Global Ocean Salinity products from SMOS The NOC experience
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www.noc.ac.uk Global Ocean Salinity products from SMOS The NOC experience Christine Gommenginger Chris Banks Meric Srokosz Helen Snaith Contact: [email protected] [email protected]
Transcript of Global Ocean Salinity products from SMOS The NOC experience
www.noc.ac.uk
Global Ocean Salinity products from SMOS The NOC experience
Christine Gommenginger Chris Banks
Meric Srokosz Helen Snaith
Contact: [email protected] [email protected]
www.noc.ac.uk
Use of SMOS products at NOC
• Produce validated Level 3 SMOS sea surface salinity (SSS) products useful for science – 1˚x1˚, monthly in the first instance
• Based on ESA Level 2 SMOS data – Similar analyses and products for Aquarius
• Explore mitigation strategies to reduce artefacts & outliers
• Comparisons with data assimilating ocean model output (FOAM/NEMO) and in situ data (Argo, ship underway, PIRATA, drifters)
www.noc.ac.uk
Model Output: UKMO FOAM/NEMO Forecasting Ocean Assimilation Model based on
Nucleus for European Modelling of the Ocean
• operational • ¼º resolution daily • Averaged (mean) to 1º and
then monthly • Assimilates Argo data (as
well as SST, SSH and sea ice)
www.noc.ac.uk
Can FOAM/NEMO be used for validation?
Monthly – Nov 2011
www.noc.ac.uk
SMOS L3 Product v.1 • Based on ESA L2 (3_16) OS (Sept 2010) • Ascending and descending separately • 1ºx1º grid, monthly • Atlantic sector only [60ºS,60ºN],[80ºW,10ºE] • In-house QA:
– Keep only SSS>30 and SSS<40 – Keep if Nobs>25 in 1ºx1º cell
• Flags: – Reject <40 km from land – Keep if no issues with retrieval due to galactic noise,
sun- or moon-glint
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SMOS SSS Sept 2010 (Desc)
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Model 1 Model 2
Model 3 WOA05
Banks et al (In press) TGRS SMOS Special Issue
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SMOS L3 Product v.2 • Based on ESA L2 (3_17) OS (July 2011) • Ascending and descending separately • 1ºx1º grid, monthly • Global between [60ºS, 60ºN]
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SSS error distribution in different locations
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SSS Distribution 1º cell July 2011 July 2011 (A)
Model 1 July 2011 (D)
Model 1
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Location of SSS with error distribution
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July 2010 (A) Model 1
SSS1 (A) 1ºx1º cell July 2011
July 2010 (D) Model 1
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SMOS L3 Product v.3 • based on ESA L2 (3_17) OS (Feb-July 2011) • Ascending and descending separately • 1ºx1º, monthly median • Global between [60ºS, 60ºN] • No flags except
– Reject <40 km from land • In-house QA
– Nobs>25, SSS Error < 1
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SSS1 (D)
Feb 2011
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Processor error
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SSS1 (D)
March 2011
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SSS1 (D)
April 2011
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SSS1 (D)
May 2011
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SSS1 (D)
June 2011
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SSS1 (D)
July 2011
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L3 Temporal variability A vs D
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L3 Temporal variability A vs D
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L3 Temporal variability A vs D
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L3 Temporal variability A vs D
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L3 Temporal variability A vs D
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L3 Temporal variability A vs D
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SMOS L3 Product v.4 • Based on ESA L2 (5_00) OS (Nov 2011) • Ascending and descending separately • 1ºx1º, monthly median • Global between [60ºS, 60ºN] • In-house QA: Nobs>=25, SSS Error < 1 • Flags
– Reject >40 km from land – Keep if no geophysical issues (e.g. outliers, glint) (flag 25) – Keep if no retrieval issues (e.g. poor quality convergence)
(flag 26)
www.noc.ac.uk
Descending Ascending
SMOS L3 SSS1
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Nov 2011
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Descending Ascending
FOAM/NEMO minus L3 SMOS SSS1
-1 +1 ±0.1
Nov 2011
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Ascending
FOAM/NEMO cf L3 SMOS SSS1
Nov 2011
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FOAM/NEMO cf L3 SMOS SSS1
Descending
Nov 2011
www.noc.ac.uk
SMOS User feedback (1) • Not yet looked at latest processor version (V5_50)
– Successive ESA L2 OS products getting better ! • Frequent changes of processor makes analyses and
validation difficult – Need full time series of SMOS L2 OS products obtained
consistently with the same version(s) of the processor(s) – Consistent datasets essential to interpret temporal and
spatial changes of SMOS SSS and diagnose anomalies – Cannot compare more than one to ~ few months as ESA
processor(s) changes often & without warning • For scientific exploitation, we use (and recommend)
the CATDS/Ifremer products !
www.noc.ac.uk
• For non-expert users (like NOC), details about the processing and major changes to the processing are difficult to obtain – e.g. Tb calibration ? Application of OTT ?
• Contact with expert labs and ESA through regular science meetings is absolutely essential !
• Significant effort needed to educate potential users of SMOS data e.g. software to read data ! – Useful URLs we point people to (when asked, frequently)
• www.argans.co.uk/smos/pages/faqs.php • ww.argans.co.uk/smos/pages/history.html • smos.array.ca/web/smos/matlab-tool
SMOS User feedback (2)
