Effects of Dust on Radiation Transfer in the Martian Atmosphere (I)

Abstract

The equations of infrared radiation transfer are numerically solved for the Martian atmosphere, with consideration of the effect of dust, which absorbs, emits and scatters light. Primary mineral constituent of dust, we assumed, is quartz. Three cases on dust concentration are considered : the first corresponds to a heavy dust storm event, the second to a dusty case and the third to out-of-storm case. From the solutions obtained by the method of an iterative numerical integration, radiative heating or cooling rates in the atmosphere are calculated as a function of height. The computation results show that on Mars, the infrared radiative cooling rates due to dust cannot be overlooked in the lower levels within dusty atmosphere. Especially, at a dust storm event, cooling in the infrared regions would be a very important term as well as heating due to absorption of the incident solar radiation by dust, and the thermal structure of the Martian atmosphere seems to be determined by dust alone. Our result also indicates that even at out-ofstorm events, cooling rate due to dust seems to have the same order as the magnitude of infrared radiative cooling due to CO2.

A spectral model of the atmospheric general circulation of Mars: A numerical experiment including the effects of the suspended dust and the topography

“…There are several indications that a fairly large amount of dust is suspended in the Martian atmosphere, not only at the time when a great dust storm event occurs but also during ordinary conditions. Recent observations by space probes and recent theoretical studies [e.g., Moriyama, 1974Moriyama, , 1975Zurek, 1978] have led us to investigate the effect of dust on the atmospheric general circulation. A strong tidal forcing in the Martian atmosphere would be mainly caused by direct absorption of the solar radiation owing to dust.…”

Characterization of dust activity on Mars from MY27 to MY32 by PFS-MEX observations

“…In our analysis we neglect the impact of CO 2 on atmospheric heating and cooling rates. The CO 2 absorbs only 1% of solar radiation, producing cooling and heating rates around 4 -5 K/day when sun is in zenith (Moriyama, 1974;Savijarvi et al, 2005). The trace gases have also a negligible effect on heating and cooling rates when compared to dust.…”

“…Our results are in good agreement with previous theoretical calculations. Moriyama (1974) showed that in lower portion of dust layers, cooling due to the IR radiation of dust becomes one of the most predominant term in heat budget. In dusty atmospheres, cooling rates of 60-80 K/days can be observed close to the surface (Moriyama, 1974).…”

Effects of Dust on Radiation Transfer in the Martian Atmosphere (II)

“…The thermal tide is likely to be strongly related with the thermal effects due to dust. Absorption of solar radiation due to dust is also a very important term as energy source of atmospheric motion (Gierasch and Goody, 1973;Golitsyn, 1973;Hess, 1973: Leovy et al, 1973 In the previous paper (Moriyama, 1974), we studied the effect of dust on infrared radiation transfer, and pointed out its importance to the thermal structure of the Martian atmosphere. As an extension of our study on radiative effects of dust, now we investigate quantitatively heating of the Martian atmosphere due to absorption of the visible solar radiation in the present paper.…”