放射伝達に及ぼす火星大気中のダストの効果(その1)

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.