ott/drift analysis level 2 ocean salinity
DESCRIPTION
OTT/drift analysis Level 2 Ocean Salinity. 24 October 2012. ARGANS & L2OS ESL. Retrieved salinity drift during 2012. SSS1 – same results with SSS2/3, same trend with ascending/descending, so not TEC or GN. Retrieved salinity anomaly. - PowerPoint PPT PresentationTRANSCRIPT
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SMOS L2 Ocean Salinity
OTT/drift analysisLevel 2 Ocean Salinity
24 October 2012
ARGANS & L2OS ESL
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SMOS L2 Ocean Salinity
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SMOS L2 Ocean Salinity
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SMOS L2 Ocean Salinity
Retrieved salinity drift during 2012
SSS1 – same results with SSS2/3, same trend with ascending/descending, so not TEC or GN
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SMOS L2 Ocean Salinity
Retrieved salinity anomaly
Why large drifts in anomalies: OTT are referenced to climatology?
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SMOS L2 Ocean Salinity
Retrieved salinity anomaly
Anomalies not so bad in SSS anomalies for 2011 REPR, same period
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SMOS L2 Ocean Salinity
OTT evolution
REPR from month 1 to 23; OPER after month 24Are OPER OTT good quality? Do they show same trends as 2011?
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SMOS L2 Ocean Salinity
OTT evolution
REPR from month 1 to 23; OPER after month 24Are OPER OTT good quality? Do they show same trends as 2011?
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SMOS L2 Ocean Salinity
OTT evolution
9 day time series products blur transitions due to OTT
Monthly OTT
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SMOS L2 Ocean Salinity
Are there any annual/long term drift trends in OTT?
Ascending AFFOV median deltaTB
Descending AFFOV median deltaTB
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SMOS L2 Ocean Salinity
OTT drift trends?
Ascending driftHH + 0.021 K/monthVV ~0 K/month
Descending driftHH + 0.013 K/monthVV ~0 K/month
Ascending AFFOV median deltaTB
Descending AFFOV median deltaTB
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SMOS L2 Ocean Salinity
OTT annual cycle?
Descending cycle stronger then ascending – why?
Individual OTT sometimes far from trends – why?
Ascending AFFOV median deltaTB
Descending AFFOV median deltaTB
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SMOS L2 Ocean Salinity
OTT mean
Physical temperature of antenna patches
(Tx+Ty)/2
with Sun in FOV
with Sun in FOV
LOCEAN (XB) analysis: positive correlation between OTTs and Sun declination.
(No correlation with galactic noise, emission from flat sea or roughness)
Annual variations Descending orbits
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SMOS L2 Ocean Salinity
(Tx+Ty)/2
with Sun in FOV
with Sun in FOV
OTT mean
Physical temperature of antenna patches
Annual variations Ascending orbits
LOCEAN (XB) analysis: negative correlation between OTTs and Sun declination.
(No correlation with galactic noise, emission from flat sea or roughness)
www.argans.co.uk
SMOS L2 Ocean Salinity
OTT/drift conclusions• All 3 L2OS ESLs have identified biases in SMOS Tbs very well correlated
with Tp7 (at least on descending orbits; R=0.9!); why? (the reprocessing was expected to correct for Tp7, but it does not).
• These biases cannot be explained by galactic noise, although we know that our galactic noise correction is probably imperfect. Justification:– in OTT computations, we exclude Tbs affected by large scattered GN (>4K);– when looking at the across track temporal evolution of the biases and of GN
averaged along dwell lines, the temporal evolution of the Tb biases is the same whatever the location across track contrary to the GN variations for which the phase of the temporal evolution depends on the across track location;
– the evolution of large GN and Tb biases seen by Joe are not well phased.
(JB email 17/10/2012)
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SMOS L2 Ocean Salinity
OTT/drift: the way forward?DPGS• Use a single MOTT for all orbits
– made from all 2012 DPGS (or 2011 REPR) OTTs– either keep MOTT offset constant & see drift in retrieved salinity– or apply parametric best-fit polynomial drift to MOTT
• Maintain running average OTT– either by regular execution of compareTBs on selected orbits (IDEAS)– or extend L2OS to write data for an OTT post-processor
REPR• NIR centred OTT, parametric, or running average?