Lamont-Doherty Earth Observatory Activities
in the NY Bight Region
75 W
45 N
Ulster Cty
Esopus KINGSTON
Creek
Rondout
Creek
45 N
ME
VT
Parker River
NH
HYDE PARK
• Controls on the carbon balance and
ecosystem health in estuaries of the
northeastern United States, including the
New York Bight and the Hudson River.
NY
W
al
lki
ll
Ri
ve
r
CT
NEWBURGH
West Point
PA
Hudson
River
POUGHKEEPSIE
NY
MA
CT
Plum
Island
Sound
RI
MA
Croton River
HAVERSTRAW
OSSINING
A
Motivation
70 W
CANADA
Wappinger
Creek
40 N
NJ
40 N
NJ
MD
Gulf of
Maine
Atlantic Ocean
N
DE
75 W
NY
B
CT
New Haven
Harbor
70 W
CT
River
Thames
River
RI
Long Island
Sound
NY
• Process studies related to air-water gas
exchange in coastal sytems (i.e., rivers,
estuaries and the coastal oceans)… Anoxia.
C
• Long-term measurements of high winds and
waves to better understand the impacts on
the coast.
Christopher J. Zappa & Wade R. McGillis
Lamont-Doherty Earth Observatory, Columbia University
2006 Annual MACOORA Meeting, Baltimore, MD
Surface Processes Instrument Platform
(SPIP)
Controlled Flux Technique Mast
- Infrared Imager, Laser
Atmospheric Profile Mast
- CO2, U, T, Q
Subsurface
Characteristics of Estuaries
F = KΔc
Δc = s(pCO2 a − pCO2 w )
K ∝ Sc −n f (u ′ ,l)
High Tide
- pCO2, DO, ADCP, ADV
Low Tide
High seasonal and spatial variability in the
estuarine-atmospheric pCO2 difference.
Gasex-II Eastern Equatorial Pacific
Jan-Mar 2001
ΔpCO2 ~ 100 ppm.
1
Hudson River Haverstraw Bay
Hudson River Trapa Station
ADCP observations: streamwise velocity (u; rotated into angle of
maximum variance), streamwise veritical shear (du/dz), rangenormalized acoustic backscatter (ABS), the xz component of turbulent
stress (tau_xz), vertical turbulent viscosity (K_z), and turbulent kinetic
energy production (P). White regions within the water column signify
poor quality measurements, typically below the instrument noise floor.
Hudson River Trapa Station
•
•
http://datagarrison.com/users/1105898/1100694/plots.php
Wind Speed, RH, Air Temp, Skin Temp, Solar Radiation,
Longwave Radiation, CO2, O2, Methane
NOAA WaveWatch III
2
Field Research Facility of the US Army
Corps of Engineers
WASFAB Setup at FRF
TNO
Out to Shelf Break
IR Imager
LDEO Boom
Key:
Linear Array
•
Outer banks of North Carolina,
USA, just north of Cape Hatteras
•
600 m pier that extends out into the
coastal ocean in 8-9 m of water.
•
Infrastructure includes continuous
directional wave spectra via linear
array as well as bulk atmospheric
properties.
Wave Buoy
ADCP
Atms Buoy
WASFAB Conditions
NOAA Trailer
8m
LDEO Momentum Fluxes
Direct Covariances
τ = − ρu ′w′
3
LDEO Website of FRF Data
Close-up of LDEO Instrumentation on Boom
Extended 8 m at FRF
• WASFAB 2005 Experiment
Gill 3-D Anemometer
http://www.ldeo.columbia.edu/~felixt/ocp/zappa/Duck_2005/index.html
• Long-Term Measurements
Heitronics
Longwave Radiometer (SST)
http://www.ldeo.columbia.edu/~felixt/ocp/zappa/Duck_Longterm/index.html
LiCor 7500
(Water Vapor)
• Status of instruments, processing, data
Video Camera
• Diagnostics of Waves, Wind, Met, & Fluxes
Riegl Wave Altimeter
Plum Island Sound Estuary
Turbulent Mixing Control on Gas Transfer
•
Variety of environmental forcing and processes (Wind,
Currents, Rain, Waves, Breaking, Surfactants, Fetch)
•
Wind speed does not capture the process variability of airwater exchange.
•
Turbulent dissipation shows promise for estimating K in a
variety of dynamic systems.
– Near-surface is critical
Study Site on the
Parker River
Parker Estuary, Plum Island
Sound LTER Site
Flow (m3s-1)
11
Watershed Size (km2)
609
Length of Study Site (km)
30
Residence Time (days)
5-20
Wanninkhof [1992] quadratic relationship
4
Infrared Imagery of Air-Sea
Interaction Processes
•
Tides
Field data of K measured in estuaries
is lacking, and not in good agreement.
Infrared imagery shows the
spatial and temporal variability
that affects air-water exchange.
Wind
Rain
Non-dome studies
Dome studies
-1
Complex interplay between
tidally- and wind-driven
exchange.
30
k600 (cm hr )
•
Gas Transfer in Estuaries
Magnitude and direction of the gas flux is controlled by wind AND tides.
