Five Decades of Coastal Circulation Studies at Oregon State University

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Five Decades of Coastal Circulation Studies at
Oregon State University
A very brief overview by Jane Huyer (Seminar
Presented 7 April 2009)
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In the beginning . . .
Cold War - undersea warfare, -gt funds for oc
research Sophisticated Mechanisms - bottles,
thermometers, messengers, glassware -
desk-top calculators Support Staff -
secretaries, typists, filing clerks,data
dollies - technicians, engineers, student
workers, gras

• Coastal oceanography out to the 1000 fathom
  depth has been neglected. This is particularly
  true of our west coast . . .
• Oregon State College is in a unique position to
  carry out a research program of vital importance
  to the nation.
• - (Wayne V Burt, 1958)

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First Decade (1959-1969)
(Block funding rapid growth young faculty
students new ships)

• Major Projects
• 1959 TENOC begins,
• routine hydrography
• 1966 CoOc begins,
• First CM Mooring
• 1969 TENOC CoOc continue

1961, R/V Acona
1966
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First Decade (1959-1969) - TENOC
(Cold War Contd sound speed depends on TS
which vary spatially)
TENOC Hydrography - Nansen or NIO bottles
drift bottles - reversing thermometers, -
salinity from titration, density from tables -
NH-Line sampled every 1-3 months, 1961-71 -
very labor intensive - Wayne Burt, June
Pattullo, Bruce Wyatt - grad students at sea 12
days/year - several full-time hydro technicians
1966
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First Decade Contd (1965-1969)
CoOc Coastal Oceanography (June Pattullo et al)

• - First Current Meter moorings
• - Smith, Pillsbury, Mooers, Collins
• Braincon - Savonius rotor large vane, -
  speedometer glowing compass -
  photographic film read by eye- low-cost,
  reliable hardware
• central computers (punched cards)

1966-68
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First Decade Insights on Coastal Upwelling
Repeated Sections can yield ratesof upwelling
and cross-shelf patterns
s , V
60
0
May 63
200
Sloping Pycnoclines lead to fronts,
coastal jet, undercurrent
T, 3 days apart
U (cm/s)
Local Heating can change density of upwelled
water, which may sink at the front (causing
inversions)
Sep 66
Cross-Shelf Flow Patterns??
Smith, Pattullo, Lane Mooers, Collins, Smith,
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Second Decade (1969-1979)
(Block funding ended hypotheses required group
science encouraged)
Data Collection circa 1970 - monitoring is
out of fashion - regular NH sampling ends -
sampling designed for specific goals - Geodyne
CTD (inductive), recording on punched paper
tape - NIO bottle samples for calibration -
reversing thermometers - inductive salinometers
(CSIRO) - Aanderaa cm record aver. speed
inst. direction on mag tape - grad students at
sea 8 days/year - local computers - instrument
techs increase

• Projects/Highlights
• 1969 CoOc continues
• 1972 CUE-I, Oregon
• 1973 SCOR WG 35 at OSU CUE-II, Oregon
• CUEA Theor Workshop
• 1974 Poinsettia, Oregon
• JOINT-I, NW Africa
• 1975 WiSp, Oregon
• 1976 JOINT-II, Peru
• 1977 JOINT-II, Peru
• 1978 SUCS, Oregon

