Circulation in Narragansett Bay: Water flow & mixing Transport of chemical-biological material Exchange between sub-regions of Bay

Motivation: Episodic hypoxia in NB & Developing management tools for the Bay ecosystem National Capitol Columns at the United States National Arboretum in Washington, D.C. CHRP Coupled Ecological Modeling (GEMBox - ROMS Model) Fundamental Column: Detailed understanding of physical processes Biological processesChemical Processes

Physical Drivers: –Tides –Winds –River discharge –Density differences Role of physical processes in the health of the Bay

Physical Drivers: –Tides –Winds –River discharge –Density differences Out with the bad Role of physical processes in the health of the Bay

Physical Drivers: –Tides –Winds –River discharge –Density differences Out with the bad In with the good

Circulation in Narragansett Bay: 3 Basic Methods Hydrographic data (currents, density) Numerical Modeling (ROMS : ( Regional Ocean Modeling System) Physical - Laboratory Modeling

Physics: Observations Acoustic Doppler Current Profilers Bottom mountedShip mounted / underway Data coverage: Excellent temporal Poor Spatial Data coverage: Good spatial Poor Temporal

Tilt Current Meters : (tilt proportional to water velocity) Buoyant cylinder Flexible membrane Mooring weight Water flow

Initial Conditions Forcing Conditions Output Shallow Water Equations Momentum balance x & y directions:  u + v  u – fv =  + F u + D u  t  x  v + v  v + fu =  + F v + D v  t  y Potential temperature and salinity :  T + v  T = F T + D T  t  S + v  S = F S + D S  t The equation of state:  =  (T, S, P) Vertical momentum:  = -  g  z  o Continuity equation:  u +  v +  w = 0  x  y  z Numerical Model ROMS Model Regional Ocean Modeling System

Fluid Dynamics Laboratory Models (a.k.a analog models) Fall, 2008 at GFD Lab, Australian National University:. Developed flume tank to represent the upper Providence River Lab models provide excellent check against numerical models Shipping Channel Edgewood Shoal Port Edgewood Save the Bay Hurricane Barrier Save the Bay

Circulation in Narragansett Bay: 3 Basic Methods Lots of great students!! Bridget Sullivan (1st developed SCRUM, then ROMS) William Deleo (data at Bay Mouth, detailed study of Mt. Hope Bay) Kurt Rosenberger (data at Bay Mouth and in Rhode Island Sound) Deanna Bergondo (develop ROMS model/data for Providence River, initial CHRP proposal) Justin Rogers (ROMS, Mid-Bay Data ) Nicole LaSota (ROMS Prov. River dye dispersion study) Anna Pfeiffer-Herbert (Detailed data RIS, mouth, Greenwich Bay, Bay-Shelf Exchange) Christelle Balt (Greenwich Bay & Prov. River Data, ROMS flushing exeriments, Mixing schemes)

Circulation in Narragansett Bay: 3 Basic Methods Lots of great students Heaps of excellent support Bridget Sullivan (1st developed SCRUM, then ROMS) William Deleo (data at Bay Mouth, detailed study of Mt. Hope Bay) Kurt Rosenberger (data at Bay Mouth and in Rhode Island Sound) Deanna Bergondo (develop ROMS model/data for Providence River, initial CHRP proposal) Justin Rogers (ROMS, Mid-Bay Data ) Nicole LaSota (ROMS Prov. River dye dispersion study) Anna Pfeiffer-Herbert (Detailed data RIS, mouth, Greenwich Bay, Bay-Shelf Exchange) Christelle Balt (Greenwich Bay & Prov. River Data, ROMS flushing exeriments, Mixing schemes)

Bridget Sullivan (1st developed SCRUM, then ROMS) William Deleo (data at Bay Mouth, detailed study of Mt. Hope Bay) Kurt Rosenberger (data at Bay Mouth and in Rhode Island Sound) Deanna Bergondo (develop ROMS model/data for Providence River, initial CHRP proposal) Justin Rogers (ROMS, Mid-Bay Data ) Nicole LaSota (ROMS Prov. River dye dispersion study) Anna Pfeiffer-Herbert (Detailed data RIS, mouth, Greenwich Bay, Bay-Shelf Exchange) Christelle Balt (Greenwich Bay & Prov. River Data, ROMS flushing exeriments, Mixing schemes) NB GB PR MHB RIS RI Sea Grant Quick summary:

