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Improved automatic estimation of winds at the cloud top of Venus using superposition of cross-correlation surfaces

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Title: Improved automatic estimation of winds at the cloud top of Venus using superposition of cross-correlation surfaces
Authors: Ikegawa, Shinichi Browse this author
Horinouchi, Takeshi Browse this author →KAKEN DB
Keywords: Venus
Venus, atmosphere
Atmospheres, dynamics
Issue Date: Jun-2016
Publisher: Elsevier
Journal Title: Icarus
Volume: 271
Start Page: 98
End Page: 119
Publisher DOI: 10.1016/j.icarus.2016.01.018
Abstract: Accurate wind observation is a key to study atmospheric dynamics. A new automated cloud tracking method for the dayside of Venus is proposed and evaluated by using the ultraviolet images obtained by the Venus Monitoring Camera onboard the Venus Express orbiter. It uses multiple images obtained successively over a few hours. Cross-correlations are computed from the pair combinations of the images and are superposed to identify cloud advection. It is shown that the superposition improves the accuracy of velocity estimation and significantly reduces false pattern matches that cause large errors. Two methods to evaluate the accuracy of each of the obtained cloud motion vectors are proposed. One relies on the confidence bounds of cross-correlation with consideration of anisotropic cloud morphology. The other relies on the comparison of two independent estimations obtained by separating the successive images into two groups. The two evaluations can be combined to screen the results. It is shown that the accuracy of the screened vectors are very high to the equatorward of 30 degree, while it is relatively low at higher latitudes. Analysis of them supports the previously reported existence of day-to-day large-scale variability at the cloud deck of Venus, and it further suggests smaller-scale features. The product of this study is expected to advance the dynamics of venusian atmosphere. (C) 2016 Elsevier Inc. All rights reserved.
Rights: © 2016, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Type: article (author version)
Appears in Collections:環境科学院・地球環境科学研究院 (Graduate School of Environmental Science / Faculty of Environmental Earth Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

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