Mass and heat exchanges across the Greenland Scotland Ridge and the AMEX budget balance
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image:AGU 2003 Steingrímur Jónsson, University of Akureyri & Marine Research Institute Héðinn Valdimarsson, Marine Research Institute, Reykjavik Bogi Hansen, Faroe Marine Research Institute, Tórshavn Karin Margretha H. Larsen, Faroe Marine Research Institute, Tórshavn Barbara Berx, Marine Scotland Science, Marine Laboratory, Aberdeen Toby Sherwin, SAMS, Scottish Marine Institute, Oban Steffen M. Olsen, Danish Meteorological Institute , Copenhagen Kerstin Jochumsen, Institut für Meereskunde, Universität Hamburg Detlef Quadfasel, Institut für Meereskunde, Universität Hamburg Svein Østerhus, Uni Research, Bergen from space by winds by ocean currents Heat Mass and heat exchanges across the Greenland Scotland Ridge and the AMEX budget balance Trieste 10 Oct. 2013
description
Mass and heat exchanges across the Greenland Scotland Ridge and the AMEX budget balance. from space. Heat. by winds. by ocean currents. Steingrímur Jónsson, University of Akureyri & Marine Research Institute Héðinn Valdimarsson , Marine Research Institute, Reykjavik - PowerPoint PPT Presentation
Transcript of Mass and heat exchanges across the Greenland Scotland Ridge and the AMEX budget balance
image:AGU 2003
Steingrímur Jónsson, University of Akureyri & Marine Research InstituteHéðinn Valdimarsson, Marine Research Institute, ReykjavikBogi Hansen, Faroe Marine Research Institute, TórshavnKarin Margretha H. Larsen, Faroe Marine Research Institute, TórshavnBarbara Berx, Marine Scotland Science, Marine Laboratory, AberdeenToby Sherwin, SAMS, Scottish Marine Institute, ObanSteffen M. Olsen, Danish Meteorological Institute , CopenhagenKerstin Jochumsen, Institut für Meereskunde, Universität HamburgDetlef Quadfasel, Institut für Meereskunde, Universität HamburgSvein Østerhus, Uni Research, Bergen
from space
by winds
by ocean currents
Heat
Mass and heat exchanges across the Greenland Scotland Ridge
and the AMEX budget balance
Trieste 10 Oct. 2013
Bering S tra it
N aresStra it D avis S tra it
C ard iganStra it
LancasterSound
Denmark Strait
Hudson Strait
FSC
IFR
EnglishChannel
Arctic Mediterranean ExchangesAMEX
Transport (mass and heat) observatories1995-ongoing
From Bogi’s presentation at the kick-off
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Dep
th(m
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FaroeP lateau
FaroeBank
3°C2°C
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6°C7°C<8°C
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<-0.5°C>1.1 m/s 1 m/s
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FC FB FAAtla nticWa te r
Fa ro e Ba nk C ha nne l
Fa ro eBa nk
Fa roePla tea u
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NACLIM
Tools
Current meters (ADCP)Hydrography CTD-sections
image:AGU 2003
Atlantic inflow volume transport
No trend !!!!!!!!!!!!!!!!!!!!!!!!!
Icelandbranch
Inflowing Atlantic water (millions m3/second)
Faroebranch
No weakening
Shetlandbranch
No trend
image:AGU 2003
Icelandbranch
Inflowing Atlantic water (millions m3/second)
Faroebranch Shetland
branch
Atlantic inflow volume transport
Total Atlantic Volume Inflow1997-2011
7.1 Sv+- 1 Sv
8.5 Sv (Østerhus et al. 2005)
New results
Hansen et al. 2010, Jonsson and Valdimarsson 2012, Berx et al. 2013
0.7 Sv
Berx, Hansen, Østerhus, K. M. Larsen, T. Sherwin, and K. Jochumsen, (2013).
Combining in-situ measurements and altimetry to estimate volume, heat and salt transport variability through the Faroe Shetland Channel
Monthly mean net inflow from observations (FSC+IF+DS) and overflow (FBC+DS). Only months where all three (two) inflow (overflow) have been monitored are included. The net exchange is defined where both inflow and overflow are monitored.
