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

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

On the simulation photonic band gap Filters

International audienc

Intense polar temperature inversion in the middle atmosphere on Mars

Current understanding of weather, climate and global atmospheric circulation on Mars is incomplete, in particular at altitudes above about 30 km. General circulation models for Mars are similar to those developed for weather and climate forecasting on Earth and require more martian observations to allow testing and model improvements. However, the available measurements of martian atmospheric temperatures, winds, water vapour and airborne dust are generally restricted to the region close to the surface and lack the vertical resolution and global coverage that is necessary to shed light on the dynamics of Mars' middle atmosphere at altitudes between 30 and 80 km. Here we report high-resolution observations from the Mars Climate Sounder instrument on the Mars Reconnaissance Orbiter. These observations show an intense warming of the middle atmosphere over the south polar region in winter that is at least 10–20 K warmer than predicted by current model simulations. To explain this finding, we suggest that the atmospheric downwelling circulation over the pole, which is part of the equator-to-pole Hadley circulation, may be as much as 50% more vigorous than expected, with consequences for the cycles of water, dust and CO2 that regulate the present-day climate on Mars

Dust and cloud detection at the Mars limb with UV scattered sunlight with SPICAM

The UV detector of Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) on board Mars Express has measured several profiles of light scattered at the limb of Mars. In this paper we present 33 profiles taken between January 2004 and August 2005. Scattering of UV light at the limb of Mars is due to the molecules of the atmosphere, dust particles, and sometimes cloud particles which appear as detached layers above the extended dust layer. We have used a radiative transfer model to retrieve the haze and cloud properties. Rough estimate of the particle size shows that both cloud particles and dust particles above 20 km are in the range 10 to 100 nm. Such particles are much smaller than micron-sized dust particles previously observed in the lower atmosphere, generally from landers. Gravitational segregation is thought to be responsible for these differences in particle size between low and high atmosphere