Mars Emission Model Tool


This is a tool set up to help those interested in the prediction of the emission of Mars at IR and longer wavelengths. The model was originally written by Don Rudy while a graduate student at Caltech, and is described in:
Rudy et al. 1987 and Muhleman & Berge 1991

The model was based on data taken at the VLA in the A-configuration (most spread out - maximum baselines of ~36 km). The data were calibrated in flux density with observations of 3C286, using the Baars et al. 1977 flux density scale. Images were made, averaged over time (so longitudinally smeared). These maps were then fit with a full thermophysical model, fitting for a dielectric constant separately for each of the wavelengths, a radio absorption length common to both wavelengths, all as a function of latitude. A whole-disk average dielectric constant was also fitted for, which is independent of the flux density scale (as it relies on the polarization response). These bulk properties were then fed into a much more sophisticated thermophysical model which used results from Viking (thermal inertia and albedo as a function of location), and derived a surface and subsurface temperature profile as a function of both longitude (7.5 deg bins) and latitude (5 deg bins). This was done for a suite of models of varying electrical and thermal parameters, and then a best fit to the maps was performed to get the best fit parameters on the above grid. At the time, the north polar seasonal CO2 cap was large, and easily seen in the images, so they also fit for the effective thermal parameters of the CO2 caps.

Since the original model, it has been updated to include surface roughness effects, proper sub-pixel gridding, and potential resolution of the disk by whatever antenna might be used to observe it. It has also had the WMAP correction applied (see the description in Perley & Butler 2013 which is based on the WMAP observations described in Weiland et al. 2011).

This model has been commonly used to calibrate observations in the millimeter and submillimeter wavelength regions, and seems to work quite well. There are, however, a number of caveats that should be kept in mind when applying it:


     Year        Month        Day        UT Hour (including fraction)  

     Frequency (GHz)  

     Beam FWHM (asec)        beam type:   Gaussian    Besselian

     mean surface slope (deg)        roughness type:   Gaussian    Exponential

     dielectric (0 for default, -1 for Burgdorf et al.)  

     show geometry image          show model image  



Bryan Butler
Email: bbutler at nrao dot edu
Snail mail:
     800 Bradbury SE Suite 235
     Albuquerque, NM    87106
Phone: 505-925-1239

Last Modified on 2023-Apr-12