Return flow / overflow
Volume budget”Old numbers”
( 1 Sv = 106 m3/s )
Q = 8.5 Sv (Østerhus et al. 2005)
6 Sv
2.5 Sv
Volume budget”New numbers”
( 1 Sv = 106 m3/s )
Q = 7.1 +- Sv
6 -? Sv
2.5 -? Sv
assumption: Bering Strait inflow ~ West of Greenland outflow. English Channel ~ NaN
Bering S tra it
N aresStra it D avis S tra it
C ard iganStra it
LancasterSound
Denmark Strait
Hudson Strait
FSC
IFR
EnglishChannel
Arctic Mediterranean Exchanges
AMEX BudgetGap Branch Sv Referance
Greenland Scotland Ridge Atlantic Inflow DS 0,90Jonsson & Valdimarson Atlantic Inflow IFR 3,50Hansen et al.
Atlantic Inflow FSC 2,70Berx et al 2013
Orkney–Shetland inflow 0,30Otto et al. (1990)
Surface outflow EGC -0,50Balance DS_Overflow -3,00Jochumsen et al IF_Overflow -0,70Beaird et al. 2013 FBC_Overflow -2,10Hansen & Østerhus 2007 WTR_Overflow -0,20Sherwin et al.English Channel Inflow 0,10Prandle et al. (1996)
Bering Strait 2001=0.7 2011=1.1 1,10Woodgate et al., 2012David Strait 2004-2005 -2,30Curry et al. (2011)Rivers + E-P 0,20Ref?Balance 0,00
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Heat Transport
Cooling: ΔT
Heat import = c · Q · ΔT ≈ c · Q · T
Volumetransport: Q
Temperature: T
Shetland branch
Faroe branch
Iceland branch
Atlantic inflow temperature 1950 – 2010
Heat import = c · Q · T
Temperature in Atlantic layer at station M1948-2010
Monthly mean
Yearlymean
The effect of SPG shrinkage(Hakkinen & Rhines, 2004; Hátún et al., 2005)
Warmer and more saline
Before 1995After 1995
3.01.5
0-1.5-3.0
Observed and simulated gyre index(SSH averaged for 60°W–15°W, 48°N–65°N)
Lohman et al. (2009)
Weak
Strong
3.01.5
0-1.5-3.0
Weak and Strong Gyre index
Lohman et al. (2009)
Weak
Strong
Atlantic Water Temperature in the Nordic Seas (M)
Bering S tra it
N aresStra it D avis S tra it
C ard iganStra it
LancasterSound
Denmark Strait
Hudson Strait
FSC
IFR
EnglishChannel
Arctic Mediterranean Exchanges
Next
• Including time series from Bering and David straits
• Combining observation and model results• Closing the AMEX budget on down to
seasonal / monthly time scale
Intensity and seasonality of the ocean exchange system with the Arctic Mediterranean west (a) and east (b) of Greenland. Stacked, monthly averaged contributions 1948-2010 from individual inflow (bottom) and outflow (top) branches are shown including in a) the English Channel (EC) light inflow (grey), Faroe Shetland Channel (FSC) Atlantic inflow (red) and dense, deep outflow (red), the Denmark Strait (DS) Atlantic inflow (green) and dense outflow (green) and the East Greenland Current (EGC) polar water outflow (blue). The net exchange is shown in black (positive for net inflow). In b) the inflow includes the light inflow through Bering Strait (BS) and outflows the polar water in Lancaster Sound (LS) and Nares Strait (NS).
Variability of transport estimates of inflow, overflow and outflow from the global model east of Greenland compared against observations. Model values have been bias corrected and only months where observational data exists are included in the annual means
Model (bias) Observed Model 1992-2010
East of GreenlandFSC inflow 2.65 (+0.05) 2.71 2.71IF inflow 3.88 (-0.34) 3.54 3.92DS inflow 0.73 (+0.1) 0.83 0.72EC inflow 0.08FSC overflow 1.73 (+0.41) 2.14 1.69
IF overflow 0.00DS overflow 2.41 (+0.96) 3.37 2.40EGC outflow 3.35Total in/out 7.35/7.44West of GreenlandBS inflow 1.03NS outflow 0.93LS outflow 0.24Total in/out 1.03/1.17
Comparison of modeled and observed exchanges for the individual period of observations. For reference, the model average budget is included for the complete 1992-2010.
Seasonality and characteristics of observed (black) and modeled (red) exchanges across the GSR. Seasonality (curves) is calculated as the average of monthly composites from available data in the period 1992 to 2012 and for the full model series (dashed). Variability of de-seasoned and de-trended data is illustrated by their distribution.
The research leading to these results has received funding from the European Union 7th Framework Programme (FP7 2007-2013), under grant agreement n.308299NACLIM www.naclim.eu
