HR: 0800h
AN: A31A-0051    [Abstracts]
TI: Footprint for the Dynamical Solar Impact from the Stratosphere: A Coupled Ocean-Atmosphere Model Study
AU: Yukimoto, S
EM: yukimoto@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: Recent studies show a possible solar influence on climate through changes in stratospheric circulation. This mechanism was mainly discussed on the 11-year solar cycle using atmospheric general circulation models. To understand a longer variation, the use of a coupled ocean-atmosphere model is necessary. Unfortunately, however, usually the coupled ocean-atmosphere models neither extend sufficiently high nor treat active ozone to realistically simulate the solar influence in the stratosphere. The solar impact in the stratosphere can be characterized as change in the wave mean-flow interaction in the winter stratosphere. So that for a mimic of solar forcing, a zonal symmetric momentum forcing was imposed in the upper stratosphere to study the dynamical response in the troposphere and to compare with the observed solar cycle responses. The model was integrated one hundred years for each east- and westward forcing experiment. The result shows that the AO or AAO type circulation anomalies appear in the high latitude of the troposphere during the winter and change mid-latitudes ocean temperature. The anomalous sea surface temperatures (SSTs) persist until summer by interacting atmosphere in baroclinic zone and modulate midlatitudes rainfall. Circulation anomalies also produce change in the mean SST in the equatorial central Pacific region similar to the La Nina condition. In the equatorial region, changes in Brewer Dobson circulation in the stratosphere modulate Hadley circulation which affects the summer monsoon activities. Stronger polar vortex condition, comparable to high solar activity, suppresses rainfall in the equatorial Africa but reinforce Indian monsoon.
DE: 3362 Stratosphere/troposphere interactions
DE: 4219 Continental shelf processes
DE: 1600 GLOBAL CHANGE (New category)
DE: 1620 Climate dynamics (3309)
DE: 1650 Solar variability
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting