ATMO Seminar: Lon Hood

Thursday, Jan 17, 2013
3:30 pm
Location: Physics-Atmospheric Sciences
Room: 220

Lon Hood
Lunar and Planetary Laboratory

"The Surface Climate Response to 11-Yr Solar Forcing During Northern Winter"

The surface climate response in sea level pressure (SLP) and sea surface temperature (SST) to 11-Yr solar forcing during boreal winter (DJF) is investigated using a combination of observational analyses and comparisons with GCM simulations. First, a multiple linear regression (MLR) statistical model is applied to DJF averages of Hadley Centre SLP and SST data over the 1880-2009 period. In addition to a significant positive SLP response in the North Pacific found in previous studies, a positive SST response is obtained across the midlatitude North Pacific. Negative but insignificant SLP
responses are obtained in the Arctic. The derived SLP response at zero lag therefore resembles a positive phase of the Arctic Oscillation. For comparison, a similar MLR analysis is applied to model SLP and SST data
from a series of simulations using an atmosphere-ocean general circulation model (EGMAM). The simulations, which were performed by a German group (U. Cubasch and colleagues), differed only in the assumed solar cycle variation of stratospheric ozone. It is found that the simulation that assumed an ozone variation estimated from satellite data, tapering to zero at the poles, produces solar SLP and SST responses that are most consistent with
observational results, especially during a selected centennial period. This indicates that top-down forcing (via the stratosphere) is probably important for producing the observed surface response.