scholarly journals 3D reconstruction of ocean velocity from high-frequency radar and acoustic Doppler current profiler: a model-based assessment study

Ocean Science ◽  
2020 ◽  
Vol 16 (3) ◽  
pp. 575-591
Author(s):  
Ivan Manso-Narvarte ◽  
Erick Fredj ◽  
Gabriel Jordà ◽  
Maristella Berta ◽  
Annalisa Griffa ◽  
...  
Keyword(s):  
3D Reconstruction ◽  
Current Velocity ◽  
High Frequency ◽  
Acoustic Doppler Current Profiler ◽  
Marine Ecology ◽  
Optimal Interpolation ◽  
Data Reconstruction ◽  
Reconstruction Methods ◽  
Current Profiler

Abstract. The effective monitoring and understanding of the dynamics of coastal currents is crucial for the development of environmentally sustainable coastal activities in order to preserve marine ecosystems as well as to support marine and navigation safety. This need is driving the set-up of a growing number of multiplatform operational observing systems, aiming for the continuous monitoring of the coastal ocean. A significant percentage of the existing observatories is equipped with land-based high-frequency radars (HFRs), which provide real-time currents with high spatio-temporal coverage and resolutions. Several approaches have been used in the past to expand the surface current velocity measurements provided by HFR to subsurface levels, since this can expand the application of the technology to other fields, like marine ecology or fisheries. The possibility of obtaining 3D velocity current fields from the combination of data from HFRs with complementary data, such as the velocity current profiles provided by in situ acoustic Doppler current profiler (ADCP) moorings is explored here. To that end, two different methods to reconstruct the 3D current velocity fields are assessed by a standard approach conceptually similar to OSSEs (observing system simulation experiments), where 3D numerical simulations are used as true ocean in order to evaluate the performance of the data-reconstruction methods. The observations of currents from a HFR and ADCP moorings are emulated by extracting the corresponding data from the 3D true ocean, and used as input for the methods. Then, the 3D reconstructed fields (outputs of the methods) are compared to the true ocean to assess the skills of the data-reconstruction methods. These methods are based on different approaches: on the one hand, the reduced order optimal interpolation uses an approximation to the velocity covariances (which can be obtained from historical data or a realistic numerical simulation) and on the other hand, the discrete cosine transform penalized least square is based on penalized least squares regression that balances fidelity to the data and smoothness of the solution. This study, which is based on the configuration of a real observatory located in the south-eastern Bay of Biscay (SE-BoB), is a first step towards the application of the data-reconstruction methods to real data, since it explores their skills and limitations. In the SE-BoB, where the coastal observatory includes a long-range HFR and two ADCP moorings inside the HFR footprint area, the results show satisfactory 3D reconstructions with mean spatial (for each depth level) errors between 0.55 and 7 cm s−1 for the first 150 m depth and mean relative errors of 0.07–1.2 times the rms value for most of the cases. The data-reconstruction methods perform better in well-sampled areas, and both show promising skills for the 3D reconstruction of currents as well as for the computation of new operational products integrating complementary observations, broadening the applications of the in situ observational data in the study area.

scholarly journals Quantifying Suspended Sediment using Acoustic Doppler Current Profiler in Tidung Island Seawaters

2021 ◽  
Vol 29 (1) ◽  
Author(s):  
Henry Munandar Manik ◽  
Randi Firdaus
Keyword(s):  
Water Column ◽  
Suspended Sediment ◽  
Suspended Solids ◽  
Acoustic Doppler Current Profiler ◽  
Sediment Concentration ◽  
In Situ Measurement ◽  
Ocean Current ◽  
Echo Intensity ◽  
Current Profiler

