engleski

North Atlantic SSTs as a link between wintertime NAO and the following spring climate

In this paper we explore a potential seasonally-lagged impact of wintertime North Atlantic Oscillation (NAO) on the subsequent spring climate over European region. Supported by the observational indication of the wintertime NAO – spring climate connection, a modeling approach is used employing the International Centre for Theoretical Physics (ICTP) atmospheric general circulation model (AGCM) as a stand-alone model and also coupled with a mixed layer ocean in the North Atlantic. Both observational and modeled data indicate a pattern of sea surface temperatures (SST) in North Atlantic as a possible link between wintertime NAO and following spring climate anomalies. The SST pattern is associated with wintertime NAO and persists through the following spring. It is argued that these SST anomalies can affect the springtime atmospheric circulation and surface conditions over Europe. The atmospheric response is recognized in observed as well as in modeled data (mean sea level pressure, temperature and precipitation). Additionally, an impact on springtime storm activity is found as well. It is demonstrated that the SST anomalies associated with wintertime NAO persist into the subsequent spring. These SST anomalies enable atmosphere-ocean interaction over the North Atlantic and consequently affect the climate variability over Europe. Although with relatively weak impact, the described mechanism provides a temporal teleconnection between the wintertime NAO and subsequent spring climate anomalies.

North Atlantic Oscillation; atmosphere-ocean interaction; delayed impact

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