observations and modeling of narragansett bay nutrient...

Observations and modeling of Narragansett Bay nutrient dynamics:

Do we run the west coast offense?

Presenters: Chris Kincaid & Kevin Rosa, Graduate School of Oceanography, University of Rhode Island Colleagues: Scott Nixon, David Ullman, Steve Granger, URI-GSO

R. Wally Fulweiler, Boston University

Anna Pfeiffer-Herbert, Richard Stockton University

Rhode Island Coastal Waters: Narragansett Bay & Rhode Island Sound East Coast Offense: Nutrients from watershed Urbanized Higher runoff West Coast Offense: Nutrients from shelf Lower runoff

Narragansett Bay

Marthas Vineyard

Rhode Island Sound (RIS)

Inner shelf

Providence

Block Is.

Buzzards Bay

L. I. Sound

Greenwich Bay

Providence River

Focus on Watershed Nutrients to Narragansett Bay Estuary

West Passage

River nutrients: Northern Blackstone River Pawtuxet River Woonasquatucket/Moshas. Eastern Taunton River

Blackstone

Mt. Hope Bay KEY PT. SOURCES: WWTFs or

waste-water treatment facilities Fields Pt. & Bucklin Pt. (NBC)

Fall River

Providence

Greenwich Bay

Providence River

Connecting Circulation > Nutrients > Water Quality

West Passage

Blackstone

Mt. Hope Bay

Fall River

Providence

Greenwich Bay

Edgewood Shoal

Chronic Low Oxygen Regions

Seekonk R.

Red = hypoxia

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

FULLBAY ROMS

Tilt Current Meters Laboratory

Utilize a 3-legged stool approach to

Coastal circulation

e.g. Edgewood Shoals Region

ROMS Numerical Model Regional Ocean Modeling System Scaled Physical Model Spatial-Temporal Observations

Tilt Current Meters Lagrangian Drifters

Bottom-mounted ADCP

Ship-mounted ADCP

Circulation Data

20 Years of Bay Data: Circles=BM-ADCPs

Lines=Shipmounted-ADCPs

Yellow regions = 10-25 TCMS

20 Years of Bay Data: Counterclockwise residual flow

Up east, Out west Impacted embayments

Retention gyres Reduced flushing

METHOD 3: Computer Models

Input Forcing: Tides Runoff Winds Air Temperature Water Density (Salt, Temp.)

ROMS Model Solves Equations: Conserve Mass Momentum Conserve Energy / Salt

ROMS 3. Output: 4-D Flow & Salt/Temp. Transport Todays talk (a) Chemical Dyes (b) Ecosystem Processes

ROMS Cases. Terrestrial (East-coast) nutrient dynamics

-January – September 2010

-River discharge (USGS), Winds (PORTS), Tides (ADCIRC), Atmospheric (reanalysis-NARR) , rain (TF Green).

-Blackstone River nutrients (Pt. & Non-Pt.) UMass Blackstone River Water Quality Model ( P. Rees, Mass Water Resourses Res. Center).

-Pawtuxet River nutrients - NBC data.

-Other rivers: empirical flow vs. nutrients model (from UMass model).

-WWTF nutrients (data from plant managers and hypothetical levels)

(1) Nutrients as passive chemical dye advection/diffusion only Dye sources supplying low-DO areas?

(2) ROMS NPZD Model N=nutrients, P=phytoplankton, Z=zooplankton, D=detritus

Factors controlling phytoplankton biomass?

Case 1 Case 2

Forcing files detail

16 Distinct Dyes 9 Rivers 7 WWTFs 1) How each dye through system? 2) Flushing vs. accumulation? 3) Cost/benefit of WWTF (nutrient) reduction strategies?

Mosh/Woon

Blackstone (Pt. vs. Non Pt.)

