Assimilation of Ship-Mounted ADCP Data for Barotropic Tides: Application to the Ross Sea

2005 ◽  
Vol 22 (6) ◽  
pp. 721-734 ◽  
Author(s):  
S. Y. Erofeeva ◽  
Laurie Padman ◽  
Gary Egbert
Keyword(s):  
Numerical Solutions ◽  
Ross Sea ◽  
Acoustic Doppler Current Profiler ◽  
Tidal Currents ◽  
Open Boundary ◽  
Open Boundary Conditions ◽  
Current Profiler ◽  
Inverse Solutions ◽  
Adcp Data ◽  
Mean Circulation

Abstract The application of a generalized inverse approach for assimilating vessel-mounted acoustic Doppler current profiler (VM-ADCP) data into numerical solutions of barotropic tides is described. The derived estimates of tidal currents can be used to detide the VM-ADCP data and expose underlying mean circulation. The methodology is illustrated with data assimilation models of tidal currents in the Ross Sea. The prior solution, obtained by solving the nonlinear shallow-water equations by time stepping with a linear bottom friction parameterization and elevation of open boundary conditions obtained from a circum-Antarctic tide model, provides reasonably good fit to most available moored current meter data. Two inverse solutions were obtained: one assimilating moored current meter records and the other assimilating three cruises of VM-ADCP data. Fitting either the mooring time series or the VM-ADCP records leads to only small changes relative to the prior solution currents, except over the shelf break where short length scale, energetic diurnal topographic vorticity waves are present. It is shown that the dynamics embedded in the representer functions provides reasonable tidal corrections even with no prior information about forcing at open boundaries.

scholarly journals Detiding ADCP Data in a Highly Variable Shelf Sea: The Celtic Sea

2005 ◽  
Vol 22 (1) ◽  
pp. 84-97 ◽  
Author(s):  
L. Carrillo ◽  
A. J. Souza ◽  
A. E. Hill ◽  
J. Brown ◽  
L. Fernand ◽  
...  
Keyword(s):  
Least Squares ◽  
Least Squares Method ◽  
Three Dimensional ◽  
Acoustic Doppler Current Profiler ◽  
Tidal Currents ◽  
Shelf Area ◽  
Residual Currents ◽  
Current Profiler ◽  
Adcp Data ◽  
Celtic Sea

Abstract This paper presents a comparison of two conventional detiding techniques carried out for ship-mounted acoustic Doppler current profiler (ADCP) data collected in the European shelf area of the Celtic Sea during the summer of 1998. One technique consisted of extracting the vertically averaged tidal currents obtained from a barotropic three-dimensional numerical tidal model. The second technique consisted of fitting the spatiotemporal ADCP data using least squares and polynomial spatial functions. In the least squares technique, the incorporation of zero velocity normal to the coast appears to improve the estimation of the tidal currents near the coast. Quantitative comparisons of the results from both techniques with historical current meter observations are shown. However, both methods showed limitations in accurately representing the tidal currents in the study area. Consequently, an alternative detiding technique is proposed. This technique consists of blending the tidal currents derived from the numerical model with those fitted to the ADCP data from the least squares method. Improved results were obtained using the blending technique. ADCP-derived residual currents were comparable with contemporaneous flows measured using drifting buoys and also with estimates obtained by geostrophic calculations.

scholarly journals Vertical structure of currents in the vicinity of the Iceland-Scotland Ridge

2005 ◽  
Vol 23 (6) ◽  
pp. 1963-1975 ◽  
Author(s):  
C. Carollo ◽  
I. Astin ◽  
J. Graff
Keyword(s):  
General Circulation ◽  
Bottom Topography ◽  
Acoustic Doppler Current Profiler ◽  
Tidal Currents ◽  
Residual Flow ◽  
Residual Currents ◽  
Tidal Motion ◽  
Dominant Component ◽  
Current Profiler ◽  
The Mean

Abstract. An analysis of current profiles carried out on moored Acoustic Doppler Current Profiler data sets recorded during the Variability of Exchanges In the Northern Seas project is presented here for several locations in three sections in the vicinity of the Iceland-Scotland Ridge: (1) north of the Faroes, (2) in the Faroe-Bank Channel and (3) in the Faroe-Shetland Channel. Total currents have been decomposed into three components, namely the mean residual flow, tide and surge. The mean residual flow is found to be dominant. Results for the major tidal constituents (M2, S2, N2, O1 and K1) are shown and discussed. It is found that the predominant tidal harmonic M2 becomes steered through depth to align with the bottom topography. The mean residual flow is found to be generally larger than the surge, particularly in the Faroe-Bank Channel below 500m depth where it is the dominant component. Here tidal rectification, i.e. the topographic rectification of tidal currents originating in nonlinearities that rectify the oscillatory tidal motion, is identified as the process enhancing the large mean residual currents found. From the current structure, two water masses are identified in the channel: the upper slowing moving inflow water and the colder outflow water characterised by a 3–6-day periodicity. In the Faroe-Shetland Channel the flow is characterised by large tidal currents, particularly in shallow waters. Instead, north of the Faroes none of the component was identified as dominant. The results show that the variability of the current components is strongly dependent upon topography and water depth. Keywords. Oceanography: Physical (Currents; General circulation; General or miscellaneous)

scholarly journals Analysis of tidal currents in the North Sea from shipboard acoustic Doppler current profiler data

