Currents and Temperature in Lake Erie - LEMN · Objective To conduct intensive measurements in Lake...
Transcript of Currents and Temperature in Lake Erie - LEMN · Objective To conduct intensive measurements in Lake...
2004 Experiment:
EC: Ram Yerubandi, M. Charlton, W. Schertzer, M. SkafelV. Richardson, D. Lam, M. Neilson
Collaborators:
NOAA-GLERL: N. Hawley, D. Schwab, D. BeletskyU. Windsor: J. Cibrowski, U Waterloo: R. SmithOMNR: T. Johnson
2005 IFYLE:EC: Ram Yerubandi, M. Charlton, V. Richardson
Currents and Temperature in Lake Erie
SupportTech Ops & Eng Services (NWRI)Data Processing: Bob Rowsel, J. Milne
L=388 kmB=93 kmTr=2.7 yr
BackgroundNutrient management plans started in 70s reduced
- Eutrophication, Hypoxia & TP in the central basin90s Issues
- Warmer temperatures, alteration in the ecosystem due to zebra mussel invasion etc.
- Re-emergence of some 70s issues (Cladophora, Increased TP, Low DO levels never went away in the CB)
Need to revisit nutrient management plans of the lake?
Recent Model SimulationsWater Quality Simulations (Lam et al. 2002)
Lake Erie water quality model simulations (post zebra mussel scenarios) indicated that
• Mussels can affect the phosphorous concentrations in the Lake
• Simulations have not shown any affect of Mussels on the DO in the central basin
• DO variability is related to the interannual variability of the meteorological conditions.
Limitations and future needs (gaps) of these simulations
•Substantial experimental data such as circulations, thermal structure, horizontal and vertical exchanges and biochemical data need to be incorporated in models to improve the predictions.
•Increased understanding of nearshore-offshore exchanges is needed & incorporate these effects in models
•Recalibration of water quality model parameters (for eg. sedimentation and resuspension) in the present conditions
•The models require better tributary loading estimatesPrevious experiments
Project Hypo (1970) & Bi-National Program (1979-80)
Objective
To conduct intensive measurements in Lake Erie for providinghydrodynamic and thermal observations required to assess/predictchanges in water quality and aquatic ecosystem components concurrentlywith the cooperative monitoring in 2004.
Sub-objectives•Develop a data base for calibration and verification of hydrodynamicmodel and 9 Box Model.
• Estimate Water residence times• Estimate Inter basin transports on daily scale for model input• Study bottom currents and dissolved oxygen in the hypolimnion of the
central basin •Estimate onshore-offshore exchanges during summer episodicevents (upwelling) along the north shore of the central basin
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Figure 2. Station locations for the Lake Erie surveillance program 1994-1998.
Great Lakes Surveillance Program•8 CCGS LIMNOS surveys•Spring sampling = surface
•Summer sampling a. 1 m below water surface, plusb. 1 m above the thermocline, plusc. mid-thermocline, plusd. 1 m below the thermocline, pluse. bottom minus 10 and 2 meters.
1. The linear slope shows a depletion of 0.07 mg/L/d.2. Some stations show anoxic conditions from mid-July to the middle of August.
