Catchment-Averaged Monthly Evaporation Timeseries 1984--2020 Derived from GRACE-like TWS Change via Terrestrial Water Budgets

Description: This data set provides monthly resolved timeseries of area-averaged evaporation ET over a selection of eleven globally distributed river catchments from 1984-01 to 2020-12. The term 'evaporation' here refers to the net sum of non-precipitative water fluxes between surface and atmosphere, including condensation, deposition and evaporation from vegetation by means of transpiration and interception, where fluxes towards the atmosphere are defined negative (losses).
Hence, the provided ET values represent the spatially averaged monthly net sum of those fluxes over the shape of the catchment upstream from the river gauge stations, respectively.

Method and Input-Data: Evaporation is derived solving the terrestrial water budget equation dS/dt=P-ET-R for ET, where P is monthly precipitation from the GPCC v2022 full data monthly product (WMO, DWD) and R is catchment-averaged equivalent water height of observed river discharge as provided by GRDC, Koblenz, Germany.
dS/dt refers to temporal change of terrestrial water storage built from the TWSTORE (https://zenodo.org/records/15827789, Hacker et al.) reconstruction by means of monthly central differences. TWSTORE is a GRACE-like reconstruction of terrestrial water storage that makes use of correlations with various climate variables in combination with SLR/DORIS observations of the change Earth's gravitational potential. A more comprehensive description is given in Hacker et al. (2025).

Data format: The data (core variable 'et') are stored in netCDF4 format with timestamps given in seconds since 1970-01-01T00:00:00Z. 
File names follow the format ET_ts_{TWS}_{PRECIP}_{DISCHARGE}_{YYYY_ZZZZ}_{RIVER}_{STATION}_{GRDC_ID}.nc,
where: 

• TWS: Short name of source TWS product (TWSTORE)
• PRECIP: Short name of precipitation input data (GPCC)
• DISCHARGE: Short name of river discharge input data
• YYYY--ZZZZ: Start- and end-year of covered time span, e.g. 1984--2020
• RIVER: Name of the stream (river); note that this can also be a tributary to a major stream, e.g. Tisa, which is a sub-region of the Danube Ceatal-Izmail catchment.
• STATION: GRDC name of the river gauge station, with blanks or special characters replaced where appropriate; note that some station names include a number that is NOT the GRDC ID.
• GRDC_ID: Seven-digit integer GRDC identification number of the river gauge station; corresponding HydroSHEDS-based shapes of watershed boundaries are provided by GRDC.