Universität zu Köln

Ando, Hiroki, Takagi, Masahiro ORCID: 0000-0002-4629-6279, Fukuhara, Tetsuya, Imamura, Takeshi, Sugimoto, Norihiko ORCID: 0000-0002-5135-7179, Sagawa, Hideo, Noguchi, Katsuyuki, Tellmann, Silvia, Paetzold, Martin, Haeusler, Bernd, Murata, Yasuhiro, Takeuchi, Hiroshi ORCID: 0000-0001-5863-4653, Yamazaki, Atsushi, Toda, Tomoaki, Tomiki, Atsushi, Choudhary, Rajkumar, Kumar, Kishore, Ramkumar, Geetha and Antonita, Maria (2018). Local Time Dependence of the Thermal Structure in the Venusian Equatorial Upper Atmosphere: Comparison of Akatsuki Radio Occultation Measurements and GCM Results. J. Geophys. Res.-Planets, 123 (9). S. 2270 - 2281. WASHINGTON: AMER GEOPHYSICAL UNION. ISSN 2169-9100

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Abstract

Plain Language Summary Temperature profiles of the Venus atmosphere obtained by the Akatsuki radio occultation measurements showed a prominent local time dependence above 65-km altitude at low latitudes equatorward of 35 degrees. A zonal wavenumber 2 component is predominant in the temperature field, and its phase (i.e., isothermal) surfaces descend with local time, suggesting its downward phase propagation. A general circulation model (GCM) for the Venus atmosphere, AFES-Venus, reproduced the local time-dependent thermal structure qualitatively consistent with the radio occultation measurements. Based on a comparison between the radio occultation measurements and the GCM results, the observed zonal wavenumber 2 structure is attributed to the semidiurnal tide. Applying the dispersion relationship for internal gravity waves to the observed wave structure, the zonally averaged zonal wind speed at 75- to 85-km altitudes was found to be significantly smaller than that at the cloud top. The decrease of the zonal wind speed with altitude is attributed to the momentum deposition by the upwardly propagating semidiurnal tide excited in the cloud layer. Akatsuki radio occultation measurements showed the local time dependence of the Venus atmosphere in the equatorial region. By comparing the measurements with a general circulation model, it is attributed to the upward propagating semidiurnal tide generated in the cloud layer. And then, we proposed a new method to estimate the zonal wind speed above the cloud layer, where any optical instruments cannot be measured, for the first time.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Ando, Hiroki UNSPECIFIED UNSPECIFIED UNSPECIFIED Takagi, Masahiro UNSPECIFIED orcid.org/0000-0002-4629-6279 UNSPECIFIED Fukuhara, Tetsuya UNSPECIFIED UNSPECIFIED UNSPECIFIED Imamura, Takeshi UNSPECIFIED UNSPECIFIED UNSPECIFIED Sugimoto, Norihiko UNSPECIFIED orcid.org/0000-0002-5135-7179 UNSPECIFIED Sagawa, Hideo UNSPECIFIED UNSPECIFIED UNSPECIFIED Noguchi, Katsuyuki UNSPECIFIED UNSPECIFIED UNSPECIFIED Tellmann, Silvia UNSPECIFIED UNSPECIFIED UNSPECIFIED Paetzold, Martin UNSPECIFIED UNSPECIFIED UNSPECIFIED Haeusler, Bernd UNSPECIFIED UNSPECIFIED UNSPECIFIED Murata, Yasuhiro UNSPECIFIED UNSPECIFIED UNSPECIFIED Takeuchi, Hiroshi UNSPECIFIED orcid.org/0000-0001-5863-4653 UNSPECIFIED Yamazaki, Atsushi UNSPECIFIED UNSPECIFIED UNSPECIFIED Toda, Tomoaki UNSPECIFIED UNSPECIFIED UNSPECIFIED Tomiki, Atsushi UNSPECIFIED UNSPECIFIED UNSPECIFIED Choudhary, Rajkumar UNSPECIFIED UNSPECIFIED UNSPECIFIED Kumar, Kishore UNSPECIFIED UNSPECIFIED UNSPECIFIED Ramkumar, Geetha UNSPECIFIED UNSPECIFIED UNSPECIFIED Antonita, Maria UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-174144
DOI:	10.1029/2018JE005640
Journal or Publication Title:	J. Geophys. Res.-Planets
Volume:	123
Number:	9
Page Range:	S. 2270 - 2281
Date:	2018
Publisher:	AMER GEOPHYSICAL UNION
Place of Publication:	WASHINGTON
ISSN:	2169-9100
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language GENERAL-CIRCULATION MODEL; MIDDLE ATMOSPHERE; DOPPLER VELOCIMETRY; CLOUD LEVEL; ZONAL WINDS; TIDES; TEMPERATURE; EXPRESS; MESOSPHERE; IMAGES Multiple languages Geochemistry & Geophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/17414