A Comparison of an Unmanned Survey Vessel to Manned Vessels for Nearshore Tidal Current and Transport Measurements

2011 ◽  
Vol 45 (5) ◽  
pp. 71-77 ◽  
Author(s):  
Eddie Weeks ◽  
Chunyan Li ◽  
Harry Roberts ◽  
Richard F. Shaw ◽  
Nan Walker
Keyword(s):  
Energy Efficiency ◽  
Water Use ◽  
Current Velocity ◽  
Autonomous Vehicles ◽  
Tidal Current ◽  
Acoustic Doppler Current Profiler ◽  
Side Scan Sonar ◽  
Coastal Embayments ◽  
Current Profiler ◽  
Chirp Sonar

AbstractThe focus of marine autonomous vehicles has largely been for offshore applications. The use of such observational platforms in estuaries and coastal embayments has been limited by the designs of the widely used AUVs, which are mostly for open ocean studies. Here we discuss the development and testing of an automated unmanned boat for shallow water use for (1) current velocities using an acoustic Doppler current profiler, (2) bathymetry using an echo sounder, (3) seabed configuration using a side-scan sonar, or (4) shallow, sub-bottom stratigraphy using a chirp sonar. After 91 h and 453 km of total distance surveyed, results demonstrate the numerous advantages this automated boat (Auto-boat) possesses over manned survey vessels. For example, the Auto-boat had the advantage in the accuracy of repeating a planned route continuously over at least a tidal cycle to resolve tidal and subtidal current velocity profiles. It provides endurance, energy efficiency, ease of operation, and capability of coverage of shallow areas close to shore.

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 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 Identifikasi Arus Pasang Surut di Perairan Kemujan, Karimunjawa Berdasarkan Data Pengukuran Acoustic Doppler Current Profiler

2021 ◽  
Vol 24 (2) ◽  
pp. 247-254
Author(s):  
Elis Indrayanti ◽  
Denny Nugroho Sugianto ◽  
Purwanto Purwanto ◽  
Hendry Syahputra Ropinus Siagian
Keyword(s):  
Tidal Current ◽  
Acoustic Doppler Current Profiler ◽  
Tidal Currents ◽  
Residual Current ◽  
Least Square ◽  
Ocean Currents ◽  
Velocity Data ◽  
Raw Data ◽  
Current Profiler ◽  
X 24

Ocean currents are dynamic hydro-oceanographic parameters which is play an important role in the transport of nutrients, larvae, sediment, and so on. Therefore, the identification of ocean currents including velocity, direction, sea level and the type of currents important to be studied. The research was conducted in Kemujan Water, Karimunjawa. Data for this research is based on velocity data measured using the Acoustic Doppler Current Profiler (ADCP) for 3 x 24 hours. Furthermore, the raw data of the measurement are analyzed using least square methods to obtain the characteristic of tidal current. The total current is separated into tidal currents and residual current (non-tidal currents). Result shown that the characteristic of current in Kemujan Water, Karimunjawa was tidal current. Tidal current moves bi-directional, toward the northeast and the southwest.. Arus laut merupakan parameter hidro-oseanografi yang dinamis dan mempunyai peran penting dalam transpor nutrien, larva, material, dan lain sebagainya. Oleh karena itu identifikasi arus laut meliputi kecepatan, arah, elevasi muka air laut dan tipe arus laut perlu untuk dikaji. Penelitian dilaksanakan di Perairan Kemujan  yang merupakan salah satu gugusan pulau di Karimunjawa. Data  yang dianalisa merupakan data kecepatan arus hasil pengukuran langsung menggunakan Acoustic Doppler Current Profiler (ADCP) selama 3x24 jam. Selanjutnya raw data hasil pengukuran diolah dengan metode least square untuk mengetahui karakteristik arus. Arus total dipisahkan menjadi arus pasang surut dan arus non-pasang surut (residu). Hasil penelitian menunjukkan bahwa prosentase arus pasang surut lebih besar dari arus residu, sehingga arus di Perairan Kemujan, Karimunjawa teridentifikasi sebagai arus pasang surut. Arus  bergerak secara bertolak belakang (bi-directional) yaitu pada saat surut menuju pasang arah arus menuju ke timur laut dan pada saat pasang menuju surut arah arus menuju ke barat daya.

Measurements of Tidal Current Velocities in the Folda Fjord, Norway, With the Use of a Vessel Mounted ADCP

2014 ◽  
Author(s):  
Nicole Carpman ◽  
Mats Leijon
Keyword(s):  
Tidal Current ◽  
Energy Resource ◽  
Acoustic Doppler Current Profiler ◽  
Renewable Energy Resource ◽  
Mean Velocity ◽  
Average Width ◽  
First Approximation ◽  
Current Profiler ◽  
Current Water ◽  
Mean Current

Measurements of tidal current water velocities is an important first step in evaluating the potential for a tidal site to be used as a renewable energy resource. For this reason, on site measurements are performed at the inlet of a fjord situated at the coast of Norway. The site has an average width of 580 m and a depth of 10–15 m which is narrow and shallow enough to give rise to water velocities that can be of use for energy conversion. With the use of an Acoustic Doppler Current Profiler (ADCP) cross-section measurements are conducted along four transects. The measurements covered flood and ebb currents around one tide and the data give a first approximation of the magnitude and distribution of the flow field. Depth averaged mean current velocities are calculated along the transects for horizontal bins with sizes in the order of 50 × 50 m. Maximum mean velocity for the flood currents were 1.31 m/s and 1.46 m/s for the ebb currents. The measurements show that even a small amount of data can give an indication of the potential and characteristics of the site.

scholarly journals Using Orthogonal Combined Signals in Broadband ADCP for Improving Velocity Measurement

2020 ◽  
Vol 8 (6) ◽  
pp. 450
Author(s):  
Yujing Lin ◽  
Fei Yuan ◽  
En Cheng
Keyword(s):  
Current Velocity ◽  
Velocity Measurement ◽  
Water Environment ◽  
Acoustic Doppler Current Profiler ◽  
Processing Method ◽  
Velocity Measurements ◽  
Signal Parameters ◽  
Current Profiler ◽  
Signal Combination ◽  
Conventional Signal

Broadband Acoustic Doppler Current Profiler (BBADCP) is a widely used technology in velocity measurements. To adapt to the varied water environment and different measurement requirements, flexible tuning of transmitted signal parameters will improve the feasibility and accuracy of velocity measurement. Compared with the conventional signal, the orthogonal combined signal designed in this paper can generate a wealth of signal combination examples and improve the accuracy of the velocity measurement under the same conditions. The proposed orthogonal combined signal consists of two orthogonal sub-signals with a symmetrical spectrum. Each is designed based on time delay to eliminate or weaken the current velocity ambiguity. Then, the processing method of the received signal when the pulse signals are the same or different coded signal is discussed. The numerical simulation results show that, when using the proposed method, the standard deviation of the estimated current velocity has different degrees of reduction at different current velocities. Our simulation also shows that, compared to the convention method, the proposed method can improve the SNR by 10 dB. This can help significantly increase the scope of the configuration.

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