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


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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. CHRP Coupled Ecological Modeling (GEMBox - ROMS Model).

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

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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 l.jpg

Motivation: Episodic hypoxia in NB & Developing management tools for the Bay ecosystem

CHRP Coupled Ecological Modeling (GEMBox - ROMS Model)

Fundamental Column:

Detailed understanding of physical processes

Biological processes

Chemical Processes

National Capitol Columns at the United States National Arboretum in Washington, D.C.


Role of physical processes in the health of the bay l.jpg

Role of physical processes in the health of the Bay

  • Physical Drivers:

    • Tides

    • Winds

    • River discharge

    • Density differences

http://www.geo.brown.edu/georesearch/insomniacs


Role of physical processes in the health of the bay4 l.jpg

Role of physical processes in the health of the Bay

  • Physical Drivers:

    • Tides

    • Winds

    • River discharge

    • Density differences

  • Out with the bad

http://www.geo.brown.edu/georesearch/insomniacs


Role of physical processes in the health of the bay5 l.jpg

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

http://www.geo.brown.edu/georesearch/insomniacs


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Circulation in Narragansett Bay:

3 Basic MethodsHydrographic data (currents, density)

Numerical Modeling (ROMS : ( Regional Ocean Modeling System)

Physical - Laboratory Modeling


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Physics: Observations

Acoustic Doppler Current Profilers

Bottom mounted

Ship mounted / underway

Data coverage:

Excellent temporal

Poor Spatial

Data coverage:

Good spatial

Poor Temporal


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Tilt Current Meters : (tilt proportional to water velocity)

Water flow

Buoyant cylinder

Flexible membrane

Mooring weight


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Numerical Model

Shallow Water Equations

Momentum balance x & y directions:

u + vu – fv = f + Fu + Du

t x

v + vv + fu = f + Fv + Dv

ty

Potential temperature and salinity :

T+ vT = FT + DT

t

S + vS = FS + DS

t

The equation of state:

r= r (T, S, P)

Vertical momentum:

f = - r g

z ro

Continuity equation:

u+v+w = 0

x y z

Initial Conditions

Forcing Conditions

ROMS Model

Regional Ocean

Modeling System

Output


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Fluid Dynamics Laboratory Models

(a.k.a analog models)

Save the Bay

Hurricane Barrier

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

Edgewood Shoal

Shipping Channel

Shipping Channel

Save the Bay

Edgewood Shoal

Port Edgewood


Circulation in narragansett bay 3 basic methods lots of great students l.jpg

Circulation in Narragansett Bay: 3 Basic MethodsLots 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 l.jpg

Circulation in Narragansett Bay: 3 Basic MethodsLots of great studentsHeaps 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)


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Quick summary:

PR

RI Sea Grant

GB

MHB

NB

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)

1999-2001

RIS


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Narragansett Bay Commission

2001-2005

PR

GB

MHB

NB

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)

99-01

RIS


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Narragansett Bay Commission

& CHRP award, 2006

2005

PR

GB

2006

MHB

NB

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)

99-01

RIS


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Narragansett Bay Commission

RI Sea Grant

& CHRP award, 2007

2005

PR

GB

2006

MHB

NB

2007

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)

99-01

RIS


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RI Sea Grant &

CHRP award, 2008

2005

PR

GB

2006

MHB

NB

2007

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)

99-01

RIS 2008


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RI Sea Grant &

CHRP award, 2009

Most ambitious physical sampling survey ever…..

Focus on key CHRP Dye Boxes

2005

PR

GB

2006

2009

MHB

NB

2007

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)

99-01

RIS 2008


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Data tell a physical story……..

Providence River Model

Full Bay Model Domain

RIS-NB Model Domain(Rogers, 2008)


Circulation and transport in upper narragansett bay justin rogers ms thesis 08 l.jpg

Data Example

Circulation and Transport in Upper Narragansett BayJustin RogersMS Thesis,08


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West Passage (Tidal flows)

North - IN

Surf.

Fast in,

Faster out

Bot.

East Passage Channel (Tidal flows)

North - IN

Slow in,

Slowerout

Decimal Day in 2006 (summer)


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Examples what these data look like:

Data tell a physical story……..over lots of different scales (different forcing)

Providence River Model

Full Bay Model Domain

RIS-NB Model Domain(Rogers, 2008)


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Residual (de-tided) Flow

West Passage

On-average…southward

Surface Bottom


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Residual (de-tided) Flow

West Passage

On-average…southward

Surface

Bottom

East Passage Channel

On-average…northward


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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

?


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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

Deep EP

Bottom Temperature @ ADCP

?


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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

Providence River Model

Full Bay Model Domain

RIS-NB Model Domain(Rogers, 2008)


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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?