Palmer

Taunton

2 Greenwich Bay Rivers

GB WWTF

Fields Pt. WWTF

Bucklin Pt. WWTF

Pawtuxet

WWTF

Fall River WWTF

EP-WWTF

10-Mile

Hunt

Case 1

Shoal

Channel

Chemical Dye from Fields Pt. WWTF: Focus on upper Providence River

Red = Dimensionless Concentration of 1

Dye from Fields Point WWTF: Transport examples

Plume in outflow jet Plume entrained in shoal gyre Plume flushed

(near-surface) Blackstone River Dye: Repeatable Mid-Bay Transport Paths

1. West Passage: Weak wind SW-ward wind

2. Greenwich Bay Intrusion: Seabreeze NW-ward wind

3. East Passage Strong NE-ward wind

Greenwich Bay?

Nitrogen Contributors to Greenwich Bay: SPRING HIGH FLOW (+30days)

1) Blackstone, 2) Pawtuxet , 3) Fields Pt, 4) Taunton, 5) Internal

41% 20%

24%

2. Greenwich Bay

Late Summer – August, 2010

Blackstone

Pawtuxet

Greenwich Bay

From east From north

Greenwich Bay? Nitrogen to Greenwich Bay Late Summer 2010: 1) Internal , 2) Blackstone, 3) Fields Pt, 4) Pawtuxet

Variable with season, runoff, wind

41% 20%

24%

2. Greenwich Bay

Late Summer – August, 2010

Greenwich Bay

Edgewood Shoals Bottom Water

Near-bottom Taunton Dye in Providence River

Taunton Dye

Conclusions: Dye Transport Patterns Complex.

Northern sources variable down-bay paths.

Accumulations in impacted areas vary seasonally (winds, runoff)

Counterclockwise residual flow & layered estuarine flow: eastern & southern dyes to impacted northern areas.

Second set of ROMS Models: ROMS NPZD Ecosystem Model

Z=zooplankton Also Detritus Equation

N= Total nitrogen

P=phytoplankton

Uptake rate

Light penetration term

Multiple runs: Uptake rate, light extinction, grazing, mortality, WWTF levels

Nitrogen not a conservative dye.

Start with focus on bay-wide bloom, June, 2010

Total Nitrogen: Surface Reference case: Vm2.5, KL0.75, ZG1.0 . Contours in milli-Mole/m^3 (divide by 75 to get to mg/l).

50 mM/m^3 Transport oscillations:

Northern nutrients

1) down East Passage,

2) down West Passage.

3) pumped into Greenwich Bay Wind, tide, runoff controls

a)

Total Nitrogen Contours: (near-surface, summer 2010) Mid-Bay Transport Paths Similar to Dye

Transport oscillations:

Northern nutrients

1) down East Passage,

2) down West Passage.

3) pumped into Greenwich Bay Wind, tide, runoff controls

Providence River N. Prudence S. Prudence Lower Bay

Fundamental observation in Bay: TN reduction from Seekonk to Mouth of Providence River

All runs (pre-bloom) have TN match basic observation:

1. 40% reduction Head of Prov. River to Mouth

2. Seekonk 50% higher than upper Prov. River

See

kon

k R

iver

Tota

l Nit

roge

n

Latitude

Phytoplankton Contours: (early summer bloom 2010)

RED= 20 mM m-3

Day 165 (June 14)

SURFACE BOTTOM

Initiate Mid-bay and migrate northward

Surface Phytoplankton Contours: (early summer bloom 2010)

RED= 20 milli-M m-3

Day 165 (June 14)

Movie: Bloom starts mid-Bay Moves northward

Greenwich Bay

Phillipsdale

DATA

Large uptake rate, more light

Slow uptake rate, more light

Fast uptake rate, less light

Modeled bloom matches a) nutrient magnitudes, b) mid-Bay start, c) timing of northward march

Ph

yto

pla

nkt

on

Co

nc.

