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Observations of Lake Superior Physical Processes. Jay Austin Large Lakes Observatory, UM-Duluth CSMI meeting 24 September 2013. Outline. Mooring array, 2005-Present Meteorological buoys Glider operations Profiler operations. NSF mooring array.
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Observations of Lake Superior Physical Processes Jay Austin Large Lakes Observatory, UM-Duluth CSMI meeting 24 September 2013
Outline • Mooring array, 2005-Present • Meteorological buoys • Glider operations • Profiler operations
NSF mooring array • 2005-present, up to seven locations in Lake Superior • 10-15 thermistors/mooring, ADCPs, DO, sed traps, ice profiler • Visited each 1-2/year • core moorings currently deployed • Recent results • Austin 2013, L&O, “Near Inertial oscillations in Lake Superior” • Titze and Austin, sub. To L&O, “Winter Thermal structure in Lake Superior” • Brethauer and Austin, in prep., “Observations of radiatively driven convection in Lake Superior” • Gloege and Austin, in prep., “Distribution of near-inertial energy in Lake Superior”
Lake Superior Mooring Array Core Moorings: Western, Central, and Eastern Outer Moorings: Far Western, Northern, Southern, Far Eastern
Lake Superior Mooring Array • Year-round deployment • Thermistors span the water column at each location • Temperatures recorded at 1- to 10- minute intervals • Surface temperature near core moorings available from NDBC
Thermistor Data • General dimictic pattern • Strong summer stratification • Weaker negative stratification in the winter
Interannual and Spatial Variations • Significant interannual and spatial variation in the data • 2009 – Cold winter with high ice cover • 2012 – Warm winter with very little ice cover
Raw velocities, WM (E-W and N-S) East-West North-South
Meteorology buoys • Two buoys in western arm- near McQuade, offshore (NDBC 45027, 45028) • 2010-present, Apr-Nov • WS/WD, AT, WT x10, RH, PAR, SW, BP • Used by NWS Duluth for near-shore forecasts
Glider program • Active field activities in 2011 (~50 days) , 2012 (~35 days), and 2013 (~18 days, +12 Tahoe) • Repeats of line in Western arm in 2011-12 • Keweenaw IR in 2013 (3x so far) • T, C, P, DO, Tr, Chl-A, CDOM • Very high horiz. Resolution • High endurance • No weather bias (but ice bias) • Austin, JGLR 2013, “Potential for Autonomous Gliders in large lake research”
Temperature, conductivity, depth • Chl-a and CDOM fluoresence • Backscatter @700nm • Dissolved oxygen • (position- lat/lon)
Too close to shore Just right Too deep- bottom currents weak
Temperature/Conductivity/Depth • Currents (ADCP) • Chl-a, CDOM, PC, and PE fluoresence • Backscatter @ 700nm • Dissolved Oxygen • Nitrate • PAR