Tidung Island, located near Jakarta Bay, is a tourism and conservation area. It is necessary to keep these seawaters unpolluted. To calculate the level of pollution, it is necessary to know the sediment concentration. Quantifying concentration suspended sediment is important for knowledge of sediment transport. Researchers usually use water sample analysis and optical method for quantifying suspended sediment in seawater. Less accuracies of these methods are due to under sample of seawater and the existence of biological fouling. One promising method to measure concentration of suspended sediment is using Acoustic Doppler Current Profiler (ADCP). ADCP is usually used by oceanographer and hydrographer to measure ocean current. In this research, ADCP with 300 kHz operating frequency was used effectively to measure suspended sediment concentration (SSC) and ocean current simultaneously. The echo intensity received from suspended sediment was computed using sonar equations to quantify SSC. The empirical equation between echo intensity and SSC was found. The SSC value obtained by ADCP was also compared with in situ measurement. The result showed that quantified SSC value obtained by ADCP was nearly equal with SSC obtained from in situ measurement with coefficient correlation of 0.98. The high concentration ranged from 55 mg/L to 80 mg/L at the surface layer to a depth 12 m, moderate concentration ranged from 45 mg/L to 55 mg/L at a depth 12 m to 40 m, and low concentration less than 45 mg/L at a depth greater than 40 m. The distribution of SSC was correlated with ocean current condition. In small currents, suspended solids will settle faster so that the concentration in the water column will decrease. Conversely, if the velocity is high, suspended solids will continue to float carried by the current in the water column so that the concentration is high.

scholarly journals A Method for Processing Acoustic Doppler Current Profiler Velocity Data from Towed, Undulating Vehicles

2008 ◽  
Vol 25 (9) ◽  
pp. 1710-1716 ◽  
Author(s):  
Jiayi Pan ◽  
David A. Jay
Keyword(s):  
Surface Waters ◽  
High Frequency ◽  
Acoustic Doppler Current Profiler ◽  
Small Time ◽  
Ocean Current ◽  
Near Surface ◽  
Vertical Range ◽  
External Reference ◽  
Current Profiler ◽  
Adcp Measurements

Abstract The utility of the acoustic Doppler current profiler (ADCP) for sampling small time and space scales of coastal environments can be enhanced by mounting a high-frequency (1200 kHz) ADCP on an oscillating towed body. This approach requires both an external reference to convert the measured shears to velocities in the earth coordinates and a method to determine the towed body velocities. During the River Influence on the Shelf Ecosystems (RISE) project cruise, a high-frequency (1200 kHz) and narrowbeam ADCP with mode 12 sampling was mounted on a TRIAXUS oscillating towfish, which steers a 3D path behind the ship. This deployment approach extended the vertical range of the ADCP and allowed it to sample near-surface waters outside the ship’s wake. The measurements from a ship-mounted 1200-kHz narrowbeam ADCP are used as references for TRIAXUS ADCP data, and a method of overlapping bins is employed to recover the entire vertical range of the TRIAXUS ADCP. The TRIAXUS vehicle horizontal velocities are obtained by removing the derived ocean current velocity from the TRIAXUS ADCP measurements. The results show that the method is practical.

scholarly journals Global Wavenumber Spectrum with Corrections for Altimeter High-Frequency Noise

2015 ◽  
Vol 45 (2) ◽  
pp. 495-503 ◽  
Author(s):  
Xiao-Hui Zhou ◽  
Dong-Ping Wang ◽  
Dake Chen
Keyword(s):  
High Frequency ◽  
Acoustic Doppler Current Profiler ◽  
High Energy ◽  
Frequency Noise ◽  
Spectral Estimates ◽  
Current Profiler ◽  
Adcp Measurements ◽  
Corrected Data ◽  
Geostrophic Turbulence ◽  
The Tropics

AbstractThe altimetry wavenumber spectra of sea surface height (SSH) provide a unique dataset for testing of geostrophic turbulence. While SSH spectral slopes of k−11/3 and k−5 are expected from theories and numerical simulations, the altimetry spectra from the original unfiltered and instrument noise–corrected data often are too shallow, falling between k−2 and k−3. In this study, the possibility that the flattened spectral slopes are partly due to contamination by unresolved high-frequency (<10 days) motions is tested. A spatiotemporal filter based on empirical orthogonal function expansion (EOF) is used to remove the temporally incoherent signals. The resulting spectral slopes are much steeper than in the previous studies. Over 70% of the revised global spectral estimates, excluding the tropics, are above k−3. Moreover, in high energy regions like the Gulf Stream and Kuroshio, the spectral slopes are about k−5, which is consistent with the classical quasigeostrophic (QG) turbulence. The spectral slopes are validated with the eddy kinetic energy (EKE) spectra from shipboard acoustic Doppler current profiler (ADCP) measurements in the high and low energy regions.

