Rainfall measurements with navigational radar

A novel approach to measuring rainfall in the ocean is presented. The metho d is based on the remote sensing of rain by navigational radar and subseque nt calibration of the radar signal against the upper ocean salinity changes . The estimate of the area-average precipitation is obtained as the product of the calibration factor and the fraction of area covered by rainfall. We describe an application of this technique in the field during a recent voy age of the Australian R/V Franklin to the eastern tropical Indian Ocean. It is suggested that with further refinement of radar signal processing, navi gational radar can be used to routinely measure open ocean precipitation fr om research vessels and ships of opportunity.