Effects of field of view inhomogeneities on the rain estimation from microwave radiometry

We present a method to estimate the beamfilling correction factor for rain rates calculated from SSM/I data at 19 GHz, horizontal polarization. An application to a tropical situation is presented, where brightness temperatures vary typically from 175 K to 235K. We show the quantitative dependence of this correction with the fraction of the field of view covered by rain. This leads to a correction factor in the range 1.5-3.