Potential impacts of climate change on precipitation patterns over Iran (an arid/semi-arid climate)

Abstract

In this study, two objectives were paramount. One is to assess the spatio-temporal patterns of precipitation in Iran and the other is to investigate the projected changes in these patterns for the period 2071-2100 as compared to 1965-2010. These were achieved by using monthly precipitation data from 256 rain gauge stations and the outputs of the HadCM3 global circulation model (under the A2 and B2 scenarios). The statistical (delta method) and dynamical (PRECIS) downscaling techniques were compared in terms of their results for projecting annual isohyets, annual march of monthly precipitation and the precipitation homogeneity. The results showed that, by HadCM3_Delta Method_A2, HadCM3_Delta Method_B2, HadCM3_PRECIS_A2 and HadCM3_PRECIS_B2 projections, the annual mean precipitation over the country (which is already 254 mm) would be 208.6, 187.1, 174.1 and 175.0 mm, respectively. Also, the corresponding values for the average of precipitation homogeneity index would change from 57% in the current conditions to 53, 54, 59 and 61% in climate change conditions, respectively. Although temporal and spatial monthly precipitation was envisaged, there was no impressive impact of climate change on precipitation pattern, but it is effect on time of maximum precipitation was subtle.