Ableitung der thermischen und kompositionellen Struktur der Oberfläche und der unteren Atmosphäre der Venus auf der Basis der Ergebnisse des VIRTIS-Instruments der Venus Express-Mission

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The exploration of Venus, the closest planet to the Earth, both in terms of distance and in terms of its physical character, in the context of comparative planetology is an important key to understanding the crucial aspects of solar system formation, planetary evolution, geology, and climate change. The discovery of the near-infrared atmospheric windows on the nightside of Venus has opened a new opportunity for detailed studies of the planetary surface and lower atmosphere. The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) aboard the European Venus Express mission (VEX) is the first experiment that continuously records the nightside thermal emission from the planet over a long period of time. Thus, for the first time, a global and systematic investigation of Venus’ surface and lower atmosphere has now become possible.The proposed work focuses on separating atmospheric and surface radiance contributions in the measured VIRTIS signals to derive surface temperatures, soil emissivities and lower atmospheric gas abundances in large spatial scales. This objective will be achieved by applying new radiative transfer models, which have not been available up to now. They are going to eliminate the masking of the nightside windows by pressure-induced and far line-wing absorptions of carbon dioxide as well as multiple scattering by the dense cloud deck. This opens a fresh line of research in the field of radiative transfer theory. The extraction and evaluation of absolute calibrated VIRTIS data sets, which cover areas of various surface elevations, will provide high-quality retrievals of atmospheric and surface parameters of Venus. It will be accomplished by the development of special algorithms for a multi-spectral use of atmospheric windows.The research results are expected to open new insights into the physics and chemistry of the Venus’ lower atmosphere, its interaction with the planetary surface and the thermal and compositional characteristics of the soil. New information about cloud composition and circulation will be gathered as well.