The Tropical Tropopause Layer 1960–2100 A. Gettelman1, T. Birner2, V. Eyring3, H. Akiyoshi4, S. Bekki6, C. Brühl8, M. Dameris3, D. E. Kinnison1, F. Lefevre6, F. Lott7, E. Mancini11, G. Pitari11, D. A. Plummer5, E. Rozanov10, K. Shibata9, A. Stenke3, H. Struthers12, and W. Tian13 1National Center for Atmospheric Research, Boulder, CO, USA 2University of Toronto, Toronto, ON, Canada 3Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, Germany 4National Institute for Environmental Studies, Tsukuba, Japan 5Canadian Centre for Climate Modeling and Analysis, Victoria, BC, Canada 6Université Pierre and Marie Curie, Service d'Aeronomie, Paris, France 7L'Institut Pierre-Simon Laplace, Ecole Normale Superieur, Paris, France 8Max Planck Institut für Chemie, Mainz, Germany 9Meteorological Research Institute, Tsukuba, Japan 10Physikalisch-Meteorologisches Observatorium Davos, Davos, Switzerland 11Universita degli Studi de L'Aquila, L'Aquila, Italy 12National Institute for Water and Atmosphere, New Zealand 13University of Leeds, Leeds, UK
Abstract. The representation of the Tropical Tropopause Layer (TTL) in
13 different Chemistry Climate Models (CCMs) designed to represent
is analyzed. Simulations for 1960–2005 and 1980–2100 are analyzed.
Simulations for 1960–2005 are compared to reanalysis model output.
CCMs are able to reproduce the basic structure of
the TTL. There is a large (10 K) spread in annual mean tropical cold point
CCMs are able to reproduce historical trends in
tropopause pressure obtained from reanalysis products.
Simulated historical trends in cold point tropopause
temperatures are not consistent across models or reanalyses.
The pressure of both the tropical tropopause and the level of main
convective outflow appear to have decreased (increased altitude)
in historical runs as well as in reanalyses.
Decreasing pressure trends in the tropical tropopause and level of
outflow are also seen in the future. Models consistently predict
decreasing tropopause and convective outflow pressure, by
several hPa/decade. Tropical cold point temperatures are projected to increase
by 0.09 K/decade. Tropopause anomalies
are highly correlated with tropical surface temperature anomalies and
with tropopause level ozone anomalies, less so with stratospheric
temperature anomalies. Simulated stratospheric water vapor at 90 hPa
increases by up to 0.5–1 ppmv by 2100.
The result is consistent with the simulated increase in
temperature, highlighting the correlation of tropopause
temperatures with stratospheric water vapor.
Citation: Gettelman, A., Birner, T., Eyring, V., Akiyoshi, H., Bekki, S., Brühl, C., Dameris, M., Kinnison, D. E., Lefevre, F., Lott, F., Mancini, E., Pitari, G., Plummer, D. A., Rozanov, E., Shibata, K., Stenke, A., Struthers, H., and Tian, W.: The Tropical Tropopause Layer 1960–2100, Atmos. Chem. Phys., 9, 1621-1637, doi:10.5194/acp-9-1621-2009, 2009.