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Second Decade Contd (1969-1972)
CoOc Coastal Oceanography (June Pattullo et al)
- Analysis of early Current Meter records -
temporal variability weather tides -
correlation with coastal sea level -gt continental
shelf waves
(Cutchin Smith, 1973)
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Second Decade CUE-I, CUE-II CUEA
(OSU, PMEL, FSU, Miami, WHOI, etc)
Initial Questions - typical/average magnitudes of
vertical velocity? - cross-shelf circulation
patterns 1-cell, 2-cell, T anomaly? - 2-D?,
i.e., uniform alongshore? - response times of u,
v, w, density? - offshore scales of u, v, w,
density? - is alongshore current geostrophic?
45N
Eq
45S
70W
135W
Yoshida, 1967
Mooers, Collins, Smith
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Second Decade CUE-I, CUE-II CUEA
General Approach Multiple Field Studies
- first off Oregon, later off NW Africa Peru
Theoretical Studies - including a
Theoretical Workshop in Corvallis
John Allen at sea!
Mooers, Pedlosky, Mysak, others
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Second Decade CUE-I, CUE-II CUEA
Question Magnitude of vertical
velocity? Approach - deploy a vertical current
meter, - follow it acoustically, get radar
positions, - record depth and rotations, -
recover it and read data Result variability is
huge -gt null result!
John Allen
(D. Deckard, MS, 1974)
Ken Burt, John Cooper, Allen Morton, WHOI
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CUE-I, CUE-II (contd)
Questions Cross-shelf Circulation?
Uniform Alongshore? One Approach Dense CTD
surveys - 5 cross-shelf sections 5 nm apart
- measure T, C, P, calculate S,
density Results- T anomaly is due to
alongshore advection, not cross-shelf
circulation - offshore scales vary with
bathymetry
(Huyer, 1974)
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CUE-I, CUE-II (contd)
Questions Cross-shelf Circulation?
Uniform Alongshore? One Approach Current
Meter Arrays - measure u(x,z,t), v(x,z,t) -
calculate average ltu(x,z)gt Results- u much
smaller than v- fluctuations much larger than
average- ltugt very sensitive to axis
orientation- CUE-I bathymetry too complex-
CUE-II in simpler region - offshore
transport in thin srfc layer - onshore transport
is at mid-depth (see next slide)
(Kundu Allen, 1976)
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Mid-Shelf, July-August 1973
CUE-I, CUE-II (contd)
Question Cross-shelf Circulation? Approach
dense mid-shelf mooringResult from CUE-II cm
array - offshore at surface, - onshore
in interior, -gt single cell
Average U (cm/s)
(Huyer, 1976, using data from Halpern,
Pillsbury Smith)
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CUE-I, CUE-II, CUEA contd
Wind, mid-shelf current sea level
Questions Response times of velocity? V
geostrophic?Approach moored arraysResults
- rapid barotropic response (1-2 days) -
slower baroclinic response (at least in
summer) - both are geostrophic to
first approximation
(Kundu, Allen Smith, 1975)
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CUE-I, CUE-II (contd)
Question Response Times of T, S,
density?Approach Rapidly repeated CTD
sectionsResult very rapid (1-2 days) in surface
layer - much slower in interior (days- weeks)
(Halpern, 1976)
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CUE-I, CUE-II, CUEA Contd
Cross-Shelf Separations
Question Offshore decay scales?Approach
moored arrays, repeated CTD
sectionsResults - 25 km at 45 N (Oregon) -
80 km at 15 S (Peru) - consistent with theory
(latitude, stratification) to first
approximation
Alongshore Separations
(Kundu Allen, 1976)
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Alongshore Propagation
Second Decade Other Results
(Kundu Allen 1976)
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Poinsettia -- seasonal cycle
Second Decade Other Results
- a 17-month record of mid-shelf current
temperature with winds sea level (all 40-hr
low-passed)
1 Jan 73
1 Jan 74
(Huyer and Smith, 1978)
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Second Decade Other Results
WiSp (1975) Winter-Spring (OSU, UW, IOS) -
seasonal average flow patterns over the
shelf - narrow, strong jet in spring, -
wider jet in summer, - poleward flow in
winter - weak undercurrent in summer -
fluctuations more baroclinic in winter than in
spring and summer, - transition occurs
rapidly, - correlated with drop in coastal sea
level SUS (1977-8) Slope Undercurrent Study
(OSU, UW) - mean flow pattern very subtle (weak
undercurrent), - strong inertial currents in
winter - a persistent anticyclonic eddy over
slope
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Third Decade (1979-1989)

• Research Tools circa 1980
• NBIS CTD, excellent T P,
• much improved S data,
• recording on mag tape
• - samples for S calibration
• - precision salinometers (Autosal)
• - reliable current meters
• - developing ADCP ADP
• - developing GPS
• - satellite SST
• - desk-top computers
• - national SuperComputers

