Assessing improvement in the fifth‐generation ECMWF atmospheric reanalysis precipitation over East Africa

Abstract

This study aims to assess the performance of European Center for Medium-Range Weather Forecasting (ECMWF) Reanalysis fifth generation (ERA5) in terms of the progress made over its predecessor, ERA-Interim, over East Africa (EA) in reproducing observed rainfall. The observed rainfall used as reference rainfall are Global Precipitation Climatology Center (GPCC) and Climate Research Unit Time Series (CRU-TS). The performance of ERA5 to its predecessor is evaluated using root-mean-square error (RMSE), correlation, and bias. The reductions of wet bias from ERA-Interim to ERA5 are 16.81-6.94% from June to September (JJAS), 31.99-19.33% from September to December (SOND), and 29.24-17.69% from December to February (DJF) over most of EA relative to CRU-TS. Similar reductions in the wet bias relative to GPCC are also noted. Spatially, notable reductions are observed over western Ethiopia, Sudan Republic, South Sudan, and Uganda. The decreasing trends revealed in the bias of seasonal ERA5 rainfall relative to CRU-TS and GPCC are attributed to an increase in the number and quality of assimilated observations in ERA5 over its predecessors. RMSE of ERA5 rainfall relative to the two reference rainfall and correlations with the two reference rainfall are consistent with spatial and temporal features captured in the bias. Specifically, the correlation of the monthly time series of ERA5 ranges from 0.90 with CRU-TS over equatorial EA (EEA) to 0.98 with GPCC over southern EA (SEA) in contrast to that of ERA-Interim which ranges from 0.84 with CRU-TS over EEA to 0.93 with CRU-TS over SEA. However, the wet bias in ERA5 along the Great Rift Valley remained the same as in ERA-Interim whereas spatial correlation of ERA5 with the two reference rainfall is relatively weaker than that of ERA-Interim.

Evaluating the potential footprints of land use and land cover and climate dynamics on atmospheric pollution in Pakistan

“…For example, the hydrological regime of the Gilgit Basin was studied using ERA5 in Pakistan (Nazeer et al, 2022). Five meteorological parameters (Precp, SP, WS, Tmax, and Tmin) were obtained from the Fifth Generation (ERA5) ECMWF atmospheric reanalysis data (https:// www.ecmwf.int/en, accessed on 28 September 2022) (Lees et al, 2021;Assamnew and Mengistu Tsidu, 2023), as provided in Table 1. Moreover, the Moderate-Resolution Imaging Spectroradiometer (MODIS) land cover with 500 m resolution is available from 2000 to 2020 (Sulla-Menashe and Friedl, 2018).…”

Spatial and Temporal Evolution of Precipitation in the Bahr el Ghazal River Basin, Africa

“…At the MALAKAL station, monthly, wet season, and annual precipitation deviations are within 1%, with simulated values slightly lower than observed values. A study by Assamnew et al [57] evaluating the performance of ERA5 in simulating East African rainfall used CRU TS as a reference, signifying its representativeness in East Africa. Akinsanola et al [58] assessed five different precipitation products for their ability to characterize African rainfall, considering GPCC, CRU, and TRMM the most outstanding datasets suitable for African precipitation assessment.…”

Evaluation of precipitation forecasting base on GraphCast over mainland China

“…Due to the advanced forecasting system of ECMWF, the fifth-generation ECMWF reanalysis data has been widely utilized in various types of weather forecasting [31][32][33][34][35] . In this study, the GraphCast model utilizes ERA5 reanalysis data on pressure levels from 1940 to the present and ERA5 reanalysis data on single levels from 1940 to the present.…”