The TRMM and Other-GPI Calibration Rainfall Product algorithm (3B42) produce the gridded precipitation product by combining the four independent precipitation measurements that include the monthly average unclipped TRMM Microwave Imager (TMI) estimate (intermediate product from Algorithm 3B42), the monthly average Special Sensor Microwave/Imager (SSM/I) estimate (3A46), pentad-average adjusted merged-infrared (IR) estimate (3B42), and monthly accumulated Climate Assessment and Monitoring System (CAMS) or Global Precipitation Climatology Centre (GPCC) rain gauge analysis (3A45) (Huffman et al., 1995)