Investigating the Output of Numerical Prediction Models under RCP4.5 Scenario for Forecasting Meteorological Droughts

Climate change increases the repetition and frequency of droughts and this event has undergone significant changes. Water resources and agriculture in Iran has not been spared from the harm of these changes. In this study, because of the importance of Kashafrood basin in the North-East of Iran, the meteorological droughts in the region over the next three years (2027-2018), (2037-2028) and (2047-2038) will be discussed. Since the Standardized Precipitation Index (SPI) is one of the most useful indices of drought, this index was calculated in this study. Numerical calculations and dynamic models are the most accurate sources for prediction of meteorological variables. In this research, the precipitation outputs of the EC-EARTH model under the RCP4.5 scenario that has been downscaled with RCA4 dynamic model were used. According to the resolution of the RCA4 dynamical model, the Kashafrood basin was divided into 6 pixels (0.44 at 0.44 degrees) and then assessment values were determined on each pixel. The results showed that the EC-EARTH model is competent in the prediction of precipitation at a confidence level of 99% with a correlation coefficient averaged 64%. The average number of dry and very dry months was calculated on the whole basin. Analysis of the results in the next three years compared to the observation period (2016-1987) showed that the number of droughts will increase, but the severity of future droughts will be reduced