Mar Apr May Jun Jul Aug Sep02468
101214161820222426
Slope=-0.07 m g/L/dayDO
mg/
L &
Hypo
Thi
ckne
ss (m
)
2004
W inklers Profiles Hypo Thickness
(M. Charlton & J. Milne)
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Lake ErieCentral BasinGLNPO stnsJuly 21, 2004
Temp & DO
Dept
h (m
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'896o '896p '896w '896t
'897do '897p '897w '897t
'898do '898p '898w '898t
Dept
h (m
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'899do '899p '899w '899t
Temp & DO
'915do '915p '915w '915t
'916do '916p '916w '916t
Dept
h (m
)
'918do '918p '918w '918t
Temp & DO
'919do '919p '919w '919t
'920do '920p '920w '920t
Temp & DO
Dept
h (m
)
'980do '980p '980w '980t
(M. Charlton & J. Milne)
TemperatureDO
Experimental Set-up (Physical measurements)
Penn. Ridge Box
W. Basin box
RT
RT
OMEE
Jeff Reuter’s buoys
OMNR & UW
Currents• 6 RDI-ADCPs for inter-basin transports, • Sontek Hydra station (+75 cm above bottom)
in the central basin for studying the hypolimnion characteristics.• 5 NOBSKA MAVs for Coastal exchange processesTemperature
Thermistor chain moorings near all ADCP and Met stations.Meteorology
3 Meteorological buoys in three basins with Radiation sensorsWater Quality
2 Stations with transmissometers at two depths3 YSI 6600 (2 in the central basin) Hydrolab stations in the western basin
Deployed:12-16 April 2004Refurbished: July & August 2004Retrieved: First week of October
Meteorology
Central basin buoy
Wind stress and Heat flux in the east basin
Thermal structure in the east basin
Thermocline formation
Relaxation/thermocline oscillations
SE wind storm
Temperature and DO in the central Basin
1. Stratification started from middle of June2. Hypo depth & Low DO3. Effects of physical processes on DO
0.37 mg/L/d
-0.3 mg/L/d -0.4 mg/L/d
-0.082 mg/L/d
(CPH)
6-7 day
Currents: Spectral Characteristics
1. 6-7 day period2. Near-inertial
Rotary Spectra
Stn: Penn Channel
Wind and current vectors (low-pass filtered in EB)
1104
hrs
, 200
4/10
/27
-83.5 -83 -82.5 -82 -81.5 -81 -80.5 -80 -79.5 -79
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Stn 84
Longitude [°]
Latit
ude
[ °]
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Lake Erie Stn84 2004 Hyrda deploy. A and B
A: major: 3.3 cm/s, 80.8°T; minor: 2.6 cm/s. For B: major: 4.1 cm/s, 85.4°T, minor: 2.9 cm/s
Near Bottom Currents
Currents are not very weak as typical parameterizations assumecurrent fluctuations were some times as high as 8 -10 cm/sBBL processes- resuspension processes needs more data and analysis
Deployed in the central and west basins
Cross-validation of DO and temperaturedata is being carried out in Hamilton Harbour
Water Quality time series
Lake Erie Central Basin B at 23.2 m04B0263_AB
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Julian Day 2004
Temp C pH Depth m
Lake Erie Western Basin B at 23.2 m04B0263_AB
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Julian Day 2004
SpCond uS/cm
Lake Erie Western Basin B at 23.2 m04B0263_AB
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DOsat %
Lake Erie Western Basin B at 23.2 m04B0263_AB
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Turbidity NTU
recalibrated
DO is practically zero?, and sudden recovery due to easterly storm
Inter-basin Exchanges
1. Correlation with along-the-lake wind2. Return flow3. Thermocline depth
230 235 240 245 250 255 260 265 270 275 280
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-15
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-5
Dep
th (m
)
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epth
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-0.06
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a)
b)
Low-pass filtered Penn. Channel ADCP currents
Cross-lake
Along-lake
+ towards the eastTowards the CB
Mean currents
Currents in Penn. Ridge
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cmC/s
Dep
th
<u'T'> <v'T'>
Fluxes13 14 15 16 17 18 19 20 21
Temp
Temp
Mean heat fluxes are towards the CB
Transports & exchanges are being calculatedHydrodynamic modeling work in progress
N-Penn Ridge
S-Penn Ridge
Both alongshore & Crosshore exchanges are episodic
0 20 40 60 80 100-20-10
01020
cm/s
Days from April 16, 2004
cross-shore722
-20-10
01020
cm/s
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-20-10
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cm/s
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-20-10
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cm/s
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May 26Jul 5
Currents during spring deployment
Horizontal exchanges in the coastal zone
Lake wide forcings;meteorology- nearshore/offshore accelerations-well-known
Summary
2004 Measurements:
• Large experiment after 20 years in the lake• Physical limnology and surface meteorology parameters• Extensive lake-wide surveys• Data analysis & Hydrodynamic and water quality
modeling (In progress)
2005 Measurements with IFYLE:
• ADCP, Temp, Met moorings • Higher resolution in the thermocline and BBL• Long-term deployments of YSI at four stations in the
central basin
International Field Year on Lake Erie
2005- GLERL & NWRI Collaborative Moorings