Universität zu Köln

Imamura, Takeshi, Miyamoto, Mayu, Ando, Hiroki, Haeusler, Bernd, Paetzold, Martin, Tellmann, Silvia, Tsuda, Toshitaka, Aoyama, Yuichi, Murata, Yasuhiro, Takeuchi, Hiroshi ORCID: 0000-0001-5863-4653, Yamazaki, Atsushi, Toda, Tomoaki and Tomiki, Atsushi (2018). Fine Vertical Structures at the Cloud Heights of Venus Revealed by Radio Holographic Analysis of Venus Express and Akatsuki Radio Occultation Data. J. Geophys. Res.-Planets, 123 (8). S. 2151 - 2162. WASHINGTON: AMER GEOPHYSICAL UNION. ISSN 2169-9100

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Abstract

Radio occultation (RO) is one of the most efficient techniques for studying fine vertical structures in planetary atmospheres. However, the geometrical optics (GO) method, which has been used for the analysis of RO data, suffers blurring by the finite width (Fresnel scale) of the radio ray and cannot decipher multipath propagation, which also prevents retrieval of fine structures. Here we apply Full Spectrum Inversion (FSI), which is one of the radio holographic methods, to RO data taken in Venus Express and Akatsuki missions to retrieve fine structures in Venus' cloud-level atmosphere. The temperature profiles obtained by FSI achieve vertical resolutions of similar to 150m, which is much higher than the typical resolution of 400-700m in GO, and resolve structures in multipath regions. Thin, near-neutral layers are found to be ubiquitous at cloud heights; we suggest here that those layers are caused by the mixing associated with the breaking of short-wavelength gravity waves. The wavenumber spectra of small-scale structures are consistent with the semiempirical spectrum of saturated gravity waves and show larger amplitudes at higher latitudes. Temperature profiles in the high latitudes frequently show a sharp temperature minimum near the cloud top, below which the vertical temperature gradient is near adiabat, implying that the sharp temperature minimum is created by adiabatic cooling associated with convective plumes that impinge on the overlying stable layer.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Imamura, Takeshi UNSPECIFIED UNSPECIFIED UNSPECIFIED Miyamoto, Mayu UNSPECIFIED UNSPECIFIED UNSPECIFIED Ando, Hiroki UNSPECIFIED UNSPECIFIED UNSPECIFIED Haeusler, Bernd UNSPECIFIED UNSPECIFIED UNSPECIFIED Paetzold, Martin UNSPECIFIED UNSPECIFIED UNSPECIFIED Tellmann, Silvia UNSPECIFIED UNSPECIFIED UNSPECIFIED Tsuda, Toshitaka UNSPECIFIED UNSPECIFIED UNSPECIFIED Aoyama, Yuichi 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
URN:	urn:nbn:de:hbz:38-177608
DOI:	10.1029/2018JE005627
Journal or Publication Title:	J. Geophys. Res.-Planets
Volume:	123
Number:	8
Page Range:	S. 2151 - 2162
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 ATMOSPHERIC GRAVITY-WAVES; JUPITERS IONOSPHERE; VERA ONBOARD; SPECTRUM; FLUCTUATIONS; TEMPERATURE; CONVECTION; TURBULENCE Multiple languages Geochemistry & Geophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/17760