Understanding the impact of surface waves on Microwave Water Level measurements

Heitsenrether, Robert; Bushnell, Mark; Boon, John D.

doi:10.1109/oceans.2008.5151923

Cited by 10 publications

(5 citation statements)

References 1 publication

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“…The use of a protective antenna cover (end cap) to prevent ice buildup inside the antenna does effectively mitigate the ice problem but introduces another where moisture accumulation on the cover impedes the signal . The microwave beampattern also needs evaluation to ensure that interference from pilings/mounting structures does not impede imaging the water surface, and in surface wave sensing applications the footprint of the beam introduces a spatial filter (Heitsenrether, 2008).…”

Section: Discussionmentioning

confidence: 99%

“…The emergence of microwave water level sensors without temperature dependence or hydraulic pressure effects and with substantially reduced installation and maintenance costs has motivated NOAA to transition from acoustic systems to microwave sensors where possible . However, the microwave sensors have limitations such as signal scattering/blockage from rain or flotsam, and a variable surface area footprint dependent on sensor beamwidth and range from the water which introduces a spatial filter (Heitsenrether, 2008).…”

Section: Microwave Water Level (Mwwl) Phase II Analysismentioning

confidence: 99%

“…The sensor is remarkably insensitive to temperature variation (0.2 mm/ o K, 5 mm maximum) and has accuracy of 0.03% of the measured range. However, microwave sensors have limitations such as signal scattering/blockage from rain, ice or flotsam and sidelobe interference from pilings or other infrastructure, and, as the range to the water changes, the surface area imaged by the sensor also changes, which introduces a changing spatial filter (Heitsenrether, 2008).…”

Section: Microwave Water Levelmentioning

confidence: 99%

See 2 more Smart Citations

Water Level and Wave Height Estimates at NOAA Tide Stations from Acoustic and Microwave Sensors

Park

Heitsenrether

Sweet

2014

Journal of Atmospheric and Oceanic Technology

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The National Oceanic and Atmospheric Administration (NOAA) is transitioning the primary water level sensor at the majority of tide stations in the National Water Level Observation Network (NWLON) from an acoustic ranging system to a microwave radar system. Field comparison of the acoustic and microwave systems finds statistically equivalent performance when temperature gradients between the acoustic sensor and water surface are small and when significant wave height is less than roughly 0.5 m. When significant wave height is greater than approximately 0.5–1 m, the acoustic system consistently reports lower water levels. An analysis of 2 months of acoustic and microwave water level data at Duck, North Carolina, finds that the majority of differences between the two sensors can be attributed to systemic errors in the acoustic system and that the microwave system captures water level variability with higher fidelity than the acoustic system. NWLON real-time data products include the water level standard deviation, a statistic that can serve as a proxy for significant wave height. This study identifies 29 coastal water level stations that are candidates for monitoring wave height based on water level standard deviation, potentially adding a significant source of data for the sparsely sampled coastal wave fields around the United States, and finds that the microwave sensor is better suited than the acoustic system for wave height estimates.

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Section: Discussionmentioning

confidence: 99%

Section: Microwave Water Level (Mwwl) Phase II Analysismentioning

confidence: 99%

Section: Microwave Water Levelmentioning

confidence: 99%

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Water Level and Wave Height Estimates at NOAA Tide Stations from Acoustic and Microwave Sensors

Park

Heitsenrether

Sweet

2014

Journal of Atmospheric and Oceanic Technology

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“…Microwave radar offers an attractive solution for noncontact distance and displacement measurement. The existing radar techniques for water level monitoring mainly include FMCW radar [1] and pulse radar [2]. However, FMCW radar suffers from system complexity and is vulnerable to the clutter interference from surrounding stationary subjects, e.g.…”

Section: Introductionmentioning

confidence: 99%

Highly accurate noncontact water level monitoring using continuous-wave Doppler radar

