Pub Date : 2005-06-28DOI: 10.1109/CCM.2005.1506345
C. Teague, D. Barrick, P. Lilleboe, R. T. Cheng, C. Ruhl
Long-term, non-contact river velocity measurements have been made using a UHF RiverSonde system for several months at each of two locations having quite different flow characteristics. Observations were made on the Cowlitz River at Castle Rock, Washington from October 2003 to June 2004, where the unidirectional flow of the river ranged from about 1.0 to 3.5 m/s. The radar velocity was highly correlated with the stage height which was continually measured by the U. S. Geological Survey. The profile of the along-channel velocity across the water channel also compared favorably with in-situ measurements performed by the Survey. The RiverSonde was moved to Threemile Slough, in central California, in September 2004 and has been operating there for several months. At Threemile Slough, which connects the Sacramento and San Joaquin Rivers, the flow is dominated by tidal effects and reverses direction four times per day, with a maximum speed of about 0.8 m/s in each direction. Water level and water velocity are continually measured by the Survey at the Threemile Slough site, with velocity recorded every 15 minutes from measurements made by an ultrasonic velocity meter (UVM). Over a period of several months, the radar and UVM velocity measurements have been highly correlated, with a coefficient of determination R/sup 2/ of 0.976.
{"title":"Long-term UHF RiverSonde river velocity observations at Castle Rock, Washington and Threemile Slough, California","authors":"C. Teague, D. Barrick, P. Lilleboe, R. T. Cheng, C. Ruhl","doi":"10.1109/CCM.2005.1506345","DOIUrl":"https://doi.org/10.1109/CCM.2005.1506345","url":null,"abstract":"Long-term, non-contact river velocity measurements have been made using a UHF RiverSonde system for several months at each of two locations having quite different flow characteristics. Observations were made on the Cowlitz River at Castle Rock, Washington from October 2003 to June 2004, where the unidirectional flow of the river ranged from about 1.0 to 3.5 m/s. The radar velocity was highly correlated with the stage height which was continually measured by the U. S. Geological Survey. The profile of the along-channel velocity across the water channel also compared favorably with in-situ measurements performed by the Survey. The RiverSonde was moved to Threemile Slough, in central California, in September 2004 and has been operating there for several months. At Threemile Slough, which connects the Sacramento and San Joaquin Rivers, the flow is dominated by tidal effects and reverses direction four times per day, with a maximum speed of about 0.8 m/s in each direction. Water level and water velocity are continually measured by the Survey at the Threemile Slough site, with velocity recorded every 15 minutes from measurements made by an ultrasonic velocity meter (UVM). Over a period of several months, the radar and UVM velocity measurements have been highly correlated, with a coefficient of determination R/sup 2/ of 0.976.","PeriodicalId":264883,"journal":{"name":"Proceedings of the IEEE/OES Eighth Working Conference on Current Measurement Technology, 2005.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127495193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-06-28DOI: 10.1109/CCM.2005.1506336
L. Wyatt, J. Green, A. Middleditch
Measurements of waves, winds and currents with the HF radar are presented to demonstrate their operational monitoring capabilities. These include measurements made during a 15 month deployment of the Pisces radar in the Celtic Sea to assess the feasibility of including radar as part of the UK wave monitoring Network, WAVENET, and measurements with the WERA radar on the Norwegian coast as part of the EuroROSE project. The accuracy of the measurements is discussed.
{"title":"Wave, current and wind monitoring using HF radar","authors":"L. Wyatt, J. Green, A. Middleditch","doi":"10.1109/CCM.2005.1506336","DOIUrl":"https://doi.org/10.1109/CCM.2005.1506336","url":null,"abstract":"Measurements of waves, winds and currents with the HF radar are presented to demonstrate their operational monitoring capabilities. These include measurements made during a 15 month deployment of the Pisces radar in the Celtic Sea to assess the feasibility of including radar as part of the UK wave monitoring Network, WAVENET, and measurements with the WERA radar on the Norwegian coast as part of the EuroROSE project. The accuracy of the measurements is discussed.","PeriodicalId":264883,"journal":{"name":"Proceedings of the IEEE/OES Eighth Working Conference on Current Measurement Technology, 2005.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131634172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-06-28DOI: 10.1109/CCM.2005.1506326
A. Williams, A. Morrison, S. R. Brody
Measurement of current in the horizontal plane requires that the azimuth of the fluid velocity vector projected onto the horizontal plane be accurately represented in Cartesian coordinates with a cosine response in the x and y direction. In the acoustic current meter that was studied, MAVS (Modular Acoustic Velocity Sensor, manufactured by Nobska Development, Inc.), the horizontal cosine response is excellent, varying from ideal by less than 5%. When a full vector current measurement is made, there is a further requirement that the projection of the fluid velocity vector onto the vertical or z axis have a cosine response to the elevation angle of the velocity vector. Structures supporting the acoustic transducers in an acoustic current meter necessarily create wakes and distort the flow. Minimizing this disturbance through faired supports improves the vertical cosine response; however, there remains a velocity defect of as much as 20% for flows exceeding a 45/spl deg/ elevation angle in MAVS. For flows elevated less than 30/spl deg/ from the horizontal plane, the deviation from ideal cosine response is less than 10% and over a 50/spl deg/ range in elevation angle the deviation from ideal cosine response is less than 5%.
{"title":"Vertical cosine response of a faired ring acoustic current meter","authors":"A. Williams, A. Morrison, S. R. Brody","doi":"10.1109/CCM.2005.1506326","DOIUrl":"https://doi.org/10.1109/CCM.2005.1506326","url":null,"abstract":"Measurement of current in the horizontal plane requires that the azimuth of the fluid velocity vector projected onto the horizontal plane be accurately represented in Cartesian coordinates with a cosine response in the x and y direction. In the acoustic current meter that was studied, MAVS (Modular Acoustic Velocity Sensor, manufactured by Nobska Development, Inc.), the horizontal cosine response is excellent, varying from ideal by less than 5%. When a full vector current measurement is made, there is a further requirement that the projection of the fluid velocity vector onto the vertical or z axis have a cosine response to the elevation angle of the velocity vector. Structures supporting the acoustic transducers in an acoustic current meter necessarily create wakes and distort the flow. Minimizing this disturbance through faired supports improves the vertical cosine response; however, there remains a velocity defect of as much as 20% for flows exceeding a 45/spl deg/ elevation angle in MAVS. For flows elevated less than 30/spl deg/ from the horizontal plane, the deviation from ideal cosine response is less than 10% and over a 50/spl deg/ range in elevation angle the deviation from ideal cosine response is less than 5%.","PeriodicalId":264883,"journal":{"name":"Proceedings of the IEEE/OES Eighth Working Conference on Current Measurement Technology, 2005.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124598146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-06-28DOI: 10.1109/CCM.2005.1506328
H. Nybo, T. Jakobsen, R. Gangstø
The range of an acoustic Doppler current profiler depends on several factors, e.g. on the level of the power output and on the acoustic backscatter level. In this article results from a study on the range performance of a profiler are discussed. Two tests were carried out in October, a time of year when Norwegian fjords are fairly clear. The tests showed that the range of the instrument changes significantly during short periods of time, follow the biological rhythm of zooplankton. To avoid predators, the zooplankton migrate down the water column during the day and up during the night (diel vertical migration). When the acoustic backscatter level was at its highest, the range was longer than the specified maximum range. During day, the maximum range was almost halved compare to the range at night. The output's power level had less influence on the range than the backscatter level. Almost the same range was obtained in low power mode as in high power mode.
{"title":"A study on the range performance of acoustic Doppler current profilers","authors":"H. Nybo, T. Jakobsen, R. Gangstø","doi":"10.1109/CCM.2005.1506328","DOIUrl":"https://doi.org/10.1109/CCM.2005.1506328","url":null,"abstract":"The range of an acoustic Doppler current profiler depends on several factors, e.g. on the level of the power output and on the acoustic backscatter level. In this article results from a study on the range performance of a profiler are discussed. Two tests were carried out in October, a time of year when Norwegian fjords are fairly clear. The tests showed that the range of the instrument changes significantly during short periods of time, follow the biological rhythm of zooplankton. To avoid predators, the zooplankton migrate down the water column during the day and up during the night (diel vertical migration). When the acoustic backscatter level was at its highest, the range was longer than the specified maximum range. During day, the maximum range was almost halved compare to the range at night. The output's power level had less influence on the range than the backscatter level. Almost the same range was obtained in low power mode as in high power mode.","PeriodicalId":264883,"journal":{"name":"Proceedings of the IEEE/OES Eighth Working Conference on Current Measurement Technology, 2005.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122331907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-06-28DOI: 10.1109/CCM.2005.1506338
J. Kohut, H. Roarty, S. Glenn, O. Schofield, R. Chant, E. Creed
One objective of the Lagrangian Transport and Transformation Experiment (LaTTE) is to determine the relative advantages of studying the Hudson River plume within the spatial and temporal context provided by an operational research observatory. Towards this end, a shelf-wide observational backbone was locally enhanced with high-resolution relocatable systems in the New York Bight apex. The permanent backbone includes local acquisition of international satellite ocean color imagery, a network of long-range High Frequency radars, and a cross-shelf Endurance line occupied by an autonomous underwater glider. The high resolution systems, including higher resolution HF Radar, glider and mooring networks, were moved to the New York Bight Apex to support the specific interdisciplinary process study. During the LaTTE field effort, datasets from the nested observation network, including a triple nested HF Radar array, were assembled in real-time at a shore-based acquisition center, and high-resolution atmospheric forecasts were performed. Surface current observations will be reviewed, with specific emphasis placed on the observed response of the Hudson River plume to local winds. The observatory results provide a spatial and temporal context for viewing the LaTTE dye release, chemical and biological results.
{"title":"Observed response of the Hudson River plume to wind forcing using a nested HF radar array","authors":"J. Kohut, H. Roarty, S. Glenn, O. Schofield, R. Chant, E. Creed","doi":"10.1109/CCM.2005.1506338","DOIUrl":"https://doi.org/10.1109/CCM.2005.1506338","url":null,"abstract":"One objective of the Lagrangian Transport and Transformation Experiment (LaTTE) is to determine the relative advantages of studying the Hudson River plume within the spatial and temporal context provided by an operational research observatory. Towards this end, a shelf-wide observational backbone was locally enhanced with high-resolution relocatable systems in the New York Bight apex. The permanent backbone includes local acquisition of international satellite ocean color imagery, a network of long-range High Frequency radars, and a cross-shelf Endurance line occupied by an autonomous underwater glider. The high resolution systems, including higher resolution HF Radar, glider and mooring networks, were moved to the New York Bight Apex to support the specific interdisciplinary process study. During the LaTTE field effort, datasets from the nested observation network, including a triple nested HF Radar array, were assembled in real-time at a shore-based acquisition center, and high-resolution atmospheric forecasts were performed. Surface current observations will be reviewed, with specific emphasis placed on the observed response of the Hudson River plume to local winds. The observatory results provide a spatial and temporal context for viewing the LaTTE dye release, chemical and biological results.","PeriodicalId":264883,"journal":{"name":"Proceedings of the IEEE/OES Eighth Working Conference on Current Measurement Technology, 2005.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116686876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-06-28DOI: 10.1109/CCM.2005.1506346
R. Marsden
Field and laboratory testing of the StreamPro ADCP obtain bottom tracking velocity standard deviation of less than 1 cm/sec with one-second integration time. Water velocity profile standard deviation measured with a new pulse-to-pulse coherent profiling mode obtains standard deviation of less than 5 mm/sec with one-second integration time. This mode is unique, having noise performance that is independent of the size of the profiling bin size over the range of 1-10 cm. The combination of low noise bottom tracking and water profiling are used to make moving platform velocity or discharge measurements in very slow and shallow water. Field data from irrigation canals and natural streams will be presented with comparison of the field data to predictions of an ADCP error model. The electronics and firmware that comprise the ADCP will be briefly discussed in relation to achieving the performance illustrated by the laboratory and field data.
{"title":"StreamPro ADCP performance characteristics","authors":"R. Marsden","doi":"10.1109/CCM.2005.1506346","DOIUrl":"https://doi.org/10.1109/CCM.2005.1506346","url":null,"abstract":"Field and laboratory testing of the StreamPro ADCP obtain bottom tracking velocity standard deviation of less than 1 cm/sec with one-second integration time. Water velocity profile standard deviation measured with a new pulse-to-pulse coherent profiling mode obtains standard deviation of less than 5 mm/sec with one-second integration time. This mode is unique, having noise performance that is independent of the size of the profiling bin size over the range of 1-10 cm. The combination of low noise bottom tracking and water profiling are used to make moving platform velocity or discharge measurements in very slow and shallow water. Field data from irrigation canals and natural streams will be presented with comparison of the field data to predictions of an ADCP error model. The electronics and firmware that comprise the ADCP will be briefly discussed in relation to achieving the performance illustrated by the laboratory and field data.","PeriodicalId":264883,"journal":{"name":"Proceedings of the IEEE/OES Eighth Working Conference on Current Measurement Technology, 2005.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130523610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-06-28DOI: 10.1109/CCM.2005.1506358
P. Devine
In recent years, there has been an increase in the use of horizontally oriented acoustic Doppler current profilers (HADCPs) for real time data collection within vessel traffic safety programs. This paper summarizes a comparison between a barge mounted HADCP and a vessel mounted ADCP in the Delaware estuary in May 2004. A rigorous investigation of the influence of passing vessels and the presence of the bottom boundary on the HADCP data is presented along with a proposed method for detecting and excluding biased data prior to use in real time systems. The HADCP data were compared with vessel mounted ADCP data collected at various ranges along the HADCP profile. Comparisons between the two measurements were used to identify bias in the velocity from the HADCP where the beams began to interact with the local bathymetry. During periods when vessels passed through the three acoustic beams velocity and data quality indicators from the HADCP were also evaluated. The goal was to identify the magnitude of water velocity bias and the corresponding signature in the data quality assurance parameters. A method using standard quality assurance parameters is proposed to screen environmental bias and produce unbiased velocity estimates during real time data collection.
{"title":"Avoiding biased data during real time HADCP data collection","authors":"P. Devine","doi":"10.1109/CCM.2005.1506358","DOIUrl":"https://doi.org/10.1109/CCM.2005.1506358","url":null,"abstract":"In recent years, there has been an increase in the use of horizontally oriented acoustic Doppler current profilers (HADCPs) for real time data collection within vessel traffic safety programs. This paper summarizes a comparison between a barge mounted HADCP and a vessel mounted ADCP in the Delaware estuary in May 2004. A rigorous investigation of the influence of passing vessels and the presence of the bottom boundary on the HADCP data is presented along with a proposed method for detecting and excluding biased data prior to use in real time systems. The HADCP data were compared with vessel mounted ADCP data collected at various ranges along the HADCP profile. Comparisons between the two measurements were used to identify bias in the velocity from the HADCP where the beams began to interact with the local bathymetry. During periods when vessels passed through the three acoustic beams velocity and data quality indicators from the HADCP were also evaluated. The goal was to identify the magnitude of water velocity bias and the corresponding signature in the data quality assurance parameters. A method using standard quality assurance parameters is proposed to screen environmental bias and produce unbiased velocity estimates during real time data collection.","PeriodicalId":264883,"journal":{"name":"Proceedings of the IEEE/OES Eighth Working Conference on Current Measurement Technology, 2005.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115344084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-06-28DOI: 10.1109/CCM.2005.1506324
P. Wiles, J. Simpson, T. Rippeth
Vertical mixing in shelf seas and estuaries is an important process that dominates the transport of water properties (e.g. sediments or pollution) in the marine environment. Acoustic Doppler Current Profilers (ADCPs) have been widely used for both monitoring and research in shelf seas and estuaries. While the potential of ADCPs to measure velocity fields has been realised, recent advances in processing techniques have allowed insights into mixing processes throughout the water column. In this presentation we describe a structure function technique to estimate Turbulent Kinetic Energy dissipation rates (/spl epsiv/) that has previously been used in the atmospheric sciences and here has been applied to ADCPs. We have compared this with 2 established methods of estimating turbulent parameters in the water column: the ADCP variance method, which estimates the momentum transfer through the water column and the Fast Light Yo-yo (FLY) microstructure profiler which measures turbulent dissipation. The structure function method compares well with the FLY microstructure dissipations, with a ratio of structure function dissipation: FLY dissipation of 0.75.
{"title":"A novel technique for measuring mixing using acoustic Doppler current profilers (ADCPs)","authors":"P. Wiles, J. Simpson, T. Rippeth","doi":"10.1109/CCM.2005.1506324","DOIUrl":"https://doi.org/10.1109/CCM.2005.1506324","url":null,"abstract":"Vertical mixing in shelf seas and estuaries is an important process that dominates the transport of water properties (e.g. sediments or pollution) in the marine environment. Acoustic Doppler Current Profilers (ADCPs) have been widely used for both monitoring and research in shelf seas and estuaries. While the potential of ADCPs to measure velocity fields has been realised, recent advances in processing techniques have allowed insights into mixing processes throughout the water column. In this presentation we describe a structure function technique to estimate Turbulent Kinetic Energy dissipation rates (/spl epsiv/) that has previously been used in the atmospheric sciences and here has been applied to ADCPs. We have compared this with 2 established methods of estimating turbulent parameters in the water column: the ADCP variance method, which estimates the momentum transfer through the water column and the Fast Light Yo-yo (FLY) microstructure profiler which measures turbulent dissipation. The structure function method compares well with the FLY microstructure dissipations, with a ratio of structure function dissipation: FLY dissipation of 0.75.","PeriodicalId":264883,"journal":{"name":"Proceedings of the IEEE/OES Eighth Working Conference on Current Measurement Technology, 2005.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128481520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-06-28DOI: 10.1109/CCM.2005.1506361
T. Sanford, J. Dunlap, J. A. Carlson, D. Webb, J. Girton
We developed an autonomous ocean profiling velocity and density float that provides exceptional vertical coverage and temporal resolution to depths of 2000 m for deployments of many years. Electrodes were added to the exterior of standard WRC APEX floats, and electronics were added inside. The electrode voltages result from the motion of seawater and the instrument through the Earth's magnetic field. Other systems included magnetic compass, tilt, CTD, GPS, and Iridium (providing sampling/mission changes). Three EM-APEX floats were deployed from a C-130 aircraft ahead of Hurricane Frances. The floats profiled for 10 hr from the surface to 200 m, then continued profiling between 30 m and 200 m with excursions to 500 m every half inertial period. The velocity computations were performed onboard and saved for later transmission. After five days, the floats surfaced and transmitted the accumulated processed observations, then the floats profiled from 500 m every half inertial period until recovered early in October located by GPS and Iridium.
{"title":"Autonomous velocity and density profiler: EM-APEX","authors":"T. Sanford, J. Dunlap, J. A. Carlson, D. Webb, J. Girton","doi":"10.1109/CCM.2005.1506361","DOIUrl":"https://doi.org/10.1109/CCM.2005.1506361","url":null,"abstract":"We developed an autonomous ocean profiling velocity and density float that provides exceptional vertical coverage and temporal resolution to depths of 2000 m for deployments of many years. Electrodes were added to the exterior of standard WRC APEX floats, and electronics were added inside. The electrode voltages result from the motion of seawater and the instrument through the Earth's magnetic field. Other systems included magnetic compass, tilt, CTD, GPS, and Iridium (providing sampling/mission changes). Three EM-APEX floats were deployed from a C-130 aircraft ahead of Hurricane Frances. The floats profiled for 10 hr from the surface to 200 m, then continued profiling between 30 m and 200 m with excursions to 500 m every half inertial period. The velocity computations were performed onboard and saved for later transmission. After five days, the floats surfaced and transmitted the accumulated processed observations, then the floats profiled from 500 m every half inertial period until recovered early in October located by GPS and Iridium.","PeriodicalId":264883,"journal":{"name":"Proceedings of the IEEE/OES Eighth Working Conference on Current Measurement Technology, 2005.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130669023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-06-28DOI: 10.1109/CCM.2005.1506350
W. E. Schmidt, K. Holland, R. Guza
A GPS-tracked drifter, designed for surfzone use and providing real-time current information, has been developed/deployed over the last 5 years. The positively-buoyant, 50 cm-draft drifter is constructed of PVC and ballasted for near-complete submergence. GPS and spread-spectrum radio antennae reside on a 70 cm-tall protruding spar. Real-time DGPS positions (/spl sim/3-5 m) are first-differenced for drifter velocity and direction. More precise (sub-meter) position information is obtained by post-processing L1 carrier-phase data. The present design has seen 25 deployments (4-6 hrs each) since July 2000 and the current fleet of 10 drifters has logged /spl sim/1000 hrs sea time in breaking wave heights up to 3 m. Studies have focused on rip currents and surfzone circulation, lagoon outflow, and surfzone mixing/dispersion. The drifter flow field observations are presented in conjunction with high-resolution digital video, bathymetric, and tidal data. These observations reveal novel features of nearshore circulation patterns that are difficult to obtain using alternate methods. The spatial structure of rip current velocity appears to be strongly linked to surfzone width and geometry. Similarly, surfzone eddies, long predicted but rarely witnessed, are observed to be long-lived (>2 hrs) and large (/spl sim/50 m diameter) bathymetrically-controlled features. The drifter is thought to be a suitable platform for additional sensor systems and capable of riverine/estuarine applications.
{"title":"Surfzone drifters: applications and observations","authors":"W. E. Schmidt, K. Holland, R. Guza","doi":"10.1109/CCM.2005.1506350","DOIUrl":"https://doi.org/10.1109/CCM.2005.1506350","url":null,"abstract":"A GPS-tracked drifter, designed for surfzone use and providing real-time current information, has been developed/deployed over the last 5 years. The positively-buoyant, 50 cm-draft drifter is constructed of PVC and ballasted for near-complete submergence. GPS and spread-spectrum radio antennae reside on a 70 cm-tall protruding spar. Real-time DGPS positions (/spl sim/3-5 m) are first-differenced for drifter velocity and direction. More precise (sub-meter) position information is obtained by post-processing L1 carrier-phase data. The present design has seen 25 deployments (4-6 hrs each) since July 2000 and the current fleet of 10 drifters has logged /spl sim/1000 hrs sea time in breaking wave heights up to 3 m. Studies have focused on rip currents and surfzone circulation, lagoon outflow, and surfzone mixing/dispersion. The drifter flow field observations are presented in conjunction with high-resolution digital video, bathymetric, and tidal data. These observations reveal novel features of nearshore circulation patterns that are difficult to obtain using alternate methods. The spatial structure of rip current velocity appears to be strongly linked to surfzone width and geometry. Similarly, surfzone eddies, long predicted but rarely witnessed, are observed to be long-lived (>2 hrs) and large (/spl sim/50 m diameter) bathymetrically-controlled features. The drifter is thought to be a suitable platform for additional sensor systems and capable of riverine/estuarine applications.","PeriodicalId":264883,"journal":{"name":"Proceedings of the IEEE/OES Eighth Working Conference on Current Measurement Technology, 2005.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133030136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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