EVALUATION OF ECMWF DATA FOR IRAN'S CLIMATIC CONDITIONS

Abstract

In this study, the validity of the European Centre for Medium-Range Weather Forecasts (ECMWF) for providing temperature parameters (minimum and maximum, mean and dew point temperature) and precipitation prediction in different regions of Iran between 2015 and 2017 with a spatial resolution of 0.5 * 0.5 degrees has been evaluated. In order to compare and evaluate ERA-Interim data, minimum and maximum, average, dew point 
temperature and monthly precipitation of five stations over Iran representing different climate zones have been used. The results showed that the ERA-Interim model predicted generally monthly scale better than the daily scales. For precipitation, the coefficient of determination at all stations were high and, in most stations, it was more than 0.6 and up to 0.99. The values of R2 for the average values of temperature, minimum temperature, and 
maximum temperature of all stations were close to one, which indicated that the observed values explained the changes in the predicted values of the model. In general, the standard error of all temperature variables was low and acceptable on a monthly scale, which indicated that the model values were with a small distance from observations. Nash Sutcliffe model efficiency coefficient varied between -2.4 and 0.9 at stations and variables. Acorrelation coefficient of average and maximum temperature was about 1 at all stations, which indicated a strong relationship between the observed values and the model. The equally assumption for the minimum temperature and the dew point was not true. In general, the model could well simulate the process of time variation of different variables at selected stations, and the accuracy of the model was acceptable.