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Revealing Geophysically-Consistent Spatial Structures in SMOS Surface Salinity Derived Maps

Learn about SMOS L2 standard product, nonlinearities, new product design, singularity analysis geophysical assessment, and conclusions. Comparison, accounting for errors, and singularity analysis are key topics.

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Revealing Geophysically-Consistent Spatial Structures in SMOS Surface Salinity Derived Maps

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  1. Revealing Geophysically-Consistent Spatial Structures in SMOS Surface Salinity Derived Maps Marcos Portabella, Estrella Olmedo, Justino Martínez, Antonio Turiel SMOS Barcelona Expert Centre Pg. Marítim de la Barceloneta 37-49, Barcelona SPAIN E-mail: smos-bec@icm.csic.es URL: www.smos-bec.icm.csic.es

  2. Outline of the talk • SMOS L2 standard product • Accounting for non-linearities • New product design • Geophysical assessment with singularity analysis • Conclusions

  3. SMOS standard L2 product (I)

  4. SMOS standard L2 product (II) Comparison of distribution functions (real->grey theoretical->green): PORTION OF DISGARDED POINTS IS NOT ALLWAYS THE SAME Nm=97 Nm=33 Nm=137 Xi2/Nm>1.25 ALL THESE POINTS ARE FILTERED Xi2/Nm>1.25 ALL THESE POINTS ARE FILTERED Xi2/Nm>1.25 ALL THESE POINTS ARE FILTERED

  5. SMOS standard L2 product (III) Comparison of density functions (real->red theoretical->blue): Nm=33 Nm=97 Nm=137 >95% GOOD QUALITY >95% >95% GOOD QUALITY GOOD QUALITY BAD QUALITY BAD QUALITY BAD QUALITY BAD QUALITY BAD QUALITY <5% <5% <5%

  6. Accounting for nonlinearities (I) 1.- Floor error: smaller on 1st Stokes parameter

  7. Accounting for nonlinearities (II) 2.- Land sea contamination and 18-day subcycle: 18-day is the (approx.) repeat subcycle of the satellite; land-sea contamination has this inner cycle also (J. Tenerelli, private comm.) Intra-annual variability Inter-annual variability Annual mean From 9-day averages From 18-day averages

  8. Accounting for nonlinearities (III) 3.- Climatology may induce some biases

  9. Accounting for nonlinearities (IV) 4.- Some tails, many ripples  Nodal sampling Average reduction of std. dev. of 0.7 K

  10. Accounting for nonlinearities (V) 5.- Histograms of single retrievals of SSS have greater dispersion than expected 18-day single-angle SSS histograms

  11. Design of a new product (I) • Taking into account the discussed non-linear effects, we have designed a new L3 product: • Daily OTT • Derived from 1st Stokes parameter • 18-day, 0.5º resolution • Nodal sampling applied • SSS is computed averaging all single-angle SSS retrievals 3 psu around the mode of their distribution. • We have compared it with the standard DPGS product

  12. Standard 18-day binned map (CP34-BEC)

  13. Mean around the mode

  14. Standard 18-day binned map (CP34-BEC)

  15. Mean around the mode

  16. Comparison with Argo Real-Time Mode

  17. Geophysical assessment via SA (I) What is singularity analysis? All ocean scalars are submitted to the action of flow advection (the same for all them) plus other dynamic effects (specific). The ocean is a turbulent flow, both in 3D (vertical mixing, small scales of order of meters) and in 2D (horizontal dispersion, important at sub-mesoscale and greater scales). In a turbulent flow, advection creates sharp changes and irregularities in all scalars, which may be of small amplitude but are well characterized by a dimensionless scalar field: the singularity exponents field (denoted by h). Singularity analysis is a sophisticated mathematical technique to extract singularity exponents from maps of a given scalar.

  18. Geophysical assessment via SA (II) What is SA useful for? Singularity exponents of different ocean scalars must correspond, so they can be used to assess the quality of different products h = 0,15 SSS SST

  19. Standard 18-day binned map (CP34-BEC)

  20. Mean around the mode

  21. Standard 18-day binned map (CP34-BEC)

  22. Mean around the mode

  23. Conclusions • Many on-linear effects impact SSS retrievals in SMOS. • We have made an effort to reduce those effects and to create new maps as less biased as possible. • When compared to Argo, the new maps are globally less precise (greater. std. dev.) but more accurate (smaller bias) • Singularity analysis reveals consistent geophysical structures in the new products.

  24. GUI Singularity Analysis Singularity Analysis Web Service is now operational (registered users) http://cp34-bec.cmima.csic.es/CP34GUIWeb/

  25. SMOS-Mission Oceanographic Data Exploitation SMOS-MODE www.smos-mode.eu info@smos-mode.eu SMOS-MODE supports the network of SMOS ocean-related R&D Last meeting during 2nd SMOS Science Conference (May 2015)

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