Aerosols and Tides in the Martian Tropics During Southern Hemisphere Spring Equinox From Mars Climate Sounder Data

Abstract

Thermal tides are global-scale oscillations of atmospheric temperature, pressure and wind, which are sub-harmonics of a solar day. They are driven by solar heating of the atmosphere and surface, and due to Mars' thinner atmosphere they play a much more significant role than on Earth. They can influence surface pressure and wind, affect the transport of aerosols, and propagate into the upper atmosphere (Forbes, 2002;

Observations of Ubiquitous Nighttime Temperature Inversions in Mars' Tropics After Large‐Scale Dust Storms

“…They were slower in appearing though, not forming until ∼30° of L S after the peak of the GDE. In fact, the strongest temperature inversions observed in the tropics occurred after the early Z storm in MY29 (Steele et al., 2021). The inversions began forming at L S ≈ 150°, and continued to strengthen until L S ≈ 200°, at which point they rapidly disappeared (Figure 2a).…”

“…The seasonal evolution of nighttime temperatures in the tropics during the dusty season is shown in Figure 2 for MY29–34. Here we show the temperatures averaged between 0°–10°N and 60°–90°W, as this is the region where temperature inversions are typically strongest and longest lasting (Steele et al., 2021). As can be seen by comparing Figure 2 with the tropical dust column opacity in Figure 1c, temperature inversions are linked to the occurrence of dust storms.…”

“…Analyses of temperature profiles obtained by the MCS instrument suggest that temperature inversions can also occur in the tropics during southern hemisphere spring equinox, where they are found at altitudes ∼15–25 km higher than those seen in the aphelion season RO observations (Steele et al., 2021). Here we analyze six Mars years of MCS data, and make use of the ability of the instrument to observe the atmosphere at a range of local times, spanning a period of ∼3 h in the tropics during both the daytime and nighttime.…”

Observations of ubiquitous nighttime temperature inversions in Mars' tropics after large-scale dust storms

“…This can strengthen the diurnal and semidiurnal tides (Hinson and Wilson, 2004;Kleinböhl et al, 2013), leading to increased dynamical warming at the tops of the inversions. Indeed, the lapse rates at the tops of the inversions follow the adiabatic lapse rate, suggesting warming via downwelling (Steele et al, 2021). Conversely, the lower opacity clouds which occur after the A dust storms tend to weaken as night progresses, and cannot cause as much strengthening of the diurnal and semidiurnal tides.…”

“…Analyses of temperature profiles by the Mars Climate Sounder (MCS) suggest that temperature inversions can also occur in the tropics during southern hemisphere spring equinox, where they are found at altitudes ∼15-25 km higher than those seen in the aphelion season RO observations (Steele et al, 2021).…”