, mM

/m3

0

20

40

WWTFs @ 5, 3 & 0 mg/mL

Plots from mid-Bay: North Prudence

Phytoplankton bloom intensity vs. parameters:

3. different WWTF releases levels

1. ecosystem parameters (uptake, light, death)

2. environmental factors

Variations In Wind

Eliminate Greenwich Bay

Change Light Extinction

Changing Growth Rate

Dif

fere

nce

in T

ota

l B

loo

m M

agn

itu

de

Difference in

Integrated Bloom Magnitude over 10 days

= -

ROMS Case A ROMS Case B

Absolute value

Use differential-integrated phytoplankton bloom index to quantify relative sizes of a) environmental factors and

b) managed nutrient changes c) NPZD parameters (uptake, light, grazing)

Variations In Wind




Dif

fere

nce

in T

ota

l B

loo

m M

agn

itu

de

Difference in

Integrated Bloom Magnitude over 10 days

= -

ROMS Case A ROMS Case B

If big difference then blooms very to sensitive to this parameter

Absolute value



3 v

s. 0

Variations In Wind




Dif

fere

nce

in T

ota

l B

loo

m C

on

cen

trat

ion



WWTFs nutrient release levels at 0 mg/L versus 3 mg/L

0 v

s 3

3

vs

5

5 v

s 1

5

Variations In Wind




Dif

fere

nce

in T

ota

l B

loo

m C

on

cen

trat

ion

Bigger difference 5 mg/L vs. 15 mg/L WWTF releases, factor of 10

3 t

o 0

Medium Growth Rate

5 t

o 3

15

to

5

Variations In Wind




Changing WWTF Nutrient Outputs

Dif

fere

nce

in T

ota

l B

loo

m C

on

cen

trat

ion

Higher phytoplankton uptake rate, 15 to 5 mg/l change in WWTF release, bigger impact

Higher Growth Rate

3 t

o 0

5 t

o 3

15

to

5

Medium Growth Rate

High Growth Rate





Dif

fere

nce

in T

ota

l B

loo

m C

on

cen

trat

ion

Sou

thea

stw

ard

N

ort

hw

estw

ard

N

ort

hea

stw

ard

So

uth

wes

twar

d

Variations In Wind

Compare changes in applied prevailing wind to a reference case of no-wind. Natural effect of wind changes has similar impact as 15 to 5 mg/l WWTF change

3 t

o 0

5 t

o 3

15

to

5

3 t

o 0

5 t

o 3

15

to

5

Medium Growth Rate

High Growth Rate

Variations In Wind Change

Light Extinction



Dif

fere

nce

in T

ota

l B

loo

m C

on

cen

trat

ion

Sou

thea

stw

ard

No

rth

wes

twar

d

No

rth

east

war

d

Sou

thw

estw

ard

Med

ium

to

Hig

h

Low

to

Med

ium

Changes in light penetration parameter larger impact on integrated total bloom than managed (e.g. 5mg/l to 3/mg/l) nutrient reductions from WWTFs.

3 t

o 0

5 t

o 3

15

to

5

3 t

o 0

5 t

o 3

15

to

5

Medium Growth Rate

High Growth Rate

Variations In Wind Change

Light Extinction

Changing Phytoplankton Uptake Rate Changing

WWTF Nutrient Outputs

Dif

fere

nce

in T

ota

l B

loo

m C

on

cen

trat

ion

Sou

thea

stw

ard

No

rth

wes

twar

d

No

rth

east

war

d

Sou

thw

estw

ard

Med

ium

to

Hig

h

Low

to

Med

ium

Low

to

Me

diu

m

Med

ium

to

Hig

h

Phytoplankton uptake rate key parameter for integrated total bloom

3 t

o 0

5 t

o 3

15

to

5

3 t

o 0

5 t

o 3

15

to

5

Conclusions:

Order of factors controlling bloom size 1) Ecosystem parameters (growth, light, etc) 2a) Environmental parameters (winds) 2b) 15 to 5 mg/l drop in WWTF releases 3) 5 to 3 mg/l drop in WWTF releases

Relative importance of shelf (RIS) nutrients for Bay ecosystem?

Narragansett Bay

Marthas Vineyard

Rhode Island Sound (RIS)

Inner shelf

Providence

Block Is.

