Understanding the distribution and change of oceanic rainfall patterns is a major component of global/regional water cycle and climate change. Underwater acoustic measurements of rainfall can be used to detect and classify marine rainfall type and subsequently quantify the rainfall rate and its drop size distributions. These measurements if proven robust and accurate can be used to (1) provide continuous measurements of precipitation characteristics in the Oceans and (2) as in situ reference to physically validate satellite observations. In turn, the acoustic measurements of rain need to be evaluated using near-range high-quality weather radar and if possible co-located rain gauge arrays and disdrometers. These type of data will be available from the POSEIDON project operated by the Hellenic Centre for Marine Research (HCMR) and represents a unique data set worldwide to pursue this concept. Dr. Nystuen is the world leader in the interpretation of the underwater sound to measure rainfall. By working closely with scientists from HCMR Dr. Nystuen will be able to transfer knowledge and understanding of the technique to European scientists and allow them to become competitive for future grants applying the acoustical measurement of rainfall to validate radar and satellite rainfall observations and other related opportunities.