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R. Moreno, S. Guilloteau (IRAM), E. Lellouch, T. Encrenaz (DESPA), F. Forget, E. Chassefiere, F. Jegou (LMD)
On May 15, 24, 25 and June 6 1999, we observed Mars (Ls ~ 140) with the IRAM Plateau de Bure Interferometer. Observations were obtained in the CO(2--1) and CO(1--0) rotational lines at 230.538 and 115.271 GHz respectively, with a spectral resolution up to 40 kHz. Mars' average angular size was equal to 15\arcsec ~and the spatial resolution in our CO(2--1) and CO(1--0) maps is about 2.5\arcsec ~and 5\arcsec, respectively. The high spectral resolution will allow us to determine and map Doppler shifts, especially in the (2--1) line, and therefore to directly investigate Mars' middle atmosphere (near 50 km) circulation. Such wind measurements have been obtained before on Mars from single--dish observations (Lellouch etal. Ap. J. 1991), but with a much lower spatial resolution (~ 10"). In addition, combining the CO(1--0) and CO(2--1) data will permit to derive the thermal structure field (e.g. Gurwell et al DPS 1993). These measurements will therefore provide constraints to Mars General Circulation Models in the poorly characterized middle--atmosphere. Preliminary wind results will be presented.