Notes

Outline

The Physical Oceanography of Georges Bank and Its Impact on Biology Bob Beardsley, Ken Brink, Dick Limeburner, Jim Churchill, Jim Ledwell, Jim Irish (WHOI) Charles Flagg (BNL) Changsheng Chen, Jim Bisagni (UMD) Ron Schlitz (NMFS) Peter Smith, Dave Brickman, Guoqi Han (BIO)

Primary Objectives Better understand the physical dynamics and interactions of several specific processes (e.g., those associated with 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. 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. Provide other Phase 4 investigators with as complete a description and understanding of the basic physical processes affecting their observations as possible

Slide 3

GLOBEC moored arrays

Primary GLOBEC Data Sets

Finite-Volume Coastal Ocean Model (FVCOM) Changsheng Chen and Hedong Liu An unstructured grid, finite-volume, three-dimensional (3D) primitive equation ocean circulation model that combines advantages of Finite element method for geometric flexibility (e.g.,    Quoddy) Finite-difference method for simple discrete computation (ECOM-si) Model features triangular horizontal grid, sigma coordinate in vertical, Mellor-Yamada level 2.5 turbulent closure Currents, temperature and salinity are computed using integral forms of governing equations => improved conservation of mass, momentum, heat, salt over existing Quoddy and ECOM-si models.

Proposed Research Topics FVCOM application and evaluation Environmental Chronology Stratification and Flow Process Studies and Interannual Variability on the Bank Edges Tidal Mixing Front over Southern Flank

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)

2. Environmental Chronology Build online physical/biological timeline for 1995-1999 with focus on synoptic scale Physical variables include: T, S, Currents, Met,Cruise coverage, SW intrusions, W-C rings,SSC’s, other major perturbations) Biological variables ……

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).