• Projects/Highlights
• 1979 CUEA analysis continues
• Analyt. numer. models
• 1980 FTS, Oregon
• 1981 CODE (38-39 N)
• SuperCODE (35-44 N)
• Peru Currents
• 1982-3 El Nino
• 1984 ACE (East Australia)
• 1987-8 CTZ

(Sea-time no longer required for all grad
students!)
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Third Decade (1979-1989)
Dynamical Analyses Modelling - boundary
layer transports, - response to local wind
forcing, - estimating terms of momentum
equations, - coastal trapped waves, -
response to remote (equatorial) forcing -
increasing competence sophistication in
numerical analyses models
(Allen, Brink, Enfield, Newberger, Federiuk,
many more)
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Third Decade, continued
SuperCODE A Large-Scale West Coast Shelf
Experiment 1981-1983
Seasonal Wind Stress and Currents
Time Series - coastal winds, sea level,
shelf currents, - large alongshore extent, -
seasonal cycles? - coherence of
fluctuations? Hydrography - CTD sections
across margin, - at several latitude
- in different seasons
(Strub et al., 1987)
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SuperCODE Large-Scale Wind Forcing of Coastal
Currents
Wind Stress
Current at 48 N vs coastal winds
V (48N) vs t(y,t)
Alongshore distance (km)
Wind at 48 N vs coastal winds
t(48N) vs t(y,t)
(Denbo Allen, 1987)
Coastal winds influence shelf currents farther
north (through CTWs) (propagating at 250
km/day)
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Supercode Offshore migration of Coastal Front
Jet
16 Apr 83
20 May 83
Density (at 42 N)
Geostrophic Velocity rel to 150 m
(Huyer, 1990)
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Third Decade, Contd CODE

• Coastal Ocean Dynamics Experiment at 38-39 N
• - WHOI, SIO, OSU (Beardsley, Davis, Allen, et
  al)
• - similar in design to CUE-I, CUE-II,
• - simpler bathymetry,
• - much windier,
• - shipborne ADCP (Regier Kosro, SIO)
• - surface drifters (Davis, SIO)
• New Results
• - squirts and jets (currents diverge from
  coast)
• - significant curl in wind stress (expansion
  fan)
• - cold filaments extend far offshore

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Third Decade, Contd El Niño 1982-83

• Peru Currents, 1982-1984
• - design somewhat similar to SuperCode
• - fewer moorings,
• - longer CTD sections,
• - overlap in time
• - designed to study normal conditions
• - captured strong El Niño, simultaneously
• off Oregon Peru
• Results
• - current anomalies propagate poleward
• in coastal wave guide
• - offshore scale varies with latitude
• - atmospheric El Niño signals affect local winds
• - both local and remote forcing occurs during El
  Niño

45N
Eq
45S
70W
135W
Yoshida, 1967
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Third Decade , Coastal Transition Zone
Questions What is the nature structure of
cold filaments? What causes them to
form? Answers Meandering baroclinic jet is
baroclinically unstable small eddies grow,
potential energy is converted to kinetic.
V at 25 m 9-18 Jun 87
(see papers by Strub, Kosro, Walstad and many
others, JGR, 1991)
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June 1987 Meandering Jet
Third Decade , CTZ, contd
Temperature (C)
Northward Current (m/s)
(Smith, 1992)
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Fourth Decade (1989-1999)

• Research Tools circa 1990
• SBE CTD, excellent C,T P,
• recording on computers
• SeaSoar
• conventional ADP current meters
• shipboard ADCP with GPS
• satellite SST
• satellite altimeters
• - unix WorkStations PCs
• - national SuperComputers

• Projects/Highlights
• 1989 CTZ analysis continues
• Analyt. numer. models
• EBC (NorCal)
• Coastal Jet Separation
• NMFS survey of PUC
• 1997-8 El Nino
• GLOBEC NEP LTOP

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Studies of Meandering Jets/Eddies
Fourth Decade

