Open AccessThermal and dynamical changes of the stratosphere since 1979 and their link to ozone and CO 2 changes
Author(s) -
Langematz Ulrike,
Kunze Markus,
Krüger Kirstin,
Labitzke Karin,
Roff Gregory L.
Publication year - 2003
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2002jd002069
Subject(s) - stratosphere , atmospheric sciences , polar vortex , middle latitudes , sudden stratospheric warming , climatology , environmental science , northern hemisphere , latitude , atmospheric model , atmosphere (unit) , ozone depletion , ozone layer , ozone , geology , physics , meteorology , geodesy
This study examines which part of the observed stratospheric thermal and dynamical changes since 1979 can be attributed to the observed stratospheric ozone (O 3 ) losses and CO 2 increases. Further, the processes are studied that lead to temperature and circulation changes when stratospheric O 3 and CO 2 are modified. We compared results from simulations of the Freie Universität Berlin Climate Middle Atmosphere Model (FUB CMAM) using observed O 3 and CO 2 changes with observed trends of stratospheric temperature and circulation for the period 1979–2000 from FUB data and National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalyses. The observed O 3 decrease leads in the FUB CMAM to a global mean stratospheric cooling, which is enhanced in the upper stratosphere by the imposed CO 2 increase. While the model is able to reproduce the observed stratospheric cooling in the upper stratosphere, it underestimates the observed trends in the lower stratosphere, particularly in middle latitudes and during Northern Hemisphere (NH) spring. The observed intensification and increased lifetimes of the polar vortices in spring are captured by the model but with smaller magnitude than observed. It is suggested that the observed upper stratospheric temperature trends during the past two decades in low to middle latitudes are caused by radiative effects due to the O 3 and CO 2 changes, while the cooling of the polar stratosphere in winter is enhanced by changes in dynamical heating. However, in northern midlatitudes and in Arctic spring, other effects than O 3 and CO 2 changes must be considered to fully explain the observed changes in the lower stratosphere.