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Effects of 3-dimensional cloud structures on satellite observations of the Ring effect, trace gas absorptions and radiance

Thomas Wagner(1), Steffen Beirle(1), Michael Grzegorski(1) and Tim Deutschmann(2)

(1) MPI for Chemistry, Becher-Weg 27, D-55128 Mainz, Germany
(2) University of Heidelberg, Institut for Environmental Physics, D-69120 Heidelberg, Germany

Abstract

In this study, we explore the effects of 3-dimensional cloud structures on satellite observations using our 3-dimensional Monte-Carlo radiative transfer model TRACY-2. Besides the observed radiance we also simulate the absorptions of the oxygen molecule (O2), the oxygen dimmer (O4) and the Ring effect (the filling-in of solar Fraunhofer lines due to rotational Raman scattering). These quantities can be observed from novel UV/vis satellite instruments like GOME1/2, SCIAMACHY or OMI. We study in detail the influence of the satellite viewing direction, the solar zenith angle and the size of the cloud patches. It is found that the observed quantities show different dependencies on these parameters. Thus they could be used to retrieve information on 3D cloud effects from satellite observations. In addition to these sensitivity studies also measurements of very large atmospheric photon paths are presented. It is shown that these observations can not be explained by simple 1D clouds but by more complex 3D cloud structures.