The north atlantic oscillation (NAO) and the water temperature of the Sava river in Serbia

Abstract

The data on the water temperature of the Sava in Serbia (hydrological stations Sabac and Belgrade, period 1961-2015) were used for the research, as well as the data on the surface air temperature. The temperature trends were determined and the significance (at p lt = 0.05 and p lt = 0.01) was established on the basis of the t-test. The Pearson correlation coefficient (R) was used for the calculation of the correlation. Increasing trends of the water temperature of the Sava were recorded in all cases at both stations. However, in the case of the HS Sabac, the trends for 6 months (February-April and September-November) were not statistically significant. In the case of the HS Belgrade, all the calculations (except for April) showed statistically significant increasing trends, which can be explained by anthropogenic influence. High level of correlation between the surface air temperature and the water temperature was also determined. In this research, the lowest values of R were recorded for October (0.561 for Belgrade), and on the seasonal level, for autumn (0.625 for Sabac). The research on the correlation between the water temperature of the Sava River and the NAO index showed the highest values of R for January (0.512 for HS Sabac and 0.528 for HS Belgrade). On the seasonal level, the highest values were recorded for winter (0.422 for HS Sabac and 0.432 for HS Belgrade).