Wang

Rice

et al. 2013

2013 IEEE Topical Conference on Wireless Sensors and Sensor Networks (WiSNet)

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A novel water level monitoring technique using continuous-wave (CW) Doppler radar is presented. The CW radar works with a DC-coupled baseband that allows accurate monitoring of the slow-varying water level. Ray tracing model has been used to simulate and validate the feasibility of water level monitoring in the presence of ripple.The proposed technique is robust against clutter interference and the fluctuation of water ripples by properly choosing the carrier frequency. Experiment was carried out to monitor the water level in a rain barrel when the water was draining out.Both simulation and experiment shows that the proposed technique can accurately monitor the water level with a high accuracy in millimeter-scale.

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“…Currently the Aquatrak ® acoustic sensor functions as the primary water level sensor at the majority of NOAA's National Water Level Observation Network (NWLON) stations [1]. More recently, microwave radar has emerged as a promising technology for water level measurement [2] and the Waterlog Model H-3611i microwave (MW) radar sensor by Design Analysis Associates, Inc., has been evaluated by CO-OPS for operational service as a water level sensor [3,4,5,6,7,8]. The Waterlog differs from previous sensors in having no components in contact with the water, a feature which significantly lowers both installation and maintenance costs.…”

Section: Introductionmentioning

confidence: 99%

Multi-sensor evaluation of microwave water level measurement error

2012

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A microwave radar water level sensor, the Design Analysis Waterlog H-3611 has recently entered service at tide stations operated by the National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), Center for Operational Oceanographic Products and Services (CO-OPS) as part of the National Water Level Observation Network (NWLON). The microwave water level sensor combines high accuracy with low sensitivity to variations in air temperature and humidity but differs from other water level sensors in utilizing an unconfined radar beam aimed vertically downward to the water surface. Many potential benefits of using microwave radar sensors for short-term flood advisories and long-term sea level monitoring have been identified by several organizations throughout the ocean observing community. The most notable advantage of radar sensors is their ability to measure water level remotely with no parts directly in contact with the water column. Water level measurement stations that employ remote radar sensor technology will avoid many problems typical of long-term subsurface ocean sensors including biological fouling and corrosion. Remote sensing also results in a significant reduction in system hardware components and overall installation and maintenance requirements. Results from a series of laboratory and field tests conducted by CO-OPS over the last few years have led to operational use of Waterlog radar units in certain specific applications. It is acknowledged, however, that most test data collected and analyzed to date for the purpose of assessing the sensor's capabilities have focused on enclosed coastal regions with limited fetch and a low-wave environment (average significant wave height nominally less than 1 m). Although these test results are relevant to many CO-OPS applications of interest, including the majority of NWLON stations located in low-wave environments, uncertainty remained after the initial test phase and led to a new outlook toward sensor performance in open ocean environments that experience significant wave heights frequently in excess of 1 m. Additional testing under these conditions has presented a greater challenge as both the test and reference NWLON sensors are likely to encounter limitations in the presence of large waves. Analytical tools including spectral analysis of sensor output signals and an evaluation of sample statistics were needed to better understand the nature of these limitations. In order to address the remaining uncertainty in sensor performance capability, a multi-sensor test deployment was recently conducted at an open-ocean test site, the U.S. Army Corps of Engineers Field Research Facility at Duck, NC (Duck FRF). The resulting multi-sensor data set has allowed sensor measurement error to be estimated for the first time from measurement residuals about an ensemble average series. Comparing ensemble-based error estimates with corresponding Duck FRF nearshore wave data averaged over selected measurement periods shows that sensor error increases, as expe...

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Understanding the impact of surface waves on Microwave Water Level measurements

Cited by 10 publications

References 1 publication

Water Level and Wave Height Estimates at NOAA Tide Stations from Acoustic and Microwave Sensors

Water Level and Wave Height Estimates at NOAA Tide Stations from Acoustic and Microwave Sensors

Highly accurate noncontact water level monitoring using continuous-wave Doppler radar

Multi-sensor evaluation of microwave water level measurement error

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