scholarly journals Kajian Pola Arus Laut dan Distribusi Sedimen Di Perairan Pantai Muara Kamal Jakarta Utara

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Permana Ari Soerjawo ◽  
Thonas Indra Maryanto
Keyword(s):  
Current Velocity ◽  
High Tide ◽  
Clay Fraction ◽  
Secondary Data ◽  
Acoustic Doppler Current Profiler ◽  
Google Earth ◽  
Ocean Current ◽  
Primary Data ◽  
Sediment Distribution ◽  
Current Profiler

ABSTRAKPola arus laut dan distribusi sedimen merupakan proses dinamika di suatu perairan yang mempunyai karakteristik berbeda-beda, sehingga berpengaruh terhadap pembentukan geomorfologi pantai di seluruh dunia. Penelitian ini bertujuan untuk mengetahui pola arus dan sedimen di perairan Pantai Muara Kamal Jakarta Utara di tahun 2012. Data yang digunakan merupakan data primer dan data sekunder, data primer meliputi data arus yang didapat dari pemasangan ADCP(Acoustic Doppler Current Profiler), data pasang surut dan sedimen perairan yang diambil dengan sedimen grab. Data sekunder berupa peta LPI (Lingkungan Pantai Indonesia) tahun 2000 skala 1:50.000 dari BIG (Badan Informasi Geospasial) dan citra satelit Google Earth tahun 2009. Hasil penelitian menunjukan bahwa kecepatan arus yang paling besar terdapat pada lapisan permukaan dengan kecepatan 0,242 m/s kearah barat daya (207,8o), kecepatan arus terkecil terdapat pada lapisan dasar yaitu 0,141 m/s kearah barat daya (207o). Hasil simulasi model hidrodinamika 2D, menunjukkan bahwa pada saat pasang arus laut mengarah ke daratan (selatan) dan pada saat surut arus laut mengarah ke laut lepas (barat laut). Berdasarkan kandungan ukuran butir sedimen di perairan Pantai Muara Kamal Jakarta Utara adalah pasir (64.98 - 72.15%) fraksi pasir tertinggi distasiun B(belakang geotekstil), lanau (24.56 - 29.36%) fraksi lanau tertinggi di stasiun C (depan geotekstil) dan Lempung (1.64 – 5.64%) fraksi lempung tertinggi di stasiun C (depan geotekstil). Kata kunci: Arus, Pantai Muara Kamal, Sedimen, model hidrodinamika 2D   ABSTRACTOcean current and sediment distribution are the dynamic process that have different charactheristic and therefore influenced beach geomorfophology around the world. This research aims to understand both ocean current and sediment pattern in Muara Kamal North Jakarta in 2012. This research used primary and secondary data, primary data were consisted of current data from ADCP (Acoustic Doppler Current Profiler), tidal data and bottom sediment samples. Secondary data involved of Indonesia Coastline Environmental map of year 2000 with scale 1:50.000 from Geospatial information Agency and a satellite data from Google earth of year 2009. The results showed that greatest ocean current velocity contained in the surface layer at a speed of 0,242 m/s with to southwest direction (207.8o), the smallest current velocity was in bottom layer is 0.141 m/s with southwest directiont (207o). Based on 2D hydrodynamic model simulation indicated that when high tide ocean current was flowed to the mainland (south) when low tide the current was flowed to the open sea direction. Based on the content grain size of the sediment, the studi area consisted of sand (64.98 - 72.15%) the highest sand fraction at station B(rare of geotextile) , silt (24.56 - 29.36%) the highest silt fraction at station C (front of geotextile) andclay (1.64 – 5.64%) the highest clay fraction at station C(front of geotextile) Key Words: Current, Muara Kamal Shoreline, Sediment, 2D hydrodynamics model

scholarly journals Coastal Current Intrusions from Satellite Altimetry

2020 ◽  
Vol 12 (22) ◽  
pp. 3686
Author(s):  
Daniele Casella ◽  
Marco Meloni ◽  
Anne A. Petrenko ◽  
Andrea M. Doglioli ◽  
Jerome Bouffard
Keyword(s):  
Acoustic Doppler Current Profiler ◽  
Point Of View ◽  
Ocean Dynamics ◽  
False Alarms ◽  
Coastal Current ◽  
Learning Tools ◽  
In Situ Data ◽  
Number Of False Alarms ◽  
Current Profiler