• EBC (Eastern Boundary Current study) - large
  SeaSoar/ADCP surveys of a large region
  off northern California,-gt surface subsurface
  eddies interact with jet, -gt interactions have
  biological consequences,-gt poleward flow along
  continental slope,-gt subsurface eddies originate
  in undercurrent
• CJS (Coastal Jet Separation) - SeaSoar/ADCP
  surveys of Cape Blanco region,- multiple
  satellite-tracked drifters-gt meandering jets off
  CA continue the coastal jet off Oregon
• NMFS Survey of Poleward Undercurrent
• - ADCP measurement during fish assessment cruise
• -gt PUC continues from 35N to 51N, though weak
  at 43-48 N

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Fifth Decade (1999-2009)

• Research Tools circa 2000
• SBE CTD, SeaSoar, Minibat,
• conventional ADP current meters
• shipboard ADCP with GPS
• coastal radar for surface currents
• Chameleon (for turbulence/mixing)
• satellite SST
• satellite altimeters
• satellite wind-stress
• powerful PCs workstations
• parallel computing
• data assimilation methods
• local, regional global models
• turbulence mixing models

• Major Projects
• 1999 Globec LTOP continues
• Analyt. numer. Models
• 1999 NOPP
• 2000 Stonewall Bank Oc Mix
• Globec NEP Process
• 2001 COAST summer
• 2002 COAST winter
• 2002 Globec NEP Process
• 2003 GLOBEC LTOP ends
• 2006 RISE
• 2007 OrCOOS, NANOOS

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Fifth Decade -- Explosion!
Excerpt from Poster
Clearly beyond my ability to summarize this
decade!
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GLOBEC North East Pacific LTOP(Long Term
Observation Program)
Fifth Decade
Repeated CTD/ADCP surveys (42-45 N), drifters,
mooring

• Major Results
• Large Scale Influences
• El Nino in 1997-8
• Advection from Subarctic in 2002
• Effect of Regional Wind Stress Curl (Npt cf
  CresCity)
• (see next slides)
• Climate Change (NH-Line during LTOP cf TENOC)

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Two Upwelling Domains in Mid-SummerNH CR
sst
A. Huyer, J. Fleischbein, J. Keister, P.M. Kosro,
N. Perlin, R.L. Smith, P.A. Wheeler
sss
Journal of Marine Research, 63, 901-929, 2005
sea level
mld
NH and CR sections Surface properties Physical
chemical variables Plankton biomass Significant
Differences are due to wind field fresh water
input
nitrate
integ chlor
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Mean North-South Surface Current at 45 42 N
Two Upwelling Domains, contd
Blue ADCP V at 25 m
Magenta sum of Vg (0/25) plus ADCP at
25m
Main core of coastal jet lies inshore off
Newport, offshore off Crescent City
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Local Summer Winds (QuikSCAT satellite, Jun-Sep,
2000-01)
Two Upwelling Domains, contd
Wind Stress Curl

• Wind Stress

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Long-Term Change in Summer Temperature
Fifth Decade contd GLOBEC LTOP
1961-71
1997-2005
Difference
95, 99confidence intervals
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LTOP -TENOC Differences at NH-85 (all seasons
combined)
Long-Term Climate Change, Contd
Surface layer- warmer, lighter
NPIW layer warmer, saltier
Deeper layer - fresher, lighter
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COAS At Age 50 Exciting Developments!

• Breaking Internal Waves and Vigorous Mixing-
  likely explain why we were never satisfied with
  our estimates of the average cross-shelf
  circulation Thank you Jim, Jonathan company!
• Interaction between SST Wind Stress Curl- with
  a little chaos, may well cause interannual
  variability. Thank you Dudley, Michael
  company!
• Sophisticated Models (of currents AND of
  mixing) Thank you Roger, Bill, Eric company!
• Weve come a long way, and still have miles to
  go.

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Acknowledgements

• Coastal circulation studies at OSU have been
  supported over these decades by
• Office on Naval Research
• National Science Foundation
• National Oceanic and Atmospheric Administration,
  and
• National Aeronautics and Space Administration

Jane Huyers work in preparing this overview was
supported by NSF Grant OCE-0434810
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