Investigating circular patterns in linear polarization observations of Venus

Gourav Mahapatra, Daphne Stam, Loic Rossi, M. Rodenhuis, Frans Snik, Christoph Keller

Research output: Contribution to journalMeeting AbstractScientific


ESA’s Venus Express mission has revealed our neighbouring planet to be a highly dynamic world, with everchanging cloud properties and structures, wind speeds that increase in time, and variable concentrations of atmospheric trace gases such as SO2. The SPICAV-IR instrument on Venus Express has provided us with close-up linear polarization data of sunlight reflected by Venus’s clouds and hazes, that allows a characterisation of their composition and particle sizes. Here, we analyse linear polarization data of the planet at a distance, obtained with the Extreme Polarimeter (ExPo) on the William Herschel Telescope on La Palma. These spatially resolved, high-accuracy polarization observations of Venus show faint circular patterns centered on the sub-solar point that are absent in the flux observations. So far, careful analyses have ruled out instrumental effects which leaves us to wonder about atmospheric properties as the cause of the circular patterns. Using numerical simulations of the flux and polarization of sunlight that is reflected by Venus, we have investigated the relation between the observed patterns and several atmospheric properties, such as variations in particle sizes, composition, density and altitude. We discuss the plausibility of the possible causes in the view of the current knowledge of the composition and dynamical processes in Venus’s atmosphere.
Original languageEnglish
Article numberEGU2017-15926
Number of pages1
JournalGeophysical Research Abstracts (online)
Publication statusPublished - 2017
EventEGU General Assembly 2017 - Vienna, Austria
Duration: 23 Apr 201728 Apr 2017


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