SPURS-2: Salinity Processes in the Upper-Ocean Regional Study 2 – The Eastern Equatorial Pacific Experiment

In this special issue of Oceanography we explore the results of SPURS-2, the second Salinity Processes in the Upper-ocean Regional Study (SPURS), conducted in the eastern equatorial Pacific. SPURS is an ambitious multiyear field program to study surface salinity in evaporation-​dominated (SPURS-1) and precipitation-dominated (SPURS-2) regions of the global ocean. The primary goal was to further our understanding of the global oceanic freshwater cycle through investigation of the physical processes controlling the upper-ocean salinity balance: air-sea interactions, transport, and mixing. With the advent of satellites capable of measuring sea surface salinity, such as NASA’s Aquarius instrument and the Soil Moisture Active Passive (SMAP) satellite, as well as the European Space Agency’s Soil Moisture and Ocean Salinity (SMOS) platform, a near-synoptic view of such processes has become possible (Figure 1). To take full advantage of such observations, we need to understand the link between upper-ocean dynamics and the oceanic freshwater cycle.