#
#  script to make height correction grid in mm using deflection of the vertical grids.
#  the satellite altitude is set to 1000 km but could be changed using the factor
#  500000000 = 1000 km * 1000 mm/km / 2.
#
#  extract the vertical deflection data and change 0.1 microradian units to radians
#
img2grd east.img.23.1 -T1 -S.0000001  -V -D -N2  -R0./360/-80.00/80.00 -Geast.grd
img2grd north.img.23.1 -T1 -S.0000001 -V -D -N2 -R0./360/-80.00/80.00 -Gnorth.grd
#
grdmath north.grd north.grd MUL east.grd east.grd MUL ADD 500000000. MUL = DH.grd
#
#  clean up
rm east.grd north.grd