CHELSA-W5E5 v1.0: W5E5 v1.0 downscaled with CHELSA v2.0 ...

• Main Authors: Karger, Dirk N., Lange, Stefan, Hari, Chantal, Reyer, Christopher P.O., Zimmermann, Niklaus E.
• Format: Dataset
• Language: English
• Published: ISIMIP Repository 2022
• Subjects: EARTH SCIENCE > ATMOSPHERE > ATMOSPHERIC RADIATION > SHORTWAVE RADIATION; EARTH SCIENCE > ATMOSPHERE > ATMOSPHERIC TEMPERATURE > SURFACE TEMPERATURE; EARTH SCIENCE > ATMOSPHERE > PRECIPITATION; Arctic; Arctic Ocean
• Online Access: https://dx.doi.org/10.48364/isimip.836809.3; https://data.isimip.org/10.48364/ISIMIP.836809.3

The CHELSA-W5E5 dataset was created to serve as observational climate input data for the impact assessments carried out in phase 3a of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP3a). Version 1.0 of the CHELSA-W5E5 dataset covers the entire globe (except the Arctic Ocean beyond 84°N) at 30 arcsec horizontal and daily temporal resolution from 1979 to 2016. Data sources of CHELSA-W5E5 are version 1.0 of WFDE5 over land merged with ERA5 over the ocean (W5E5; Lange, 2019; Cucchi et al., 2020), the ERA5 global reanalysis (Hersbach et al. 2020) and the Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010; Danielson and Gersch, 2011). Variables (with short names and units in brackets) included in the CHELSA-W5E5 dataset are Daily Mean Precipitation (pr, kg m-2 s-1), Daily Mean Surface Downwelling Shortwave Radiation (rsds, W m-2), Daily Mean Near-Surface Air Temperature (tas, K), Daily Maximum Near Surface Air Temperature (tasmax, K), Daily Minimum Near Surface Air Temperature (tasmin, ... : CHELSA-W5E5 v1.0 is a downscaled version of the W5E5 v1.0 dataset, where the downscaling is done with the CHELSA v2.0 algorithm (Karger et al. 2017, Karger et al. 2021). In the following we outline how this algorithm works. The CHELSA algorithm applies topographic adjustments based on the surface altitude, orog, from GMTED2010. Since it does not add any value over the ocean, all values over the ocean are masked. The CHELSA algorithm is applied day by day. CHELSA-W5E5 tas is obtained by applying a lapse rate adjustment to W5E5 tas, using differences between CHELSA-W5E5 orog and W5E5 orog in combination with temperature lapse rates from ERA5. Those lapse rates are calculated based on atmospheric temperature, ta, at 950 hPa and 850 hPa, and the geopotential height, zg, of those pressure levels. The lapse rate used for the adjustment is calculated as the daily mean of hourly values of (ta_850-ta_950)/(zg_850-zg_950). The variables tasmax and tasmin are downscaled in the same way, using the same lapse rate value. ...