Simulation of climate change in Iran during 2071-2100 using PRECIS regional climate modelling system

Parameters such as future precipitation, temperature, snowfall, and runoff were modeled using precis regional climate modeling system in iran with the horizontal resolutions of 0.44×0.44°c in latitude and longitude under sres a2 and b2 scenarios. the dataset was based on hadam3p during the periods of 1961-1990 and 2071-2100. the overall precipitation error of the model in the period of 1961-1990 was 5.3%. minimum errors were found to be over azari, north-central, and kordi regions. maximum and minimum monthly precipitation errors were found in september and may, respectively; but, minimum and maximum seasonal biases were found in spring and winter with -0.1 and -17.2% errors, respectively. results revealed a decrease in mean annual precipitation toward the end of the 21st century by 7.8 mm in b2 scenario and 10.1 mm in a2 scenario with maximum regional decrease of 100 mm in the southeast of the caspian sea. the decrease in precipitation was higher for a2 scenario, whereas it was minimum for b1 scenario. mean annual temperature of iran during 2071-2100 would be projected to increase by 4.5-5.5°c in a2 scenario and 3-4°c in b2 scenarios compared to 1961-1990. it was shown that mean annual changes in runoff over the country were negligible both in a2 and b2 scenarios. maximum annual amount of runoff increase was found over western part of the caspian sea, zagros and alborz mountain chains by 6.4-15. 8mm. results also indicated that annual snowfall would decrease by the maximum amount of 22.9-23.7 cm over zagros and alborz mountain chains.