|
|
 |
|
|
Ann. Geophys., 20, 835-846, 2002
www.ann-geophys.net/20/835/2002/
© European Geosciences Union 2002
The Lagrangian structure of ozone mini-holes and potential vorticity anomalies in the Northern Hemisphere
P. M. James1,2 and D. Peters1
1Leibniz-Institut für Atmosphärenphysik, Kühlungsborn, Germany
2Lehrstuhl für Bioklimatologie und Immissionsforschung, Technische Universität München, Am Hochanger 13, D-85354 Freising-Weihenstephan, Germany
Correspondence to: P. M. James
(paul@meteo.physik.uni-muenchen.de)
Abstract. An ozone mini-hole is a
synoptic-scale area of strongly reduced column total ozone, which undergoes a
growth-decay cycle in association with baroclinic weather systems. The tracks
of mini-hole events recorded during the TOMS observation period over the
Northern Hemisphere provide a database for building anomaly fields of various
meteorological parameters, following each mini-hole center in a Lagrangian
sense. The resulting fields provide, for the first time, a complete mean
Lagrangian picture of the three-dimensional structure of typical ozone
mini-holes in the Northern Hemisphere. Mini-holes are shown to be associated
with anomalous warm anticyclonic flow in the upper troposphere and cold
cyclonic anomalies in the middle stratosphere. Ascending air columns occur
upstream and descent downstream of the mini-hole centers. Band-pass filtering
is used to reveal the transient synoptic nature of mini-holes embedded within
larger scale circulation anomalies. Significant correlations between ozone and
Ertel’s potential vorticity on isentropes (IPV) both near the tropopause and
in the middle stratosphere are shown and then utilized by reconstructing the
Lagrangian analysis to follow local IPV anomalies instead of ozone minima. By
using IPV as a proxy for ozone, the geopotential anomaly dipolar structure in
the vertical characteristic of mini-holes is shown to result from a
superposition of two largely independent dynamical components, stratospheric
and tropospheric, typically operating on different time scales. Hence, ozone
mini-holes may be viewed primarily as phenomena of coincidence.
Key words. Meteorology and
atmospheric dynamics (middle atmosphere dynamics; synoptic-scale meteorology)
Full Article in PDF (2081 KB) |
|
|
