American Geophysical Union Become an AGU Member
Subscribe to AGU Journals		 AGU Home AGU Publications

Read Full Article (file size: 1686681 bytes)    Cited by

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.