Does ERA-5 Outperform Other Reanalysis Products for Hydrologic Applications in India?

Global reanalysis products are extensively used for hydrologic applications in sparse data regions. European Centre for Medium-Range Weather Forecasts Re-Analysis version 5 (ERA-5), among the new-era reanalysis products, has been significantly improved for horizontal and vertical resolutions and data assimilation. However, the new-era reanalysis products (ERA-5, Climate Forecast System Reanalysis, ERA-Interim, Modern Era Retrospective Analysis for Research and Applications version 2, and Japanese 55-year Reanalysis Project) have not been evaluated for the hydrologic applications in India specially to understand if ERA-5 outperforms the other reanalysis products or not. Here we use the five new-era reanalysis products for the monsoon (June–September) season precipitation, maximum (T<inf>max</inf>) and minimum (T<inf>min</inf>) temperatures, total runoff, evapotranspiration, and soil moisture against the observations from India Meteorological Department in India for 1980–2018. We use a well-calibrated and evaluated hydrological model (the Variable Infiltration Capacity model) to simulate hydrologic variables using the forcing from India Meteorological Department and reanalysis products. In addition, we evaluated the reanalysis products for streamflow and annual water budget for the two basins located in the diverse climatic settings in India. Our results show that ERA-5 outperforms the other reanalysis products for the monsoon season precipitation, T<inf>max</inf>, evapotranspiration, and soil moisture. However, Climate Forecast System Reanalysis performs better than ERA-5 for the monsoon season total runoff in India. Performance for streamflow and annual water budget for ERA-5 is either better or comparable to the other reanalysis products in the two river basins. Overall, we find that ERA-5 performs better than the other reanalysis products and can be used for the hydrologic assessments in India.