The use of satellite-based data in coastal regions for the monitoring of fine-scale ocean dynamics, impacting marine ecosystems, is a difficult challenge. A random forest algorithm to detect slope current intrusions into the Gulf of Lion, Mediterranean Sea, has been developed using both improved coastal altimetry data and 10 year-long numerical simulations. The results have been compared to an independent dataset of in situ measurements from a bottom-moored Acoustic Doppler Current Profiler. The algorithm results are very promising: 93% of slope current intrusions have been correctly identified, and the number of false alarms is moderate. The dependence of the algorithm on several environmental factors is discussed in the paper. From the oceanographic point of view, our results confirm the strong impacts of horizontal winds in the dynamic of the intrusion events in the study area. Our methodology combining numerical modeling, in situ data and new machine-learning tools proves effective in improving the capabilities of ocean remote sensing in coastal areas.

Combining current velocity data from different sources as input to coastal zone management

2021 ◽  
Author(s):  
Jenny Ullgren ◽  
Anne Stene
Keyword(s):  
Organic Carbon ◽  
Coastal Zone ◽  
Current Velocity ◽  
Coastal Zone Management ◽  
Marine Ecology ◽  
Management Tool ◽  
Thematic Maps ◽  
In Situ Data ◽  
Zone Management

&lt;p&gt;Sustainable development of the aquaculture industry depends on wise coastal zone management.&amp;#160; Aquaculture in Norway is typically found in small, rural municipalities that may lack expertise in marine ecology. In the project &amp;#8220;Precise coastal zone planning with focus on aquaculture&amp;#8221; we combine marine maps with in situ data and model results to produce a management tool for easier and more efficent aquaculture planning.&lt;/p&gt;&lt;p&gt;Our study area comprises five municipalities in Western Norway and includes both fjords and open coast. High resolution marine maps exist for the area. We also have access to environmental assessments from aquaculture sites, sediment samples for Total Organic Carbon (TOC), and current velocity time series from oceanographic moorings. We will compare the in situ data with output from two current models (Sinmod and NorKyst-800). The data will be used to produce thematic maps of key characteristics, mainly current and organic carbon content, to help administrators identify areas suitable for different types of aquaculture.&lt;/p&gt;&lt;p&gt;Here, we present results from in situ measurements that will provide the current velocity input to the thematic maps. Data from seven oceanographic moorings placed in the fjord system show the current variability on time scales from hours to years. In addition we have done four 1-month deployments of a current profiler on sites selected to improve the geographical data coverage. We show preliminary results and discuss the challenges in simplifying variable current fields in an area with complex geography into an overall map.&lt;/p&gt;

scholarly journals Analysis of in situ water velocity distributions in the lowland river floodplain covered by grassland and reed marsh habitats - a case study of the bypass channel of Warta River (Western Poland)

2017 ◽  
Vol 65 (4) ◽  
pp. 325-332 ◽  
Author(s):  
Ireneusz Laks ◽  
Krzysztof Szoszkiewicz ◽  
Tomasz Kałuża
Keyword(s):  
Acoustic Doppler Current Profiler ◽  
Water Velocity ◽  
Concrete Slabs ◽  
Lowland River ◽  
Vegetation Types ◽  
Velocity Measurements ◽  
Flow Energy ◽  
Current Profiler

