emissivity: .846 (.840, .854)

Incidence angle (deg): 42.

Smooth and Rough-Surface Diel. Values: 3.4, 5.0