Can salt prevent Pacific island water crises? An "oceanic rain gauge" for water management

The tropical Pacific is especially vulnerable to changing rainfall patterns, and devastating floods and droughts are routine.  Rainfall shortages impact water supplies needed for agriculture, industry, tourism, and human health, while excess rainfall can cause floods, mudslides, and increased rates of water born disease. Future population pressure and climate change are expected to increase the impact and rate of these water crises. Successful natural disaster planning and climate change adaption begins with understanding the nature of environmental change. Accurate information on the patterns and trends in large-scale rainfall is essential.

This study explores the use of an “oceanic rain gauge” based on continuous upper-ocean salinity observations made by the global network of Argo profiling floats.  These salinity observations reflect the balance of freshwater storage (rainfall-minus-evaporation) and advection by ocean currents, and are a sensitive measure of the changes in the atmospheric convergence zones that dominate tropical water supplies.  For the tropical Pacific, Argo observations may provide improved estimates of large-scale precipitation relative to traditional island-based rainfall measurements, which are biased by topographic effects, or satellite-based measurements, which are calibrated against island rain gauges.

Already, oceanographic observations are beginning to reveal seasonal-to-interannual variability of the water cycle due to climate change and phenomena such as El Niño.  Our objective is to utilize this new source of information to inform more effective natural disaster preparations.