Universität zu Köln

Tellmann, S., Haeusler, B., Hinson, D. P., Tyler, G. L., Andert, T. P., Bird, M. K., Imamura, T., Paetzold, M. and Remus, S. (2012). Small-scale temperature fluctuations seen by the VeRa Radio Science Experiment on Venus Express. Icarus, 221 (2). S. 471 - 481. SAN DIEGO: ACADEMIC PRESS INC ELSEVIER SCIENCE. ISSN 1090-2643

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Abstract

The Venus Express Radio Science Experiment VeRa retrieves atmospheric profiles in the mesosphere and troposphere of Venus in the approximate altitude range of 40-90 km. A data set of more than 500 profiles was retrieved between the orbit insertion of Venus Express in 2006 and the end of occultation season No. 11 in July 2011. The atmospheric profiles cover a wide range of latitudes and local times, enabling us to study the dependence of vertical small-scale temperature perturbations on local time and latitude. Temperature fluctuations with vertical wavelengths of 4 km or less are extracted from the measured temperature profiles in order to study small-scale gravity waves. Significant wave amplitudes are found in the stable atmosphere above the tropopause at roughly 60 km as compared with the only shallow temperature perturbations in the nearly adiabatic region of the adjacent middle cloud layer, below. Gravity wave activity shows a strong latitudinal dependence with the smallest wave amplitudes located in the low-latitude range, and an increase of wave activity with increasing latitude in both hemispheres; the greatest wave activity is found in the high-northern latitude range in the vicinity of Ishtar Terra, the highest topographical feature on Venus. We find evidence for a local time dependence of gravity wave activity in the low latitude range within +/- 30 degrees of the equator. Gravity wave amplitudes are at their maximum beginning at noon and continuing into the early afternoon, indicating that convection in the lower atmosphere is a possible wave source. The comparison of the measured vertical wave structures with standard linear-wave theory allows us to derive rough estimates of the wave intrinsic frequency and horizontal wavelengths, assuming that the observed wave structures are the result of pure internal gravity waves. Horizontal wavelengths of the waves at 65 km altitude are on the order of approximate to 300-450 km with horizontal phase speeds of roughly 5-10 m/s. 2012 (C) Elsevier Inc. All rights reserved.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Tellmann, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Haeusler, B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hinson, D. P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Tyler, G. L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Andert, T. P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bird, M. K. UNSPECIFIED UNSPECIFIED UNSPECIFIED Imamura, T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Paetzold, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Remus, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-479304
DOI:	10.1016/j.icarus.2012.08.023
Journal or Publication Title:	Icarus
Volume:	221
Number:	2
Page Range:	S. 471 - 481
Date:	2012
Publisher:	ACADEMIC PRESS INC ELSEVIER SCIENCE
Place of Publication:	SAN DIEGO
ISSN:	1090-2643
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language INTERNAL GRAVITY-WAVES; LOWER ATMOSPHERE; MIDDLE ATMOSPHERE; OCCULTATION MEASUREMENTS; GENERAL-CIRCULATION; THERMAL STRUCTURE; MORPHOLOGY; DYNAMICS; MARS; TURBULENCE Multiple languages Astronomy & Astrophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/47930