# GRACE Satellite Gravimetry

GRACE and GRACE-FO satellites sense only total column water, so groundwater must be separated by subtracting soil moisture, snow and canopy storage, and the models used for that step underestimate the largest trends. A physics-constrained decomposition LSTM splits each cell's groundwater signal into a trend, a seasonal cycle and a residual, holding the trend inside the net atmospheric supply and enforcing basin mass balance during training. The reconstruction reached a root mean squared error of 6.97 centimeters and a Nash-Sutcliffe efficiency of 0.69 on withheld months, and its trend error against monitoring wells was lower than an independent hydrological model and a data-assimilation product at every scale tested.

GRACE and GRACE-FO satellites sense only total column water, so groundwater must be separated by subtracting soil moisture, snow and canopy storage, and the models used for that step underestimate the largest trends. A physics-constrained decomposition LSTM splits each cell's groundwater signal into a trend, a seasonal cycle and a residual, holding the trend inside the net atmospheric supply and enforcing basin mass balance during training. The reconstruction reached a root mean squared error of 6.97 centimeters and a Nash-Sutcliffe efficiency of 0.69 on withheld months, and its trend error against monitoring wells was lower than an independent hydrological model and a data-assimilation product at every scale tested.