20
10
0
0
2
4
6
8
Wind (m s-1)
Method
Floating Domes
Investigating Wave Processes Important to
Air-Sea Fluxes Using Infrared Techniques
Spatial/Temporal
Footprint
m2 / min
Problems
Dome Leakage; Artificial
Turbulent Regime
Natural Tracers (Rn,
CFC’s, etc.)
km2 / days
Unknown Sources/Sinks;
Complex Mixing Regimes
Purposeful Gas Additions
(SF6)
km2 / days
Complex Mixing Regimes
Air-Sea Flux Processes
Christopher J. Zappa
Lamont-Doherty Earth Observatory, Columbia University
W.R. McGillis – LDEO
G. De Leeuw – TNO
M.M. Moerman – TNO
M. Smith – Leeds
S. Norris – Leeds
M. Banner – LDEO
R. Morison – UNSW
Host of Army Corp of Engineers Field
Research Facility Personnel
2006 ASI Workshop Heidelberg
September 6-8, 2006
5
Scaling Gas Transfer
F=D
Fick’s Law
K=
Turbulent Mixing Control on Gas Transfer
∂C D
=
(Cw − αCa ) = K (Cw − αCa )
∂z δ D
D
Boundary Layer Scaling
δD
⎛νD 2 ⎞
⎟
⎜ ε ⎟
⎝
⎠
δD ∝ ⎜
K ∝ (εν )
1
4
−1
Sc
2
1
Batchelor [1959] (Melville [1996]);
Brumley and Jirka [1987,1988]
•
Variety of environmental forcing and processes (Wind,
Currents, Rain, Waves, Breaking, Surfactants, Fetch)
•
Wind speed does not capture the process variability of airwater exchange.
•
Turbulent dissipation shows promise for estimating K in a
variety of dynamic systems.
– Near-surface is critical
4
Batchelor Length Scale – turbulent microscale
for a passive scalar
Inertial Dissipation
Surface Renewal: Lamont and Scott [1970]
Breaking Waves: Kitaigorodskii [1984]
• Kinetic energy cascades from larger scales down to smaller scales.
• Turbulent kinetic energy dissipation rate describes the rate at which
this process occurs
Experiments Estimated Turbulent Scales:
- Asher and Pankow [1986]
- Dickey et al. [1984]
- recently others
Wanninkhof [1992] quadratic relationship
SST Modulation by Swell
Motivation
•
Historical Perspective of Wave Modulation of SST.
•
Wave processes have been shown to be important to air-sea
fluxes.
– Miller and Street [1977] observed modulation in the laboratory
that shifts from downwind to upwind side with wind speed
– Simpson and Paulson [1980] observed SST modulation from
FLIP
– Jessup and Hesany [1996] also observed from FLIP variability in
the phase of the SST modulation as a function of relative wind
swell direction
– Zappa et al. [2004] observed enhanced transfer in laboratory
experiments
•
Waves, Air-Sea Fluxes, Aerosols, and Bubbles (WASFAB)
Experiment 2006
– Coastal Ocean
– Air-Sea Fluxes by Direct Covariance and ACFT
– Waves, Turbulence
•
•
Peak in the coherence spectra occurs at the peak wave frequency.
Phase angle between the SST and wave height at the peak wave frequency is -30°,
indicating warm SST on the upwind side of the crest
•
Phase spectrum increases from -30 at 0.06 Hz to 100 at 0.4 Hz, implying that at 0.4 Hz
warm SST fluctuations associated with steep gravity waves downwind of the crest
–
–
Due to locally enhanced wind stress that thins TBL
Due to the generation of turbulence from surface instabilities or the enhancement of capillary waves
Simpson and Paulson [1980]
6
SST Modulation by Swell
SST Disturbance due to Microbreaking
Incipient breaking of small scale waves that do not entrain air.
Cleaned surface and U = 5.5 m s-1
•
For the wind and swell aligned,
the maximum SST modulation
occurs on the downwind side of
the swell.
•
For the wind and swell
opposed, the phase changes
by roughly 180° corresponding
to the rear face (again the
downwind side).
•
Suggests that microbreaking is
a mechanism that is consistent
with the shift in phase
depending on the alignment of
the wind and swell.
IR Imagery of Microbreaking
Jessup and Hesany [1996]
Enhancement due to Microbreaking
Field Research Facility of the US Army
Corps of Engineers
Incipient breaking of small scale waves that do not entrain air.
IR Imagery of Microbreaking
Cleaned surface and U = 5.5 m s-1
Out to Shelf Break
Key:
Linear Array
•
Outer banks of North Carolina,
USA, just north of Cape Hatteras
•
600 m pier that extends out into the
coastal ocean in 8-9 m of water.
•
Infrastructure includes continuous
directional wave spectra via linear
array as well as bulk atmospheric
properties.
