The impact of curvature on surface current near the rounded corners of a scatterer.

2019 ◽  
Author(s):  
Paul D. Smith ◽  
Audrey J. Markowskei
Keyword(s):  
Surface Current ◽  
The Impact

scholarly journals Bridging the gap between observational oceanography and users

Ocean Science ◽  
2017 ◽  
Vol 13 (1) ◽  
pp. 161-173 ◽  
Author(s):  
Christiane A. Eschenbach
Keyword(s):  
Product Life Cycle ◽  
Cost Benefit ◽  
Surface Current ◽  
Quality Parameter ◽  
Offshore Wind ◽  
Arctic Seas ◽  
Stakeholder Interaction ◽  
Data Products ◽  
Products Analysis ◽  
The Impact

Abstract. In order to ensure relevance and societal impact of research and to meet the various requirements of different target groups, the Coastal Observing System for Northern and Arctic Seas (COSYNA) developed and pursued a broad range of activities for knowledge transfer and stakeholder interaction. Potential user groups of data and data products include (but are not limited to) science, administration, renewable energies, engineering, tourism, and nature conservation. COSYNA data and data products are publicly accessible and available free of charge via the Internet (data portal; www.cosyna.de). The stakeholder interaction is integrated into the COSYNA product life cycle outlined here and the steps undertaken are exemplified for the product Surface Current Fields in the German Bight. Initial surveys revealed COSYNA's potential relevance in the national and international context. After the technological and mathematical realization of high-quality parameter fields, external experts evaluated the scientific value, informational value, innovative leap, cost/benefit aspects, operability, etc., of the data products. In order to improve products and their usability and to pave the way for future co-operation, interviews and workshops with potential users from the offshore wind energy industry were conducted. The stakeholder interaction process was successful, revealing relevant insights into user demands and usability of (possible) products. Analysis of data download provided some evidence for impact beyond academia. Other criteria for the increasingly demanded evaluation of the impact of coastal research are discussed. By sharing first-hand experiences, this study contributes to the emerging knowledge on integration of science and end users.

The Impact of Reprocessing Efforts on the Mid-Atlantic's Surface Current Product

2019 ◽  
Author(s):  
Teresa G. Updyke ◽  
Hugh J. Roarty ◽  
Michael Smith ◽  
Laura Nazzaro
Keyword(s):  
Surface Current ◽  
Current Product ◽  
The Impact

scholarly journals Measurement of turbulence in the oceanic mixed layer using Synthetic Aperture Radar (SAR)

2012 ◽  
Vol 9 (5) ◽  
pp. 2851-2883 ◽  
Author(s):  
S. G. George ◽  
A. R. L. Tatnall
Keyword(s):  
Surface Layer ◽  
Synthetic Aperture Radar ◽  
Wave Interaction ◽  
Surface Current ◽  
Surface Flow ◽  
Synthetic Aperture ◽  
Small Scale ◽  
Radar Images ◽  
The Impact ◽  
Aperture Radar

Abstract. Turbulence in the surface layer of the ocean contributes to the transfer of heat, gas and momentum across the air-sea boundary. As such, study of turbulence in the ocean surface layer is becoming increasingly important for understanding its effects on climate change. Direct Numerical Simulation (DNS) techniques were implemented to examine the interaction of small-scale wake turbulence in the upper ocean layer with incident electromagnetic radar waves. Hydrodynamic-electromagnetic wave interaction models were invoked to demonstrate the ability of Synthetic Aperture Radar (SAR) to observe and characterise surface turbulent wake flows. A range of simulated radar images are presented for a turbulent surface current field behind a moving surface vessel, and compared with the surface flow fields to investigate the impact of turbulent currents on simulated radar backscatter. This has yielded insights into the feasibility of resolving small-scale turbulence with remote-sensing radar and highlights the potential for extracting details of the flow structure and characteristics of turbulence using SAR.

scholarly journals Assimilating realistically simulated wide-swath altimeter observations in a high-resolution shelf-seas forecasting system

