To model the dynamics and thermodynamics of the ocean climate system it is necessary to determine the surface buoyancy flux. In many areas the contribution of evaporation and precipitation to the buoyancy flux may exceed that of the thermal transfer. Schmitt et al. The importance of the freshwater to the buoyancy flux, and the large uncertainty in its magnitude, demands that a great improvement in quantification of the ocean hydrologic cycle be achieved if climate models are to be improved. In addition to monitoring the buoyancy changes caused by surface freshwater forcing, it is important to account for the mass flux.
Ocean currents transport many times as much water as the atmospheric branch of the hydrologic cycle.
A prime example is the flow through the Bering Strait, which returns most of the excess precipitation received over the fresh North Pacific to the salty, evaporation-dominated Atlantic. It is important to determine such interbasin transports since they define the net water and salt fluxes carried across coast to coast ocean sections. As Wijffels et al. While it may be useful in regional studies to examine positive or negative freshwater anomalies away from a reference salinity, such an approach cannot be extended to a global scale because there is no universal reference salinity. Indeed, the average salinity of the ocean must have varied with the changing ice volume during glacial periods.