The impact of rainfall assimilation on the NASA GEOS Reanalysis: Diurnal variability of the hydrologic cycle and radiative fluxes

Satellite rainfall retrievals from a 5-satellite constellation, including TMI from TRMM, SSM/I from DMSP F13, F14, and F15, and AMSR-E from EOS-AQUA, are assimilated into the NASA GEOS Data Assimilation System using a 1-D variation assimilation algorithm.

The physical impact of rainfall assimilation on the GEOS reanalysis is evaluated at the diurnal time scale, with focuses on the variability of cloud, precipitation and radiative fluxes. Through compensating for the systematic errors arising from both the model's moist physics and the initial condition, the experiment with rainfall assimilation is physically more consistent with the observations than the one without at the diurnal time scale.