THOR Annual MeetingTHOR Annual Meeting
Paris, 24 November 2009Paris, 24 November 2009
Nuno Nunes,Nuno Nunes,
Jürgen Fischer,Rainer Zantopp, Martin VisbeckJürgen Fischer,Rainer Zantopp, Martin Visbeck
Recent changes in properties andRecent changes in properties and
transport in the Labrador Seatransport in the Labrador Sea
GreenlandScotland Ridge
O
erfl
Ve
ntila
tion
Compensating flow
v
OverflowWater 0°C
6 Sv
NADW 3°C16-18 Sv
6 Sv
Mixing 12 Sv
Arctic
CoolingLowlatitude
En
train
me
nt
6°CL
ab
rad
or S
ea
Ve
nt.: 4
-6 S
v
Up-welling
Surface outflow 3 Sv
Fresh-water
Atlantic inflow
ow
Overturning Circulation in NA
THOR Annual Meeting – Paris 2009 – Nunes/Fischer/Zantopp/Visbeck
Overview
Update on Labrador Sea mooring operations
Variability of the WBC at 53°N
Central Labrador Sea (K1) temperature timeseries
THOR Annual Meeting – Paris 2009 – Nunes/Fischer/Zantopp/Visbeck
Mooring operationsMaria S. Merian 12/1
(May/June 2009)
4 moorings recovered and re-deployed 2 additional moorings on 53 N array will be serviced again in July 2010 (RV Meteor)
THOR Annual Meeting – Paris 2009 – Nunes/Fischer/Zantopp/Visbeck
Mooring operations
THOR Annual Meeting – Paris 2009 – Nunes/Fischer/Zantopp/Visbeck
K8
K9
K10
Mooring operations
THOR Annual Meeting – Paris 2009 – Nunes/Fischer/Zantopp/Visbeck
K9 drifted for 5 weeks prior to recovery
Argo Watchdog allowed
us to follow drift path
Recovered approx.
75 nm from mooring
position
10 out of 12 instruments
recovered with full record
AR recovered, locked:
anchor chain corrosion?
Mooring operations
THOR Annual Meeting – Paris 2009 – Nunes/Fischer/Zantopp/Visbeck
“normal” appearance of recovered chain
…and what was left of K10's anchor chain!!!
Mooring operations
THOR Annual Meeting – Paris 2009 – Nunes/Fischer/Zantopp/Visbeck
?
Mooring operations
K9 after 5 weeks adrift
A bit of weather...
(photo courtesy of T. Wasilewski)
THOR Annual Meeting – Paris 2009 – Nunes/Fischer/Zantopp/Visbeck
Complete array from June 1997- July 1997 only
1999-2001: 2 moorings
2001-2003: 3 moorings
2003-2005: 1 mooring
2005-2007: 1 mooring
2007-2009: 3 moorings
2009-2011: 5 moorings (funded elsewhere)
53°N
Present -- DSOW part will be strengthened
THOR Annual Meeting – Paris 2009 – Nunes/Fischer/Zantopp/Visbeck
WBC at 53°N
WBC at 53°N
THOR Annual Meeting – Paris 2009 – Nunes/Fischer/Zantopp/Visbeck
LS Boundary Current Data1.Two years with full array2.10 years reduced coverage
Full Array
Reduced Array
Structure by EOF‘s Expl. Variances
Det. of uncertainties
regress to EOF‘s
Integrate 12 y BC
Transport + Errortime series
WBC at 53°N
THOR Annual Meeting – Paris 2009 – Nunes/Fischer/Zantopp/Visbeck
EOF‘s 1997-1999•Mode 0 – mean flow field•Mode 1 – LC-mode with annual cycle•Mode 2 – meander mode •Mode 3 – BC pulsation
Modes for annual subsets very similar!
Modes 1-3 explain 80% of the variance
WBC at 53°N
THOR Annual Meeting – Paris 2009 – Nunes/Fischer/Zantopp/Visbeck
WBC at 53°N
THOR Annual Meeting – Paris 2009 – Nunes/Fischer/Zantopp/Visbeck
WBC at 53°N
THOR Annual Meeting – Paris 2009 – Nunes/Fischer/Zantopp/Visbeck
Central Lab Sea temperature
THOR Annual Meeting – Paris 2009 – Nunes/Fischer/Zantopp/Visbeck
Central Lab Sea temperature
THOR Annual Meeting – Paris 2009 – Nunes/Fischer/Zantopp/Visbeck
Heat flux anomaly (Vage et al., 2008)
Central Lab Sea temperature
Convection and bouyancy fluxes
Patchy vs. basin-wide convection: connection with depth?
What can Argo floats tell us?
THOR Annual Meeting – Paris 2009 – Nunes/Fischer/Zantopp/Visbeck