Bridget Sullivan (1st developed SCRUM, then ROMS) William Deleo (data at Bay Mouth, detailed study of Mt. Hope Bay) Kurt Rosenberger (data at Bay Mouth and in Rhode Island Sound) Deanna Bergondo (develop ROMS model/data for Providence River, initial CHRP proposal) Justin Rogers (ROMS, Mid-Bay Data ) Nicole LaSota (ROMS Prov. River dye dispersion study) Anna Pfeiffer-Herbert (Detailed data RIS, mouth, Greenwich Bay, Bay-Shelf Exchange) Christelle Balt (Greenwich Bay & Prov. River Data, ROMS flushing exeriments, Mixing schemes) NB GB PR MHB RIS Narragansett Bay Commission

Bridget Sullivan (1st developed SCRUM, then ROMS) William Deleo (data at Bay Mouth, detailed study of Mt. Hope Bay) Kurt Rosenberger (data at Bay Mouth and in Rhode Island Sound) Deanna Bergondo (develop ROMS model/data for Providence River, initial CHRP proposal) Justin Rogers (ROMS, Mid-Bay Data ) Nicole LaSota (ROMS Prov. River dye dispersion study) Anna Pfeiffer-Herbert (Detailed data RIS, mouth, Greenwich Bay, Bay-Shelf Exchange) Christelle Balt (Greenwich Bay & Prov. River Data, ROMS flushing exeriments, Mixing schemes) NB GB PR MHB RIS Narragansett Bay Commission & CHRP award,

Bridget Sullivan (1st developed SCRUM, then ROMS) William Deleo (data at Bay Mouth, detailed study of Mt. Hope Bay) Kurt Rosenberger (data at Bay Mouth and in Rhode Island Sound) Deanna Bergondo (develop ROMS model/data for Providence River, initial CHRP proposal) Justin Rogers (ROMS, Mid-Bay Data ) Nicole LaSota (ROMS Prov. River dye dispersion study) Anna Pfeiffer-Herbert (Detailed data RIS, mouth, Greenwich Bay, Bay-Shelf Exchange) Christelle Balt (Greenwich Bay & Prov. River Data, ROMS flushing exeriments, Mixing schemes) NB GB PR MHB RIS Narragansett Bay Commission RI Sea Grant & CHRP award,

Bridget Sullivan (1st developed SCRUM, then ROMS) William Deleo (data at Bay Mouth, detailed study of Mt. Hope Bay) Kurt Rosenberger (data at Bay Mouth and in Rhode Island Sound) Deanna Bergondo (develop ROMS model/data for Providence River, initial CHRP proposal) Justin Rogers (ROMS, Mid-Bay Data ) Nicole LaSota (ROMS Prov. River dye dispersion study) Anna Pfeiffer-Herbert (Detailed data RIS, mouth, Greenwich Bay, Bay-Shelf Exchange) Christelle Balt (Greenwich Bay & Prov. River Data, ROMS flushing exeriments, Mixing schemes) NB GB PR MHB RIS RI Sea Grant & CHRP award,

Bridget Sullivan (1st developed SCRUM, then ROMS) William Deleo (data at Bay Mouth, detailed study of Mt. Hope Bay) Kurt Rosenberger (data at Bay Mouth and in Rhode Island Sound) Deanna Bergondo (develop ROMS model/data for Providence River, initial CHRP proposal) Justin Rogers (ROMS, Mid-Bay Data ) Nicole LaSota (ROMS Prov. River dye dispersion study) Anna Pfeiffer-Herbert (Detailed data RIS, mouth, Greenwich Bay, Bay-Shelf Exchange) Christelle Balt (Greenwich Bay & Prov. River Data, ROMS flushing exeriments, Mixing schemes) NB GB PR MHB RIS RI Sea Grant & CHRP award, 2009 Most ambitious physical sampling survey ever….. Focus on key CHRP Dye Boxes

RIS-NB Model Domain(Rogers, 2008) Full Bay Model Domain Providence River Model Data tell a physical story……..

Circulation and Transport in Upper Narragansett Bay Justin Rogers MS Thesis,08 Data Example

West Passage (Tidal flows) East Passage Channel (Tidal flows) Fast in, Faster out North - IN Surf. Bot. Decimal Day in 2006 (summer) Slow in, Slower out North - IN

Examples what these data look like: RIS-NB Model Domain(Rogers, 2008) Full Bay Model Domain Providence River Model Data tell a physical story……..over lots of different scales (different forcing)

Residual (de-tided) Flow Surface Bottom On-average…southward West Passage

Residual (de-tided) Flow Surface Bottom On-average…southward On-average…northward West Passage East Passage Channel

Physical Story of the Bay, by Residual Q. Data Water enters eastern EP Dominant re-supply up EP Outflow through WP* Enhance: Eastward winds Southward winds Northward, then Southward winds Stall/reverse: Northwestward winds stall / reverse ?

