Global atmospheric sensitivity
"Global atmospheric sensitivity
to tropical SST anomalies throughout the Indo-Pacific Basin."
Joseph J. Barsugli. and Prashant D. Sardeshmukh
Journal of Climate, 1 December 2002
ABSTRACT
The sensitivity of the global atmospheric response to sea surface temperature
(SST) anomalies throughout the tropical Indian and Pacific Ocean basins is
investigated using the NCEP MRF9 general circulation model (GCM). Model
responses in January are first determined for a uniform array of 42 localized
SST anomaly patches over the domain. Results from the individual forcing
experiments are then linearly combined using a statistically-based smoothing
procedure to produce sensitivity maps for many target quantities of interest,
including the geopotential height response over the PNA region and regional
precipitation responses over North America, South America, Africa, Australia,
and Indonesia.
Perhaps the most striking result from this analysis is that many important
targets for seasonal forecasting, including the PNA response, are most
sensitive to SST anomalies in the Niqo-4 region of the central tropical
Pacific, with lesser and sometimes opposite sensitivities to SST anomalies in
the Niqo-3 region of the eastern tropical Pacific. However certain important
targets, such as Indonesian rainfall, are most sensitive to SST anomalies
outside both the Niqo-4 and Niqo-3 regions.
These results are also relevant in assessing atmospheric sensitivity to
changes in tropical SSTs on decadal to centennial scales associated with
natural as well as anthropogenic forcing. In this context it is interesting to
note the surprising result that warm SST anomalies in one-third of the
Indo-Pacific domain lead to a decrease of global mean precipitation.
Please contact Joe Barsugli (joseph.barsugli@colorado.edu) for further information.
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