Evaluation of spatial and temporal relationships between large-scale atmospheric oscillations and meteorological drought indexes in Turkey

Spatial and temporal linkages between large-scale atmospheric oscillations, namely, North Atlantic Oscillation (NAO), Southern Oscillation (SO) and North Sea-Caspian Pattern (NCP), and meteorological droughts in Turkey were investigated in this study. The corresponding oscillation indexes (NAOI, SOI and NCPI) were considered as monthly time indicators of the oscillations while the Standard Precipitation Index (SPI) obtained from 148 stations was used to define meteorological droughts. The suitability of various probability distributions was evaluated to obtain precise estimations of SPI values. Correlation analyses were then conducted to assess spatial and temporal distribution of the relationship between the oscillation and drought indexes. The linkages between the NAOI, NCPI and SPI were found to be more significant at the lag-0, while the SOI had significant positive and negative correlations with SPI series at lag-1-2. Moreover, our results revealed that the NAO is more dominant in the west and in the central Anatolia regions while the NCP has more influence on the northern and eastern regions.