That's only if you take the average of all the measurements collected across the entire ocean for decades. In one spot, salinity is not consistent. Patterns of

That's only if you take the average of all the measurements collected across the entire ocean for decades. In one spot, salinity is not consistent. Patterns of evaporation and rainfall affect not only salinity but also the presence of organic matter and other random contaminants. Such fluctuations are most pronounced at the surface, where this device is meant to operate.