RFM Flags

NAD Flag: Nadir-Viewing

06JUL17

Enabled
Calculate spectra viewing downwards into a plane parallel atmosphere
*TAN (or *SEC) section of Driver Table specifies airmass factor for calculation (eg, 1.0=vertical, 2.0= 60 deg to vertical)
Used in combination with FLX flag, can specify upwards fluxes, or transmittance from each level to surface.

Disabled
Assume limb view (or other geometry)

Restrictions
SFC Flag must also be enabled.
Incompatible with CRV, FOV, GEO, GRA, HOM, LOS, TAB, and ZEN Flags.

Notes
  1. The plane parallel atmosphere allows several simplifications: no refraction, no field-of-view effects, analytical Curtis-Godson path parameters.
  2. It is also possible to define a nadir view with the full spherical atmosphere calculations, replacing *TAN section label with *ELE and setting an elevation angle -90.
  3. Use of FLX Flag redefines NAD flag.

Bugs
Bug#108 (Fixed v4.34)
Bug#105 (Fixed v4.34)