Modified Monthly Oceanic Rain-Rate Algorithm to Account for TRMM Boost

We provide a modified algorithm for computing Tropical Rainfall Measuring Mission (TRMM) monthly oceanic rain rates (3A11) for TRMM Microwave Imager data using the Microwave Emission Brightness Temperature Histogram (METH) technique developed by Wilheit Shin and Chiu examined changes associated with TRMM boost by adjusting the microwave brightness temperature (T_b) for the postboost data to match the preboost data. We computed a new relation between T_b and rain rate (T_b-R) for the postboost characteristics using the same radiative transfer model of Wilheit and modified the algorithm by providing two T_b-R relations for the preboost and postboost era, respectively. The modified algorithm is applied to TRMM data without T_b adjustment. Preliminary results show a significant improvement over the unmodified algorithm in terms of biases and linear trends. Their differences on the application of the METH technique to other microwave data for climate-scale rainfall are discussed.