NUMERICAL MODELING OF COASTAL CIRCULATION:

1
PRESENTATION TO NATIONAL CENTERS FOR
ENVIRONMENTAL PREDICTION CAMP SPRING, MD
NUMERICAL MODELING OF COASTAL CIRCULATION
FRONTS, CROSS-SHELF TURBULENT FLUXES AND COASTAL
CLIMATOLOGY NADYA VINOGRADOVA
USM/DMS/SSC OCTOBER 26, 2004
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OUTLINE

• INSTABILITY OF SHELF-BREAK FRONTS AND CROSS-SHELF
  EXCHANGE
• INTRODUCTION AND STUDY AREA
• GOALS AND OBJECTIVES
• METHODS
• NUMERICAL EXPERIMENTS
• SUMMARY AND CONCLUSIONS
• COASTAL CLIMATOLOGY USING VARIATIONAL
  INTERPOLATION

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1. INTRODUCTION AND STUDY AREA
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1. GOALS AND OBJECTIVES

• TO EXAMINE THE ROLE OF LOCAL FRONTAL INSTABILITY
  ON THE CROSS-FRONTAL EXCHANGE IN THE ABSENCE OF
  EXTERNAL FORCES
• TO STUDY SENSITIVITY OF FRONTAL STABILITY AND
  CROSS-FRONTAL EXCHANGE TO EXTERNAL FACTORS
• BOTTOM TOPOGRAPHY
• WIND STRESS
• RIVER INFLOWS
• LOOP CURRENT EDDY INTRUSION

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1. METHODS

• FRONTAL DYNAMICS AND CROSS-FRONTAL EXCHANGE ARE
  EXAMINED USING TWO NUMERICAL MODELS
• NRL MODEL (REALISTIC EXPERIMENT)
• REAL-TIME INTRA-AMERICAS SEA OCEAN
  NOWCAST/FORECAST SYSTEM
• DEVELOPED AT NRL (MARTIN, 2000). RESULTS ARE
  PROVIDED BY DR. KO AND DR. PRELLER
• DAILY FORECAST OF ARE USED AS BACKGROUND
  DATA FOR COMPARISON

MONTHLY MEAN SURFACE TEMPERATURE
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1. METHODS

• 2. ECOM MODEL (IDEALIZED EXPERIMENTS)
• TO ISOLATE DOMINANT PROCESSES AND TO STUDY OCEAN
  RESPONSE TO INDIVIDUAL FACTORS
• TO USE SIMPLIFIED NUMERICAL MODEL AS A CONTROLLED
  
• ENVIRONMENT TO UNDERSTAND PHYSICS OF THE
  PROMINENT
• PHENOMENA
• RESULTS OF THE IDEALIZED MODEL ARE COMPARED WITH
• THE NRL (REALISTIC) MODEL RESULTS TO IDENTIFY
  SIMILAR PHYSICS AND PROCESSES
• ESTUARINE AND COASTAL OCEAN MODEL (ECOM),
  DESIGNED BY HYDROQUAL, INC. (2002) IS USED AS
  IDEALIZED MODEL

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1. METHODS

• 2. IDEALIZED EXPERIMENTS (CONT.)
• ECOM
• 3D, TIME-DEPENDENT, SIGMA-COORDINATE, FREE
  SURFACE
• SEEKS A SOLUTION ON A INITIAL-BOUNDARY VALUE
  PROBLEM IN A DOMAIN
• GOVERNING EQUATIONS CONSERVATION OF MOMENTUM,
  HEAT, SALT AND MASS (HYDROSTATIC AND BOUSSINESQ
  APPROX.) EQUATION OF STATE
• MIXING IS PARAMETERIZED USING TURBULENCE
  CLOSURE VERTICAL MELLOR-YAMADA 2.5
  (MELLOR-YAMADA, 1982), HORIZONTAL SMAGORINSKY
  (SMAGORINSKY, 1963)
• MODE SPLITTING TECHNIQUE 2D (EXTERNAL) AND 3D
  (INTERNAL)
• ECOM WAS TESTED IN COASTAL ENVIRONMENT
  (HYDROQUAL, MS BIGHT)

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1. METHODS

• ECOM EXPERIMENTS
• FIVE TYPES OF THE ECOM EXPERIMENTS
• REFERENCE EXPERIMENT
• TOPOGRAPHIC EXPERIMENTS
• WIND EXPERIMENTS
• RIVER DISCHARGE EXPERIMENTS
• OCEANIC EDDY INTRUSION EXPERIMENT

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1. REFERENCE EXPERIMENTS - DESIGN
OBJECTIVES TO EXAMINE THE ROLE OF LOCAL FRONTAL
INSTABILITY ON THE CROSS-FRONTAL
EXCHANGE EXPERIMENT DESIGN 1. ECOM DOMAIN 300
KM x 200 KM x 1KM Y NORTHWARD, X EASTWARD,
ALIGNED WITH ISOBATHS
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1. REFERENCE EXPERIMENTS - DESIGN

• 2. ECOM BOTTOM TOPOGRAPHY
• DETERMINED FROM THE FIT TO AN ALONG-SHORE AVERAGE
  BOTTOM SLOPE
• HYPERBOLIC FUNCTION FIT

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1. REFERENCE EXPERIMENTS - DESIGN

• 3. ECOM RESOLUTION
• HORIZONTAL GRID SPACING 5 KM lt ROSSBY RADIUS
  (HORIZONTAL SCALE OF RESPONSE, 20 30 KM IN MS
  BIGHT)
• VERTICAL 16 SIGMA LAYERS
• VERTICAL INCREMENT VARIES
• HIGHER RESOLUTION
• NEAR SURFACE AND BOTTOM

ECOM VERTICAL RESOLUTION
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1. REFERENCE EXPERIMENTS - DESIGN

• 4. ECOM INITIAL CONDITIONS
• THE GOAL IS TO EXAMINE EVOLUTION OF THE FRONT
  TYPICAL FOR THE MS BIGHT ? THE ECOM IS
  INITIALIZED WITH THE OBSERVED FRONT

• DATA WERE COLLECTED DURING NORTHEASTERN GULF
  MEXICO PHYSICAL OCEANOGRAPHY PROGRAM (NEGOM)

• CTD TRANSECTS WERE ? TO ISOBATHS COVER THE AREA
• DATA IS AVERAGED ALONG-SHORE AND BI-LINEARLY
  INTERPOLATED IN SPACE ? I.C. FOR THE ECOM
• THERMOCLINE IS OBSERVED AT 50 70 M

ECOM INITIAL TEMPERATURE
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1. REFERENCE EXPERIMENTS - RESULTS

• 1. GEOSTROPHIC ADJUSTMENT
• IN EACH EXPERIMENT, ECOM IS RUN DIAGNOSTICALLY
  FROM THE STATE OF REST FOR 15 DAYS TO REACH THE
  EQUILIBRIUM

SSH AND CURRENTS
SSH

• SSH ADJUSTS TO PRESCRIBED TEMPERATURE AND
  SALINITY
• COLDER SHELF ? LOWER SSH
• MAX GRADIENT AT SHELFBREAK (100 KM OFFSHORE)

• AFTER 2 WEEKS STEADY GEOSTROPHIC JET
• JET LOCATION SHELFBREAK, ALIGNED WITH THE FRONT
• JET VELOCITY 25 CM/S, SIMILAR TO OBSERVED 25
  20 CM/S IN THE NEGOM DATA

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1. REFERENCE EXPERIMENTS - RESULTS

• 2. FRONTAL INSTABILITY
• AFTER ADJUSTMENT, THE ECOM IS RUN FOR 30 DAYS

SSH TEMPERATURE AT THE THERMOCLINE DEPTH
(50 M)

• SHELF IS GRADUALLY COOLING ? TOPOGRAPHIC
  UPWELLING
• UPWARD VERTICAL VELOCITY AT THE SHELFBREAK

• ZONAL STRUCTURE IS MODIFIED
• FRONT BECOMES NARROWER
• DISTURBANCES PROPAGATE EASTWARD
• END ANTICYCLONIC WARM EDDIES ARE DEVELOPED

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1. REFERENCE EXPERIMENTS - RESULTS

• 2. FRONTAL INSTABILITY
• ANALYSIS OF ENERGETICS REVEALS NATURE OF
  DISTURBANCES
• FIELDS ARE DECOMPOSED INTO ALONG-CHANNEL AVERAGE
  (MEAN, OVEBAR) AND DEVIATION (EDDY COMPONENT,
  PRIME) , WHERE
• AVERAGING IS APPLIED TO ALL ECOM EQUATIONS
• SUBSTITUTION INTO ORIGINAL GIVES A NEW SYSTEM FOR
  EDDY QUANTITIES
• MANIPULATIONS ? EQUATION FOR EDDY KINETIC ENERGY

1. CONVERSION OF MEAN TO EDDY KINETIC ENERGY BY
   REYNOLDS STRESSES
2. CONVERSION OF POTENTIAL ENERGY TO EDDY KINETIC
   ENERGY
3. LOSS OF ENERGY BY DISSIPATION

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1. REFERENCE EXPERIMENTS - RESULTS
2. FRONTAL INSTABILITY

• MEAN KE AND EDDY KE
• MEAN KE ?
• EDDY KE ? AS MEANDERS GROW

• TOTAL PE AND TOTAL KE
• LIGHTER SLOPE WATER ?, HEAVIER SHELF WATER ? TO
  TAKE ITS PLACE ? PE DROP
• TKE ?, HOWEVER AMPLITUDE OF KE IS LESS THAN
  AMPLITUDE OF PE

• BAROCLINIC AND BAROTROPIC TERMS
• BAROCLINIC PE IS CONVERTED TO EKE
• BAROTROPIC SOURCE OF INSTABILITY IS KE OF MEAN
  FLOW
• 1 WEEK BAROCLINIC INSTABILITY
• 2-3 WEEKS BAROTROPIC TERM lt 0 ? EDDIES
  INTENSIFY MEAN FLOW THROUGH REYNOLDS STRESSES

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1. REFERENCE EXPERIMENTS - RESULTS

• 3. CROSS-FRONTAL EXCHANGE
• ASSUME , CROSS-FRONTAL TURBULENT HEAT
  EXCHANGE IS COMPUTED AS VELOCITY-TEMPERATURE
  COVARIANCE
• POSITIVE CROSS-FRONTAL DIRECTION IS OFFSHORE,
  I.E. DIRECTION OF

ECOM HEAT FLUX
NRL MODEL HEAT FLUX
NRL MODEL SST

• COMPARISON WITH NRL MODEL FLUX TO DETERMINE
  CONTRIBUTION OF LOCAL FRONTAL INSTABILITY
• FLUX IS COMPUTED ALONG CHARACTERISTIC SLICE AT
  THERMOCLINE DEPTH
• SIMILAR BEHAVIOR WITH ECOM FLUX
• AMPLITUDE DIFFERENCE IS DUE TO EXTERNAL FORCES ?
  CONTRIBUTION OF LOCAL INSTABILITY 35

• COMPUTED AT THERMOCLINE DEPTH
• X DISTANCE FROM THE FRONT. ZERO FRONTAL
  POSITION
• COLD SHELF lt 0 - TRANSPORT OF COLD WATER
  OFFSHORE gt 0 OFFSHORE TRANSPORT OF HEAT
• FRONT ENHANCES TRANSPORT

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1. TOPOGRAPHIC EXPERIMENTS - DESIGN

• OBJECTIVES
• TO INVESTIGATE THE IMPACT OF TOPOGRAPHY ON THE
  FRONTAL STABILITY AND EXCHANGE ACROSS THE SHELF
• EXPERIMENT DESIGN
• 4 EXPERIMENTS WITH VARYING SLOPE ARE CONDUCTED
• SLOPE MAGNITUDE INCREASES GENTLE, MEDIUM,
  REFERENCE, LARGE AND STEEP SLOPES
• ECOM SLOPES REPRESENT WESTERN (GENTLE) AND
  EASTERN (STEEP) REGIONS OF MS BIGHT

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1. TOPOGRAPHIC EXPERIMENTS - RESULTS

• 1. GEOSTROPHIC ADJUSTMENT
• DIAGNOSTIC RUN FOR TWO WEEKS TO REACH EQUILIBRIUM
• SSH AMPLITUDE DECREASES WITH STEEPNESS
• A SIMPLE ANALYTICAL MODEL, DERIVED FOR THE ECOM
  DIAGNOSTIC COMPUTATIONS, CONFIRMS THE RESULT FOR
  THE SPECIFIED DENSITY DISTRIBUTION

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1. TOPOGRAPHIC EXPERIMENTS - RESULTS

• 1. FRONTAL INSTABILITY

SSH TEMPERATURE AT THE THERMOCLINE DEPTH
(50 M)

• INSTABILITIES GENERATE A WAVE , WHICH PROPAGATES
  EASTWARD
• SLOPE STEEPNESS DETERMINES EDDY ACTIVITY
• GENTLE SLOPE WEAK ACTIVITY
• STEEP SLOPE MEANDERS PINCH OFF AS EDDIES

• STEEPNESS LEADS TO LARGER AMPLITUDES OF
  INSTABILITIES
• CROSS-FRONTAL GRADIENT RISES
• THERMAL FRONT IS DISTORTED
• STRONG UPWELLING

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1. TOPOGRAPHIC EXPERIMENTS - RESULTS

• 1. FRONTAL INSTABILITY

• JET MEANDERS TO CONSERVE PV
• CURRENT MOVES DOWN-SLOPE ? DEPTH INCREASES ?
  POSITIVE VORTICITY, CCW MOTION
• CCW MOTION BRINGS WATER UP-SLOPE ? DEPTH
  DECREASES ? ADD NEGATIVE VORTICITY, CW MOTION
• CW MOTION BRINGS WATER DOWN-SLOPE
• . MEANDERING CURRENT

• STEEPER SLOPE ? LARGE PV GRADIENT ? INDUCES
  MEANDER DEVELOPMENT

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1. TOPOGRAPHIC EXPERIMENTS - RESULTS

• 2. CROSS-FRONTAL EXCHANGE

• LINEAR RELATION BETWEEN GS, MS, RS
• LINEARITY COEFFICIENT 1 (BLUE LINE)

CROSS-FRONTAL FLUX VALUES
FLUX CHANGE VS. BOTTOM SLOPE CHANGE

• ABSOLUTE VALUES OF MEAN CROSS-FRONTAL FLUX
• INCREASES WITH STEEPNESS
• COLD SHELF INTRODUCE GRAVITATIONAL ACCELERATION
  COMPONENT
• EFFECT IS STRONGER FOR STEEPER TOPOGRAPHY

• LS, SS NO SUCH RELATION
• STEEPER SLOPE DIVERGES MORE ? CRITICAL VALUE OF
  THE SLOPE INCREASE

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1. TOPOGRAPHIC EXPERIMENTS - RESULTS

• 2. CROSS-FRONTAL EXCHANGE
• COMPARE WITH NRL MODEL
• CROSS-FRONTAL FLUX ALONG TWO TRANSECTS GENTLE
  AND STEEP

NRL MODEL CROSS-FRONTAL FLUX

• POSITIVE CORRELATION BETWEEN BOTTOM STEEPNESS
  AND FLUX MAGNITUDE
• STEEPER SLOPE RESULTS IN LARGER FRONTAL FLUX

NRL MODEL BATHYMETRY AND TRANSECT POSITIONS
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1. WIND EXPERIMENTS - DESIGN
OBJECTIVES TO INVESTIGATE THE IMPACT OF WIND ON
THE FRONTAL STABILITY AND EXCHANGE ACROSS THE
SHELF EXPERIMENT DESIGN

• MS BIGHT WINTERTIME WINDS ARE VARIABLE
• WIND SPEED AND DIRECTION AT NDBC BUOY (EAST OF
  MS DELTA)
• WINDS ROTATE CW CHANGE DIRECTION EVERY 7-10
  DAYS
• MONTHLY MEAN WIND 6.6 M/S, NORTHEASTERLY
  COMPONENT
• 4 TYPES OF WIND EXPERIMENTS
• SW SEWARD (0O FROM NORTH)
• LW LANDWARD (180O FROM NORTH)
• DN DOWNWELLING-FAVORABLE (90O)
• UP UPWELLING-FAVORABLE (270O)

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1. WIND EXPERIMENTS - RESULTS

• 1. FRONTAL INSTABILITY

SSH TEMPERATURE AT THE THERMOCLINE DEPTH
(50 M)

• WIND CAUSES ADDITIONAL FLUCTUATIONS
• UP OFFSHORE MOVEMENT OF HEAVIER WATER ATOP OF
  LIGHTER WATER ? ADDITIONAL SOURCE OF
  INSTABILITIES
• STRONG VERTICAL MOTION
• UP, SW INITIAL TOPOGRAPHIC UPWELLING IS
  INTENSIFIED DN, LW ADDITIONAL DOWNWARD MOTION

• WIND-DRIVEN MOTION ALTERS INITIAL FLOW
• UP FASTEST GROWTH RATES (ADD DOWNWIND COMPONENT)
• BOTH ANTICYCLONIC/CYCLONIC EDDIES ARE DEVELOPED

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1. WIND EXPERIMENTS - RESULTS

• BEGINNING SIGNIFICANT HEAT EXCHANGE IS DUE TO
  ADJUSTMENT OF DENSITY CURRENT
• AFTER ADJUSTMENT FLUX INCREASES DUE TO MEANDER
  DEVELOPMENT
• GENERAL TREND FLUX AMPLITUDE DECREASES

• 2. CROSS-FRONTAL EXCHANGE

CROSS-FRONTAL FLUX VALUES
CROSS-FRONTAL FLUX TIME SERIES

• EDDIES MAJOR SOURCES FOR CROSS-FRONTAL TURBULENT
  EXCHANGE ? EDDY ACTIVITY AND HEAT FLUX ARE
  POSITIVELY CORRELATED
• WIND FROM EITHER DIRECTION ENHANCES EXCHANGE
  RELATIVE TO THE REFERENCE EXPERIMENT
• DN MIN UP MAX, ALMOST DOUBLE

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1. WIND EXPERIMENTS - RESULTS
NRL MODEL HEAT FLUX DURING UPWELLING AND
DOWNWELLING WINDS

• 2. CROSS-FRONTAL EXCHANGE (COMPARISON WITH NRL
  MODEL)

NRL MODEL MONTHLY MEAN VERTICAL VELOCITY AT 50 M

• STRONG UPWARD MOTION ALONG THE JET
• SIMILAR RESULTS IN THE ECOM MAX VELOCITY AT
  SHELFBREAK SIMILAR MAGNITUDES (10-4)
• TWO NRL MODEL SOLUTIONS ARE CONSIDERED
  DOWNWELLING AND UPWELLING EVENTS (t1, t2)
• HEAT EXCHANGE DURING UPWELLING ALMOST DOUBLED VS.
  DOWNWELLING

ECOM VERTICAL VELOCITY FOR UPWELLING AND
DOWNWELLING WINDS
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1. RIVER DISCHARGE EXPERIMENTS - DESIGN

• RIVER/OCEAN INTERACTION BEGINS IN ESTUARY, WHERE
  MIXING OCCURS
• AFTER MIXING, MODIFIED WATER DISCHARGES ON SHELF
  

• OBJECTIVES
• TO EXAMINE THE EFFECTS OF TRANSFORMED WATER ON
  FRONTAL CIRCULATION
• EXPERIMENT DESIGN
• 4 EXPERIMENTS WITH VARYING CROSS-FRONTAL
  ANOMALIES (WEAK TO STRONG)
• FRESHWATER DISCHARGE DURING WINTER IS MODERATE ?
  INITIAL ANOMALIES AS REFERENCE
• SEASONAL VARIATIONS
• INITIAL ANOMALIES REDUCED 20, 40 - FALL
  (LOWEST DISCHARGE IN MS BIGHT)
• INITIAL ANOMALIES AMPLIFIED 20, 40 - SPRING
  (MAXIMUM DISCHARGE)

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1. RIVER DISCHARGE EXPERIMENTS - RESULTS

• 1. FRONTAL INSTABILITY

SSH TEMPERATURE AT THE THERMOCLINE DEPTH
(50 M)

• ADJUSTMENT
• JET INTENSIFICATION FOR HIGHER ANOMALIES, WHICH
  IS CONSISTENT WITH GEOSTROPHIC ASSUMPTION
• WEAK ANOMALIES (LOW DISCHARGE) HAVE SLIGHT EFFECT
  ON MEANDER DEVELOPMENT
• STRONG GRADIENTS INDUCE LARGE-AMPLITUDE
  INSTABILITIES

• AMPLIFIED GRADIENT CAUSES STRONGER VERTICAL
  MOTION AND UPWELLING AT THE SHELFBREAK

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1. RIVER DISCHARGE EXPERIMENTS - RESULTS

• 2. CROSS-FRONTAL EXCHANGE

CROSS-FRONTAL FLUX VALUES
FLUX CHANGE VS. DISCHARGE CHANGE

• LOW DISCHARGE INHIBITS EXCHANGE, DUE TO LOW EDDY
  ACTIVITY AND LOW CROSS-FRONTAL GRADIENTS
• LINEAR RELATION BETWEEN ANOMALIES AND FLUXES IS
  PREDICTED, I.E. INCREASE OF CROSS-FRONTAL
  ANOMALIES BY 40 CAUSES INCREASE OF FLUX VALUE BY
  80
• NEGATIVE OFFSET IMPLIES THAT RELATION BETWEEN
  SMALL (lt 20) CROSS-FRONTAL ANOMALIES AND FLUX
  CHANGES IS NON-LINEAR

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1. OCEANIC EDDY INTRUSION EXPERIMENTS - DESIGN

• OBJECTIVES
• TO EXAMINE THE EFFECTS OF INTRUSION OF OCEANIC
  EDDY ON FRONTAL CIRCULATION
• EDDY
• SPAWNED FROM LC THROUGH INSTABILITY AND REACHED
  SHELFBREAK
• EXPERIMENT DESIGN
• 3 EXPERIMENTS WITH GAUSSIAN-STRUCTURE EDDY
  PLACED AT SHELFBREAK
• EDDY CORE WATER ANOMALIES SIMULATE COLLISION OF
  SE, ME, AND LE WITH THE FRONT

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1. OCEANIC EDDY INTRUSION EXPERIMENTS - RESULTS

• 1. FRONTAL INSTABILITY

SSH TEMPERATURE AT THE THERMOCLINE DEPTH
(50 M)

• EDDY SPLITTING
• PAIR OF ANTICYCLONIC/CYCLONIC EDDIES IS FORMED
• PAIR MIGRATES EASTWARD AND INDUCES INSTABILITIES
  ? MEANDERS DETACHMENT ? JET DISTORTION

• IN ALL EXPERIMENTS EDDY IS ADVECTED EASTWARD BY
  THE JET
• SE ASSIMILATED BY AMBIENT WATERS
• ME, LE NORTHERN SIDE OF EDDY INTERACTS LONGER ?
  GREAT DISTORTION OF THE JET

• EDDY MAINTAIN ITS IDENTITY TO DAY 5-7, AFTER
  THAT, IT IS ERODED AND MOVED AWAY, CAUSING
  ADDITIONAL INSTABILITIES

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1. OCEANIC EDDY INTRUSION EXPERIMENTS - RESULTS

• 2. CROSS-FRONTAL EXCHANGE

CROSS-FRONTAL FLUX VALUES

• HEAT FLUX GROWS DUE TO INSTABILITY AND RAPID
  MEANDER FORMATION AS EDDY AMPLITUDE INCREASES
• NO LINEAR RELATION BETWEEN EDDY AMPLITUDE AND
  HEAT FLUX IS FOUND

FLUX CHANGE VS. EDDY AMPLITUDE CHANGE

• FLUX IN THE FRONTAL VICINITY ARE ARE
  NON-SYMMETRICAL , INDICATING DIFFERENT TRANSPORT
  INTENSITIES ON BOTH SIDES OF THE FRONT

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1. SUMMARY AND CONCLUSIONS

1. IN THE MS BIGHT, WINTERTIME SHELFBREAK FRONT IS
   UNSTABLE AND UNDERGOES 3 PHASES OF DEVELOPMENT
   (1) ADJUSTMENT, (2) MEANDER GROWTH , AND (3) EDDY
   DETACHMENT
2. A HYBRID BAROCLINIC-BAROTROPIC LOCAL INSTABILITY
   OF FRONTAL FLOW SIGNIFICANTLY CONTRIBUTES TO
   CROSS-FRONTAL EXCHANGE
3. FRONT ENHANCES CROSS-SHELF TRANSPORT AND DOES NOT
   ACT A BARRIER FOR TURBULENT CROSS-FRONTAL
   EXCHANGE OF PROPERTIES IN IDEALIZED EXPERIMENTS
4. ONSHORE HEAT FLUX EXHIBITS MAXIMUM VALUE AT THE
   POSITION OF THE FRONT

