HR: 0800h
AN: A31A-0047    [Abstracts]
TI: Solar Variability and Stratosphere-Troposphere Coupling
AU: * Baldwin, M P
EM: mark@nwra.com
AF: Northwest Research Associates, 14508 NE 20th Street, Bellevue, WA 98007 United States
AB: Observations suggest that the atmosphere is approximately twice as sensitive to solar variability as would be expected from radiative calculations. This suggests that processes amplify an atmospheric solar signal, which is seen in the stratosphere, to affect surface climate. However, the mechanism is not well understood. During the winter season, zonal wind anomalies in the stratosphere tend to progress northward and downward through the stratosphere on a timescale of a few weeks. The process of wave, mean-flow interaction in effect amplifies the anomalies as the progress downward from ~1 hPa to the troposphere. This creates a plausible pathway for solar effects on climate during winter. This process cannot be the complete explanation because solar-climate effects are seen year-round. A plausible year-round mechanism involves the modulation of the wave guide for planetary scale waves, even in summer. I will provide an overview of the winter mechanism for solar effects on climate, with examples from observations and simulations. I will also discuss the effects of lower stratospheric circulation anomalies on planetary-scale waves in the summer, and argue that this mechanism could communicate stratospheric variability downward even in summer.
DE: 3362 Stratosphere/troposphere interactions
DE: 1650 Solar variability
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting