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The Soil Moisture and Ocean Salinity mission will provide sea surface salinity maps over the oceans, beginning in late 2009. In this paper an ocean salinity error budget is described, an analysis needed to identify the magnitude of the error sources associated with the retrieval. Instrumental, external noise sources, and geophysical errors have been analyzed, stressing their relative impact. This paper includes results from previous studies, addressing the impact of multisource auxiliary sea surface temperature and wind speed data on the final salinity error. It provides, moreover, a sensitivity analysis to the uncertainty of the auxiliary salinity field. Salinity retrieval has been addressed in a wide set of configurations of the inversion algorithm. [ABSTRACT FROM AUTHOR]

Velocity probability density functions (PDFs) are a key tool to study complex flows and are of great importance to model particle dispersion. The PDFs of geostrophic velocities derived from sea level anomalies maps for the Mediterranean Sea have been computed and analyzed, guided by recent results found in studies of two-dimensional and geostrophic turbulence. At the basin scale results show that the geostrophic velocity PDF derived from SLA maps is non-Gaussian. To understand the origin of this non-Gaussianity, a topological partition of the flow based on the Okubo–Weiss parameter is applied to separate the contribution of coherent vortices from the background field. After such separation the non-Gaussian part of the PDF appears mostly associated with the presence of such structures. Only about 20% of the vortices identified in the dataset are mainly responsible for this deviation. These vortices, called intense vortices in previous works, are those vortices with values of the amplitude larger than or equal to two standard deviations of the Okubo–Weiss parameter and correspond to vortices with a radius on the order of 40 km. [ABSTRACT FROM AUTHOR]

Abstract: Three Algerian eddies (open sea big anticyclonic eddies in the Algerian basin, western Mediterranean sea) are studied in detail using altimetric and in situ data. To characterize their spatial structure we make use of the Okubo–Weiss parameter, which allows to separate the flow into vorticity-dominated and deformation-dominated regions. The application of this parameter to geostrophic velocity fields obtained from Sea Level Anomaly maps show that the observed eddies have a spatial structure in close resemblance to that found in coherent vortices of two-dimensional turbulence. These eddies appear to have a rather coherent vorticity-dominated core region surrounded by an outer region dominated by deformation with a very complicated and variable in time structure. This analysis is also applied to CTD data collected across three eddies sampled between 1997 and 1998. From these data eddy cores are equivalently defined as the interior region enclosed by the maximum of azimuthal velocity, and are consistent with the horizontal structures seen in SLA maps. The distinction between the core and the outer region (circulation cell) is particularly important to understand the role of transport and stirring of properties associated to eddies, as illustrated by the observed salinity structure, some selected SST images, and drifter trajectories. The core is characterized by very small isopycnal salinity gradients, while the surrounding cell is characterized by a strong slope of isohalines with respect to isopycnals. Persistent stagnation points are observed around the eddy and correspond to regions of high values of deformation with respect to vorticity. These regions allow analyzing characteristic patterns seen in the corresponding SST images. In addition, drifters trajectories exhibit very different behavior when crossing such regions. [Copyright &y& Elsevier]