Anomalous quasi-stationary planetary waves over the Antarctic region in 1988 and 2002

A V Grytsai,G P Milinevsky,O M Evtushevsky

doi:10.5194/angeo-26-1101-2008

Abstract

Abstract. Anomalies in the Antarctic total ozone and amplitudes of the quasi-stationary planetary waves in the lower stratosphere temperature during the winter and spring of 1988 and 2002 have been compared. Westward displacement of the quasi-stationary wave (QSW) extremes by 50°–70° relative to the preceding years of the strong stratospheric polar vortex in 1987 and 2001, respectively, was observed. A dependence of the quasi-stationary wave ridge and trough positions on the strength of the westerly zonal wind in the lower stratosphere is shown. Comparison of the QSW amplitude in the lower stratosphere temperature in July and August shows that the amplitude distribution with latitude in August could be considered as a possible indication of the future anomalous warming in Antarctic spring. In August 2002, the QSW amplitude of 10 K at the edge region of the polar vortex (60° S–65° S) preceded the major warming in September, whereas in August 1988, the highest 7 K amplitude at 55° S preceded the large warming in the next months. These results suggest that the peak value of the lower stratosphere temperature QSW amplitude and the peak latitudinal position in late winter can influence the southern polar vortex strength in spring.

Highlights

In late September 2002 the first major stratospheric sudden warming was observed in the Antarctic region (Varotsos, 2002)
Up to the time of the major warming the losses inside the polar vortex were similar to previous years, the unusual dynamics led to an ∼250 DU increase in the total ozone near the pole in late September (Hoppel et al, 2003)
The unusual behavior of the ozone hole during spring 2002 was preconditioned by enhanced planetary wave activity throughout the winter months, which weakened the polar vortex and warmed the stratosphere (Allen et al, 2003; Newman and Nash, 2005; Scaife et al, 2005), possibly setting the stage for the major stratospheric warming in late September (Randall et al, 2005)

Summary

Introduction

In late September 2002 the first major stratospheric sudden warming was observed in the Antarctic region (Varotsos, 2002). The unusual behavior of the ozone hole during spring 2002 was preconditioned by enhanced planetary wave activity throughout the winter months, which weakened the polar vortex and warmed the stratosphere (Allen et al, 2003; Newman and Nash, 2005; Scaife et al, 2005), possibly setting the stage for the major stratospheric warming in late September (Randall et al, 2005). The seven latitude circles with the step of 5◦ within the interval 50◦ S–80◦ S have been selected This zone includes the edge and inner regions of the ozone hole and adjacent middle latitudes, where a high level of the planetary wave activity is usually observed during the southern winter-spring seasons. Zonal wind velocity for individual years was obtained from NCEP-NCAR reanalysis data

Seasonal change in the total ozone zonal mean

QSW zonal structure

QSW amplitude: meridional distribution

Findings

Discussion and conclusions