engleski

ENSO impact on precipitation in regional climate model simulations over European region

The ability of 15 regional climate models (RCMs) within the European ENSEMBLES project to represent wintertime El Niño Southern Oscillation (ENSO) impact on precipitation over European domain is analysed with a focus on winter and spring season. Models are driven by ERA40 reanalysis data, so the examined period corresponds to 1961-2000. Models’ performance in simulating ENSO impact is estimated using composite analysis (based on categorization upon wintertime Niño3.4 index) applied on multi-model mean and each model separately. Composites of simulated precipitation are compared with those calculated for precipitation provided by ERA40 and Climatic Research Unit (CRU) data. Additionally, ENSO effect is compared to that associated with North Atlantic Oscillation (NAO). In general, examined RCMs have a good performance in reproducing the observed wintertime ENSO impact on both winter and spring precipitation. Models simulate successfully even some details that are not found in ERA40, but which are consistent with the observed (i.e. CRU) precipitation. Moreover, spatial correlation analysis of simulated and observed seasonal precipitation fields indicates that RCMs capture winter and spring precipitation over European region more realistically for years associated with a wintertime ENSO event. While correlation coefficients calculated for NAO composites show increase in winter season (concurrently with NAO event), coefficients obtained for ENSO composites reveal substantial increase in two seasons: winter (associated with contemporaneous ENSO effect) and spring (associated with delayed ENSO effect).

ENSO; precipitation; regional climate models; Europe

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