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1. SUMMARY AND CONCLUSIONS

• FRONTAL CIRCULATION AND EDDY HEAT EXCHANGE IS
  VERY SENSITIVE TO
• BOTTOM TOPOGRAPHY
• SLOPE STEEPNESS ENCHAINS EXCHANGE DUE TO PV
  CONSTRAINTS AND ADDITIONAL GRAVITATIONAL
  COMPONENT
• LOCAL WINDS
• JET IS MODIFIED IN A MANNER CONSISTENT WITH EKMAN
  DYNAMICS
• UPWELLING WIND IS THE MOST EFFICIENT IN DRIVING
  CROSS-FRONTAL EXCHANGE, WHICH COULD ALMOST DOUBLE
  THE TRANSPORT COMPARED TO DOWNWELLING WINDS
• FRESHWATER DISCHARGE
• POSITIVE CORRELATION BETWEEN RIVER DISCHARGE AND
  FLUX INTENSITY
• CHANGES IN DENSITY ANOMALIES MORE THAN 20 COULD
  DOUBLE CORRESPONDING CHANGES OF THE CROSS-FRONTAL
  HEAT FLUX
• INTERACTION WITH OCEANIC EDDIES
• SMALL-AMPLITUDE EDDIES ARE ASSIMILATED BY AMBIENT
  WATER
• LARGER-AMPLITUDES EDDIES CAUSE FRONT DISTORTION,
  GET ERODED AND MOVE AWAY, INDUCING INSTABILITY
  AND CROSS-FRONTAL EXCHANGE

1. TURBULENT PROCESSES PLAY AN IMPORTANT ROLE IN MS
   BIGHT CIRCULATION. IT IMPLIES THAT TEMPORAL AND
   SPATIAL SCALES OF THE FLOW ARE SMALL. THEREFORE,
   HIGH RESOLUTION SAMPLING AND MODELING ARE
   NECESSARY TO RESOLVE EDDY CONTRIBUTION TO THE
   CROSS-SHELF EXCHANGE.

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2. COASTAL CLIMATOLOGY USING VARIATIONAL
INTERPOLATION

• NORTHERN GULF OF MEXICO LITTORAL INITIATIVE
  (NGLI) IS A MULTI-AGENCY PROGRAM TO FORECAST
  CIRCULATION, SEDIMENT TRANSPORT AND WAVES IN MS
  BIGHT
• IN-SITU OBSERVATIONS (USM, NAVO) SHIP SURVEY
  DURING FEB 99 SEPT 00
• 1339 CTD STATIONS 21 TIME-SERIES STATIONS
• ECOM WAS APPLIED TO MS BIGHT TO HINDCAST
  TEMPERATURE AND SALINITY DURING ONE OF THE NGLI
  SURVEY (AUGUST/SEPTEMBER 2000)

• OBJECTIVES
• TO VALIDATE THE ECOM ON DIFFERENT TEMPORAL SCALES
• TO COMPARE OBSERVED AND SIMULATED CLIMATOLOGIES

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2. COASTAL CLIMATOLOGY USING VARIATIONAL
INTERPOLATION

• INTERPOLATION FROM IRREGULAR COARSE DATA GRID TO
  REGULAR FINE GRID
• TAKING INTO ACCOUNT OBSERVED VARIABILITY TO
  RECREATE A MEAN STATE OF THE OCEAN LARGE-SCALE
  CLIMATOLOGY
• MINIMIZATION OF THE COST FUNCTION

J(X) (1) (IX-D)TWD(IX-D) (2)
(X-XREF)TWREF(X-XREF) (?2X)TWSM(?2X) (3)
(?H? ?X)TWBOT(?H? ?X)
August/September 2000 NGLI CTD Data
Attracts the field to the observations. I -
interpolating operator, D - observations, WD -
data error covariance matrix
(1)
Takes into account the correlation in the
observed field XREF - expected value WREF
diagonal matrix of variances,WSM non-diagonal
matrix describing correlation between different
nodes of X.
(2)
Describes correlation between bottom topography H
and observed field X.
(3)
J(X) ? min
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2. COASTAL CLIMATOLOGY USING VARIATIONAL
INTERPOLATION
SURFACE SALINITY (DATA-MODEL) / ERRORVAR.INT.
ECOM SALINITY
ECOM CLIMATOLOGY TEMPORAL AVERAGE OVER TWO WEEKS
ECOM VS. OBSERVED CLIMATOLOGY
ECOM TEMPERATURE
SURFACE TEMPERATURE (DATA-MODEL) / ERRORVAR.INT.
A good model/data agreement within the error of
estimators.
39
EMAIL Nadya.Vinogradova_at_usm.edu WEB
http//ocean.otr.usm.edu/nvinogra
THANK YOU !