acoustic-microwave water level sensor comparisons in an estuarine environment john d. boon john m....
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Acoustic-Microwave Water Level Acoustic-Microwave Water Level Sensor Comparisons in an Sensor Comparisons in an
Estuarine EnvironmentEstuarine Environment
John D. BoonJohn D. BoonJohn M. BrubakerJohn M. Brubaker
Virginia Institute of Marine ScienceVirginia Institute of Marine ScienceCollege of William and MaryCollege of William and MaryGloucester Point, VA 23062Gloucester Point, VA 23062
OCEANS’08 MTS/IEEE MEETING, QUEBEC, CANADA
Acoustic Sensor Aquatrak 3000 Series
Primary Sensor
NOAA/NOS National Water Level Observation Network (NWLON)
Selected Microwave SensorsSelected Microwave Sensors
Miros Design Analysis Ohmart/Vega Sutron
2 signal types: pulse and frequency modulated continuous wave
Heitsenrether et al., OCEANS’08 MTS/IEEE QUEBEC
Test SetupTest Setup
Heitsenrether et al., OCEANS’08 MTS/IEEE QUEBEC
Microwave Sensor Design Analysis Associates (DAA)
Model H-3611
Virginia Institute of Marine Science (www.vims.edu/tidewatch)
Acoustic
Microwave
STORM TIDE EMERGENCYSTORM TIDE EMERGENCY MANAGEMENT (STEM)MANAGEMENT (STEM) ( (www.vims.edu/tidewatch)
Storm SurgeStorm Surge
Tidal Water LevelsTidal Water Levels
Subtidal Water LevelsSubtidal Water Levels
6-minute data in near real-time6-minute data in near real-time
STORM TIDE EMERGENCYSTORM TIDE EMERGENCY MANAGEMENT (STEM)MANAGEMENT (STEM) ( (www.vims.edu/tidewatch)
Storm SurgeStorm SurgeTidal Water LevelsTidal Water Levels
Subtidal Water LevelsSubtidal Water Levels6-minute data in near real-time6-minute data in near real-time
Tsunami Warning SystemsTsunami Warning Systems1-minute data in near-real time1-minute data in near-real time
HANNA
JAMESTOWN FERRY PIER, VA
Hurricane IKE
Water Level MeasurementsWater Level Measurements Fixed Sampling Interval Fixed Sampling Interval
Noise (Gaussian) + Signal (periodic)Noise (Gaussian) + Signal (periodic)
Water Level MeasurementsWater Level Measurements Fixed Sampling Interval Fixed Sampling Interval
Noise (Gaussian) + Signal (periodic)Noise (Gaussian) + Signal (periodic)
Standard error = Standard error = σσ/√n /√n (moving average)(moving average)
Water Level MeasurementsWater Level Measurements Fixed Sampling Interval Fixed Sampling Interval
Noise (Gaussian) + Signal (periodic)Noise (Gaussian) + Signal (periodic)
Standard error = Standard error = σσ/√n /√n (moving average)(moving average)
More is betterMore is betterInterval doesn’t matterInterval doesn’t matter
Water Level MeasurementsWater Level Measurements Fixed Sampling Interval Fixed Sampling Interval
Noise (Gaussian) + Signal (periodic)Noise (Gaussian) + Signal (periodic)
Standard error = Standard error = σσ/√n /√n (moving average)(moving average)
More is betterMore is betterInterval doesn’t matterInterval doesn’t matter
Energy-Frequency distribution Energy-Frequency distribution (numerical filter) (numerical filter)
Water Level MeasurementsWater Level Measurements Fixed Sampling Interval Fixed Sampling Interval
Noise (Gaussian) + Signal (periodic)Noise (Gaussian) + Signal (periodic)
Standard error = Standard error = σσ/√n /√n (moving average)(moving average)
More is betterMore is betterInterval doesn’t matterInterval doesn’t matter
Energy-Frequency distribution Energy-Frequency distribution (numerical filter) (numerical filter)
Longer is betterLonger is betterInterval mattersInterval matters
Data Collection Rate: 1 sample/sec (Data Collection Rate: 1 sample/sec (1Hz1Hz))
Acoustic Water Level (AWL)Acoustic Water Level (AWL)Aquatrak 3000 NOAA/NOSAquatrak 3000 NOAA/NOS
Data Collection Rate: 1 sample/sec (Data Collection Rate: 1 sample/sec (1Hz1Hz)) Filtering: 181-second Moving AverageFiltering: 181-second Moving Average
Acoustic Water Level (AWL)Acoustic Water Level (AWL)Aquatrak 3000 NOAA/NOSAquatrak 3000 NOAA/NOS
Data Collection Rate: 1 sample/sec (Data Collection Rate: 1 sample/sec (1Hz1Hz)) Filtering: 181-second Moving AverageFiltering: 181-second Moving Average Outliers: Values>3Outliers: Values>3σσ eliminated eliminated
Acoustic Water Level (AWL)Acoustic Water Level (AWL)Aquatrak 3000 NOAA/NOSAquatrak 3000 NOAA/NOS
