SPURS Synthesis Research Objectives: Budget calculations Resolve important terms of the freshwater and heat budgets of the upper 1000 m on temporal scales of a few days and spatial scales of the order of 100 to 1000 km around the salinity maximum. Mixed layer formation, restratification, and erosion Identify and quantify the processes responsible for the formation of a ~100-m thick surface mixed layer in the winter, for its re-stratification in the spring and summer and its relationship to the sub-surface salinity maximum. Assess the importance of lateral gradients in the time evolution of the mixed layer. Near-surface measurements Provide a detailed description and analysis of the near-surface (top 5 m) temperature and salinity fields during a complete annual cycle, paying special attention to the role of this near-surface structure in air-sea interaction and its relevance to interpretation of satellite measurements.

Budget calculations Specific Tasks: -Estimate horizontal advection and vertical advection. -Estimate entrainment fluxes during the wintertime mixed layer. -Synthesize turbulence estimates (Gliders, ship-based profilers, MLF, mooring). -Make objective maps of the all the data in the SPURS region -Calculate salt and heat budgets -Evaluate how representative the SPURS measurements are in the context of seasonal and interannual variability

Budget calculations: Objective maps Moorings Seagliders Argo floats UCTD Note: Size of data marker is scaled by when it was collected relative to the central time. Decorrelation scales: 40 km and 5 days

Budget calculations: Turbulence timeseries Extended (many months) dissipation measurement from autonomous Seagliders.

Mixed layer dynamics Specific Tasks: -Investigation of seasonal evolution of the mixed layer depth and thermohaline characteristics in response to changing surface forcing, advection, and mixing. -Investigation of intrusions at the base of the mixed layer. -Investigation of inertial motions and internal waves. Left: Evolution of the upper ocean salinity observed by Mixed Layer Lagrangian floats. Right: Advection of Lagrangian floats relative to the center of the mooring array and the “SPURS box” (grey square).

Near-surface variability Specific Tasks: -Investigation of the diel cycle. -Study the impact of evaporation under low wind conditions on the near surface salinity. -Investigation of transient fresh pools. Temperature in the upper 10 meters over two days of T-Glider profiling, showing afternoon warming, particularly on Sept. 29 th. Such days were also characterized by enhanced surficial salinity and enhanced near-surface turbulence.