Martian Lee-wave cloud near Ascraeus Mons during Martian years 33 and 34: a study based on the Mars color camera (MCC) images

Abstract

The north-eastern slope of Ascraeus Mons in Mars shows evidence of gravity wave cloud formation, commonly known as Lee-wave cloud. Mars color camera, onboard India’s first Mars orbiter mission, has captured over 25 images of Lee-wave clouds during Martian years 33 and 34. In our present study, our main objective is to estimate the atmospheric parameter associated with wave cloud appears over the Lee side of Ascraeus Mons and to interpret our results physically for the observed events. We have analyzed all the images of Lee-wave clouds and estimated the physical parameter such as wavelength, wind speed, height, formation temperature, nature of the cloud particle, and other atmospheric parameters related to the events. The wavelength of the Lee-wave cloud varies from 25 to 35 km. The wind speed ranges from 36 to 52 m/s at the height of 25–37 km from the planet’s surface. We consulted the global circulation model to validate our initial results. The estimated AOD value varies from 0.9 to 2.3 for the blue channel. In contrast, the scale height of AOD varies from 3 to 5 km for the observed region indicating the presence of a non-homogeneous mixture of air and airborne dust near the Lee side of Ascraeus Mons. We find the central part of the Lee-wave cloud is considered to be composed of water–ice particles. The formation temperature for the Lee-wave cloud is estimated to be 160–180 K during solar longitude 73° to 136° indicating a temporal distribution of the clouds near the Lee side of the mountain during the observed period.