We have a very good idea about deep intrusions where they come from, what drives them, and their thermal advection Steady Re-supply up East Passage Enhanced by: Eastward winds Southward winds Northward, then Southward winds ? Bottom ADCP Deep EP

RIS-NB Model Domain(Rogers, 2008) Full Bay Model Domain Providence River Model Data tell a physical story…. Data always limited in space and/or time….. Models extend us towards full physical story of the Bay, all places, for all time

RIS-NB Model Domain(Rogers, 2008) Full Bay Model Domain Providence River Model Data tell a physical story…. Data always limited in space and/or time….. Models extend us towards a full physical story of the Bay, all places, for all time Models….do we trust them? do the data and model wiggles match?

ROMS Modeling for Narragansett Bay is built on years of GSO student efforts Bergondo: Providence River model Rogers: Bay - Rhode Island Sound Model Rogers, Ullman, Balt: Full Narragansett Bay Model RIS-NB Model Domain(Rogers, 2008) Full Bay Model Domain Providence River Model

ROMS Modeling for Narragansett Bay is built on years of GSO student efforts Bergondo: Providence River model Rogers: Bay - Rhode Island Sound Model Rogers, Ullman, Balt: Full Narragansett Bay Model RIS-NB Model Domain(Rogers, 2008) Full Bay Model Domain Providence River Model 2006 wind, runoff, air conditions Tides, mouth forced by large model 15 terrain-following vertical coordinates <50 meter horizontal grids

Models match instantaneous (tidal) flows/heights very well Data ( R) vs Model (B) Tidal response Skill =.98 Skill =.97 Skill =.98 Water Level Decimal Day, 2006

Validation using fixed- point data VARIABLESKILL Surface Temperature 0.98 Surface Salinity 0.94 Bottom Temperature 0.79 Bottom Salinity From C. Balt,09

ROMS Assessment : Quantitative comparisons with fixed station data Tide heights: Skill >0.95 // Velocity fields: Skill // T,S: Skill Actual forcing dataROMS Model Time series model output at buoy locations Statistical metrics: Skill = 0 poor Skill = 1 perfect + Time series buoy data

Full Bay Model Domain Providence River Model Data tell a physical story…. Data always limited in space and/or time….. Models extend us towards a full physical story of the Bay, all places, for all time Models….do we trust them? do the data and model wiggles match? does the model predict the gross character shown in data?

Modeled upper bay transport: Vertically integrated along N. Prudence Line --- Zero wind Summer 2006 forcing, except winds

Modeled upper bay transport: Vertically integrated along N. Prudence Line --- Zero wind --- Northward wind GYRE STALLS

Modeled upper bay transport: Vertically integrated along N. Prudence Line --- Zero wind --- Northward wind GYRE STALLS --- Southwestward wind GYRE ENHANCED Patterns match ADCP data OUT IN

RIS-NB Model Domain(Rogers, 2008) Full Bay Model Domain Providence River Model Data tell a physical story…. Data always limited in space and/or time….. Models extend us towards a full physical story of the Bay, all places, for all time Models….do we trust them? do the data and model wiggles match? does the model predict the gross character shown in data? Quasi-trusted models….how can we use them?

Key Management Issue: The role of flushing dynamics as the root of chronic water quality problems? Out with the Bad

Flushing Time using Fraction of Water Method (assume complete mixing) Simple estimates: ~4 days Simple estimates: ~10 days

Flushing processes may be more complex……. Greenwich Bay: Rogers thesis models using ROMS show longer times Future: Test model predictions with dense current meter network Providence River: NBC data & Fluid Dynamics Lab Models suggest longer times Future: Test predictions using dense current meter network

Flushing processes may be more complex……. Greenwich Bay: Rogers thesis models using ROMS show longer times Future: Test model predictions with dense current meter network Providence River: NBC data & Fluid Dynamics Lab Models suggest longer times Future: Test predictions using dense current meter network CHRP models must represent flushing accurately

Providence River flushing may not follow simple estimates Models & Data Suggest a Bimodel Residence Time Edgewood shoals channel NBC Save the Bay EYC

