Input data set: W5E5v2.0

Observed atmospheric climate.

Version 2.0 of the W5E5 dataset covers the entire globe at 0.5° horizontal and daily temporal resolution from 1979 to 2019. The W5E5 dataset was compiled to support the bias adjustment of climate input data for the impact assessments carried out in phase 3b of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP3b).

W5E5 is a merged dataset. It combines WFDE5 data over land with ERA5 data over the ocean. The mask used for the merge is included in the dataset. The mask is equal to 1 over land and equal to 0 over the ocean.

Over land, orog is the surface altitude used for elevation corrections in WFDE5. For all other variables already included in WFDE5 (huss, prsn, ps, rlds, rsds, sfcWind, tas), W5E5 data over land are equal to the daily mean values of the corresponding hourly WFDE5 data.

Over the ocean, W5E5 data are based on temporally (from hourly to daily resolution) and spatially (from 0.25° to 0.5° horizontal resolution) aggregated ERA5 data.

Compared to W5E5 v1.0 (Lange, 2019), W5E5 v2.0 covers three additional years (2017-2019) and is based on WFDE5 v2.0 instead of WFDE5 v1.0 over land. Differences between the two WFDE5 versions are threefold. First, more recent versions of CRU TS (v4.04 compared to v4.03) and GPCC (v2020 compared to v2018) were used for bias adjustment in v2.0. Secondly, a bug that affected the computation of rsds was fixed in v2.0. This has reduced the annual global (land) mean rsds by about 2 W m-2. Lastly, the method used for the bias adjustment of the monthly mean diurnal temperature range was changed from a purely multiplicative method to a mixed multiplicative-additive method, see the product user guide of WFDE5 v2.0 (C3S, 2021). This update has reduced the intra-monthly variability of the diurnal temperature range for months and grid cells where this range is biased low in ERA5. As a result, the excessively high daily maximum temperature values that occurred in some months and grid cells in v1.0 do no longer occur in v2.0.

Data sources of W5E5 are version 2.0 of WATCH Forcing Data methodology applied to ERA5 data (WFDE5; Weedon et al., 2014; Cucchi et al., 2020), ERA5 reanalysis data (Hersbach et al., 2020), and precipitation data from version 2.3 of the Global Precipitation Climatology Project (GPCP; Adler et al., 2003).