Structure and dynamics of the Martian lower and middle atmosphere as observed by the Mars Climate Sounder: Seasonal variations in zonal mean temperature, dust, and water ice aerosols

Abstract

[1] The first Martian year and a half of observations by the Mars Climate Sounder aboard the Mars Reconnaissance Orbiter has revealed new details of the thermal structure and distributions of dust and water ice in the atmosphere. The Martian atmosphere is shown in the observations by the Mars Climate Sounder to vary seasonally between two modes: a symmetrical equinoctial structure with middle atmosphere polar warming and a solstitial structure with an intense middle atmosphere polar warming overlying a deep winter polar vortex. The dust distribution, in particular, is more complex than appreciated before the advent of these high (∼5 km) vertical resolution observations, which extend from near the surface to above 80 km and yield 13 dayside and 13 nightside pole-to-pole cross sections each day. Among the new features noted is a persistent maximum in dust mass mixing ratio at 15-25 km above the surface (at least on the nightside) during northern spring and summer. The water ice distribution is very sensitive to the diurnal and seasonal variation of temperature and is a good tracer of the vertically propagating tide.

The impact of resolution on the dynamics of the martian global atmosphere: Varying resolution studies with the MarsWRF GCM

“…Over the northern pole, the polar temperature maximum is not only increased with increasing resolution, but the maximum is pushed significantly poleward, bringing peak temperatures from about 60°N for the LR case to directly over the pole for the HR case. The temperature pattern derived from the HR simulation is in much better agreement with MCS observations than the LR case, although peak temperatures at these levels remain over 10 K cooler than observed (McCleese et al, 2010).…”

Seasonal Variation in Martian Water Ice Cloud Particle Size

“…Despite our limited view of the polar (winter) atmosphere with CRISM, there is still a clear delineation between tropical clouds and polar clouds in most seasons, with a band of comparatively cloud‐free atmosphere between them. Figures and can be compared to a similar figure (Figure 17) shown by McCleese et al (; also Figure 11 of Guzewich et al, showing Thermal Emission Spectrometer limb‐viewing retrievals) which depicts the zonal average seasonal evolution of water ice clouds as viewed by the Mars Climate Sounder during Mars Year 29.…”

Threshold for sand mobility on Mars calibrated from seasonal variations of sand flux

“…The value of stress threshold inferred should be interpreted as the effective threshold, which is a unique threshold for initiation and sustenance of sand flux, for the instantaneous mean wind over scales from kilometers to a few degrees. This threshold is much lower than would be expected for turbulence-resolving models, wind tunnel experiments or lander-based local in situ observations 1,20 .…”

“…The apparent contradiction between rare implied saltation and reasonably common dust lifting 17,18 remains unresolved but has variously been ascribed to the uncertainties in interparticle cohesion, the role of electrostatics, the role of gustiness and the vertical wind shear and suction in dust devils 18,19 . Indeed, a major dust storm occurred during the time period between the acquisitions of the two images analyzed in the preceding Nili Patera High Resolution Imaging Science Experiment (HiRISE) study 10,20 , allowing the possibility that anomalously high storm winds accounted for a significant fraction of the measured sand flux.…”