Investigation of snow cover changes affected by climate change In North West of Iran

 In this study in order to monitor snow cover, the Moderate Resolution Imaging Spectroradiometer (MODIS) optical images were used, while for detection of snow covered areas, the  snow index-NDSI, was applied. The results showed - according to the climatic conditions of the region- during the following months: December, January, February and March, most of the area is covered by snow and the maximum extent of snow cover occurred in January. In West Azerbaijan province there is found a negative trend of snow cover with a drastically reduction in January, as well as the provinces East Azerbaijan and Ardebil showed the decreasing of snow cover in this month. The results of this study show that, changes in snow cover imply a rise in temperature in this region leading to the reduction of snow cover in January. This trend represents global warming and climate change impacts on snow cover in the study area. Investigation of extreme indices  confirms the assumption that by taking temperature increase into consideration, regional winter precipitation pattern has been changed from snow to rain, causing the reduction of snow storage in the catchment of study area. In addition ,the extreme temperature index study  in the period of 2011- 2040 and the baseline by considering climate change approach in North West of Iran by using outputs of general circulation models under A2 scenario and downscaling models LARS-WG indicates the number of frost days or the number of  icy days decreased compared to the baseline which is not unexpected according to reports by the Intergovernmental Panel on Climate Change (IPCC) as well as several studies confirmed  global warming. Moreover, indices such as growth period increased, while diurnal temperature variation decreased compared to the baseline confirming   snow cover reduction in the region as a threat of snow storage in the region.