Circulation in the “Freshwater Switchyard” of the Arctic Ocean Michael Steele Polar Science Center, APL/UW Peter Schlosser & Bill Smethie Lamont-Doherty Earth Observatory, Columbia Univ. Ron Kwok Jet Propulsion Laboratory, NASA/Caltech
The “Canadian/Greenland Data Hole”: …perhaps the most poorly sampled region of the Arctic Ocean! EWG winter SSS obs. (200 km bins) Freshwater outflows
Large-scale sections Boundary current section The “freshwater switchyard”: A good place to detect the origins of freshwater that’s about to leave the Arctic Ocean …based on Jones et al. (1998); Steele & Boyd (1998); Proshutinsky et al. (2002); Rigor et al. (2002) • 3 project components: • Large-scale hydrochemical sections (Schlosser/Smethie/Swift) • Boundary current section at the shelf break (Steele) • Sea ice transport studies (Kwok)
Details Alert-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 stations CTD-O, XCP, surface layer bottles. • Sea ice transport studies: satellites • uice: AMSR passive μwave, ENVISAT SAR; • hice: altimeters on IceSAT (laser) & ENVISAT, CryoSAT (radar) …modified from Newton & Sotirin (1997)
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.
summer BSW Temperature (°C) Atlantic water Salinity Oxygen (ml/L) 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 extrema
Switchyard remote sensing 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. • 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
2) Share helo logistics w/ Falkner? 2) Share helo logistics w/ Falkner? 3) CRYOSAT 1) THICR deployed for Alert-NP section(s) 3) ENVISAT, AMSR, IceSAT 1) THICR development; NPEO does Alert-NP 2) bdry. current survey 3) prelim. satellite anal. spring, 2003 2004 2005 2006 2007 Timeline&Linkages We are here! • 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?