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L.V. Zasova, I.V. Khatountsev, N.I. Ignatiev, V.I. Moroz (Space Research Institute, Moscow), V. Formisano, G. Bellucci (Instituto di Fisica del Spazio Interplanetario, Rome)
Middle atmosphere of Venus (50 - 100km) is a very important part of the atmosphere. More than 70 % of the absorbed solar energy deposits there, providing an important source of energy to support thermal structure and dynamics.
We investigate the thermal tides distribution, which is possibly responsible for the support of the superrotation. Temperature and aerosol vertical profiles were retrieved in a self consistent way from Venera-15 IR spectrometry data with vertical resolution of several kilometers. The temperature variation at the isobaric levels vs. solar longitude was presented as a superposition of the cosines with periods of 1, 1/2, 1/3 and 1/4 Venusian days with amplitude and phase depending on latitude and altitude. In particular, in the upper clouds, where most of the solar energy absorbs, all four tidal components have significant amplitudes.
For the midlatitude jet the solar related periods were also found with maximal amplitude of 1/2 days period. It was also discovered that the jet changes its position in such a way that the laws of the conservation of momentum and flux are satisfied.
The Fourier spectrometer on Venera-15 may be considered as a precursor of the instrument of this kind for the future missions. A functioning of the Planetary Fourier Spectrometer, with spectral range 1-50 mkm, proposed for Venus Express mission together with UV (0.2-0.5 mm) mapping spectrometer, will be enable to get answers to the fundamental questions of the middle atmosphere: clouds formation, nature of the ``unknown" UV-absorber and the mechanism of support of the superrotation.
This work was supported by the grant RFFI - 02-01-17841.
The author(s) of this abstract have provided an email address for comments about the abstract: zasova@irn.iki.rssi.ru