Any attempt to understand the global hydrological cycle must include a detailed study of freshwater fluxes into and out of the ocean on a global scale. Sea surface salinity, which is affected by rain, evaporation and turbulent transport, can serve as an indicator of the ocean hydrological cycle.

The European Space Agency’s Soil Moisture and Ocean Salinity (SMOS) mission is the first satellite mission to measure ocean surface salinity from space. By measuring the sea surface brightness temperature, the surface salinity can be inferred and global coverage of it is provided. The Air-Sea Interaction Profiler (ASIP), developed by the National University of Ireland in Galway, is a state-of-the-art, one-of-a-kind instrument that offers an unprecedented level of detail in salinity measurements from below the mixed-layer depths right up to the air-sea interface, with sub-centimeter resolution. In this research project, SMOS (satellite measurements) and ASIP (oceanographic measurements) will simultaneously probe the same fundamental area of ocean from both above and below the air-sea interface.

The experimental part of the project consists of data from the Labrador Sea, and upcoming ocean campaigns during the Spanish and French components of the SPURS (Salinity Processes in the Upper-Ocean Regional Study) experiment.

Data from these campaigns will be processed to obtain profiles of temperature, salinity, and shear with high spatial resolution. The shear measurements provide the level of turbulence, which is quantified by the dissipation rate of turbulent kinetic energy. This dissipation and the temperature and salinity profiles are essential to determining the vertical turbulent fluxes of salt and temperature in a stratified system, which is the main mechanism of transport of these scalars. Because of the high spatial resolution of the salinity profiles, the sea surface salinity can be determined exactly and related to the bulk salinity and the turbulent fluxes.