1 / 15

Past, current and envisioned activities in the Labrador Sea of IFM-GEOMAR (Kiel)

Past, current and envisioned activities in the Labrador Sea of IFM-GEOMAR (Kiel). Torsten Kanzow (tkanzow@ifm-geomar.de). Input from Jürgen Fischer, Nuno Nunez, Rainer Zantopp. Outline. History of boundary current measurements at 53°N Goals of proposed experiment

hedda
Télécharger la présentation

Past, current and envisioned activities in the Labrador Sea of IFM-GEOMAR (Kiel)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Past, current and envisioned activities in the Labrador Sea of IFM-GEOMAR (Kiel) Torsten Kanzow (tkanzow@ifm-geomar.de) Input from Jürgen Fischer, Nuno Nunez, Rainer Zantopp

  2. Outline • Historyofboundarycurrentmeasurementsat 53°N • Goals ofproposedexperiment • envisionedimplementation, logistics, etc • Future fundingpropectsfor 53°N • Central 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 K9 Fischer et al. (2004) Fischer et al. (2010) Annual mean Velocity 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 • Observeseasonalchangesofnewlyformed Labrador SeaWater in • the DWBC at 53°N continuously (transports in densityclasses). • VerifyPickartandSpall. • Whatmechanismsets downwelling: Eddies orsurfacebuoyancy • fluxes? Are therestrong seasonalchanges in sinking? • Link DWBC measurementstoother OSNAP elementstoinfer • Labrador Seaoverturningcontinuously • Maintain 53°N measurementsas MOC indicator • Role of boundary processes in Labrador Sea for the strength and • temporal variability of the basin-wide MOC

  7. Background • A. Estimatesforoverturning in Labrador Seaareveryuncertain • PickartandSpall (2007): 1 Sv (depthspace) or 2 Sv (densityspace) •  Based on spring /summerhydrographicdata Numerical Simulation at 53°N: Same year ventilated / total transport Numerical Simulation: Ventilation tracer in May Brandt et al. (2007)

  8. Downwelling B. Downwelling in Labrador Sea takes place along boundaries (e.g. Spall 2004) • Two main processes for downwelling: DWBC looses heat due to 2. Lateral heat flux 1. Heat loss to the atmosphere Eddy kinetic energy (Funk et al., 2009) Pickart et al. (2008)

  9. Downwelling • Downwelling producesalong-boundarypressure • changeofoppositesign in upperanddeeplayer

  10. Elements of proposed observing system 53°N array (red circles) to compute export of LSW, in collaboration with DFO-BIO, UW. Use of pressure sensor (blue triangle)at 3 isobaths (500m, 1000m, 1500m) both upstream (60.5°N) an downstream (53°N) of downwelling area at western boundary. Miguel Maqueda (Liverpool) will deploy additional pressure sensors at eastern end of AR7W line. Density mooring upstream of 53°N at the continental slope at western end of AR7W (green square) to observe mixed layer depths (near-boundary water transformation) , in collaboration 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 boundary • Upslope pressure sensors to compute downwelling

  12. Propects of Future Funding for 53°N • fundedthrough BMBF (ministryofeducationandresearch) • Second 4-year phase 2008 – 2012 • Unclearwhether 3rd observationalphase will bepossible • (nocallissued, yet; but positive signsreceived) • Submittedproposalto DFG (German Research Association) • tocover 2012 – 2014 • Possibilitiesmight also comeupduring • nextphaseof EU THOR • IFM-GEOMAR isprogressingfrom • Leibniz Association (WGL) • to Helmholtz Association (HGF) •  Long-term monitoring in Labrador Seahasbeenidentifiedas • activitytobecoveredthrough HGF basicfunding (5 yearfunding; • hasyettobereviewed)

  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 MOC • Understand mechanisms for downwelling & locate areas of downwelling.

  14. Logistics • 2012 cruise Fischer & Quadfasel • service ADCP in Flemish Pass (U Ham) • service 53N array • recoverCentraL Labrador Seamooring • deploy BPRs at 60°N & 53°N • hydrography in Labrador Seaof 53°N • sectionto Cape Farewell • Service Central IrmingerSeamooring • (CIS; IFM-GEOMAR,KIEL) • serviceAngmagssalikarray • Service DenmarkStrait ADCPs (U Ham) • Mixing/entrainment in overflowplume • (U HAM: hydrography + moorings; • IFM-GEOMAR: Micrstructure on AUV) • 2014 cruise proposalneedtobesubmitted in November 2011 • 2016 ...

  15. Central Labrador Sea mooring • Monitoring of mixed layer depths since 1995 • Gaps party filled with Argo Float data • Currenly 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)

More Related