Presentation on theme: "Past, current and envisioned activities in the Labrador Sea"— Presentation transcript:
1 Past, current and envisioned activities in the Labrador Sea of IFM-GEOMAR (Kiel)Torsten KanzowInput from Jürgen Fischer, Nuno Nunez, Rainer Zantopp
2 Outline History of boundary current measurements at 53°N Goals of proposed experimentenvisioned implementation, logistics, etcFuture funding propects for 53°NCentral Labrador Sea Mooring continued?
3 DWBC measurements at the exit of Labrador Sea Fischer et al. (2004)
4 DWBC measurements at the exit of Labrador Sea Warming of LSW at K9Fischer et al. (2004)Fischer et al. (2010)Annual meanVelocity profiles
5 “The Impact of Ocean Margin Processes in the Labrador Sea on the Atlantic Meridional Overturning Circulation”proposed to German Science Association (DFG) by T. Kanzow and C. Böning (IFM-GEOMAR, KIEL)OSNAP Subpolar Observing System
6 Goals Observe seasonal changes of newly formed Labrador Sea Water in the DWBC at 53°N continuously (transports in density classes).Verify Pickart and Spall.What mechanism sets downwelling: Eddies or surface buoyancyfluxes? Are there strong seasonal changes in sinking?Link DWBC measurements to other OSNAP elements to inferLabrador Sea overturning continuouslyMaintain 53°N measurements as MOC indicatorRole of boundary processes in Labrador Sea for the strength andtemporal variability of the basin-wide MOC
7 BackgroundA. Estimates for overturning in Labrador Sea are very uncertainPickart and Spall (2007): 1 Sv (depth space) or 2 Sv (density space) Based on spring /summer hydrographic dataNumerical Simulation at 53°N:Same year ventilated / total transportNumerical Simulation:Ventilation tracer in MayBrandt et al. (2007)
8 Downwelling 2. Lateral heat flux B. Downwelling in Labrador Sea takes place along boundaries(e.g. Spall 2004)Two main processes for downwelling: DWBC looses heat due to2. Lateral heat flux1. Heat loss to the atmosphereEddykineticenergy(Funk et al.,2009)Pickart et al.(2008)
9 Downwelling Downwelling produces along-boundary pressure change of opposite sign in upper and deep layer
10 Elements of proposed observing system 53°N array (red circles) to compute exportof LSW, in collaboration with DFO-BIO, UW.Use of pressure sensor (blue triangle)at 3isobaths (500m, 1000m, 1500m) bothupstream (60.5°N) an downstream (53°N) ofdownwelling area at western boundary.Miguel Maqueda (Liverpool) will deployadditional pressure sensors at eastern end ofAR7W line.Density mooring upstream of 53°N at thecontinental slope at western end of AR7W(green square) to observe mixed layer depths(near-boundary water transformation) , incollaboration with DFO-BIO.
11 The proposed modified 53°N array Current meter + density (CTD) to compute transport in density classes.Density (salinity) and oxygen to detect newly transformed waters near the boundaryUpslope pressure sensors to compute downwelling
12 Propects of Future Funding for 53°N funded through BMBF (ministry of education and research)Second 4-year phase 2008 – 2012Unclear whether 3rd observational phase will be possible(no call issued, yet; but positive signs received)Submitted proposal to DFG (German Research Association)to cover 2012 – 2014Possibilities might also come up duringnext phase of EU THORIFM-GEOMAR is progressing fromLeibniz Association (WGL)to Helmholtz Association (HGF) Long-term monitoring in Labrador Sea has been identified asactivity to be covered through HGF basic funding (5 year funding;has yet to be reviewed)
13 High resolution modelling (Böning / Biastoch) Use of a high resolution (1/20°) nest in a global eddy-permitting (1/4°, ORCA025) model. Perform 50 year runs and sensitivity studies (e.g. isolation of buoyancy or wind forcing) to:Infer role of boundary processes in Labrador Sea for the strength and temporal variability of the basin-wide MOCUnderstand mechanisms for downwelling & locate areas of downwelling.
14 Logistics 2012 cruise Fischer & Quadfasel service ADCP in Flemish Pass (U Ham)service 53N arrayrecover CentraL Labrador Sea mooringdeploy BPRs at 60°N & 53°Nhydrography in Labrador Sea of 53°Nsection to Cape FarewellService Central Irminger Sea mooring(CIS; IFM-GEOMAR,KIEL)service Angmagssalik arrayService Denmark Strait ADCPs (U Ham)Mixing/entrainment in overflow plume(U HAM: hydrography + moorings;IFM-GEOMAR: Micrstructure on AUV)2014 cruise proposal need to be submitted in November 2011
15 Central Labrador Sea mooring Monitoring of mixed layer depths since 1995Gaps party filled with Argo Float dataCurrenly funded through EU THOR Programme (ends 2012)Future is uncertain: Can Argo floats take over?will be a topic during Canada-Germany workshop (Halifax; 06/2011)