12th Conference on Middle Atmosphere

Wednesday, 6 November 2002
Physical Mechanism of the Arctic and Antarctic Oscillations
Evgeny A. Jadin, Central Aerological Observatory, Dolgoprudny, Moscow, Russia; and V. E. Kadygrov
One of the basic questions concerning to the Arctic (AO) and Antarctic (AAO)Oscillations is that of the physical nature and mechanism of their generation. It has been shown in the numerical experiments with mechanistic planetary wave model that west-eastward shifts of the SST anomalies can result in large changes of the eddy ozone transport and stratospheric dynamics (wave hypothesis, Jadin [1990]). Mechanism of the wave hypothesis can be associated with an interference of the orographic (Rockies in the NH and Andes in the SH) and thermal sources of the stationary planetary waves, latter of which depends on the SST anomalies. This simple mechanism is similar to that of the interference of two sources in the optics. Analysis of the interannual and intra-decadal variations of the total ozone (TOMS), stratospheric circulation (NMC-NCEP), SST anomalies (COADS)confirmed the reality of this mechanism (see, for example, Jadin [2002]). Using the EOF and SVD analyses, it was shown that only subtle features of the SST anomalies are strongly associated with the stratospheric circulation and total ozone changes both in the NH and SH. The cause of the AO and AAO can be associated with the influence of long-term SST anomalies (dipole across Rockies in the North Pacific and North Atlantic in the NH, dipole across Andes and Africa in the South Oceans in the SH) on the planetary changes according to the wave hypothesis. Many aspects of the AO and AAO features can be explained by this mechanism: their similarity, the leading role of the SSTs North Atlantic and NAO in the AO, relations of the AO and AAO with ozone layer changes, including the appearance of the ozone hole in the Antarctic, etc. It is shown that the AO is not the annular mode in the stratosphere. Moreover, there is the dipole-like interannual changes of the stratospheric circulation between the west and east Arctic, which are associated with the longitudinal asymmetry of the stratospheric warmings. A new method for predictions of the extreme weather events (for example, cold winters in Russia) using the total ozone variations is proposed.

Jadin, 1990, Izvestia of Academy of Science of USSR, Physics of Ocean and Atmosphere, 26, 1156-1160.

Jadin, 2002, International Journal of Geomagnetism and Aeronomy, submitted, (http://eos.wdcb.ru/gpo/2002/gai02393/gai02393.pdf) or .ps

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