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SMOS-BEC – Barcelona (Spain)
Revealing Geophysically-Consistent Spatial Structures in SMOS Surface Salinity Derived
Maps
Marcos Portabella, Estrella Olmedo, Justino Martínez, Antonio Turiel
SMOS Barcelona Expert CentrePg. Marítim de la Barceloneta 37-49, Barcelona SPAINE-mail: [email protected]: www.smos-bec.icm.csic.es
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Outline of the talk
• SMOS L2 standard product
• Accounting for non-linearities
• New product design
• Geophysical assessment with singularity analysis
• Conclusions
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SMOS standard L2 product (I)
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SMOS standard L2 product (II)
Xi2/Nm>1.25
ALL THESE POINTS ARE FILTERED
Nm=33 Nm=97 Nm=137
Xi2/Nm>1.25
ALL THESE POINTS ARE FILTERED
Xi2/Nm>1.25
ALL THESE POINTS ARE FILTERED
Comparison of distribution functions (real->grey theoretical->green):PORTION OF DISGARDED POINTS IS NOT ALLWAYS THE SAME
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SMOS standard L2 product (III)
5 / 10
Nm=33 Nm=97 Nm=137
Comparison of density functions (real->red theoretical->blue):
>95%
<5%
BAD QUALITY
BAD QUALITY
GOOD QUALITY
GOOD QUALITY
GOOD QUALITY
>95% >95%
<5% <5%
BAD QUALITY
BAD QUALITY
BAD QUALITY
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Accounting for nonlinearities (I)
1.- Floor error: smaller on 1st Stokes parameter
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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.)
From 9-day averages From 18-day averages
Annual meanIntra-annual variabilityInter-annual variability
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Accounting for nonlinearities (III)
3.- Climatology may induce some biases
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Accounting for nonlinearities (IV)
4.- Some tails, many ripples Nodal sampling
Average reduction of std. dev. of 0.7 K
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Accounting for nonlinearities (V)
5.- Histograms of single retrievals of SSS have greater dispersion than expected
18-day single-angleSSS histograms
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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
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Standard 18-day binned map (CP34-BEC)
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Mean around the mode
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Standard 18-day binned map (CP34-BEC)
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Mean around the mode
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Zone Description Latitude Longitude
Global Tropics and mid-latitudes 60S-60N All
Tropic Tropics 30S-30N All
NPac A region of the North Pacific 45N-60N 170E-140W
Z122 A region of the South Eastern Pacific 30S-0N 150W-120W
Z124 A region of the South Western Tropical Pacific 24S-10S 165E-165W
Z126 Equatorial Oceans 10S-10N All
Z131 Southern Ocean 60S-40S All
Z132 Intertropical Pacific 5N-15N 110W-180W
OTT Zone used for the OTT computation 45S-5S 140W-95W
Comparison with Argo Real-Time Mode
ARGO comparison
Global Tropic Npac Z122 Z124 Z126 Z131 Z132 OTT
CP34-BEC (18-d)
Mean -0.19 -0.20 -0.62 -0.09 -0.10 -0.22 0.02 -0.21 -0.05
Std 0.38 0.33 0.69 0.20 0.28 0.33 0.53 0.26 0.23
Nbuoys 3720 2221 66 151 372 798 566 125 295
Mean around mode
Mean 0.03 -0.05 -0.17 0.07 0.04 -0.08 0.43 -0.06 0.25
Std 0.56 0.49 1.11 0.25 0.38 0.43 0.80 0.33 0.28
Nbuoys 4243 2602 88 155 386 842 530 125 297
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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.
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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
Geophysical assessment via SA (II)
SSTSSS
h = 0,15
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Standard 18-day binned map (CP34-BEC)
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Mean around the mode
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Standard 18-day binned map (CP34-BEC)
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Mean around the mode
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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.
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GUI Singularity Analysis
27 / 10
http://cp34-bec.cmima.csic.es/CP34GUIWeb/
Singularity Analysis Web Service is now operational (registered users)
Last meeting during 2nd SMOS Science Conference (May 2015)
SMOS-Mission Oceanographic Data ExploitationSMOS-MODE
SMOS-MODE supports the network of SMOS ocean-related R&D