2018 ◽  
Vol 162 ◽  
pp. 1-12 ◽  
Author(s):  
Håvard Vindenes ◽  
Kjell Arild Orvik ◽  
Henrik Søiland ◽  
Henning Wehde
Keyword(s):  
North Sea ◽  
Acoustic Doppler Current Profiler ◽  
Tidal Currents ◽  
The North ◽  
Current Profiler ◽  
The North Sea ◽  
Profiler Data

scholarly journals Acoustic Doppler current profiler observations of herring movement

2003 ◽  
Vol 60 (4) ◽  
pp. 846-859 ◽  
Author(s):  
Len Zedel ◽  
Tor Knutsen ◽  
Ranjan Patro
Keyword(s):  
Swimming Speed ◽  
Acoustic Doppler Current Profiler ◽  
Clupea Harengus ◽  
Night Time ◽  
Individual Fish ◽  
Current Profiler ◽  
Adcp Data ◽  
Increased Activity

Abstract Observations were made of over-wintering (December 1997) and migrating (January 1998) Norwegian, spring-spawning herring (Clupea harengus) using a moored 307 kHz acoustic Doppler current profiler (ADCP). The location of herring in ADCP data is identified by regions of volume-backscatter strength greater than −60 dB re 1 m−1. The presence of herring was verified using net trawls and 38 kHz, EK500 data. While the ADCP cannot make speed measurements of individual fish, the system does provide a measure of the swimming speed and direction of large herring schools. Herring were observed to move both horizontally and vertically: horizontal speeds were from 0 to 50 cm s−1. Higher speeds were observed during daylight hours for both deployments with somewhat increased activity at both dawn and dusk. At night-time, over-wintering herring demonstrated no well-defined velocity.

Characteristics of ice in the St. Lawrence River

2003 ◽  
Vol 30 (4) ◽  
pp. 766-774 ◽  
Author(s):  
Brian Morse ◽  
Masoud Hessami ◽  
Céline Bourel
Keyword(s):  
Fuzzy Logic ◽  
Wind Velocity ◽  
Air Temperature ◽  
Acoustic Doppler Current Profiler ◽  
Navigation Channel ◽  
Current Profiler ◽  
Adcp Data ◽  
St Lawrence River ◽  
Good Agreement

The main objective of this paper is to describe the characteristics of brash ice in the St. Lawrence River downstream of Montréal over a period of three winters. We used two instruments deployed in the St. Lawrence River navigation channel through Lake St. Pierre to measure ice parameters: an acoustic Doppler current profiler (ADCP) and an ice-profiling sonar (IPS). This paper discusses the capacities of these instruments to quantify ice characteristics and to predict the risk of ice congestion. It was found that wind velocity and air temperature play major roles in the variation in ice parameters and, consequently, in the occurrence of ice congestion in the navigation channel through Lake St. Pierre. Comparison of the IPS and ADCP data showed good agreement and demonstrated that these two instruments can be very effective for certain ice applications.Key words: ice characteristics, ice congestion, ADCP, IPS, fuzzy logic.

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.

Tools and technologies for NEMO models: the case of the Generic Interfaces developed in the framework of IMMERSE

2021 ◽  
Author(s):  
Laura Stefanizzi ◽  
Stefania Ciliberti ◽  
Mehmet Ilicak ◽  
Giovanni Coppini
Keyword(s):  
Boundary Conditions ◽  
Black Sea ◽  
Numerical Solutions ◽  
Initial Boundary ◽  
Coastal Ocean ◽  
Open Boundary ◽  
The Black Sea ◽  
Marmara Sea ◽  
Open Boundary Conditions ◽  
Model Configuration

<p>Setting new model configurations based on NEMO requires the definition of initial/boundary condition and the validation of numerical solutions. In the framework of IMMERSE H2020 project, CMCC is developing new tools and technological capacities for handling in easy and reliable way external products, such CMEMS or coastal ocean data, for research-to-operations applications. Generic Interfaces for NEMO (InterNEMO) allow for 3 main scopes: 1) to access and discover the CMEMS catalogue, including both model and observational data; 2) to manipulate accessed datasets, including coastal ocean data, to extract relevant physical information to use for setting initial/boundary conditions for a new NEMO-based configurations; 3) to prepare NEMO set of upstream files and to validate NEMO solution by using CMEMS observational datasets. InterNEMO implements also technologies to connect a NEMO user to Wekeo DIAS (https://www.wekeo.eu/) for the interoperable accessing and processing of CMEMS data. In this contribution, we present the InterNEMO architecture developed in Python via Jupyter Notebooks, to support the user/researcher to easily discover, design and configure modeling components required by the new NEMO-based configuration. InterNEMO is tested for the Black Sea hydrodynamical model configuration, developed by CMCC in the framework of the Black Sea Monitoring and Forecasting Centre (BS-MFC) for CMEMS a) to show how to access CMEMS observations through Wekeo DIAS and use them to validate numerical solutions and b) to define open boundary conditions from an unstructured grid model configuration based on Shyfem, developed for the Marmara Sea.</p>

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