Adrian PITICAR & Dumitru RISTOIU
Babeş-Bolyai University, Faculty of Environmental Science and Engineering, 30 Fântânele Street, 400294, Cluj-Napoca, Romania; e-mail adrian.piticar@ubbcluj.ro, dumitru.ristoiu@ubbcluj.ro

ANALYSIS OF AIR TEMPERATURE EVOLUTION IN NORTHEASTERN ROMANIA AND EVIDENCE OF WARMING TREND

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This paper reports the results of the analysis of monthly, seasonal, and annual mean air temperature series from 10 meteorological stations distributed over Northeastern Romania for a 50-year study period (1961-2010). Various statistical tools were used to detect and characterize significant changes in these series. The Pettitt test, the Standard Normal Homogeneity Test (SNHT), the Buishand range test, the Von Neumann’s ratio test have been performed on the data to test the series for homogeneity. The Mann-Kendall test and Sen’s slope estimation for trends detection were applied to analyze temperature data sets in the studied area. To explore whether some stations behave similarly or not and if a typology is possible from a spatial point of view, we used spatial hierarchical cluster analysis. The results of the Mann-Kendall test and Sen’s slope estimation showed significant increasing trends for air temperature over the Northeastern part of Romania. The values of the statistically significant average slope varied until 0.93°C/decade for the positive slopes and until -0.29°C/decade for the negative slopes. The most important increase in air temperature trend was specific to June, July and August months when nine of the ten weather stations showed statistically significant positive slopes for all 3 months. The spatial hierarchical cluster analysis suggests the existence of two distinctive groups. One of them consists of stations located at lower elevation and the other one includes stations that are located at higher elevation.