Linking satellite SSS and SST to water mass formation Marlene Klockmann 1, Roberto Sabia 2, Diego Fernández-Prieto 3, Craig Donlon 4 1 Max Planck Institute for Meteorology, Hamburg, Germany 2 Telespazio-Vega for ESA, ESTEC, Noordwijk, the Netherlands 3 ESA, ESRIN, Frascati, Italy 4 ESA, ESTEC, Noordwijk, the Netherlands Met Office, Exeter, UK

Introduction I.Satellite surface T-S diagrams II.Water masses –Objectives –Datasets –Density flux, transformation and water masses formation –From density flux to formation –North and South Atlantic, Indian Ocean –Specific water masses “chasing” –Summary and Follow-on Outline

1. Generating routinely satellite- derived surface T-S diagrams, obviating the lack of extensive sampling of the surface open ocean Sabia et al., JGR-Oceans, 2014, SMOS-Aquarius special issue 2. Displaying the T-S diagrams variability and the distribution/dynamics of SSS, altogether with SST and the relative density with respect to in- situ measurements T-S diagrams (i) Temperature-Salinity (T-S) diagrams emphasize the mutual variability of ocean Temperature and Salinity, relating them to the corresponding density.

3. Assessing the SMOS SSS data added value in detecting geophysical signals not sensed/resolved by the Argo measurements Assessing different signals influence in ΔSST vs ΔSSS per binning of: Precipitation Wind speed Heat flux Freshwater flux T-S diagrams (ii)

T-S Diagrams and Water masses –Water masses: water body with specific T and S properties and a specific formation history –Water masses are characterized by a range of T-S values; they are formed at the surface by interaction with the atmosphere, mostly in winter. –Classified either by type of formation or their typical depth –Currently, the main focus of the study deals with the exploitation of the T-S diagrams as a prognostic tool to derive water masses formation areas. –SMOS mission is now providing the possibility of studying temporal and spatial patterns in water masses formation. Which water masses can we observe at the surface? When and where are they formed?

In-situ: –ARGO ISAS Near Real Time (produced at Ifremer, Gaillard et al, 2009) Climatology: –World Ocean Atlas 2009 (WOA 09) Sea Surface Salinity (SSS): –SMOS Level 3 SSS optimal interpolated Sea Surface Temperature (SST): –Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) Additional data: –CMORPH precipitation –OAFlux evaporation –SSM-I wind speed –NOCS Surface Flux Data Set v2.0 Datasets, 2011

Short and longwave radiation Sensible and latent heat flux Evaporation Precipitation Speer & Tzipermann (1992) Surface density flux change in density induced by surface fluxes of heat and freshwater Methodology (i)

Water mass formation Speer & Tzipermann (1992) Walin (1982) Surface density flux “Transformation equation” “Formation equation” Methodology (ii)

North Atlantic South Atlantic Indian Ocean getting lighter getting heavier Surface density flux

North Atlantic South AtlanticIndian Ocean getting lightergetting heavier Transformation in T-S space (annual)

North Atlantic South AtlanticIndian Ocean Mode waters Warm pool waters RemovalFormation Formation in T-S space (annual)

North Atlantic South AtlanticIndian Ocean Formation in T-S space (vs. Argo)

Taken from Speer et al (1995) North Atlantic South AtlanticIndian Ocean Formation in T-S space (vs. literature)

Peaks vary with the seasons Largest warm pool contribution in summer (JAS) Mode waters in autumn (OND) and winter (JFM) Eighteen Degree Water (JFM) Formation in T-S space (seasonal)

Formation areas

Discussion and outlook Good qualitative agreement with literature; quantitative comparison is subject to current efforts, besides extension to additional ocean basins over long time lags. The method is not taking into account advection/mixing processes. Uncertainties associated with the choice of the input data need to be assessed further and quantified (ongoing). This approach allows to pinpoint the range of SST and SSS in the T-S diagrams where a specific water mass is formed. Known water masses can be identified and their formation traced in time and space. The geographical representation of these points, ultimately, allows to provide a relevant temporal series of the spatial extent of the water masses formation areas. Longer time series will contribute to the understanding of the temporal variability in water mass formation (both in T-S and geographical domains). Future work aims at exploring additional datasets and at connecting the surface information to the vertical structure and to buoyancy-driven ocean circulation processes.

Follow-on Turner angle (potential instability) Master student or COST STSM opportunities? Tippins et al., 2003) Horizontal Turner angle [Tippins et al., 2003; Johnson et al., 2012], Vertical Turner angle and Climatological Turner angle atlas [Yuzhou You et al. 2012] Information on vertical gradients available (Vinogradova et al. 2013; Ifremer) Splitting into stable and unstable areas Overlap with water masses formation areas extent

Thank you

“Formation equation” (Trans-)Formation Mean annual SSσ [kgm -3 ]

Water mass (trans-)formation As a function of density 1 | Water masses from SMOS and OSTIA | Klockmann et al | EO4OAIS 2014 | ESRIN - Frascati

Indian Ocean Seasonal Formation

Mismatches