Geophysical Research Letters, Vol. 28, Iss. 21, pp. 4015-4018, 1 Nov 2001.
br_360x180.bin or br_360x180_pc.bin (radial) bt_360x180.bin or bt_360x180_pc.bin (theta) bp_360x180.bin or bp_360x180_pc.bin (phi)contain IDL unformatted data arrays of the maps of the radial (br), theta (bt), and phi (bp) components, respectively, of the vector magnetic field for Mars.
If the file(s) are to be read on a Sun or a Mac, please download the first
file for each component.
If the file(s) are to be read on a PC, please download the second file (i.e., "_pc" in the name) for each component.
The following IDL commands will allow the user to read the files:
IDL> br = fltarr(360,180) IDL> openr, lun, 'br_360x180.bin', /get_lun IDL> readu, lun, br IDL> free_lun, lun IDL> bt = fltarr(360,180) IDL> openr, lun, 'bt_360x180.bin', /get_lun IDL> readu, lun, bt IDL> free_lun, lun IDL> bp = fltarr(360,180) IDL> openr, lun, 'bp_360x180.bin', /get_lun IDL> readu, lun, bp IDL> free_lun, lunEach value in the data array represents the median for all data within an 1 degree by 1 degree bin. The arrays are arranged with the first index equal to the minimum east longitude in degrees - ranging from 0 degrees to 359 degrees - of the bin. The second index is related to the latitude where index 0 is the bin from -90 degrees to and including -89 degrees and index 179 is the bin from +89 degrees to and including +90 degrees (i.e., second index = minimum latitude + 90).
A couple examples are
To obtain an image similar to figure 1, it is necessary to first set minimum and maximum values such that they are symmetric about 0. For figure 1 (radial component), one element is set to a negative value equal to the maximum positive value to insure that the center of the colorbar is at zero field.
IDL> print, min(br), max(br) -130.005 221.079 IDL> br[0,0] = -221. IDL> tvscl, br (use xloadct to select Blue-Red colorbar and 20%-80% stretch)