Diurnal and seasonal variations of clouds in the Tharsis Montes region of Mars using the Emirates eXploration Imager (EXI) observations

Abstract

Observations of clouds on Mars have long been studied to understand activity and the Martian water cycle. The Martian volcanoes have been shown to have associated cloud formations such as the Aphelion Cloud Belt (ACB) (Wolff et al., 2022), Orographic Clouds (Benson et al., 2006), and Perihelion Cloud Trails (Clancy et al., 2021). Previous studies provide insights into how these clouds appear and contribute to the atmosphere. The objective of this study is to provide a catalog of the life cycle of clouds observed by Emirates eXploration Imager (EXI) spatially (longitude, latitude) and temporally (Solar Longitude (Ls), local time) using the following wavelength channels 635nm (red), 546nm (green), 437nm (blue) and 320nm (ultraviolet which can be used to retrieve the water ice optical depth). To undertake this study, we identified the volcanic region (Olympus Mons and Arsia Mons) as the study region due to cloud presence in the area throughout the Martian year.  EXI is a camera on board the Emirates Mars Mission (EMM) – Hope Probe. EXI acquires 12-megapixel images and has sufficient radiometric calibration for detailed scientific analysis (Jones et al., 2021). It was developed to better understand several critical constituents (e.g., dust, water ice clouds, etc) geographic and diurnal distribution in the lower atmosphere (Jones et al., 2021). We will present the results of our database for clouds for Mars year 36. Benson, J., James, P., Cantor, B., & Remigio, R. (2006). Interannual variability of water ice clouds over major martian volcanoes observed by MOC. Icarus, 184(2), 365–371. https://doi.org/10.1016/j.icarus.2006.03.014Clancy, R. T., Wolff, M. J., Heavens, N. G., James, P. B., Lee, S. W., Sandor, B. J., Cantor, B. A., Malin, M. C., Tyler, D., & Spiga, A. (2021). Mars perihelion cloud trails as revealed by MARCI: Mesoscale topographically focused updrafts and gravity wave forcing of high altitude clouds. Icarus, 362, 114411. https://doi.org/10.1016/j.icarus.2021.114411Jones, A. R., Wolff, M., Alshamsi, M., Osterloo, M., Bay, P., Brennan, N., Bryant, K., Castleman, Z., Curtin, A., DeVito, E., Drake, V. A., Ebuen, D., Espejo, J., Farren, J., Fenton, B., Fisher, C., Fisher, M., Fortier, K., Gerwig, S., . . . Yaptengco, J. L. (2021). The Emirates Exploration Imager (EXI) Instrument on the Emirates Mars Mission (EMM) Hope Mission. Space Science Reviews, 217(8). https://doi.org/10.1007/s11214-021-00852-5Wolff, M. J., Fernando, A., Smith, M. D., Forget, F., Millour, E., Atwood, S. A., Jones, A. R., Osterloo, M. M., Shuping, R., Al Shamsi, M., Jeppesen, C., & Fisher, C. (2022). Diurnal Variations in the Aphelion Cloud Belt as Observed by the Emirates Exploration Imager (EXI). Geophysical Research Letters, 49(18). https://doi.org/10.1029/2022gl100477