Global Atmospheric Sensitivity to Tropical SST Anomalies throughout the Indo-Pacific Basin

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 Pacific–North American (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 Niño-4 region (5°N–5°S, 150°W–160°E) of the central tropical Pacific, with lesser and sometimes opposite s... 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 Pacific–North American (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 Niño-4 region (5°N–5°S, 150°W–160°E) of the central tropical Pacific, with lesser and sometimes opposite s...