ANALYSIS OF SPATIALLY DISTRIBUTED ANNUAL, SEASONAL AND MONTHLY TEMPERATURES IN MARMARA REGION FROM 1975 TO 2006

This study presents an analysis of mean, mean maximum, and mean minimum temperatures of annual, seasonal, and monthly temperature data, obtained from 32 meteorological stations scattered throughout the Marmara region during from 1975 to 2006. Thiessen polygons were created for the spatial distribution of temperature over the study area, using ArcGIS software. Possible trends in the spatially distributed temperature data were examined, using the non-parametric Mann-Kendall method with statistical significance, and the magnitudes of available trends were determined using Sen's method. The findings of the study show positive trends in annual mean and mean maximum temperatures with 90%, 95%, 99% and 99.9% significance levels. August experienced the highest warming trend, with a 3.81°C increase in the mean temperature with 99.9% significance. November and December experienced a statistically insignificant decreasing trend in the mean and mean minimum temperatures. The results of this study show that there is a significantly increasing trend in temperatures during the spring, summer and autumn in the Marmara region. The annual mean temperatures experienced an increase of 1.86°C, while the annual mean maximum temperatures experienced an increase of 2.21°C over the 32-year period. On a seasonal basis, a statistically significant positive trend was determined in the summer. The mean temperature experienced an increase of 4.01°C in the summer, while the mean maximum and the mean minimum temperatures experienced an increase of 2.19°C and 3.58°C respectively. Although it is statistically insignificant, the mean maximum temperatures increased by 0.83°C in the winter. On a monthly basis, significant warming trends in the mean, maximum and minimum temperatures were observed in July and August. The highest warming trend was determined in August, with a 3.81°C increase in the mean temperature. The mean and mean minimum temperatures showed a decrease in November and December. The analysis of the recorded results indicates that there are statistically significant increasing trends in temperature. It is inevitable that these trends will affect the natural environment in the Marmara region.