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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 109,
D11112,
doi:10.1029/2003JD004123,
2004
Role of the Polar-night Jet Oscillation on the formation of the Arctic Oscillation in the Northern Hemisphere winter
Yuhji Kuroda
Climate Research Department, Meteorological Research Institute, Tsukuba, Japan
Kunihiko Kodera
Climate Research Department, Meteorological Research Institute, Tsukuba, Japan
Abstract
The coupling between the Polar-night Jet Oscillation (PJO) and the Arctic Oscillation (AO) was examined using observational
data. Positive and negative AO indices tended to appear within a specific phase of the time evolution of the PJO, and the
lifetime of the AO tended to be longer when the AO was coupled with the PJO. We performed lagged regression analyses for Eulerian
mean wave forcing to examine how the AO signal appears with the time evolution of the PJO. We found that the AO signal at
the surface is created through meridional circulation driven by the combined effect of mechanical and thermal eddy forcing
at some stage of the PJO. The effect of these wave forcings on sea level pressure (SLP) changes was investigated using a zonal-mean
quasi-geostrophic model on the sphere. Approximately 40% of the polar SLP change was found to come from thermal forcing when
the AO-like signal appeared and two thirds from the stratosphere, whereas 60% of the polar SLP change was a result of mechanical
forcing that originated almost in the troposphere. The contribution from the wave of the zonal wave number 1 component was
very important in both forcings, particularly for SLP in the polar cap region. Waves of zonal wave number 2 and 3 components
also contributed significantly to tropospheric forcing.
Received 30
August
2003;
accepted 22
March
2004;
published 9
June
2004.
Keywords: polar-night jet oscillation;
arctic oscillation;
dynamical interaction.
Index Terms: 3362 Meteorology and Atmospheric Dynamics: Stratosphere/troposphere interactions; 3334 Meteorology and Atmospheric Dynamics: Middle atmosphere dynamics (0341, 0342); 1620 Global Change: Climate dynamics (3309); 3309 Meteorology and Atmospheric Dynamics: Climatology (1620).
Read Full Article (file size: 1686681 bytes) Cited by
Citation: Kuroda, Y., and K. Kodera
(2004),
Role of the Polar-night Jet Oscillation on the formation of the Arctic Oscillation in the Northern Hemisphere winter,
J. Geophys. Res.,
109,
D11112,
doi:10.1029/2003JD004123.
Copyright 2004 by the American Geophysical Union.
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