资源环境科技发展态势分析平台

Assuming that atmosphere general circulation models (AGCMs) provide realistic estimates of the atmosphere's response to external forcing, it is here tested whether teleconnections triggered by the El Nino-Southern Oscillation (ENSO) are robust to internal atmospheric variability. To this aim, the AGCM ensemble from the European Centre for Medium-Range Weather Forecasts ERA-20CM project is used, whose 10 members are here seen as surrogates for the atmosphere's response to the observed external forcing. Results for 1900-2010 indicate that ENSO teleconnections in the tropics and in areas affected by the Pacific-North American and Pacific-South American patterns are robust, whereas in the extratropics they are otherwise generally not. Then, shorter periods are assessed during which particularly strong or weak teleconnections were found in previous studies based on observations. Results reveal that the late twentieth century teleconnections to North America, coinciding with the positive phase of the Pacific Decadal Oscillation, are robust in the southern United States and Mexico and to the south of Aleutian Islands. In contrast, according to the model experiments and methods applied here, teleconnections to the climate in southern Europe are not robust at all.