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Xiao-Hai Yan 1, Young-Heon Jo 1, Feili Li 1 and Tim Liu 2 June 9, 2010 1 Center for Remote Sensing, University of Delaware 2 M/S 300-323, 4800 Oak Grove Dr. Jet Propulsion Laboratory, Pasadena, CA 91109 Characteristic Features of DOC in the Labrador Sea based on Multi-Sensor Measurements AMOC
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DOC Studies in LS Labrador Sea Group (1998)- Labrador Sea Deep Convection Experiment Marshal and Shott (1998)- Open ocean deep convection: Observations, theory and models Yashayaev and Loder (2009)-Enhanced production of Labrador Sea Water in 2008 Vage et al.(2009)- Return of DOC to subpolar NAO in winter 2007-2008 Lozier (2009)-Overturning assumptions based on NAO Remote Sensing? Fischer et al. (1999)-DOC using SAR (?) Hermann et al. (2009)-Monitoring DOC from space (Mediterranean Sea) How Good is RS for DOC observations?
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DOC and Subsurface Phenomena Detecting Mediterranean Outflow and Meddies (Yan et al.,JPO, 2006)
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4 Methodology Integrated Multi-Sensor Data Analysis Integrated Multi-Sensor Data Analysis Where Where
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5/23/2015 5 NAUCW: North Atlantic Upper Cold Water 2.5 - 5 °C NABCW: North Atlantic Bottom Cold Water 0 - 2.5 °C
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Where is DOC in LS? When does it occur? Can we observe/monitor it? How much does water sink? How much contribution to the AMOC…… Chanut et al., 2008
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Relation between DOC and NAO Strong DOC Weak DOC
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Vertical structures of DOC from floats measurements Weak and strong DOC events? Yashayaev and Loder (2009)
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Strategy to detect DOC events using RS Two proxies for detecting DOC LST and SST differences and winds’ direction Steric heights and steric ratios Fisher et al., 1999
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Brunt-Vaisala (Buoyancy) frequency from a Float How long it takes to reach 1800m depth? Can SSHA contain DOC signals?
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Land and Sea Surface Temperature with Winds
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Satellite observations for weak and strong DOC events Weak DOC events Strong DOC events SSHA LST and SST Winds
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B C A D Proxy I for DOC events based on temperature differences
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Temperature comparisons over land and sea Monthly temperature for Jan and Feb Weekly temperature for Jan and Feb Weekly temperature from 2006 to 2008
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Steric height and its ratio (S r ) for Proxy II Where, α and β are the thermal and the salt expansion coefficients, respectively.
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Proxy II for DOC events based on steric height ratio 4900500 4900537 4900683
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STD SSHA Mean SSHA 2/15~ 4/15 2008 20072006
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Direct evidence for DOC by estimating subsurface temperature (Kang, Jo and Yan,2010)
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Simulation for STA
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Comparisons between estimated and GODAS measurements
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Spatial Empirical Mode Decomposition for SSHA (Jo, Yan, Li and Lee 2010)
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Spatial Empirical Mode Decomposition for SST (Jo, Yan, Li and Lee 2010)
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Preliminary Conclusion Difficult to detect precondition of DOC, but possible to monitoring DOC after convection. Two proxies are useful to monitor changes in water column of DOC and non-DOC sites. Temperature proxy for DOC shows that low SST requires LST threshold at - 3 C between Green Land and West of Baffin Sea. Steric height ratio proxy shows ~ 8 times larger for strong DOC than weak DOC. Subsurface temperature can be estimated from SSHA and provide information for AMOC & DOC analyses. Caution is required in analyzing with satellite data since there are still other similar signatures. EEMD can be used to decompose different spatial scales.
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