Buzzards Bay

L. I. Sound Scott Nixon, first week of work,

“let’s test how DIN from shelf gets into Bay”

Bath

ymetry (m

)

BM-ADCPS

Ship-Mounted ADCP

Building RIS Data Sets / Models RISG, Endeavor Prog.

1) 1999-2001 led by Scott Nixon 2) Recent 2005, 2009-2011, 2016

Drifter Study (x3)

Coastal Current

Strong in summer

Into RIS from SE, exit to SW Weak interior flow Summer stratification RIS to Bay Intrusions!!

1. Colors show 3 deployment sites: Solid line=3m; Dashed=6m

2. Drifters Retained in Vineyard Sound

3. Drifters ride coastal current to Bay

13 Days

May 23

June 3

Drifter Patch: In ~ 5/23/2016 midnight. Plot 6/5 noon.

4. Whats up, central RIS?

Nixon, Granger, Fulweiler and others Series of ”intensive” cruises (RISG) Narragansett Bay to RIS (99-01)

Temperature, salinity, nutrient surveys

RIS

Mt. Hope Bay

Mid-Bay High

Production Zone

Greenwich Bay

Providence River

a)

North South

RIS

BAY

BAY

DIN: 7 mg/L

1 mg/L

T=16°

T=10°

Temperature

RIS

BAY

Interface

?

Average Summer Conditions

DIN

RIS

Mt. Hope Bay

Mid-Bay High

Production Zone

Greenwich Bay

Providence River

a)

BAY

East Passage TRANSECT

West Side

East Side

INFLOW OUTFLOW

1999-2001: 17 Full tide cycle ship-mounted ADCP cruises Mouth-interface region of Bay – RIS Winter/summer residual (or subtidal) exchange similar

East Passage ADCP Sub-tidal flow

Looking north D

epth

, m

35m

Nixon: “Is deep RIS DIN an important source for Bay?

3800 meters

1300 meters

RIS a)

1999-2001: 3 moored ADCPs. East Passage, West Passage, RIS

2007: 3 BM-ADCPs East/West Pass. 2008: 2 BM ADCPs RIS

Northward Inflow

Sub

tid

al F

low

, cm

/s 18

0

0 2 4 6 8 -2

Low

er E

ast

Pass

., 2

00

0

Mean

ADCP Shows Wind-driven Intrusion

Surface

Mid

Bottom

Days since wind event, 5/20/2000

Northward wind

Southwestward wind

Wind-driven intrusion

Two Modes of RIS to Bay Flow (Pfeiffer-Herbert et al, 2015)

1) Mean residual (non-tidal) inflow to East Passage (3-5 cm/s)

2) 5-15 Wind-driven intrusions per summer

>1000 CMS 200,000 M of DIN per day

Mode 1: ”Steady” inflow 1000 CMS 200K Moles DIN per day

Mode 2: Large wind-driven inflow

>7000 CMS

7 million Moles DIN/event

a)

b)

Coastal Current HIGH DIN

RIS DEEP

Pump station

Mixed-up RIS DIN?

Subtidal flow x Height x Width x DIN = Intrusion #

Moored ADCP Data

Underway ADCP Estimates

Nixon Data

EPSCOR Funding RISG Funding

50 m

30 m

3 H

ose

inta

kes

In-line sensors, pumps, controls

East

West Side

East Side

7 mg/L?

Moored ADCPs

? mg/L ?

West Side

East Side INFLOW

OUTFLOW Lower East Passage ADCP Sub-tidal flow

Looking north

Pump station & ADCPs. Firm up Volume flux & Chemical flux vs. time

Lower East Passage

ROSA: Ongoing work, ROMS Modeling & Analysis of existing data sets Supply pathways RIS water/nutrients to Narragansett Bay. Background/steady intrusions Wind-induced, large scale intrusions High energy exchange events (Floyd).

Shelf Intrusions

Persistent trickle from Periphery Current

2-7 day wind events

Quick, Extreme events

1. ADCP under the Newport Bridge during the storm a. This is a good test of model performance: captured both the bottom

temperature and the vertical structure of the currents.