Providence River Model

Full Bay Model Domain

RIS-NB Model Domain(Rogers, 2008)


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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

Providence River Model

Full Bay Model Domain

RIS-NB Model Domain(Rogers, 2008)


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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

Providence River Model

2006 wind, runoff, air conditions

Tides, mouth forced by large model

15 terrain-following vertical coordinates

<50 meter horizontal grids

Full Bay Model Domain

RIS-NB Model Domain(Rogers, 2008)


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Models match instantaneous (tidal) flows/heights very well

Skill = .97

Data ( R) vs Model (B)

Tidal response

Skill = .98

Water Level

Skill = .98

Decimal Day, 2006


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Validation using fixed- point data

2006

From C. Balt,09


Slide33 l.jpg

Actual forcing data

ROMS Model

ROMS Assessment : Quantitative comparisons with fixed station data

Time series model output at buoy locations

+

Time series buoy data

Statistical metrics: Skill = 0 poor

Skill = 1 perfect

Tide heights: Skill >0.95 // Velocity fields: Skill 0.8 - 0.9 // T,S: Skill 0.75-0.98


Slide34 l.jpg

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?

Providence River Model

Full Bay Model Domain


Modeled upper bay transport vertically integrated along n prudence line l.jpg

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 line36 l.jpg

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 line37 l.jpg

Modeled upper bay transport: Vertically integrated along N. Prudence Line

IN

OUT

--- Zero wind

--- Northward wind GYRE STALLS

--- Southwestward wind GYRE ENHANCED

Patterns match 06-09 ADCP data


Slide38 l.jpg

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?

Providence River Model

Full Bay Model Domain

RIS-NB Model Domain(Rogers, 2008)


Key management issue the role of flushing dynamics as the root of chronic water quality problems l.jpg

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

Out with the Bad

http://www.geo.brown.edu/georesearch/insomniacs


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Flushing Time using Fraction of Water Method

(assume complete mixing)

Simple estimates: ~4 days

Simple estimates: ~10 days


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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


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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


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Providence River flushing may not follow simple estimates

Models & Data Suggest a Bimodel Residence Time

channel

NBC

Save the Bay

Edgewood

shoals

EYC


Slide44 l.jpg

Fluid Dynamics Laboratory Models

(a.k.a analog models)

Save the Bay

Hurricane Barrier

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)

Edgewood Shoal

Shipping Channel

Shipping Channel

Save the Bay

Edgewood Shoal

Port Edgewood


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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

NBC

Port

Edgewood

Port

Edgewood

Broad

Shoal

Channel

Broad

Shoal

Channel

66 cm (1000m)

Z= 2cm

33 cm

(400 m)


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Scaling:

Re#= 105

Scale on runoff prism and tidal prism :

30 CMS = 7 liters/min

1 tide cycle = 20 seconds

Channel

NBC

Broad

Shoal


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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?

Channel

NBC

Broad

Shoal


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Movies: no wind/density forcing

30 CMS (7liters/min), no tide (2 CMS NBC Fields Pt).

2 CMS runoff, 1.5 meter tide

30 CMS & 1 meter tide (late addition of 2 CMS NBC outfall)

Channel

NBC

Broad

Shoal


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Do small scale processes influence exchange & mixing? YES

Lab Models: Discharge, no tide

Eddies 10-50 meters

Small scale eddies: tilted/sheared

Vertical & horizontal structure to shoal-channel exchange:

>15 days: shoal bottom

water retention

Surface floaters rapid exchange,

but recycle


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Do small scale processes influence exchange & mixing? YES

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)


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Combined 30 CMS runoff & 1m tide: flushing ~5 cycles

Two exchange modes

1. tilted-stretched eddies


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Combined 30 CMS runoff & 1m tide: flushing ~5 cycles

Two exchange modes

1. tilted-stretched eddies

2. late flood, eastward plumes


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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


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Tilt Current Meters: 1) Gyre vorticity / shape vs. environmental forcing

2) Small scale eddy field at channel-shoal intersection

x

x

x

Testing Model Predictions


Slide55 l.jpg

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


Retention in greenwich bay wind matters l.jpg

No wind

NNE-ward wind

Retention in Greenwich Bay: Wind matters

Position of floats after 10 days of simulation after float cloud introduced,

No sea

breeze

Applied sea

breeze

summer 2006

J.M. Rogers


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Movies of Greenwich Bay Flushing: Narraganset Bay-RIS ROMS model.

Summer 2006 tides & density fields

2006 Runoff, no wind

2006 Runoff, northwestward wind


Retention in greenwich bay wind matters58 l.jpg

No wind

NNE-ward wind

Retention in Greenwich Bay: Wind matters

Residual flows are predicted to be distinctly in the two cases.

No sea

breeze

Applied sea

breeze

summer 2006

J.M. Rogers


Retention in greenwich bay wind matters59 l.jpg

No wind

NNE-ward wind

Retention in Greenwich Bay: Wind matters

Residual flows are predicted to be distinctly in the two cases.

Test with data

No sea

breeze

Applied sea

breeze

summer 2006

J.M. Rogers


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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


Slide61 l.jpg

Flushing processes may be more complex…….

CHRP Coupled Eco-model

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

Fundamental Column:

Detailed understanding of physical processes

CHRP models must represent flushing accurately


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