Ocean Science ◽  
2021 ◽  
Vol 17 (6) ◽  
pp. 1791-1813
Author(s):  
Robert R. King ◽  
Matthew J. Martin
Keyword(s):  
Mean Squared Error ◽  
Surface Current ◽  
Surface Currents ◽  
Correlated Errors ◽  
North West ◽  
Forecasting System ◽  
Negative Impacts ◽  
Ocean Topography ◽  
The Impact ◽  
Wide Swath

Abstract. The impact of assimilating simulated wide-swath altimetry observations from the upcoming Surface Water and Ocean Topography (SWOT) mission is assessed using observing system simulation experiments (OSSEs). These experiments use the Met Office 1.5 km resolution North West European Shelf analysis and forecasting system. In an effort to understand the importance of future work to account for correlated errors in the data assimilation scheme, we simulate SWOT observations with and without realistic correlated errors. These are assimilated in OSSEs along with simulated observations of the standard observing network, also with realistic errors added. It was found that while the assimilation of SWOT observations without correlated errors reduced the RMSE (root mean squared error) in sea surface height (SSH) and surface current speeds by up to 20 %, the inclusion of correlated errors in the observations degraded both the SSH and surface currents, introduced an erroneous increase in the mean surface currents and degraded the subsurface temperature and salinity. While restricting the SWOT data to the inner half of the swath and applying observation averaging with a 5 km radius negated most of the negative impacts, it also severely limited the positive impacts. To realise the full benefits in the prediction of the ocean mesoscale offered by wide-swath altimetry missions, it is crucial that methods to ameliorate the effects of correlated errors in the processing of the SWOT observations and account for the correlated errors in the assimilation are implemented.

scholarly journals Assimilating realistically simulated wide-swath altimeter observations in a high-resolution shelf-seas forecasting system

2021 ◽  
Author(s):  
Robert R. King ◽  
Matthew J. Martin
Keyword(s):  
Surface Current ◽  
Surface Currents ◽  
Correlated Errors ◽  
North West ◽  
Shelf Seas ◽  
Forecasting System ◽  
Negative Impacts ◽  
Future Work ◽  
The Impact ◽  
Wide Swath

Abstract. The impact of assimilating simulated wide-swath altimetry observations from the upcoming SWOT mission is assessed using Observing System Simulation Experiments (OSSEs). These experiments use the Met Office 1.5 km resolution North-West European Shelf analysis and forecasting system. In an effort to understand the importance of future work to account for correlated errors in the data assimilation scheme, we simulate SWOT observations with and without realistic correlated errors. These are assimilated in OSSEs along with simulated observations of the standard observing network, also with realistic errors added. It was found that while the assimilation of SWOT observations without correlated errors reduced the RMSE in sea surface height (SSH) and surface current speeds by up to 20 %, the inclusion of correlated errors in the observations degraded both the SSH and surface currents, introduced an erroneous increase in the mean surface currents, and degraded the sub-surface temperature and salinity. While restricting the SWOT data to the inner half of the swath and applying observation averaging with a 5 km radius negated most of the negative impacts, it also severely limited the positive impacts. To realise the full benefits in the prediction of the ocean mesoscale offered by wide-swath altimetry missions it is crucial that methods to ameliorate the effects of correlated errors in the processing of the SWOT observations and to account for the correlated errors in the assimilation are implemented.

scholarly journals Examining the Impact of Surface Currents on Satellite Scatterometer and Altimeter Ocean Winds

2012 ◽  
Vol 29 (12) ◽  
pp. 1776-1793 ◽  
Author(s):  
Amanda M. Plagge ◽  
Douglas Vandemark ◽  
Bertrand Chapron
Keyword(s):  
Wind Speed ◽  
Atmospheric Stability ◽  
Surface Current ◽  
Microwave Remote Sensing ◽  
Surface Velocity ◽  
Western Boundary ◽  
Length Scales ◽  
Ocean Winds ◽  
Wind Measurements ◽  
The Impact

