Circulation in the “Freshwater Switchyard” of the Arctic Ocean
Michael Steele Polar Science Center, APL/UW
Peter Schlosser & Bill SmethieLamont-Doherty Earth Observatory, Columbia Univ.
Ron KwokJet Propulsion Laboratory, NASA/Caltech
The “Canadian/Greenland Data Hole”:…perhaps the most poorly sampled region
of the Arctic Ocean!
Freshwateroutflows
EWG winter SSS obs.(200 km bins)
The “freshwater switchyard”:A good place to detect the origins of freshwater
that’s about to leave the Arctic Ocean
3 project components:
1.Large-scale hydrochemical sections (Schlosser/Smethie/Swift)
2.Boundary current section at the shelf break (Steele)
3.Sea ice transport studies (Kwok)
Large-scale sections
Boundary current section
…based on Jones et al. (1998); Steele & Boyd (1998); Proshutinsky et al. (2002); Rigor et al. (2002)
DetailsAlert-NP survey: Twin Otter aircraft, 6-9 stations
“THICR” = THrough-Ice CTD-Rosette, measuring T, S, O2, oxygen isotopes, tritium/3He, CFC’s, barium, & nutrients. Samples to be drawn at Alert.
Boundary current survey: helicopter, 6-9 stationsCTD-O, XCP, surface layer bottles.
…modified from Newton & Sotirin (1997)
Sea ice transport studies: satellites
uice: AMSR passive μwave, ENVISAT SAR;
hice: altimeters on IceSAT (laser) & ENVISAT, CryoSAT (radar)
Switchyard’03 + NPEO’03
NPEO stations
Switchyard stations
Switchyard’04
Helo ops 2004: • We plan to repeat the main
section centered at 84N, 65W.
• If time allows, we will make a second section centered at about 84N, 55W.
Twin Otter ops 2004: • We plan to repeat the Alert-
NPEO 2000/2003 section. Additional stations may be taken in coordination with helo ops.
Switchyard’03 results
Tmax: a water mass tracer • summer Bering Sea Water just
below the mixed layer.
• Atlantic water at depth
Oxygen extrema: a new discovery! • Low resolution bottle data have
often shown these extrema, but Seabird’s new continuously profiling sensor has defined them as never before.
•We propose that there exist 2 minima formed via biological processes on arctic shelves; the upper one from the
Chukchi/ESS, and the lower from the Barents/Kara seas.
Falkner, K., M. Steele, et al., Dissolved oxygen extrema in the Arctic Ocean halocline, in prep. for DSR, 2004.
Oxygen (ml/L)
Salinity
Temperature (°C)
summer BSW
Atlantic water
oxygenextrema
Switchyard remote sensing
Ice transport in the Switchyard
(here, across 45°W)• anomalously eastward in the 1990’s
• anomaly is small recently, but westward in the Lincoln Sea
Anomalies of ice motion (vectors) and surface air
pressure (contours), relative to 1978-2003 means.
Ice motion is OI blend of buoys and passive microwave.
Timeline & Linkages
Linkages with FWI:(a) observations: Proshutinsky, Falkner, Lee, other Canadian
Archipelago& Fram Strait activities, river discharge & chemical signature data (e.g., Peterson)
(b) modeling: Vörösmarty, Lettenmaier, Tremblay, other ice-ocean-river modelers
(c) logistics: NPEO, other Alert-based activities
Linkages with ARCSS:
SBI: Pickart and other boundary current studies (SBE)
Burning question: What is the fate of freshwater in the Arctic Ocean and downstream into the N. Atlantic Ocean?
spring, 2003 2004 2005 2006 2007
1) THICR development;NPEO does Alert-NPNPEO does Alert-NP
2) bdry. current survey
3) prelim. satellite anal.
1) THICR deployed for Alert-NP section(s)
3) ENVISAT, AMSR, IceSAT
2) Share helo logisticsShare helo logisticsw/ Falkner?w/ Falkner?
3) CRYOSAT
2) Share helo logisticsShare helo logisticsw/ Falkner?w/ Falkner?
We are here!We are here!