New study on the detection of cold-core rings in the Gulf Stream area using remote sensing platforms

The Gulf Stream plays a major role in the meridional transport of heat and salt across the North Atlantic Ocean. The Gulf Stream acts as a barrier between the cold (10-18 °C) and relatively fresh (salinity around 30-32 in the practical salinity scale) waters of the Labrador Current and the warm (23 °C), salty (36), clear, and unproductive waters of the Sargasso Sea. After leaving Cape Hatteras, the Gulf Stream forms large-amplitude meanders that may loop back onto themselves and break off the stream forming detached rings. Warm-core anti-cyclonic rings bring significant amounts of warm tropical water to the continental slope and shelf seas north of the Gulf Stream. Similarly, cold-core cyclonic rings bring cold, nutrient-rich shelf water, to the biologically barren Sargasso Sea waters. Detection of cold-core rings from satellite data has been quite elusive so far as the surface temperature signature rapidly disappears.

Figure 1

Sea Surface salinity on August 23, 2015 according to various SSS products with superimposed OSCAR velocities. The plot on (a) correspond to the one-degree binned Aquarius L3 map. The other three maps show the fusion of the map shown in (s) with: AVISO SSH (b); SMOS SSS (c); and AVHRR SST (d).

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New service available: Singularity Analysis

Maybe you have seen the singularity exponents maps we are offering in this CP34-BEC data server. Singularity analysis is a technique for estimating, at any point, the singularity exponent of a signal. Singularity exponents, usually denoted by h, are dimensionless variables providing information about the local regularity (if positive) or irregularity (if negative) of the signal at any given point. When h is integer it means that the function has h continuous derivatives, while non-integer values indicate a more complex topological situation.

Why should we be interested in such a mathematical, abstract concept? Because if a flow exhibits horizontal turbulence – and the ocean is a quasi-2D turbulent flow at scales greater that a few kilometers – singularity exponents derived from any ocean scalar are the same and, in fact, they represent the streamlines of the flow! (Turiel et al., Physical Review Letters, 2005; Isern-Fontanet et al, Journal of Geophysical Research, 2007; Nieves et al, Geophysical Research Letters, 2007; Turiel et al., Remote Sensing of Environment, 2008; Turiel et al., Ocean Science, 2009).

Microwave OI SST map (AMSRE-E+TMI, derived by Remote Sensing Systems) corresponding to January 1st, 2005

Microwave OI SST map (AMSRE-E+TMI, derived by Remote Sensing Systems) corresponding to January 1st, 2005

Map of associated singularity exponents

Map of associated singularity exponents

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