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Modelling the atmospheric response to doubled CO 2 and depleted stratospheric ozone using a stratosphere‐resolving coupled GCM
Author(s) -
Gillett N. P.,
Allen M. R.,
Williams K. D.
Publication year - 2003
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1256/qj.02.102
Subject(s) - stratosphere , arctic oscillation , atmospheric sciences , climatology , northern hemisphere , troposphere , ozone depletion , polar vortex , environmental science , sudden stratospheric warming , ozone , arctic , atmosphere (unit) , geology , physics , meteorology , oceanography
We investigate the atmospheric response to doubled CO 2 and stratospheric ozone depletion in three versions of a general‐circulation model with differing vertical resolution and upper‐boundary heights. We find that an approximate doubling of the vertical resolution below 10 hPa reduces the temperature response to a doubling of CO 2 from 3.4 K to 2.5 K. Much of this difference is associated with changes in the cloud response. All model versions show an increase in the Arctic Oscillation index in response to a doubling of CO 2 , but the increase is no larger in the model with an upper boundary at 0.01 hPa than in the standard model with a top level at 5 hPa. All models also show general stratospheric cooling in response to doubling CO 2 . However, unlike some other authors, we find no cooling in the Arctic winter vortex below around 10 hPa in the stratosphere‐resolving model, and a weakening of the zonal winds throughout this region. This effect is due to enhanced upward propagation of planetary waves from the troposphere, and is an effect found only in the northern hemisphere, probably because of its larger zonal asymmetries. All models show a small but significant surface cooling in response to a reconstruction of 1998 stratospheric ozone depletion, and an increase in the Antarctic Oscillation index in the southern summer. The cooling extends through most of the atmosphere, and reaches a maximum in the region of the Antarctic ozone hole in November and December. © Royal Meteorological Society, 2003. K. D. Williams's contribution is Crown copyright.