RFM User's Guide - GRA Flag

GRA Flag
RFM Flags: Horizontal Gradients		03MAY26

Enabled

Use 2D ray-tracing algorithm
*ATM section: each .atm file may have a horizontal angle (PSI) qualifier.
*NTE section: each .nte file may also have a horizontal angle (PSI) qualifier.
*OBS section: Observer location requires a horizontal angle PSIOBS
PTH flag: horizontal gradient information included in path diagnostics (.pth file).
Disabled

Use 1D ray-tracing algorithm
*ATM section: ignore any horizontal angles
*NTE section: ignore any horizontal angles
*OBS section: ignore any horizontal angle
Restrictions: Incompatible with FLX, HOM, NAD, TAB and ZEN Flags.
Notes

Incompatible with viewing geometries that don't involve a spherical atmosphere.
See *ATM section for further details.
Bugs: Bug#27 [none recent]

GRA Flag