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Abstract: We present interferometric mapping of the 225.9-GHz HDO and 203.4-GHz lines on Mars obtained with the IRAM Plateau de Bure facility (PdBI). The observations were performed during martian year 28 (MY28), at L s =320.3° for the HDO line, and at L s =324.3° for the line. The HDO line is detected at the eastern (morning) and western (evening) limbs of the northern hemisphere, corresponding to a water column density in the range 3–6pr.-. The line is not detected, which is compatible with the column densities derived from the HDO line. Quasi-simultaneous far infrared measurements obtained by the Planetary Fourier Spectrometer (PFS) onboard the Mars Express spacecraft confirm our PdBI results, yielding a 5±1pr.- meridionally constant water column abundance. Such a low water abundance during the southern mid-autumn of MY28 does not correspond to the standard martian climatology as observed during the previous years. It was however already retrieved from near-infrared observations performed by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) onboard the Mars Reconnaissance Orbiter spacecraft [Smith, M.D., Wolff, M.J., Clancy, R.T., Murchie, S.L. 2009. CRISM observations of water vapor and carbon monoxide. J. Geophys. Res. 114, doi: 10.1029/2008JE003288]. Our observations thus confirm that the planet-encircling dust storm that occurred during MY28 significantly affected the martian water cycle. Our observations also demonstrate the usefulness of interferometric submillimeter observations to survey the martian water cycle from ground-based facilities. [Copyright &y& Elsevier]

Abstract: We used Mars Express HRSC and OMEGA data to investigate mesospheric cloud features observed in the equatorial belt of Mars from December 2007 until early March 2008. This period corresponds to early northern spring of Martian year 29. The reflection peak at 4.26μm in OMEGA data identifies the clouds as CO2 ice clouds. HRSC observed the clouds together with OMEGA in five orbits. Cloud features are most prominent in the shortwave HRSC colour channels with wavelength centers at 440 and 530nm, but rarely visible in all other channels. In the period of Ls 0–36°, OMEGA and HRSC together detected mesospheric CO2 ice clouds in 40 orbits. They occur in a latitude belt of ±20° around the equator and at longitudes between 240°E (Tharsis) in the West and 30°E (Sinus Meridiani) in the East. The clouds were observed between 3 and 5 p.m. local time with mainly ripple-like to filamentary cloud forms. The viewing angles of the HRSC blue and green colour channels differ by 6.6° and the resulting parallax can be used to directly measure cloud heights by means of ray intersection. 17 HRSC data takes were found to exhibit clouds with heights from 66 to 83km with an accuracy of 1–2km. The pushbroom imaging technique also yields a time delay for the two observations in the order of 5–15s close to periapsis, and therefore time-related cloud movements can be detected. A method was developed to determine the across-track cloud displacements, which can directly be translated to wind velocities. Zonal cloud movements could be measured in 13 cases and were oriented from East to West. Related wind speeds range between 60 and 93m/s with an accuracy of 10–13m/s. [ABSTRACT FROM AUTHOR]

Abstract: The thermal emission spectrometer (TES) and the radio science (RS) experiment flying on board the Mars Global Surveyor (MGS) spacecraft have made observations of atmospheric temperatures below the saturation temperature of carbon dioxide (CO2). This supersaturated air provides a source of convective available potential energy (CAPE), which, when realized may result in vigorous convective mixing. To this point, most Mars atmospheric models have assumed vertical mixing only when the dry adiabatic lapse rate is exceeded. Mixing associated with the formation of CO2 clouds could have a profound effect on the vertical structure of the polar night, altering the distribution of temperature, aerosols, and gasses. Presented in this work are estimates of the total planetary inventory of CAPE and the potential convective energy flux (PCEF) derived from RS and TES temperature profiles. A new Mars Global Circulation Model (MGCM) CO2 cloud model is developed to better understand the distribution of observed CAPE and its potential effect on Martian polar dynamics and heat exchange, as well as effects on the climate as a whole. The new CO2 cloud model takes into account the necessary cloud microphysics that allow for supersaturation to occur and includes a parameterization for CO2 cloud convection. It is found that when CO2 cloud convective mixing is included, model results are in much better agreement with the observations of the total integrated CAPE as well as total column non-condensable gas concentrations presented by Sprague et al. [2005a, GRS measurements of Ar in Mars’ atmosphere, American Astronomical Society, DPS meeting #37, #24.08, and 2005b, Distribution and Abundance of Mars’ Atmospheric Argon, 36th Annual Lunar and Planetary Science Conference, #2085] When the radiative effects of water ice clouds are included the agreement is further improved. [Copyright &y& Elsevier]