The impacts of Arctic oscillation and the North Sea Caspian pattern on the temperature and precipitation regime in Turkey

Abstract

Arctic oscillation (AO) and the North Sea Caspian pattern (NCP) are atmospheric teleconnections that affect climate parameters such as precipitation, temperature and stream flow. The purpose of this study is to identify the relationship of the AO and NCP with Turkey's mean temperature and precipitation totals. First, Pearson correlation coefficients between the AO and NCP and climate data were calculated and the results were assessed using Student's t test. Although the results vary from region to region, highly negative correlation coefficients were observed between either the NCP or AO and the temperature, especially in the winter. Furthermore, the NCP and AO have a remarkably strong relationship with winter precipitation. Second, the NCP index (NCPI) and AO index were divided into negative and positive phases; then, the impacts of both phases on the climatic data were determined as annual and seasonal. Accordingly, the annual and seasonal mean temperature values under the effect of NCP (-) and AO (-) are higher than the annual and seasonal temperature values under the effect of NCP (+) and AO (+). In this context, the temperature differences are significant, especially in winter. The precipitation amount, under the effect of positive and negative phases of global indices, was also investigated in this study. Thus, substantial results were obtained, particularly for winter precipitation in Turkey's western regions. Finally, scatter diagrams were also prepared to examine the relationship between negative and positive phases of the AO or NCP and the temperature or precipitation.