Vertical temperature profile and mesospheric winds retrieval on Mars from CO millimeter observations

Abstract

Aims.We have recorded high spectral resolution spectra and derived precise atmospheric temperature profiles and wind velocities in the atmosphere of Mars. We have compared observations of the planetary mean thermal profile and mesospheric wind velocities on the disk, obtained with our millimetric observations of CO rotational lines, to predictions from the Laboratoire de Météorologie Dynamique (LMD) Mars General Circulation Model, as provided through the Mars Climate Database (MCD) numerical tool. Methods. We observed the atmosphere of Mars at CO(1−0) and CO(2−1) wavelengths with the IRAM 30-m antenna in June 2001 and November 2005. We retrieved the mean thermal profile of the planet from high and low spectral resolution data with an inversion method detailed here. High spectral resolution spectra were used to derive mesospheric wind velocities on the planetary disk. We also report here the use of 13 CO(2−1) line core shifts to measure wind velocities at 40 km.

Herschel/HIFI observations of Mars: First detection of O2at submillimetre wavelengths and upper limits on HCl and H2O2

“…Within each layer, the atmospheric temperature, pressure, and volume mixing ratio of carbon monoxide were assumed to be constant. The surface continuum emission was mod- eled as black-body emission using a temperature distribution falling off towards the edge of the apparent disk according to T (α) = T 0 × (1 − 0.2 × (1 − cos(α))), with α running from 0 -90 • across the apparent disk (see also Cavalié et al 2008). The diskaveraged emission was obtained by integrating over the apparent disk using sixty four concentric rings distributed unevenly over the disk and the limb region.…”

Wind measurements in Mars' middle atmosphere: IRAM Plateau de Bure interferometric CO observations

“…Fig. 14 presents a synthetic view of all these wind measurements, except for the 2001 and 2005 data, which are described by Cavalié et al (2008). Single-dish observations make use of a "point-by-point" mapping technique, in which spectra are accumulated on a sequence of individual beam positions.…”

“…References: a Lellouch et al 1991a, b Gillet and Lellouch 1994, c Jegou (2003, d Cavalié et al, 2008. …”

“…Heterodyne observations at millimeter or thermal infrared wavelengths are able to probe the martian middle atmosphere, providing temperature and wind measurements from spectrally resolved and Doppler-shifted molecular lines. Single-dish millimeter observations of CO constrain the temperature profile over 0-70 km (Clancy et al 1990), and when mapped over the martian disk, have provided the first wind measurements near 50 km altitude (see Lellouch et al 1991, Gillet and Lellouch 1994, Cavalié et al 2008from IRAM-30 m, and Clancy et al 2006. Such measurements, however, are limited by their poor, diffraction-limited, spatial resolution (typically 10 ), enabling only an essentially hemispheric resolution of the martian disk.…”

Zonal wave structures in the nighttime tropospheric density and temperature and in the D region ionosphere over Mars: Modeling and observations

“…Larger‐scale winds such as tidal oscillations are thought to be the dominant modes of the motion in the thermosphere of Mars [ Bougher et al , 2001]. Cavalie et al [2008] have reported that zonal winds are representative of the Martian seasons. One needs to know what mode of the zonal wind predominates in the troposphere of Mars.…”