Wavelet-based analysis of global index effects in air temperature and precipitation data of the black sea coast

Abstract

This study has been carried out to analyse the precipitation and air temperature data in the Black Sea region of Turkey to aid the understanding of the effects of global indices. Connections between the temperature or precipitation data and global atmospheric indices such as the North Sea Caspian Pattern (NCP), the Southern Oscillation Index (SOI) or the North Atlantic Oscillation (NAO) were studied. Results of the cross-correlations between air temperature and the NCP/NAO showed a strong relationship, especially in the winter period. The seasonal and annual differences for the temperature and precipitation data during the negative and positive phases of the global indices were computed. According to this, the annual total precipitations are higher during the positive NCP index than the negative NCP index, while the annual total precipitations are higher during the negative NAO index than the positive NAO index. On the other hand, wavelet analysis showed that some short-term periodicities in precipitation and temperature data are connected with the NAO and the extreme phases of the SOI. The influence of the NCP should also be considered for the short-term periodicities of the temperatures.