A Statistical Investigation on Analysis of Oscillations Trend and Forecasting of High Extreme Temperatures Time Series in Tehran

In this study the data relating to the maximum daily temperatures of Tehran Mehrabad synoptic station during the statistical period of 1951-2010 (60 years) have been analyzed. The regression models along with Mann-Kendal statistic were employed for detecting the significance of trend in temperature series.Considering the long-term average high extreme temperatures and compared with the average six decades in the statistical series revealed those three decades of temperature 50, 80 and 90 are below the 60 years long-term average and instead of three decades of 60, 70 and the first decade of the 21st century, temperature changes are higher than from long term average.In this regard the decade 80 is the coldest and the first decade of the 21st century, according to the minimum and the higher range of 60 and 70 decades are the warmest decades of Tehran Mehrabad station. Overall results of this study revealed the existence of seasonal fluctuations in the high extreme temperatures series of Tehran which do not have significant trend. Trend of high extreme temperature changes of Tehran was positive, meaning the increasing the intensity of summer warming.The results of high extreme temperatures forecasting indicated that the high extreme temperatures in Tehran in years 2018 will lift up to the 43.25 degree of centigrade. The results of goodness to fit test proved that the Halt-Winters model is the appropriate model to forecasting of future high extreme temperatures of Tehran.