Data Collection Rate: 1 sample/sec (Data Collection Rate: 1 sample/sec (1Hz1Hz)) Filtering: 181-second Moving AverageFiltering: 181-second Moving Average Outliers: Values>3Outliers: Values>3σσ eliminated eliminated Reporting Interval: 6 minutesReporting Interval: 6 minutes
Acoustic Water Level (AWL)Acoustic Water Level (AWL)Aquatrak 3000 NOAA/NOSAquatrak 3000 NOAA/NOS
Microwave Water Level (mwwl)Microwave Water Level (mwwl)Design Analysis Associates H-3611 Design Analysis Associates H-3611
Data Collection Rate: 1 sample/minuteData Collection Rate: 1 sample/minute
Microwave Water Level (mwwl)Microwave Water Level (mwwl)Design Analysis Associates H-3611 Design Analysis Associates H-3611
Data Collection Rate: 1 sample/minuteData Collection Rate: 1 sample/minute Filtering: Finite Impulse Response (FIR)Filtering: Finite Impulse Response (FIR)
Microwave Water Level (mwwl)Microwave Water Level (mwwl)Design Analysis Associates H-3611 Design Analysis Associates H-3611
Data Collection Rate: 1 sample/minuteData Collection Rate: 1 sample/minute Filtering: Finite Impulse Response (FIR)Filtering: Finite Impulse Response (FIR) Outliers: None removedOutliers: None removed
Microwave Water Level (mwwl)Microwave Water Level (mwwl)Design Analysis Associates H-3611 Design Analysis Associates H-3611
Data Collection Rate: 1 sample/minuteData Collection Rate: 1 sample/minute Filtering: Finite Impulse Response (FIR)Filtering: Finite Impulse Response (FIR) Outliers: None removedOutliers: None removed Reporting Interval: 6 minutesReporting Interval: 6 minutes
},,,...,,...,,{ 65445 tttttt yyyyyyVIMS DATA BLOCK: 12 one-minute water levels
ty 6ty
},,,...,,...,,{ 65445 tttttt yyyyyy
ty 6ty12ty
VIMS DATA BLOCK: 12 one-minute water levels
},,,...,,...,,{ 65445 tttttt yyyyyy
ty 6ty12ty
18ty
VIMS DATA BLOCK: 12 one-minute water levels
},,,...,,...,,{ 65445 tttttt yyyyyy
ty 6ty12ty
18ty
11 minute series
VIMS DATA BLOCK: 12 one-minute water levels
},,,...,,...,,{ 65445 tttttt yyyyyy
11-point Moving Average ?
5111
4111
111
4111
5111 ...... ttttt yyyyy
VIMS DATA BLOCK: 12 one-minute water levels
},,,...,,...,,{ 65445 tttttt yyyyyy
11-point Moving Average ?
5111
4111
111
4111
5111 ...... ttttt yyyyy
554404455 ...... ttttt ygygygygyg
Finite Impulse Response (FIR) Filter with weights ug
VIMS DATA BLOCK: 12 one-minute water levels
},,,...,,...,,{ 65445 tttttt yyyyyy
11-point Moving Average
5111
4111
111
4111
5111 ...... ttttt yyyyy
554404455 ...... ttttt ygygygygyg
uu gg Symmetric filter
Finite Impulse Response (FIR) Filter with weights ug
VIMS DATA BLOCK: 12 one-minute water levels
},,,...,,...,,{ 65445 tttttt yyyyyy
FIR Frequency Response Function*
ns
uu uggG
10 cos2)(
widthfilterns
timeunitcyclesfrequency
)/(
*Fitted using Bloomfield’s least squares approximation
VIMS DATA BLOCK: 12 one-minute water levels
6 minute stop
27 minute pass
88 minute pass
21 minute stop
RMSD = ± 6.7 mm
FindingsFindings
Microwave, acoustic sensors in agreementMicrowave, acoustic sensors in agreement
FindingsFindings
Microwave, acoustic sensors in agreementMicrowave, acoustic sensors in agreement No indication of wave-induced “offset”No indication of wave-induced “offset”
FindingsFindings
Microwave, acoustic sensors in agreementMicrowave, acoustic sensors in agreement No indication of wave-induced “offset”No indication of wave-induced “offset” FIR filter reduces outliers, standard error FIR filter reduces outliers, standard error
FindingsFindings
Microwave, acoustic sensors in agreementMicrowave, acoustic sensors in agreement No indication of wave-induced “offset”No indication of wave-induced “offset” FIR filter reduces outliers, standard error FIR filter reduces outliers, standard error H-3611: low-maintenance, high reliability H-3611: low-maintenance, high reliability
RecommendationsRecommendations
Design a filter – forgo the moving average,Design a filter – forgo the moving average,
standard deviation and throw-out methodsstandard deviation and throw-out methods
RecommendationsRecommendations
Design a filter – forgo the moving average,Design a filter – forgo the moving average,
standard deviation and throw-out methodsstandard deviation and throw-out methods Decide frequency range of interest and Decide frequency range of interest and
design the filter accordingly design the filter accordingly Open ocean comparisons needed Open ocean comparisons needed
Thank you for your attention