Nadir Microwave Spectra

RFM Examples

26JUL24

Description

Nadir-viewing microwave spectrum.

The *FLG section specifies:

NAD flag
Downward viewing through a plane parallel atmosphere;
SFC flag
Mandatory with the NAD flag, indicating that surface contributions are included. In the absence of any *SFC section in the driver table (as in this example) default values are assumed: surface temperature matches that of the lowest atmospheric temperature and surface emissivity=1
RJT flag
Output the Rayleigh-Jeans temperature spectrum (proportional to radiance, and commonly used in the microwave region)
GHZ flag
Specify spectral units in GHz rather than cm-1. This applies to the numbers in the *SPC section as well as the output spectral file.
VVW flag
Apply the Van Vleck-Weisskopf correction to the Voigt lineshape, again commonly used in the microwave region.

In the *SPC section the resolution of 0.005 GHz corresponds to just under 6000 points per cm-1 (for limb-viewing you would need something finer to capture lines limited by Doppler broadening to approx 10-6 x frequency).

Driver Table

*HDR 26JUL24 RFM Example: nadir microwave *FLG NAD SFC RJT GHZ VVW *SPC 50 70 0.005 *GAS O2 H2O *ATM ../atm/usa.atm *SEC 1.0 *HIT ../hit/hitran_2016.bin *END

Output Files

Output Spectrum

[plot.py]