Predicted changes in some of climate variables using downscale model LARS-WG and output of HADCM3 model under different scenarios

Now a day, long-term prediction of climate variables is necessary for climate change impact studies. Currently Global Circulation Models (GCM) are powerful tools to generate climate scenarios. These models are limited to capture the local climate due to their low spatial resolution. So, they cannot be directly applied for hydrological modeling in a catchment scale. In this research, first the trend of variables such as rainfall, radiation, maximum and minimum temperature were assessed for the base period with nonparametric Man-Kendall test. Second, these variables were downscaled by using the outputs of HADCM model and under three scenarios of A1, A2 and B1 which are accepted by IPCC(1971-2010) under three scenarios and their monthly changes were investigated for three periods of 2011-2030, 2046-2065 and 2080-2099 compared to the base predicted period of (1971-2010). All these scenarios showed almost similar results on precipitation shortage and increasing of solar radiation, minimum and maximum temperature over the future periods. As an example, the results of A2 scenario showed increasing of the annual mean, minimum and maximum temperature by 1.1, 3.2, and 4.6 °C, increasing of solar radiation by 0.07, 0.30 and 0.33 mJ m-2d-1 and decreasing precipitation by 16.4, 17.6 and 31.9 percent for these periods compared to the base period.