AbstractThe analysis of in situ measurements of velocity distribution in the floodplain of the lowland river has been carried out. The survey area was located on a bypass channel of the Warta River (West of Poland) which is filled with water only in case of flood waves. The floodplain is covered by grassland and reed marsh habitats. The velocity measurements were performed with an acoustic Doppler current profiler (ADCP) in a cross-section with a bed reinforced with concrete slabs. The measured velocities have reflected the differentiated impact of various vegetation types on the loss of water flow energy. The statistical analyses have proven a relationship between the local velocities and the type of plant communities.

scholarly journals Volumetric Mapping of Methane Concentrations at the Bush Hill Hydrocarbon Seep, Gulf of Mexico

2021 ◽  
Vol 9 ◽  
Author(s):  
William P. Meurer ◽  
John Blum ◽  
Greg Shipman
Keyword(s):  
Gulf Of Mexico ◽  
Water Column ◽  
Acoustic Doppler Current Profiler ◽  
Field Studies ◽  
Methane Seepage ◽  
Current Profiler ◽  
Methane Fluxes ◽  
Methane Concentrations

The role of methane as a green-house gas is widely recognized and has sparked considerable efforts to quantify the contribution from natural methane sources including submarine seeps. A variety of techniques and approaches have been directed at quantifying methane fluxes from seeps from just below the sediment water interface all the way to the ocean atmosphere interface. However, there have been no systematic efforts to characterize the amount and distribution of dissolved methane around seeps. This is critical to understanding the fate of methane released from seeps and its role in the submarine environment. Here we summarize the findings of two field studies of the Bush Hill mud volcano (540 m water depth) located in the Gulf of Mexico. The studies were carried out using buoyancy driven gliders equipped with methane sensors for near real time in situ detection. One glider was equipped with an Acoustic Doppler Current Profiler (ADCP) for simultaneous measurement of currents and methane concentrations. Elevated methane concentrations in the water column were measured as far away as 2 km from the seep source and to a height of about 100 m above the seep. Maximum observed concentrations were ∼400 nM near the seep source and decreased away steadily in all directions from the source. Weak and variable currents result in nearly radially symmetric dispersal of methane from the source. The persistent presence of significant methane concentrations in the water column points to a persistent methane seepage at the seafloor, that has implications for helping stabilize exposed methane hydrates. Elevated methane concentrations in the water column, at considerable distances away from seeps potentially support a much larger methane-promoted biological system than is widely appreciated.

Optimizing and Validating High-Frequency Radar Surface Current Measurements in the Mona Passage

2011 ◽  
Vol 45 (3) ◽  
pp. 49-58 ◽  
Author(s):  
Jorge E. Corredor ◽  
Andre Amador ◽  
Miguel Canals ◽  
Samuel Rivera ◽  
Jorge E. Capella ◽  
...  
Keyword(s):  
High Frequency ◽  
Surface Current ◽  
Acoustic Doppler Current Profiler ◽  
The United States ◽  
Repeated Measurements ◽  
Surface Velocity ◽  
High Frequency Radar ◽  
Detection And Tracking ◽  
Current Profiler ◽  
Mona Island

AbstractThe Mona Passage is a major shipping lane to the Panama Canal and a key route for illegal traffic into the United States. We have emplaced two high-frequency radar (HFR) stations on the west coast of Puerto Rico intended to allow mapping of the ocean surface velocity field of the eastern Mona Passage and to explore its performance in vessel detection and tracking. The array provides coverage of the southeastern quadrant of the Passage extending west to Mona Island and north to Rincon. Hourly results are posted online in near-real time. To optimize our results, we twice measured the antenna beam patterns and applied these corrections to the resulting radial returns. To assess the basic capability of the Mona Passage HFR array to measure surface currents in this tropical environment, we undertook validation measurements, including repeated deployment of Lagrangian drifters, deployment of an acoustic Doppler current profiler, and comparison with modeled tidal currents. Our experimental measurements showed good agreement to both modeled and in situ data lending confidence to the area-wide surface current maps generated by this system. Repeated measurements showed limited temporal variability of antenna distortion patterns, demonstrating that these are in large part the product of the surrounding environment. Comparison between a numerical particle tracking algorithm and experimental Lagrangian trajectories showed mixed results, with better agreement during periods of low intrahour variability in current direction than during periods of rapid tidal reversal.

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