Wave Buoy
ADCP
Atms Buoy
Microscale wave breaking locally enhances the K by a factor of 3.5
– contributes up to 75% of the transfer
7
Close-up of LDEO Instrumentation on Boom
Extended 8 m at FRF
WASFAB Setup at FRF
TNO
IR Imager
Gill 3-D Anemometer
Heitronics
Longwave Radiometer (SST)
LDEO Boom
LiCor 7500
(Water Vapor)
NOAA Trailer
8m
Video Camera
Riegl Wave Altimeter
IR Imagery and Controlled Flux Technique
Setup at FRF
IR and Video Imagery at FRF
Fluxes
Laser and Imager
Fluxes
8m
8
WASFAB Conditions
LDEO Momentum Fluxes
Direct Covariances
τ = − ρu ′w′
LDEO Momentum Fluxes
Direct Covariances
τ = − ρu ′w′
Magnitude Squared Coherence and Phase
C XY ( f ) =
PXY ( f )
2
PXX ( f ) PYY ( f )
•
Cross Spectra is a complex
quantity and its phase
provides information on the
location of the temperature
maximum
•
Positive phase means SST
leads the surface wave
9
WASFAB Summary of Magnitude
Squared Coherence and Phase
Phase as a Function of Wind Speed
and Wave Height
•
Similar to laboratory
measurements of Miller and
Street [1976] that phase
shifted from positive phase
with increasing wind speed.
–
•
Phase change also related
to an increase in significant
wave height
–
IR Imagery and Controlled Flux Technique
Setup at FRF
Not observed in the field by
either Simpson and
Paulson [1980] or Jessup
and Hesany [1996]
Related to wave processes
change?
Active Controlled Flux Technique
(ACFT)
CFT Patch Decay
Fluxes
TS (0, t ) = TO
h
h 2 + 4 Dt
e −λt
k heat = Dλ
Laser and Imager
Fluxes
Frames at 120 Hz
8m
Faster Decay
= Faster Renewal
= Faster Transfer
10
Active Controlled Flux Technique
(ACFT)
Heat Transfer Velocity and Heat Flux
QCFT = ρC p k heat ΔT
CFT Patch Decay
k* =
•
Green band is the range of
field data from Asher et al.
[2004]
Note that WASFAB results
fall within this range
–
•
Frames at 120 Hz
Character of the wind speed
relationship is linear
Agrees with Asher et al.
[2004]
Suggests similar behavior
for relatively high solubility
gas such DMS
Deliberate tracers may not
work
–
Faster Decay
= Faster Renewal
= Faster Transfer
–
–
Heat Transfer Velocity v. Wind Speed
QCFT
QNET
WASFAB Heat Fluxes
QH = ρw′T ′
QH = ρw′T ′
QL = ρw′q′
(
QLW = ε si QLWin − σT 4
)
QS = β (1 − α )QSWin
QL = ρw′q′
•
Character of the wind speed relationship is linear
–
–
Suggests similar behavior for relatively high solubility
gas such DMS
Deliberate tracers may not work
QNET = QL + QH + QLW + QS
11
Modulation of Dimensionless Heat Flux
QCFT = ρC p k heat ΔT
k* =
QCFT
QNET
Modulation of k* with Wind Speed and
Wave Height
•
Begin to see the influence of the swell at moderate wind
speeds
•
Enhanced flux on the forward face of the swell
Modulation of k* with Wind Speed and
Wave Height
•
Similar to laboratory measurements of microbreaking.
•
No phase relationship
–
Highly wind-forced system with minimal swell influence
Modulation of k* with Wind Speed and
Wave Height
•
Waves and wind continue to increase
•
Subtle shift in the enhanced flux from forward to rear
face
12
Modulation of k* with Wind Speed and
Wave Height
Modulation of k* with Wind Speed and
Wave Height
•
Waves and wind continue to increase
•
Highest wind and biggest waves
•
Clear shift in the enhanced flux to the rear face
•
Enhanced flux completely on the rear face
Modulation of k* with Wind Speed and
Wave Height
•
Processes Modulating k*
Why the shift?
Microbreaking
Whitecapping
13
Processes Modulating k*
Conclusions
•
Similar to laboratory measurements of Miller and
Street [1976] that phase shifted from positive to
negative phase with increasing wind speed.
–
Microbreaking
•
Phase change also related to an increase in
significant wave height
•
Dimensionless heat flux suggests enhancement of
20% to 40%
•
K* also shows modulation along the phase of the
wave
Whitecapping
–
–
Continuing Work
•
Improve our understanding of the evolution and interaction of atmospheric and oceanic boundary
layers. In particular, the influence of wave processes characteristic of low to moderate wind
conditions on air-sea fluxes.
•
Main objectives of the field program:
–
Observe air-sea transfer processes
at high resolution very near the
interface
–
Observe finescale variability in
ocean surface properties that
influence, and are influenced by airsea fluxes
Not observed in the field by either Simpson and Paulson
[1980] or Jessup and Hesany [1996]
Coincides with the shift in modulation of SST
Processes associated with the shift in modulation
Closeup of LDEO Boom Extended 8 m at
FRF
Boom has 7 m in board of End of Pier
14
NOAA Trailer Instrumentation
Downwelling Shortwave
WASFAB Conditions (Bulk)
Relative Humidity/Temperature
Campbell
Datalogger
Air-Sea Interaction Processes
Infrared Imagery of Upper Ocean Processes
Whitecapping
R/V Ron Brown
R/P FLIP
15