Climate change impact on spatial and temporal distribution of precipitation in Iran

Anticipated changes of precipitation as a result of climate change and global warming are very important in the assessment of climate change potential effects on various sectors such as water, agriculture, and surface water management. Precipitation has great complexities as the most important climatic element in Iran. The complexity is mostly due to the geographical location of vast land and has led to non-uniformspatial and temporal distribution of precipitation. this study aims is to evaluate the annual behavior of precipitation in Iran in the coming decades and precipitation statistical downscaling in Iran. In this regard, daily precipitation data of Iran 45 synoptic stations were prepared and downscaled in a period of 1981- 2010 based on the LARS-WG model format to make identical data coordinate and scale withAtmospheric-Ocean General Circulation Model (AOGCM) data. Then, precipitation changes were analyzed for 2040-2070 and 2070-2099 decades in Iran based on emission scenarios (A2, A1B, and B1), and the HADCM3 model. The results of this study showed that simulated precipitation in Iran declined 11.5% based on the most optimistic scenario (B1) for a period of 2040-2070 and declined 14.2% based onthe most pessimistic scenario (A2) for the base period. According to this scenario, Iran will not have reduced precipitation in the period of 1971- 2099 but it will have 0.8% increase in precipitation compared to baseline. Iran will have 9.6% decline in annual precipitation under the most pessimistic scenario (A2).

Keywords:

Downscaling , Atmospheric-Ocean General Circulation Model , LARS-WG , Global Warming , Iran