Analysis of Spatially Distributed Annual , Seasonal and Monthly Temperatures in Istanbul from 1975 to 2006

The present study is about the analysis of mean, mean maximum and mean minimum temperatures carried out on annual, seasonal and monthly time-scales examining the data from 8 meteorological stations in Istanbul for the period 1975-2006. Various spatial and statistical tools were used to display and analyze trends in temperature data. ArcGIS was used to produce the spatially distributed temperature data by using Thiessen method. The non-parametric Mann-Kendall test was used to determine whether there is a positive or negative trend in data with their statistical significance. Sen’s method was also used to determine the magnitude of the trends. The results reveal positive trends in annual mean and mean maximum temperatures with 95% and 99% significance. Annual mean temperatures increased 0.83°C while annual mean maximum temperatures increased 1.6°C over the 32-years period in Istanbul. On a seasonal basis, a statistically significant positive trend was observed in summer. On a monthly basis, July and August has experienced significant warming trend in mean, maximum and minimum temperatures. The analysis of the whole record reveals a tendency towards warmer years, with significantly warmer summer, spring and autumn periods and slightly colder winters. These warming patterns may have important impacts on energy consumption, water supply, human health and natural environment in Istanbul.