Observed and modeled climate variability over the United States associated with major teleconnection patterns

Climate change, atmospheric circulation patterns, and their teleconnections to surface climate are among the primary influences on climate and variability over the U.S. Here we first assess historical observed surface temperature and precipitation variability associated with six major atmospheric teleconnection patterns. We next evaluate the ability of four atmosphere-ocean general circulation models commonly used to produce simulations of future climate (PCM, HadCM3, CCSM and GFDL) to reproduce these atmospheric circulation patterns and variability, as defined by the standard indices based on pressure, geopotential heights, winds, and sea surface temperatures. Model ability to reproduce the teleconnection patterns in terms of the temporal frequency of index itself as well as the sign and magnitude of their influence on regional-scale temperature and precipitation has enormous implications for the ability of these models to simulate climate and climate change over these regions. Finally, we assess projected changes in the frequency and intensity of major teleconnection patterns under conditions of future change as simulated for the SRES A2 (mid-high) and B1 (lower) scenarios to demonstrate how these are likely to continue to influence climate over the continental U.S. in the coming century.