روند شاخص هاي حدي دما و بارش در تهران

Trend in Indices of Temperature and Precipitation Extreme in Tehran

Interest in climate changes has significantly increased in recent years due to the important economic and social consequences connected with extreme weather events. In this paper, the variability and extreme event behaviour were studied on the basis of indices of climatic extremes. The indices of temperature and precipitation extremes in this study were selected from the list of climate change indices recommended by the World Meteorological Organization-Commission for Climatology(WMO-CCL) and the Research Program on Climate Variability and Predictability (CLIVAR). The findings revealed that Fd & ID indices have significant decreasing trends and the daily minimum &mean temperature have increasing trends. In addition, warm extremes indices such as T40, CDD TR ,SU and GDD show a pronounced increasing trend rather than cold extreme. For example HDD & DTR have decreasing trends. Indices of extremes precipitation such as SDII,RR20 show low decreasing trends however the trend of indices WD, RR5, PER95 is increasing. Symmetric warming in tails of most indices is seen.