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Physical Oceanography of Georges Bank and Its Impact on Biology Update – June 2004 Grant Period: 7/02-7/05. Bob Beardsley, Ken Brink, Dick Limeburner, Jim Churchill, Jim Ledwell, Jim Irish, Mike Caruso, Jim Lerczak (WHOI) Charles Flagg (BNL) Changsheng Chen, Jim Bisagni (UMD)
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Physical Oceanography of Georges Bank and Its Impact on BiologyUpdate – June 2004Grant Period: 7/02-7/05 Bob Beardsley, Ken Brink, Dick Limeburner, Jim Churchill, Jim Ledwell, Jim Irish, Mike Caruso, Jim Lerczak (WHOI) Charles Flagg (BNL) Changsheng Chen, Jim Bisagni (UMD) Ron Schlitz (NMFS)
Primary Objectives • To understand the physical dynamics and interactions of several specific processes (e.g., the seasonal evolution of stratification on the Bank, the crucial flow field over the Northeast Peak, and cross-frontal exchange within the tidal mixing and northern flank fronts) that are thought to play critical roles in zooplankton and fish recruitment. • To combine these observationally based process synthesis studies into model-based studies to provide our best descriptions of the Bank's physical environment and its variability on time scales from minutes to monthly to seasonal for the GLOBEC field years. • To provide other Phase IV investigators with as complete a description and understanding of the basic physical processes affecting their observations as possible.
2002-2004 Activities • JGR-Oceans Special Section • Environmental Chronology • 1999 Stratification and Flow Synthesis • Process Studies and Interannual Variability on Bank Edges • 1999 Tidal Mixing Front over Southern Flank • FVCOM Development, Application, and Evaluation
U.S. GLOBEC: Physical processes on Georges BankJGR-Oceans Special Section GLOBEC (Georges Bank), Nov. 2003 • 1995 Stratification Study: surface forcing; temperature & salt balances; bottom stress & tidal boundary layer; slope water intrusions. • 1999 Frontal Studies: northern flank tidal & subtidal variability, cross-frontal fluxes and mixing. • 1997, 1999 Scotian Shelf Water “cross-overs”: spring 1997; winter-spring 1999. • 1995-1999 Bank/Seasonal Scale: surface drifter flow; ADCP flow. • Seasonal/interannual Scale: Halifax section variability; Nitrate supply and new production on GB • Model Process Studies: diurnal heating on GB stratification; wind-forced cross-front exchange on GB; temperature and flow influences on Calanus in Gulf of St. Lawrence and Scotian Shelf
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Environmental Chronology • Processing of 1999 Eastern Flank Frontal Exchange moored array and drifter data completed (Limeburner) • Reprocessing of 1994-1999 Long-Term moored array data completed (Irish, Caruso, Limeburner, Beardsley) • Preparation of WHOI Tech Report on LT data set including description of the measurements at all sites plus a physical chronology at the Southern Flank site(Irish, Caruso, Beardsley -July 2004 completion date!!!) • Analysis of LT moored data started (Brink)
1999 Stratification and Flow Synthesis • Characterization of subtidal oscillatory flow (Limeburner) • Description of eastern flank physical variability based on LT and FE moored data to be started (Beardsley, Limeburner,Flagg) Process Studies and Interannual Variability on Bank Edges • Seasonal and Interannual Variability of the Shelf-Slope Front Between 75° and 50° W (Bisagni) • Instability of Northern Flank Jet Study started (Brink, Pringle)
1999 Tidal Mixing Front over Southern Flank • Analysis of TMF ADCP array (Lerczak, Schlitz) • Analysis of 1999 Ledwell tracer release experiment started(Churchill,Ledwell) FVCOM Development, Application, Evaluation • GoM MM5 developed to produce surface forcing for 1995 and 1999 (Chen, Beardsley) • FVCOM simulation of 1995 and 1999 stratification seasons completed (Chen) • FVCOM comparison with other coastal models (POM, ROMS) on test problems (Chen, Cowles, Hedstrom, Beardsley) • FVCOM simulation for Houghton 1999 tracer release experiment completed (Chen, Houghton, Beardsley) • First FVCOM Users’ Workshop - June 2004 (Chen, Cowles, Beardsley)
Next Activities (Incomplete Draft 6/21) • Complete LT moored array Tech Report (Irish, Caruso, Beardsley) • Write up analysis of 1999 TMF ADCP array (Lerczak, Schlitz) • Write up Houghton 1999 tracer release FVCOM results (Chen,….) • Start analysis of Ledwell 1999 tracer release data (Churchill, Ledwell) • Complete LT moored array analysis, description of 1999 Eastern Flank variability (Brink, Limeburner, Flagg, Beardsley) • Evaluate FVCOM 1995 and 1999 stratification season simulations (Chen, Beardsley, …) • Complete northern flank jet instability study (Brink, Pringle, Chen) • Continue FVCOM development and scientific testing • Others ????
