engleski

Wintertime ENSO impact on spring European climate

An atmospheric general circulation model (AGCM) developed at the Abdus Salam International Centre for Theoretical Physics the ICTPAGCM has been used to investigate different aspects of ENSO impact on European climate. A large ensemble of model simulations was created to examine impact of winter ENSO on Northern Hemisphere with focus on Pacific North America (PNA) and North-Atlantic European (NAE) regions depicting that ENSO signal over the Europe is quite weak, but still detectable and statistically significant for different atmospheric parameters (like mean sea level pressure, geopotential height, precipitation etc.) which may be even strengthened in a warmer climate conditions. Furthermore, the same model coupled with the simple ocean mixed layer in North Atlantic revealed that during wintertime ENSO events tropical Pacific and North Atlantic may be connected by the atmospheric bridge. This connection enables tropical Pacific to affect sea-surface temperatures (SSTs) in North Atlantic during the winter. Persistence of the SSTs in North Atlantic allows delayed wintertime ENSO impact on spring precipitation over the NAE region. The set of targeted ICTP AGCM simulations demonstrated that the late springtime ENSO signal over the NAE is result of two contributing processes: one is direct (spring-to-spring) ENSO influence and the other is delayed (winter-to-spring) ENSO influence maintained by atmosphere-ocean interaction in North Atlantic. Furthermore, ICTP AGCM simulations manifested important stratospheric role in modelled atmospheric response to ENSO forcing.

ENSO, teleconnections, delayed impact, North Atlantic, stratosphere

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