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!