Fluid Dynamics Laboratory Models (a.k.a analog models) Fall, 2008 at GFD Lab, Australian National University:. Developed flume tank to represent the Providence River Model includes shipping channel & the Edgewood Shoals Parameters: river flow, NBC discharge, tides : (no winds) Shipping Channel Edgewood Shoal Port Edgewood Save the Bay Hurricane Barrier Save the Bay

We have modified a 3 meter long flume tank at the Fluid Dynamics Lab of the Australian National University to represent the Providence River-Fields Point- Edgewood region of the estuary. NBC Port Edgewood Port Edgewood Broad Shoal Broad Shoal Channel 66 cm (1000m) Z= 2cm 33 cm (400 m)

Scaling: Re#= 10 5 Scale on runoff prism and tidal prism : 30 CMS = 7 liters/min 1 tide cycle = 20 seconds NBC Broad Shoal Channel

Relevance to Water Quality Models Lab Models: small physics that numerical models can’t represent Do small scale processes influence exchange & mixing between shoal and channel & overall water quality? NBC Broad Shoal Channel

Movies: no wind/density forcing 1.30 CMS (7liters/min), no tide (2 CMS NBC Fields Pt). 2.2 CMS runoff, 1.5 meter tide 3.30 CMS & 1 meter tide (late addition of 2 CMS NBC outfall) NBC Broad Shoal Channel

Small scale eddies: tilted/sheared Vertical & horizontal structure to shoal-channel exchange: >15 days: shoal bottom water retention Surface floaters rapid exchange, but recycle Do small scale processes influence exchange & mixing? YES Lab Models: Discharge, no tide Eddies meters

Spring tide only, no runoff: Mid-shoal surface off in 4 cycles (2 days) Mid-shoal deep >> 10 cycles (5 days) Inside shoal >> 10 cycles (5 days) Do small scale processes influence exchange & mixing? YES

Combined 30 CMS runoff & 1m tide: flushing ~5 cycles Two exchange modes 1. tilted-stretched eddies

Combined 30 CMS runoff & 1m tide: flushing ~5 cycles Two exchange modes 1. tilted-stretched eddies 2. late flood, eastward plumes

Conclusions: Lab models show: two modes of shoal-channel exchange deformed eddies at shoal-channel interface tides & runoff drive off-shoal plumes strong vertical flow structures, deep shoal water isolation flushing times of 5-20 tide cycles Mixed basin model for Narragansett Bay is not appropriate NBC outfall on shoals increases flushing by factor of 3

x x Tilt Current Meters: 1) Gyre vorticity / shape vs. environmental forcing 2) Small scale eddy field at channel-shoal intersection x Testing Model Predictions

Flushing processes may be more complex……. Greenwich Bay: Rogers thesis models using ROMS show longer times Future: Test model predictions with dense current meter network Providence River: NBC data & Fluid Dynamics Lab Models suggest longer times Future: Test predictions using dense current meter network

No windNNE-ward wind Retention in Greenwich Bay: Wind matters Position of floats after 10 days of simulation after float cloud introduced, J.M. Rogers No sea breeze Applied sea breeze summer 2006

Movies of Greenwich Bay Flushing: Narraganset Bay-RIS ROMS model. Summer 2006 tides & density fields 1) 2006 Runoff, no wind 2) 2006 Runoff, northwestward wind

No windNNE-ward wind Retention in Greenwich Bay: Wind matters Residual flows are predicted to be distinctly in the two cases. J.M. Rogers No sea breeze Applied sea breeze summer 2006

No windNNE-ward wind Retention in Greenwich Bay: Wind matters Residual flows are predicted to be distinctly in the two cases. J.M. Rogers No sea breeze Applied sea breeze summer 2006 Test with data

Flushing processes may be more complex……. Greenwich Bay: Rogers thesis models using ROMS show longer times Future: Test model predictions with dense current meter network Providence River: NBC data & Fluid Dynamics Lab Models suggest longer times Future: Test predictions using dense current meter network CHRP models must represent flushing accurately

Flushing processes may be more complex……. Greenwich Bay: Rogers thesis models using ROMS show longer times Future: Test model predictions with dense current meter network Providence River: NBC data & Fluid Dynamics Lab Models suggest longer times Future: Test predictions using dense current meter network CHRP models must represent flushing accurately CHRP Coupled Eco-model Fundamental Column: Detailed understanding of physical processes