Nadir Brightness Temperature, Curved Atmosphere
*FLG section includes the OBS flag to show that observer altitude is specified, and the CRV flag to show that the earth's curvature is supplied (default is to assume RFM default curvature of 6367.421km).
*ELE section specifies the
path as an elevation angle relative to horizontal (-80 degrees being 10 deg
off-nadir). Although this runs the RFM in its default 'limb-viewing' mode,
the path intersects the surface so that
the usual specification of a limb
path by (refracted) tangent height cannot be used, so the
alternative definition of path by observer altitude and elevation angle is
Actually path specification by geometric tangent height (*GEO) could still be used, but that would probably require the user calculating this distance using the information they would supply anyway for the *OBS, *ELE and *CRV sections here).
*OBS section specifies that the observer altitude is 800km.
*CRV section specifies that the local radius of curvature is 6400km.
*HDR 20AUG13 RFM Example: : nadir bbt, curved atm. *FLG OBS CRV BBT SFC *SPC 1220 1230 0.1 *GAS CH4 H2O N2O *ATM ../atm/usa.atm *ELE -80.0 *HIT ../hit/hitran_2012.bin *SFC 288.20 1.0 *OBS 800.0 *CRV 6400.0 *END