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Stratospheric dryness: model simulations and satellite observations

Lelieveld, J. and Brühl, C. and Jöckel, P. and Steil, B. and Crutzen, P.J. and Fischer, H. and Giorgetta, M.A. and Hoor, P. and Lawrence, M.G. and Sausen, R. and Tost, R. (2007) Stratospheric dryness: model simulations and satellite observations. Atmospheric Chemistry and Physics, 7, pp. 1313-1332.

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Official URL: http://direct.sref.org/1680-7324/acp/2007-7-1313

Abstract

The mechanisms responsible for the extreme dryness of the stratosphere have been debated for decades. A key difficulty has been the lack of comprehensive models which are able to reproduce the observations. Here we examine results from the coupled lower-middle atmosphere chemistry general circulation model ECHAM5/MESSy1 together with satellite observations. Our model results match observed temperatures in the tropical lower stratosphere and realistically represent the seasonal and inter-annual variability of water vapor. The model reproduces the very low water vapor mixing ratios (below 2 ppmv) periodically observed at the tropical tropopause near 100 hPa, as well as the characteristic tape recorder signal up to about 10 hPa, providing evidence that the dehydration mechanism is well-captured. Our results confirm that the entry of tropospheric air into the tropical stratosphere is forced by large-scale wave dynamics, whereas radiative cooling regionally decelerates upwelling and can even cause downwelling. Thin cirrus forms in the cold air above cumulonimbus clouds, and the associated sedimentation of ice particles between 100 and 200 hPa reduces water mass fluxes by nearly two orders of magnitude compared to air mass fluxes. Transport into the stratosphere is supported by regional net radiative heating, to a large extent in the outer tropics. During summer very deep monsoon convection over Southeast Asia, centered over Tibet, moistens the stratosphere.

Document Type:Article
Title:Stratospheric dryness: model simulations and satellite observations
Authors:
AuthorsInstitution or Email of Authors
Lelieveld, J.MPI für Chemie, Mainz
Brühl, C.MPI für Chemie, Mainz
Jöckel, P.MPI für Chemie, Mainz
Steil, B.MPI für Chemie, Mainz
Crutzen, P.J.SCRIPPS Institution of Oceanography, La Jolla, CA, USA
Fischer, H.MPI für Chemie, Mainz
Giorgetta, M.A.MPI für Meteorologie, Hamburg
Hoor, P.MPI für Chemie, Mainz
Lawrence, M.G.MPI für Chemie, Mainz
Sausen, R.UNSPECIFIED
Tost, R.MPI für Chemie, Mainz
Date:2007
Journal or Publication Title:Atmospheric Chemistry and Physics
Volume:7
Page Range:pp. 1313-1332
Status:Published
Keywords:CTM, ECHAM5, stratosphere, satellite, MESSy1, ATTICA, Lagragian transport
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EO - Erdbeobachtung
DLR - Research area:Space
DLR - Program:W EO - Erdbeobachtung
DLR - Research theme (Project):W - Vorhaben Atmosphären- und Klimaforschung (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Atmospheric Dynamics
Deposited By: Prof.Dr. Robert Sausen
Deposited On:11 Sep 2007
Last Modified:12 Dec 2013 20:23

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