|
|||||
|
|
Water clouds and dust aerosols observations with PFS MEX at Mars |
|
| Authors: | L Zasova V Formisano D Grassi M Giuranna M Blecka E Lellouch A Grigoriev I Khatuntsev A Maturilli D Patsaev M Rataj |
| Institution: | a Space Research Institute of Russian Academy of Sciences (IKI), Profsoyuznaya 84/32, 117997 Moscow, Russia b Istituto di Fisica dello Spazio Interplanetario INAF-IFSI, Via del Fosso del Cavaliere 100, 00133 Roma, Italy c Planetary Science Institute, 351310, University of Washington, Seattle, WA 98195-1310, USA d Space Research Center of Polish Academy of Sciences (SRC PAS) Bartycka 18A, 00716 Warsaw, Poland e Laboratoire d’Etudes Spatiales et d’Instrumentation en Astrophysique (LESIA), Observatoire de Paris 5 Place, Janssen, 92195 Meudon, France f Dipartimento di Fisica, Universita’ degli Studi di Lecce, Via Arnesano, 73100 Lecce, Italy g German Aerospace Center (DLR), Optical Information Systems, Rutherfordstr. 2, D-12489 Berlin, Germany h Istituto Astrofisica Spaziale( INAF- IAS), Via del Fosso del Cavaliere 100, 00133 Roma, Italy i Politecnico di Milano, Dipartimento di Meccanica, Sede di Lecco, C.so Matteotti 3, 23900 Lecco, Italy |
| Abstract: | Observations of water ice clouds and dust are among the main scientific goals of the Planetary Fourier Spectrometer (PFS), a payload instrument of the European Mars Express mission. We report some results, obtained in three orbits: 37, 41 and 68. The temperature profile, and dust and water ice cloud opacities are retrieved from the thermal infrared (long-wavelength channel of PFS) in a self-consistent way using the same spectrum. Orographic ice clouds are identified above Olympus (orbit 37) and Ascraeus Mons (orbit 68). Both volcanoes were observed near noon at Ls=337° and 342°, respectively. The effective radius of ice particles is preliminary estimated as 1-3 μm, changing along the flanks. The corresponding visual opacity changes in the interval 0.2-0.4 above Olympus and 0.1-0.6 above Ascraeus Mons. In the case of Ascraeus Mons, the ice clouds were observed mainly above the Southern flank of the volcano with maximum opacity near the summit. In the case of Olympus, the clouds were found above both sides of the top. A different type of ice cloud is observed at latitudes above 50°N (orbit 68) in the polar hood: the effective particle radius is estimated to be 4 μm. Below the 1 mb level an inversion in the temperature profiles is found with maximum temperature at around 0.6 mb. Along orbit 68 it appears above Alba Patera, then it increases to the north and decreases above the CO2 polar cap. Beginning from latitude 20°S above Tharsis (orbit 68), the ice clouds and dust contribute equally to the spectral shape. Further on, the ice clouds are found everywhere along orbit 68 up to the Northern polar cap, except the areas between the Northern flank of Ascraeus Mons (below 10 km) and the edge of Alba Patera. Orbit 41 is shifted from the orbit 68 by roughly 180° longitude and passes through Hellas. Ice clouds are not visible in this orbit at latitudes below 80°S. The dust opacity is anticorrelated with the surface altitude. From 70°S to 25°N latitude the vertical dust distribution follows an exponential law with a scale height of 11.5±0.5 km, which corresponds to the gaseous scale height near noon and indicates a well-mixed condition. The 9 μm dust opacity, reduced to zero surface altitude, is found to be 0.25±0.05, which corresponds to a visual opacity of 0.5-0.7 (depending on the particle size). |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ | |