scholarly journals Using Three Acoustic Technologies on Underwater Gliders to Survey Fish

2018 ◽  
Vol 52 (6) ◽  
pp. 39-52 ◽  
Author(s):  
Chad Lembke ◽  
Susan Lowerre-Barbieri ◽  
David Mann ◽  
J. Christopher Taylor
Keyword(s):  
Demonstration Project ◽  
Data Sets ◽  
Underwater Glider ◽  
Fish Stocks ◽  
Underwater Gliders ◽  
Natural Gas Pipeline ◽  
Sensing Technology ◽  
Eastern Gulf Of Mexico ◽  
Acoustic Technologies ◽  
Passive Acoustic

AbstractAutonomous platforms and vehicles are a growing component of the ocean research fleet, producing data sets crucial to our understanding of oceanographic and fishery ecosystem processes. One emerging tool for making these measurements is underwater gliders that autonomously sample the water column for weeks to months at a time. Although originally designed to measure temperature and salinity, underwater gliders can now support a myriad of sensors. For the demonstration project described within, three complementary acoustic technologies were integrated into an underwater glider for mapping fish on the continental shelf: an acoustic telemetry receiver, a passive acoustic monitoring recorder, and a fisheries echosounder.The demonstration project was designed to evaluate the effectiveness of each sensing technology. Sixty-one fish were implanted with acoustic tags near the Gulfstream Natural Gas pipeline in the eastern Gulf of Mexico in advance of planned underwater glider missions. The glider was deployed four times over 12 months, with all three acoustic technologies to traverse the pipeline and surrounding habitat. Glider detections were compared to detections of fish at moored acoustic tag telemetry receivers and passive acoustic recorders co-located at the tagged fish locations. All three technologies identified fish along the targeted hard-bottom pipeline habitat, as well as previously uncharted areas of hard-bottom reef. The results of this study demonstrate the utility of gliders integrated with acoustic sensors as a potential tool to identify areas that merit deeper investigation to assess fish stocks.

scholarly journals Depth-Average Velocity from Spray Underwater Gliders

2018 ◽  
Vol 35 (8) ◽  
pp. 1665-1673 ◽  
Author(s):  
Daniel L. Rudnick ◽  
Jeffrey T. Sherman ◽  
Alexander P. Wu
Keyword(s):  
Average Velocity ◽  
Dead Reckoning ◽  
Water Velocity ◽  
Accurate Estimation ◽  
Underwater Glider ◽  
Underwater Gliders ◽  
Before And After ◽  
The Difference ◽  
Using Data ◽  
Acoustic Doppler Current Profilers

AbstractThe depth-average velocity is routinely calculated using data from underwater gliders. The calculation is a dead reckoning, where the difference between the glider’s velocity over ground and its velocity through water yields the water velocity averaged over the glider’s dive path. Given the accuracy of global positioning system navigation and the typical 3–6-h dive cycle, the accuracy of the depth-average velocity is overwhelmingly dependent on the accurate estimation of the glider’s velocity through water. The calculation of glider velocity through water for the Spray underwater glider is described. The accuracy of this calculation is addressed using a method similar to that used with shipboard acoustic Doppler current profilers, where water velocity is compared before and after turns to determine a gain to apply to glider velocity through water. Differences of this gain from an ideal value of one are used to evaluate accuracy. Sustained glider observations of several years off California and Palau consisted of missions involving repeated straight sections, producing hundreds of turns. The root-mean-square accuracy of depth-average velocity is estimated to be in the range of 0.01–0.02 m s−1, consistent with inferences from the early days of underwater glider design.

scholarly journals Indicators of AEI Applied to the Delaware Estuary

2002 ◽  
Vol 2 ◽  
pp. 169-189 ◽  
Author(s):  
Lawrence W. Barnthouse ◽  
Douglas G. Heimbuch ◽  
Vaughn C. Anthony ◽  
Ray W. Hilborn ◽  
Ransom A. Myers
Keyword(s):  
Meta Analysis ◽  
Juvenile Fish ◽  
Fish Populations ◽  
Weight Of Evidence ◽  
Data Sets ◽  
Delaware Estuary ◽  
Fish Stocks ◽  
Trends Analysis ◽  
Definition Of

We evaluated the impacts of entrainment and impingement at the Salem Generating Station on fish populations and communities in the Delaware Estuary. In the absence of an agreed-upon regulatory definition of “adverse environmental impact” (AEI), we developed three independent benchmarks of AEI based on observed or predicted changes that could threaten the sustainability of a population or the integrity of a community.Our benchmarks of AEI included: (1) disruption of the balanced indigenous community of fish in the vicinity of Salem (the “BIC” analysis); (2) a continued downward trend in the abundance of one or more susceptible fish species (the “Trends” analysis); and (3) occurrence of entrainment/impingement mortality sufficient, in combination with fishing mortality, to jeopardize the future sustainability of one or more populations (the “Stock Jeopardy” analysis).The BIC analysis utilized nearly 30 years of species presence/absence data collected in the immediate vicinity of Salem. The Trends analysis examined three independent data sets that document trends in the abundance of juvenile fish throughout the estuary over the past 20 years. The Stock Jeopardy analysis used two different assessment models to quantify potential long-term impacts of entrainment and impingement on susceptible fish populations. For one of these models, the compensatory capacities of the modeled species were quantified through meta-analysis of spawner-recruit data available for several hundred fish stocks.All three analyses indicated that the fish populations and communities of the Delaware Estuary are healthy and show no evidence of an adverse impact due to Salem. Although the specific models and analyses used at Salem are not applicable to every facility, we believe that a weight of evidence approach that evaluates multiple benchmarks of AEI using both retrospective and predictive methods is the best approach for assessing entrainment and impingement impacts at existing facilities.

scholarly journals Sensitivity Analysis of the Turning Motion of an Underwater Glider on the Viscous Hydrodynamic Coefficients

2021 ◽  
Vol 71 (5) ◽  
pp. 709-717
Author(s):  
Venkata Shashank Shankar Rayaprolu ◽  
R Vijayakumar
Keyword(s):  
Sensitivity Analysis ◽  
Control Mechanism ◽  
Hydrodynamic Coefficients ◽  
Underwater Glider ◽  
Dynamics Model ◽  
Roll Control ◽  
Underwater Gliders ◽  
Spiral Path ◽  
Viscous Hydrodynamic ◽  
Turning Motion

Autonomous underwater gliders (AUG) are a class of underwater vehicles that move using a buoyancy engine and forces from wings. Gliders execute turning motion with the help of a rudder or an internal roll control mechanism and the trajectory of the turn is a spiral. This paper analyses the sensitivity of the characteristics of spiral manoeuvre on the hydrodynamic coefficients of the glider. Based on the dynamics model of a gliding fish whose turn is enabled by a rudder, the effect of hydrodynamic coefficients of the hull and the rudder on the spiral motion are quantified. Local sensitivity analysis is undertaken using the indirect method. The order of importance of hydrodynamic coefficients is evaluated. It is observed that the spiral path parameters are most sensitive to the side force created by the rudder and the effect of the drag coefficient is predominant to that of the lift coefficients. This study will aid in quantifying the effect of change of geometry on the manoeuvrability of AUGs.

Benthic Habitats and the Effects of Fishing

2005 ◽  
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Fish Habitat ◽  
Weather Conditions ◽  
Data Sets ◽  
Fish Stocks ◽  
Habitat Features ◽  
The Irish Sea ◽  
Belfast Lough ◽  
Existing Data

<strong><em>Abstract. </em><strong>Fishers have often complained that standard United Kingdom groundfish survey data do not adequately reflect the grounds targeted by commercial fishers, and hence, scientists tend to make overcautious estimates of fish abundance. Such criticisms are of particular importance if we are to make a creditable attempt to classify potential essential fish habitat (EFH) using existing data from groundfish surveys. Nevertheless, these data sets provide a powerful tool to examine temporal abundance of fish on a large spatial scale. Here, we report a questionnaire-type survey of fishers (2001–2002) that invited them to plot the location of grounds of key importance in the Irish Sea and to comment on key habitat features that might constitute EFH for Atlantic cod <em>Gadus morhua</em>, haddock <em>Melanogrammus aeglefinus</em>, and European whiting <em>Merlangius merlangus</em>. Plotted grounds were cross-checked using records of vessel sightings by fishery protection aircraft (1985–1999). A comparison of the areas of seabed highlighted by fishers and the observations made on groundfish surveys were broadly compatible for all three species of gadoids examined. Both methods indicated important grounds for cod and European whiting off northern Wales, the Ribble estuary, Solway Firth, north of Dublin, and Belfast Lough. The majority of vessel sightings by aircraft did not match the areas plotted by fishers. However, fishing restrictions, adverse weather conditions, and seasonal variation of fish stocks may have forced fishers to operate outside their favored areas on the (few) occasions that they had been recorded by aircraft. Fishers provided biological observations that were consistent among several independent sources (e.g., the occurrence of haddock over brittle star [ophiuroid] beds). We conclude that fishers’ knowledge is a useful supplement to existing data sets that can better focus more detailed EFH studies.

Cross-Shelf Exchange Associated With the Gulf Stream in the South Atlantic Bight: Direct Observations Using an Autonomous Underwater Glider

2018 ◽  
Vol 52 (3) ◽  
pp. 19-27 ◽  
Author(s):  
Ruoying He ◽  
Austin C. Todd ◽  
Chad Lembke ◽  
Todd Kellison ◽  
Chris Taylor ◽  
...  
Keyword(s):  
Gulf Stream ◽  
Moving Boundary ◽  
South Atlantic ◽  
South Atlantic Bight ◽  
Underwater Glider ◽  
The South ◽  
Underwater Gliders ◽  
Direct Observations ◽  
Autonomous Underwater Glider

AbstractAn autonomous underwater glider was deployed in March 2014 to sample the Gulf Stream and its adjacent shelf waters in the South Atlantic Bight, providing a new look at cross-shelf exchange associated with Gulf Stream dynamics. Observations collected over 4 weeks reveal significant cross-shelf exchange (up to 0.5 Sv) at the shoreward edge of the Gulf Stream, which was 2 orders of magnitude larger than estimates from long-term mean hydrographic conditions. Gulf Stream frontal eddies may have contributed to some of the largest fluxes of heat (0.5°C Sv) and salt (0.03 Sv g/kg) onto the shelf. We estimate that the largest upwelling event during the mission could have brought nitrate concentrations over 20 μM to within 125 m of the surface. This study demonstrates clear capabilities of autonomous underwater gliders for sampling in and near fast moving boundary currents to obtain unique and critical in situ observations effectively.

scholarly journals ℓp-ICP Coastline Inflection Method for Geolocation Error Estimation in FY-3 MWRI Data

2019 ◽  
Vol 11 (16) ◽  
pp. 1886 ◽  
Author(s):  
Xinghui Zhao ◽  
Na Chen ◽  
Weifu Li ◽  
Shen ◽  
Peng
Keyword(s):  
Traditional Method ◽  
Weather Prediction ◽  
Real Data ◽  
Step Function ◽  
Data Sets ◽  
Sparse Regularization ◽  
The Real ◽  
Remote Sensing Technology ◽  
Sensing Technology ◽  
Geolocation Accuracy

Known as input in the Numerical Weather Prediction (NWP) models, Microwave Radiation Imager (MWRI) data have been widely distributed to the user community. With the development of remote sensing technology, improving the geolocation accuracy of MWRI data are required and the first step is to estimate the geolocation error accurately. However, the traditional method, such as the coastline inflection method (CIM), usually has the disadvantages of low accuracy and poor anti-noise ability. To overcome these limitations, this paper proposes a novel ℓ p iterative closest point coastline inflection method ( ℓ p -ICP CIM). It assumes that the field of views (FOVs) across the coastline can degenerate into a step function and employs an ℓ p ( 0 ≤ p < 1 ) sparse regularization optimization model to solve the coastline point. After estimating the coastline points, the ICP algorithm is employed to estimate the corresponding relationship between the estimated coastline points and the real coastline. Finally, the geolocation error can be defined as the distance between the estimated coastline point and the corresponding point on the true coastline. Experimental results on simulated and real data sets show the effectiveness of our method over CIM. The accuracy of the geolocation error estimated by ℓ p -ICP CIM is up to 0 . 1 pixel, in more than 90 % of cases. We also show that the distribution of brightness temperature near the coastline is more consistent with the real coastline and the average geolocation error is reduced by 63 % after geolocation error correction.

Acoustic Pyrometry for Harsh, Chemically Reacting Environments

2007 ◽  
Author(s):  
William Norris ◽  
Candice Bauer
Keyword(s):  
Waste To Energy ◽  
Reacting Flow ◽  
Data Sets ◽  
Combustion Chambers ◽  
Turbine Engine ◽  
Metal Treatment ◽  
Conventional Methods ◽  
Chemically Reacting ◽  
Pyrometry Methods ◽  
Passive Acoustic

The objective of this research is to demonstrate the feasibility of using acoustic pyrometry methods to take measurements in harsh, chemically reacting flow such as gas turbine engine combustion chambers. Conventional methods utilize flow invasive devices, have line of sight requirements, or use exterior parameters to measure the internal temperatures of a combustion chamber. Acoustic pyrometry methods can avoid many of these compromises and have been applied to a wide variety of industrial systems including the measurement of furnace exit gas temperatures, waste-to-energy boilers, cement kilns, metal treatment furnaces, and many other applications. The passive system works on the concept that temperature affects the speed of sound through a fluid. This work establishes that passive acoustic pyrometry is a viable option for determining combustor performance and for measuring fuel-to-air ratios and temperatures from acoustic resonances in an engine. The results include the ability to monitor temperature distributions and develop algorithms to obtain several other data sets. The work detailed includes research performed and compared with results obtained using conventional methods at NASA Glenn Research Center and Rolls Royce.

Evaluation of spatiotemporal imputations for fishing catch rate standardization

2017 ◽  
Vol 74 (9) ◽  
pp. 1348-1361
Author(s):  
Ross J. Marriott ◽  
Berwin A. Turlach ◽  
Kevin Murray ◽  
David V. Fairclough
Keyword(s):  
High Growth ◽  
Catch Rate ◽  
Commercial Fishing ◽  
Data Sets ◽  
Rate Data ◽  
Fishing Activity ◽  
Fish Stocks ◽  
Base Method ◽  
Catch Rates ◽  
Over Time

As commercial fishing activity shifts to target different grounds over time, spatial gaps can be created in catch rate data, leading to biases in derived indices of fish abundance. Imputation has been shown to reduce such biases. In this study, the relative performance of several imputation methods was assessed using simulated catch rate data sets. Simulations were carried out for three fish stocks targeted by a commercial hook-and-line fishery off the southwestern coast of Australia: snapper (Chrysophrys auratus), West Australian dhufish (Glaucosoma hebraicum), and baldchin groper (Choerodon rubescens). For high-growth scenarios, the mean squared errors (MSEs) of geometric and linear imputations were lower, indicating higher accuracy and precision than that for base method (constant value) imputations. For low-growth scenarios, the lowest MSEs were achieved for base method imputations. However, for the final standardized and imputed abundance indices, the base method index consistently demonstrated the largest biases. Our results demonstrate the importance of selecting an appropriate imputation method when standardizing catch rates from a commercial fishery that has changed its spatial pattern of fishing over time.

scholarly journals Forest Fire Mapping using Normalized Burned Ratio and Cloud Computing to Calculate the Losses Incurred in Mount Lawu, Magetan Regency

2021 ◽  
Vol 936 (1) ◽  
pp. 012002
Author(s):  
Bangun Muljo Sukojo ◽  
Adinda Sitaresmi Putri Arimurti
Keyword(s):  
Cloud Computing ◽  
Vegetation Index ◽  
Google Earth ◽  
Total Loss ◽  
Data Sets ◽  
High Data ◽  
Sensing Technology ◽  
Calculation Results ◽  
The Government ◽  
Applications Of Machine Learning

Abstract Forest and land fires in Indonesia are one of the most common disasters. Over time, Indonesia’s forests have experienced a decline, one of which is the result of forest and land fires. Forest and land fires can occur due to temperatures in the dry season that continue to increase. Utilization of remote sensing technology can be used for mapping forest and fire areas, and can also be used as a reference for the government to carry out reforestation or reforestation processes in fire areas. The use of Multispectral Sensors in Sentinel 2 satellite imagery can be used to produce this research. This research takes a case study on Mount Lawu, Magetan Regency. Mount Lawu is one of the climbing tourist destinations that almost every year experiences forest and land fires. And the use of the Google Earth Engine platform that supports cloud computing to facilitate this research in accessing high data sources to process large geospatial data sets. For processing satellite images using the Normalized Burned Ratio (NBR) vegetation index processing algorithm. This research was conducted in 2018 and 2019. By using the Random Forest method, which is one of the applications of Machine Learning, it will produce several accurate results from the calculation results. The results of the calculation of the area of fire in 2018 were 284.88 hectares with a total loss of Rp 42,732,000.00 and in 2019 it was 146.03 hectares with a total loss of Rp 21,904,500. The results of this study are displayed on GEE Apps so that users can directly access the resulting data.

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