ZEN Flag

RFM Flags: Upward Viewing in Plane Parallel Atmosphere



Assume other viewing geometry

Incompatible with FOV, GEO, GRA, HOM, LOS, NAD, SFC and TAB Flags.

  1. Unless an observer altitude is specified (OBS or LEV Flags) the observer is assumed to be at the surface (defined as the lowest profile level rather than 0 altitude)

  2. The plane parallel atmosphere allows several simplifications: no refraction, no field-of-view effects, analytical Curtis-Godson path parameters, no requirement for altitude coordinate (assuming hydrostatic equilibrium - see HYD Flag to turn this off).

  3. For upward-viewing calculations with a spherical atmosphere it is still possible to use the normal 'limb-viewing' geometry but the viewing direction has to be specified by elevation angle (replacing *TAN section label with *ELE and specifying positive elevation angles).

  4. Use of FLX Flag redefines ZEN flag.

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