The 1995 and 1999 GOM/GB Model Experiments Meteorological forcing GOM/GB MM5 Wind stress, heat flux Assimilation Boundary forcings • SST • Hydrographic survey CTD • ADCP • Moored current meter data • Real-time tidal forcing • River discharges • Scotian shelf water input The FVCOM GOM/GB Physical Model
1. FVCOM application and evaluation • Realistic simulations (tidal forcing, surface forcing (stress, Q, E-P), runoff, upstream forcing (Fss) • Process studies (diurnal heat flux on stratified tidal rectification; cross-front exchange across NF frontal jet) • Evaluation (comparison of time series, event behavior (Jan-Feb,1995; Apr-Jun,1999), statistical comparisons)
3. Stratification and Flow Use FVCOM to hindcast currents and T,S stratification during GLOBEC field years • Feb-Aug 1995 (can FVCOM predict accurately flow over 1-8 months; extend SF T/S budget analysis to other parts of Bank) • Jan-Jun 1999
4. Process Studies and Interannual Variability on the Bank Edges • Analysis of existing data for NF, NE Peak, NE Channel, Scotian Shelf to provide synoptic pictures of physical properties and biological content of NEP region • FVCOM simulations 1999 (realistic surface forcing; effect of WCRs on SSCs; effect of alternative wind stress on surface cross-front Ekman transport)
5. Tidal Mixing Front over Southern Flank • Detailed analysis of 1999 TMF physical data (moored, shipbroad, dye, ….) • FVCOM simulation of Mar-Jun 1999 TMF results (test of MY mixing through dye studies, VPR, drifters,..) • Extension to 1997 and 1995 periods of extensive SF TMF sampling
Proposed Work - Year 1: 2002 - 03 Complete • FVCOM dev & diurnal heating/tidal mixing front process study (1) • Physical component online environmental chronology (2) • Synthesis of 1999 bank-wide stratification data (3) • Assessment of interannual variability for SSCs on Northeast Peak from historical hydrographic database (4) • Synthesis of 1999 southern TMF physical/biological data (5) • Analysis of structure, variability, and loss potential of SSF (3, 4) Start • Realistic FVCOM simulations of 1995, 1999 stratification seasons (1, 3) • Realistic FVCOM simulation of 1999 dye dispersion/mixing data (5) • Process FVCOM studies of frontal exchange mechanisms along northern flank (1)
Year 2: 2003 - 03 Complete • Assessment of SSC interannual variability using satellite SST and TOPEX/Poseidon altimeter data • Evaluation of FVCOM 1995 and 1999 seasonal simulations • Evaluation of FVCOM 1999 tidal mixing front simulations • Process FVCOM studies of interannual variability for SSCs using a linear superposition of wind and upstream perturbations to the mean circulation • Combined analysis of towed, shipboard, and moored acoustic descriptions of zoo-plankton distributions
BIO Work Plan Topic A: What are the impacts of Scotian Shelf Cross-overs on the population dynamics of the target species? • Model studies of interannual variability of SSC events, including analysis of historical hydrographic data and altimetry and modeling of interannual drift variability using Chen’s model (Brickman, Smith, Han, Hannah) • Model study of physical mechanisms driving SSCs (Smith, Brickman). • ELS modeling of cod and haddock in SSCs,including effects of temperature, food supply, etc on growth and survival, and possibly demographics of adults stocks. (Brickman, Frank). Topic C: How do large-scale interannual and interdecadal variabilities affect population dynamics of the target species? • Analysis of upstream sources of water masses and biota, including historical hydrographic data, freshwater sources, etc. (Smith, Hannah, Loder) • Study of interannual variability of sea level (‘92-’00) using TOPEX/POSEIDON altimetry (Han, Smith, Loder).
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