Accurate measurements of global precipitation are vital to the advancement of our understanding of the global hydrological cycle. The lack of rain-gauge networks over the vast oceans points to satellite techniques as the only means by which oceanic rainfall can be measured and monitored. Passive microwave satellite measurements, obtained by the Special Sensor Microwave Imager (SSM/I) onboard the Defense Meteorological Satellite Program satellites, augmented with sophisticated retrieval and statistical techniques, can now provide quantitative climate-scale oceanic rainfall estimates.
It has long been recognized that precipitation is a major component of the global hydrological cycle and of the energetics of atmospheric circulation. However, the spatial and temporal variabilities of rain fields and the scarcity of rain-gauge networks, especially over the oceans, lead to large uncertainties in oceanic rainfall climatology.