Refractive effects at microwave frequencies of Martian dust clouds
Abstract
The S-band refractive effects of dust particles in the Martian tropopause are determined quantitatively and are analyzed to determine whether dust clouds similar to those observed by Mariner 9 are above or below the detectability threshold of radio occultation measurements. Theoretical calculation of the complex refractive index shows that the effect on the phase of a radio occultation link will be proportional to the specific volume of the dust particles as long as they are much smaller than the wavelength. The refractivity of an aerosol cloud is computed parametrically, assuming a plausible range of values for the dielectric constant and the particle radius and density. The results show that particles with a radius less than or equal to 20 microns, a density of 1000 to 1,000,000 per cu cm, and a dielectric constant of 2.5 to 5 will be below the detectability threshold, and it is concluded that Martian dust clouds as large and dense as those observed by Mariner 9 will make a negligible contribution to radio occultation measurement of the Martian atmospheric refractivity profile.
- Publication:
-
Rivista Italiana di Geofisica
- Pub Date:
- December 1974
- Bibcode:
- 1974RIG....23..261F
- Keywords:
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- Atmospheric Refraction;
- Dust Storms;
- Mars Atmosphere;
- Microwave Frequencies;
- Radio Occultation;
- Aerosols;
- Particle Density (Concentration);
- Refractivity;
- Signal Detection;
- Superhigh Frequencies;
- Temperature Profiles;
- Troposphere