Trends in Indices of Extreme Temperature and Precipitation in Iran over the Period 1960-2014
- 1 Department of Combat Desertification, Faculty of Desert Studies, Semnan University, Semnan, Iran
- 2 I.R. of Iran Meteorological Organization, Tehran, Iran
- 3 Department of Combat Desertification, Faculty of Desert Studies, Semnan University, Semnan, Iran
- 4 Royal Netherlands Meteorological Institute, De Bilt, The Netherlands
Abstract
Climate extremes can have many negative effects on different sectors. Globally, observations show significant changes in the characteristics of extreme events. We examined trends in extreme temperature and precipitation indices in Iran during the period 1960-2014. We present results from 33 quality controlled and homogenous synoptic stations (excluding stations with excessive missing data). For each station, we calculate 27 indices characterizing extreme temperature and precipitation. For all indices (including Rx5DAY, CWD, R95p, R99p, GSL and TXn) positive, negative, and insignificant trends were obtained. Generally, there were negative trends in R10mm, R20mm, R25mm, CDD, PRCPTOT, FD, TN10p, TX10p, CSDI and positive trends in Rx1DAY, SDII, SU25, TR20, TXx, TNn, TNx, TN90p, TX90p and WSDI at most stations. There is a decreasing trend in the magnitude and frequency of cold extremes and an increasing trend in magnitude and frequency of warm extremes over the observational record, which is consistent with previous research reporting the warming trends of the climate.
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