Water Engineering, Ferdowsi University of Mashhad, I.R. Iran
Global warming and then climate change are important topics studied by researchers throughout the world in the recent decades. In these studies, climatic parameters changes are investigated. Considering large-scaled output of AOGCMs and low precision in computational cells, uncertainty analysis is one of the principles in doing hydrological studies. For this reason, it is tried that investigating the uncertainty due to precision of computational cells and in passing from global scale to regional scale through LARS-WG model and CRU institute, precipitation changes in Mashhad synoptic station located in Ghareghom basin are studied. The results show enough ability of the model to simulate precipitation parameter in the base period. Using downscaled output of HadCM3 generated by CRU with high precision shows gradual decreasing of precipitation trend for frequency and sum values. Comparing the downscaled output of the AOGCM with 2.5*3.75 resolution and the output of CRU with 0.5*0.5 resolution, the uncertainty is due to precision of computational cells from global to regional scale which the latter scale is closer to real values.