Xiao-Hai Yan1, Young-Heon Jo1, Feili Li1 and Tim Liu2

1
Characteristic Features of DOC in the Labrador
Sea based on Multi-Sensor Measurements
AMOC

• Xiao-Hai Yan1, Young-Heon Jo1, Feili Li1 and Tim
  Liu2
• 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

2
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?

3
DOC and Subsurface Phenomena
Detecting Mediterranean Outflow and Meddies
(Yan et al.,JPO, 2006)
4

(Yan et
al.,JPO, 2006)
Methodology

• Integrated Multi-Sensor Data Analysis

5
NAUCW North Atlantic Upper Cold Water 2.5 - 5 C
NABCW North Atlantic Bottom Cold Water 0 - 2.5
C
6
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
7
Relation between DOC and NAO
Weak DOC
Strong DOC
8
Vertical structures of DOC from floats
measurements Weak and strong DOC events?
Yashayaev and Loder (2009)
9
Strategy to detect DOC events using RS
Fisher et al., 1999
Two proxies for detecting DOC LST
and SST differences and winds direction Steric
heights and steric ratios
10
Brunt-Vaisala (Buoyancy) frequency from a Float
How long it takes to reach 1800m depth?
Can SSHA contain DOC signals?
11
Land and Sea Surface Temperature with Winds
12
Satellite observations for weak and strong DOC
events
Weak DOC events Strong
DOC events
SSHA LST and SST Winds
13
Proxy I for DOC events based on temperature
differences
D
C
B
A
JAN JAN JAN JAN FEB FEB FEB FEB
A B C D A B C D
2006 -20.9118 4.5492 -39.3645 -31.9579 -19.5918 3.7614 -29.6853 -27.354
2007 -21.0718 4.1621 -36.757 -31.0443 -20.3802 3.7752 -27.9303 -25.0847
2008 -22.753 4.1342 -40.1385 -34.631 -20.4263 3.3542 -37.9148 -33.9247
14
Temperature comparisons over land and sea
Monthly temperature for Jan and Feb Weekly
temperature for Jan and Feb Weekly temperature
from 2006 to 2008
15
Steric height and its ratio (Sr) for Proxy II
Where, a and ß are the thermal and the salt
expansion coefficients, respectively.
16
Proxy II for DOC events based on steric height
ratio
4900500
4900537
4900683
17
2/154/15
2/154/15
2/154/15
STD SSHA
Mean SSHA
2007
2006
2008
18
Direct evidence for DOC by estimating subsurface
temperature(Kang, Jo and Yan,2010)
19
Simulation for STA
20
Comparisons between estimated and GODAS
measurements
21
Spatial Empirical Mode Decomposition for SSHA
(Jo, Yan, Li and Lee 2010)
22
Spatial Empirical Mode Decomposition for SST
(Jo, Yan, Li and Lee 2010)
23

• 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.