Goal: Understand chemistry, biology and physics of the Bay, at all points in the Bay, for all time Goal 2: Understand coupled processes given any combination of external forcing conditions

Physics: Goal of Characterizing Circulation, Mixing, Stratification Flushing, Transport, etc vs Tides Winds Runoff Density events Etc. Methods are Observations & Modeling Response Forcing

Key physical processes Flushing dynamics Transport and mixing Deep water resupply

Goal: Understand chemistry, biology and physics of the Bay, at all points in the Bay, for all time RETENTION - MIXING/TRANSPORT - RESUPPLY

ADCP deployment in Providence River Narragansett Bay Comm. x x Use ADCP Data for Model Calibrations Deployed July 7, 2005

ADCP deployment in Providence River x x Use ADCP Data > RETENTION GYRE Deployed July 7, 2005

Funding: NOAA, NBC

Flow in East Passage Flow out West Passage

Flow in East Passage Flow out West Passage Good Good or Bad?

Flow in East Passage Flow out West Passage Good Good or Bad? ? How is deep return flow partitioned?

Narragansett Bay hydrodynamic modeling Kincaid, Ullman, Bergondo, Pfeiffer-Herbert, Balt, La Sota, Rogers Funding: GSO-URI, Rhode Island Sea Grant, EPA-TMDL, Vetillson Foundation, Narragansett Bay Commission, NOAA Hypoxia

Initial Conditions Forcing Conditions Output Numerical Model ROMS Model Conservation Equations 3D T, S, Velocity Regional Ocean Modeling System

1.Providence River Developed by D. BergondoDeveloped by D. Bergondo N. La Sota’s thesisN. La Sota’s thesis 2. NB-RIS J. Roger’s thesisJ. Roger’s thesis 3. Narragansett Bay D. Ullman, C. KincaidD. Ullman, C. Kincaid & J. Rogers & J. Rogers ROMS history

Use Large Model to Drive Full Bay Model ADCIRC Forcing Tides & Currents from Roger’s Large Model Tides & Currents from Newport ADCP & Tide Data

Initial Conditions Forcing Conditions Output Numerical Model: 1. CALIBRATION Effort 2. Process Studies ROMS Model Mixing coefficients for salt, temp., momentum Conservation Equations

Model Calibration: J. Rogers URI, MS Thesis, 2008 Tidal Elevations Match Well Instantaneous Velocity Fields Match Well Data=Red/Blue Model=Pink/Cyan

Model Calibration (Temperature): J. Rogers URI, MS Thesis, 2008

Calibrated Model Applied to Bay Processes: Retention - Mixing/Transport - Resupply J. Rogers URI, MS Thesis, 2008

Flow in East Passage Flow out West Passage Good Good or Bad? ? How is deep return flow partitioned?

Wind Model Reveals How Gyre Flux Varies with Wind & Runoff

Flow in East Passage Flow out West Passage Good Good or Bad? ? How is deep return flow partitioned?

Model Reveals How Gyre Flux Varies with Wind & Runoff

Retention in Greenwich Bay Are flushing rates a function of wind (speed & direction)? Movie 1: NO WIND: Neutral density floats within GB Movie 2: NNE - ward wind

No windNNE wind Retention in GB (after 10 days)

No windNNE wind Retention in GB (after 10 days)

12 Days Wind (8 knots) 20 Days Figure 1. Frames from a ROMS model run for summer stratification, intermediate tidal amplitude and runoff and a prevailing (steady) 8 kt applied northeastward wind stress. Tracer floats are used to track water parcels and provide an estimate of advective flushing time for the Greenwich Bay (GB) system. A. Nearly initial tracer locations at day 180. B. After 12 days of simulation, only a small fraction of tracers have left. Prevailing winds set up a double gyre system (shown schematically with arrows) which limits exchange with the West Passage (WP). C. After 20 days only 40% of tracers have flushed from GB, as opposed to ~90% flushing after ~3 days for cases without this wind forcing (shown with arrows in A). The natural progression in the data-modeling cycle is a time series deployment to test this model prediction of multi-gyre residual flow patterns during specific wind conditions (locations shown in C). GB WP Normal flushing pattern Double gyre retention pattern A)B)C)

Wind Speed m/s (to northeast) Flushing of GB Strongly Dependent on Prevailing Winds

