Drought Analysis & Index Tools

The longest satellite soil moisture record available — merged active+passive retrievals back to 1978, free, no login.

Monthly total water storage change from satellite gravity — the only direct signal of large-scale groundwater depletion.

Planetary-scale geospatial analysis in the cloud — the data catalogue and compute behind modern water remote sensing.

250m, 16-day global vegetation index composites — the standard input to crop-coefficient ET and drought indices.

NASA's L-band radiometer soil moisture mission — 9km/36km near-surface moisture, daily, since 2015.

The reference R implementation of SPEI and SPI from the index's own authors.

USGS's merged surface-water and groundwater statistics program — baseflow separation, flow duration, low flows.

The Variable Infiltration Capacity model — macroscale land-surface hydrology for big basins and climate studies.

Reference Python implementations of SPI, SPEI and Palmer indices for drought monitoring.

Climate indices and bias adjustment on xarray — the operational-grade library for climate-data engineering.