Evaluation the performance of ERA5 Reanalysis Data in Iran's rainfall estimation and spatial analysis of the country's precipitation regime

Document Type : Original Article

Authors

1 a. Department of Physical Geography, Faculty of Geography, University Tehran Tehran, Iran

2 Department of Climatology, Faculty of Geography, Tehran University, Tehran, Iran

10.48308/esrj.2024.104225

Abstract

For identify the spatial distribution of the statistics and the temporal regime of Iran's precipitation, monthly precipitation reanalysis gridded data (ERA5) during the 1979 to 2021 have been used. In order to evaluate the monthly data of this database compared to the monthly rainfall data in synoptic stations of the country, the correlation coefficient, Normalized Root Mean Square Error (NRMSE), the Wilmot agreement index and the standardized Bias index were used.The results of the above statistics confirmed the high efficiency of this type of data. Precipitation usually starts in the north of the country, especially in the Caspian region, at the end of the warm period of the year from September. In general, the highest percentage of precipitation variation coefficient can be seen in these areas, which indicates the very fluctuating regime of precipitation in those areas. March is the rainiest month and August is the least rainy month in the country. The spatial distribution of the percentage of seasonal precipitation showed that the central, eastern, southern and even southwestern parts of the country receive the highest percentage of annual precipitation in the winter season, while the western banks of the Caspian and northwestern Iran receive the lowest percentage of annual precipitation in this season. have their own The time series analysis of seasonal rainfall indicates a decreasing trend of spring and winter rainfall and an increasing trend of autumn rainfall, which somehow indicates the change of the country's rainfall regime.

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Researches in Earth Sciences

Articles in Press, Accepted Manuscript
Available Online from 31 January 2024

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