feat: use rain data from satellite data

[mrustl]

as BSWT data is lacking winter half year (no impact for Beijing, but for other cities!)

Either use:
GoogleEarthEngine: GSMaP Operational (1h rainfall 2000 - current)

https://developers.google.com/earth-engine/datasets/catalog/JAXA_GPM_L3_GSMaP_v6_operational
https://developers.google.com/earth-engine/datasets/catalog/JAXA_GPM_L3_GSMaP_v6_reanalysis

Or:
ERA-5 Copernicus Data
https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-single-levels?tab=overview.

R Package for Interfacting Copernicus Climate Store:
https://cran.r-project.org/web/packages/ecmwfr/v