Hurricane Floyd

ADCP

∆z = 2 m

H = 40 m

T

http://cdn.onlyinyourstate.com/wp-content/uploads/2016/04/Aerial_view_of_Claiborne_Pell_Newport_Bridge_-_01-700x501.jpg









The ROMS model

RIVERS

WIND

HEAT, FRESHWATER

The ROMS model

Storm landfall

4°C drop

Bottom temperature time series

Cool, high-DIN shelf-water?


Bottom temperature: data vs. model

Quantifying post-storm intrusion: data only

Assessing model skill

ADCP Observations

Quantifying post-storm intrusion: data vs. models


ADCP Observations

ROMS No Stratification



ADCP Observations

ROMS No Stratification

ROMS WITH STRATIFICATION



The barotropic (constant-density) model does not predict the strong shelf-water inflow

Drifter movie 2: Effects of Stratification

Density cross-sections

Drifter movie 3: Storm vs. No Storm

Estimated Input Volume for the 4 days following Floyd:

Rivers:

5 x 107 m3

East Passage:

5 x 108 m3 (USGS Data)

(ROMS model)

Storm landfall


ADCIRC operational model: Forecasting inundation from Irma

ADCIRC operational model: Forecasting inundation from Irma

This ocean model is invaluable for informing

evacuations

but its simplified physics can’t predict

nutrient transports or ecosystem impacts.

1. Hazardous Chemical spills a. Extent of oil spills from Hurricanes Katrina and Rita is still being

assessed

Hurricanes: After the storm surge

http://www.nbcnews.com/id/10838641/ns/us_news-katrina_the_long_road_back/t/oil-company-katrina-spill-victims-got-m/

http://www.nola.com/katrina/index.ssf/2010/08/extent_of_oil_spills_from_2005_hurricanes_is_still_being_assessed.html


















1. Chemical spills a. Extent of oil spills from Hurricanes Katrina and Rita is still being assessed


2. Nutrient intrusions, plankton blooms, hypoxia a. Roman et al. (2006) “Chesapeake Bay Plankton and Fish Abundance

Enhanced by Hurricane Isabel Hurricane” b. Li et al. (2006) “Hurricane-induced storm surges, currents and

destratification in a semi-enclosed bay”

http://ripr.org/post/quahog-fisherman-pleased-progress-narragansett-bay-cleanup#stream/0 http://cdn.newsday.com/polopoly_fs/1.10821124.1441758504!/httpImage/image.JPG_gen/derivatives/display_600/image.JPG

Hurricanes: After the storm surge



http://ripr.org/post/quahog-fisherman-pleased-progress-narragansett-bay-cleanup#stream/0













http://cdn.newsday.com/polopoly_fs/1.10821124.1441758504!/httpImage/image.JPG_gen/derivatives/display_600/image.JPG

http://cdn.newsday.com/polopoly_fs/1.10821124.1441758504!/httpImage/image.JPG_gen/derivatives/display_600/image.JPG

<<TAKE-AWAYS>>

1. Goal: modeling storm events as realistically as possible.

2. Presenting results from a regional 3D baroclinic modeling that is forced by a 2D storm surge model.

a. Find that even under strong winds, baroclinic (stratification-driven) effects are critical.

3. Argue that this model is well-suited for studying water mass exchanges.

a. Volume of shelf-water input on order 10x greater than sum of all rivers.

Hurricane Floyd

1. Catastrophic flooding in eastern US, particularly North Carolina

a. 15’ storm surge in Long Beach, NC

2. 11” of rain in parts on New England

3. RI experienced increased river flows but minimal storm surge and only about 3” of rain.

https://www.weather.gov/images/mhx/19990916/Rain1.jpg

https://www.weather.gov/images/mhx/19990916/Rain1.jpg

Wind Wind Wind

Warm

Cool

Well- Mixed

Wind Wind Wind

Intermediate

Intermediate

Partially Stratified

z y

Shouldn’t vertical mixing lead to warmer bottom water?

Sea surface height and northward deep velocity


observations and modeling of narragansett bay nutrient...

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