HR: 0830h
AN: OS21B-1125    [PDF]
TI: Role of the Polar-night Jet Oscillation on the formation of the Arctic Oscillation in the northern hemisphere winter
AU: * Kuroda, Y
EM: kuroda@mri-jma.go.jp
AF: Meteorological Research Institute, 1-1 Nagamine, Tsukuba, 305-0052 Japan
AU: Kodera, K
EM: kodera@mri-jma.go.jp
AF: Meteorological Research Institute, 1-1 Nagamine, Tsukuba, 305-0052 Japan
AB: The coupling between the Polar-night Jet Oscillation (PJO) and the Arctic Oscillation (AO) was examined using observational data. It was found that positive and negative AO indices tend to appear with a specific phase of the time evolution of the PJO, and the lifetime of the AO tends to be longer when the AO is coupled with the PJO. To examine how the AO signal appears with the time evolution of the PJO, we performed lagged regression analysis for the Eulerian mean wave forcing. It is found that the AO signal is created through the meridional circulation driven by a combination of mechanical and thermal eddy forcing at the AO stage. Approximately 40% of the polar sea-level pressure (SLP) change comes from thermal forcing, and half of it comes from the stratosphere, whereas 60% of the polar SLP change comes from the mechanical forcing that originates in the troposphere. In both forcings, the contribution from the wave of the zonal wavenumber 1 component is very important, especially for the SLP in the polar cap region. Waves of zonal wavenumber 2 and 3 components also have significant contributions for the tropospheric forcing. This is in contrast with the typical AO, which is driven almost solely by the mechanical forcing of wavenumber 2 and higher waves.
DE: 1610 Atmosphere (0315, 0325)
DE: 1620 Climate dynamics (3309)
DE: 3309 Climatology (1620)
DE: 3334 Middle atmosphere dynamics (0341, 0342)
DE: 3362 Stratosphere/troposphere interactions
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting