Yvan Orsolini
NILU, PO Box 100, Instituttveien 18
N-2007 Kjeller, Norway
Francisco J. Doblas-Reyes
ECMWF, Shinfield Park
RG2 9AX, Reading, UK
The influence of low-frequency tropospheric dynamics upon column ozone interannual variability is estimated
in the spring season over the Euro-Atlantic sector. This dynamical variability of tropospheric origin is
examined in terms of leading climate patterns, derived from an empirical orthogonal function analysis of
the National Center for Environmental Prediction 500 mb geopotential height analyses. In order to
fingerprint the spatial and temporal ozone signatures of these patterns, the Total Ozone Mapping
Spectrometer satellite observations of column ozone during the last two decades are used. The geographical
ozone signatures of these climate patterns are extracted by linear regression and their time evolution
reconstructed. Geopotential anomalies associated with four leading patterns of variability (the North
Atlantic Oscillation (NAO), the Scandinavian pattern, the east Atlantic pattern and the European blocking
pattern) induce column ozone anomalies in the range of 5-15 Dobson Units per standard deviation of the
pattern index. The impact of these combined Euro-Atlantic climate patterns upon the regional ozone trends
and interannual variability is also estimated. In order to reconstruct the regional ozone trend and
variability, it proved important to incorporate several patterns, in addition to the dominant NAO. A
hitherto little-known lifting of the Arctic tropopause by the polar night jet is also shown to imprint upon
the ozone signatures of some patterns.