The teleconnections between the extreme phases of the southern oscillation and precipitation patterns over Turkey

Climatic links between monthly precipitation in Turkey and the El Nino and La Nina events using the empirical methodology of Ropelewski and Halpert are investigated. Coherent and significant precipitation responses to both the extreme phases of the southern oscillation (SO) are found in two core regions, namely western Anatolia (WA) and eastern Anatolia (EA). The geographical extent of the two regions, together with a defined signal season for each tropical event, are identified. For WA, the April-July wet period during El Nino events is the season when the teleconnection is strong and consistent. For EA, the February-June wet period during El Nino events is found to be the signal season having high rates of coherence and consistency. The occurrence of the signal season (the dry period of April-October) during La Nina events appears to be less significant in EA according to the hypergeometric model. Moreover, the annual cycle analysis implies somewhat of a modulation of regional precipitation in the WA and EA regions during the relevant signal season. From other perspectives, correlation results of seasonal precipitation and seasonal SO index values confirm the implied teleconnections, and the powers of line spectra corresponding to the El Nino occurrences supply some indications. The final aim of this work is to show some guidance for quantification of the SO-related precipitation teleconnections for the core regions by examining shifts in precipitation amounts at various percentiles as a function of the SO extremes. Overall, the results of this investigation are in good agreement with previous relevant studies (especially global-scale type) that try to understand complex global circulation dynamics. In conclusion, mid-latitude precipitation responses to the extreme phases of the SO are detectable in the climate of Turkey. Copyright (C) 2003 Royal Meteorological Society.