Are tropical SST trends changing the global teleconnection during La Niña?

Abstract

From 1950 to 2008, the linear trend of tropical sea surface temperature (SST) indicates the largest warming across the Indian and western Pacific Oceans, while the eastern Pacific trend is slightly negative. The interannual SST variations due to the El Nio- Southern Oscillation (ENSO) are superimposed onto these longer-term SST trends, which can potentially influence the structure and amplitude of the resulting atmospheric teleconnections. In this study, the cold phase of ENSO, or La Nia, is examined using composite differences based on the observations and the model-simulated response to SSTs. The analyses show that during the recent period (1980-2008), the global teleconnection pattern associated with La Nia has been associated with higher heights from the tropics to the mid-latitudes. The model simulations attribute these apparent changes in the teleconnections, across the tropics and the Northern Hemisphere, to warmer SSTs in the Indian Ocean and warm pool region. The implications of these results are discussed within the context of seasonal predictions in an evolving climate. Copyright 2010 by the American Geophysical Union.