4DHydro precipitation product: 1 km merged precipitation from IMERG-LR and SM2RAIN-ASCAT for Europe

The product is characterized by the integration of SM2RAIN-derived rainfall and GPM Late run precipitation estimates. The soil moisture-based estimates are obtained through the application of SM2RAIN to ASCAT retrievals. The two product are merged with a triple collocation technique (third product: ERA5 Land precipitation). Prior the merging, the data are downscaled at 1 km spatial resolution using CHELSA (1 km) climatology. The merging technique allows to obtain a high-resolution product (1km, 24 hour) over Europe. The product has been developed in the framework of the 4DHydro project for the entire ASCAT era (2007-2022). Acknowledgements The work is supported by the European Space Agency (ESA) through the 4DHydro grant no. ESA 4000136272/21/I-EF