Rogers: Mid-Bay Exchange - Role of Wind Forcing

Goals Process-oriented: –Simulate dynamics of flushing, mixing and shelf-water intrusions Application-oriented: –Provide exchange coefficients for ecological box model

Providence River ROMS High resolution Fast computation time Boundary close to area of interest Initial tests of methodology Field’s Point WWTF East Providence WWTF Bucklin Pt. WWTF Pawtuxet River Ten Mile River Woonasquatucket River Moshassuck River Blackstone River

Field’s Point WWTF East Providence WWTF Bucklin Pt. WWTF Pawtuxet River Blackstone River Ten Mile River Woonasquatucket River Moshassuck River Prov. River ROMS grid

Average River flow (m3/s): Blackstone Ten Mile Moshassuck Woonasquatucket Pawtuxet - 10 Average effluent flow (m3/s): Field's Pt Bucklin Pt E. Providence Average DYE concentration (mg/L): Blackstone Ten Mile Moshassuck Woonasquatucket Pawtuxet Field's Point - 8 Bucklin Point - 8 E. Providence 8 Winds (mph): Low NE Average NE High NE Low SW Average SW High SW Conditions for Prov. River model runs

Dye exchange coefficients

Greenwich Bay, no wind

Greenwich Bay, NNE wind

Field’s Point WWTF East Providence WWTF Bucklin WWTF Pawtuxet River Blackstone, Ten Mile, Woonasquatucket, and Moshassuck Rivers Open boundary

ROMS Projects: Providence River Flushing: Nicole La Sota -Dye boxes for CHRP modeling -Nutrient releases from treatment facilities Bay-Rhode Island Sound Exchange: Anna Pfeiffer-Herbert -Exchange vs. forcing -Seasonal variations -LARVAL dispersion Mid-Bay Physics: Justin Rogers -Transport through mid-Bay -Exchange with sub-regions (Prov. River, Greenwich Bay, Mt. Hope Bay) -Flushing of sub-regions vs. forcing trends -Re-supply of deep water vs. forcing NBC / Sea Grant: Sea Grant / NOAA CHRP/ NBC NOAA CHRP/ IGERT

Intermediate Scale Grid: Goals: 1. Coverage from Seekonk River to mouth of Narragansett Bay 2.Fine resolution in key areas of interest: Providence River, Mt. Hope Bay, Ohio Ledge, Greenwich Bay 3. Total grid cells which still allow for reasonable run times for model simulations. (~10-30 days of simulation per computer day).

1.Providence River Developed by D. BergondoDeveloped by D. Bergondo N. La Sota’s thesisN. La Sota’s thesis 2. NB-RIS J. Roger’s thesisJ. Roger’s thesis 3. Narragansett Bay D. Ullman, C. KincaidD. Ullman, C. Kincaid ROMS history

Goal: Understand Bay processes all positions & all time Extent of counter Concluding Remarks Bay-RIS exchange study (98-02) Mt. Hope Bay circulation/exchange /mixing study. ADCP, tide gauges (Deleo, 2001) Combination of good spatial/temporal data & modeling is a step in this direction Multiple projects: System response vs. Physical Forcing Interdisciplinary Projects: Coupling physics, Chemistry, biology NOAA: Mid-Bay Processes (-09) NBC Upper Bay Processes

In 3D, moving boundary increase cells by factor ~200 or new cells!!! SLOWS Calculation

Model Calibration (SALT): J. Rogers URI, MS Thesis, 2008

Retention Function of Winds Wind Direction (towards)

NB-RIS ROMS Low resolution Slow computation time Boundary far from area of interest

Full Bay ROMS Moderate resolution Moderate computation time Boundary intermediate distance from area of interest

Applications for Management

Hydrodynamic/Transport Models of Narragansett Bay & Rhode Island Sound Deanna Bergondo Chris Kincaid Nicole La Sota Anna Pfeiffer-Herbert Justin Rogers Dave Ullman Funding: GSO-URI, Rhode Island Sea Grant, EPA-TMDL, Vetillson Foundation, Narragansett Bay Commission, NOAA Hypoxia

Data-Model Spatial Flow Comparison: Fields Pt. outflow inflow Summer, late ebb inflow outflow