Surface Salinity Drifters: A Start to Monitoring the Global Water Cycle for Climate Change Detection


OCCI Project Funded: 2006

Proposed Research

One of the key uncertainties in global climate change science is the degree to which the global water cycle will intensify with climate warming. A warmer atmosphere can hold more water vapor; thus, stronger evaporation and precipitation patterns are expected to emerge as the planet warms. This could mean more intense droughts in some regions and more catastrophic floods in others. The oceans are the key to understanding the future evolution of the water cycle, as they harbor 97% of the planet’s water reserves, experience about 90% of the global evaporation and 80% of global precipitation. The patterns of evaporation and precipitation over the ocean are reflected in the patterns of salinity variability at the ocean surface. Whereas, evaporation and precipitation records from land are ambiguous about water cycle changes, the limited data on ocean salinity show striking trends that are the best evidence yet of a changing water cycle. 

The measurement of salinity remains a challenge, however. Presently available sensors have significant problems with biological fouling - microorganisms tend to grow on their surfaces and impair function. To solve this problem, we have developed a design for a new sensor that is able to clean itself of biological colonization using mechanical scrubbing and time released anti-foulants.  The goal is to deploy many of these new sensors on surface drifters to obtain continuous and extensive measurements of upper ocean salinity.  A large number of surface drifters are deployed every year throughout the global ocean, and we would like to add salinity sensors to these same platforms. The present grant enabled us to produce the pieces for 10 sensors. We are pursuing additional funding to assemble, test and deploy these sensors. We believe they will be a key component of future climate monitoring systems and will allow new insights into the largely unmonitored global water cycle.