Abstract A 5-yr dataset collected over two surface current and meteorological moorings allows rigorous evaluation of questions surrounding wave–current interaction and the scatterometer. Results demonstrate that scatterometer winds represent winds relative to the moving sea surface, affirming previous observational efforts that inferred the phenomenon using climatological approaches over larger time and space scales in equatorial and western boundary currents. Comparisons of wind residuals between Ku-band Quick Scatterometer (QuikSCAT) and buoy measurements show nearly one-to-one correlations with ocean surface velocity for 5-, 12.5-, and 25-km resolution wind speed products, especially under conditions of moderate wind speed and near-neutral atmospheric stability. Scatterometer and buoy wind direction differences due to currents were observed to be negligible for the range of surface velocities encountered and the length scales observed by QuikSCAT. Similar analyses are applied to C-band Advanced Scatterometer (ASCAT) satellite wind measurements at the same sites, as well as to satellite altimeter winds, and overall confirm the results seen with QuikSCAT; differences are likely the combined result of sampling, satellite wind algorithms, and geophysical wind–wave coupling in the presence of currents. On the whole, this study affirms that at length scales of 10 km and longer the scatterometer wind can be considered to be current relative. Observed differences between earth-relative and current-relative winds of order 10%–20% of the wind velocity are not uncommon in this and other ocean regions and this study more fully validates that microwave remote sensing winds appear to respond to wind stress even in the presence of larger-scale currents.

On Shipboard Marine X-Band Radar Near-Surface Current ‘‘Calibration’’

2015 ◽  
Vol 32 (10) ◽  
pp. 1928-1944 ◽  
Author(s):  
Björn Lund ◽  
Hans C. Graber ◽  
Katrin Hessner ◽  
Neil J. Williams
Keyword(s):  
Surface Current ◽  
Differential Gps ◽  
Near Surface ◽  
The Pacific ◽  
X Band ◽  
Correction Technique ◽  
Order Of Magnitude ◽  
Cross Track ◽  
The Impact ◽  
Ship Speed

AbstractThe ocean wave signatures within conventional noncoherent marine X-band radar (MR) image sequences can be used to derive near-surface current information. On ships, an accurate near-real-time record of the near-surface current could improve navigational safety. It could also advance understanding of air–sea interaction processes. The standard shipboard MR near-surface current estimates were found to have large errors (of the same order of magnitude as the signal) that are associated with ship speed and heading. For acoustic Doppler current profilers (ADCPs), ship heading errors are known to induce a spurious cross-track current that is proportional to the ship speed and the sine of the error angle. Conventional mechanical gyrocompasses are very reliable heading sensors, but they are too inaccurate for shipboard ADCPs. Within the ADCP community, it is common practice to correct the gyrocompass measurements with the help of multiantenna carrier-phase differential GPS systems. This study shows how a similar multiantenna GPS-based ship heading correction technique stands to improve the accuracy of MR near-surface current estimates. Changes to the standard MR near-surface current retrieval method that are necessary for high-quality results from ships are also introduced. MR and ADCP data collected from R/V Roger Revelle during the Impact of Typhoons on the Ocean in the Pacific (ITOP) program in 2010 are used to demonstrate the MR currents’ accuracy and reliability.

scholarly journals Power balance and efficiency of metasurface antennas

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Modeste Bodehou ◽  
David González-Ovejero ◽  
Christophe Craeye ◽  
Stefano Maci ◽  
Isabelle Huynen ◽  
...  
Keyword(s):  
Conversion Efficiency ◽  
Surface Current ◽  
Closed Surface ◽  
Basis Functions ◽  
Total Power ◽  
Power Balance ◽  
Computational Techniques ◽  
Efficiency Conversion ◽  
The Impact ◽  
First Time

Abstract This paper presents two methods for the efficient evaluation of the power balance in circular metasurface (MTS) antennas implementing arbitrary modulated surface impedances on a grounded dielectric slab. Both methods assume the surface current in the homogenized MTS to be known. The first technique relies on the surface current expansion with Fourier-Bessel basis functions (FBBF) and proceeds by integration of the Poynting vector on a closed surface. The second method is based on the evaluation of the residue of the electric field spectrum at the surface-wave (SW) pole, and is demonstrated by using a current expansion in Gaussian ring basis functions (GRBF). The surface current expansions can be directly obtained either by analyzing the antenna with a Method of Moments (MoM) tool for homogenized MTSs based on FBBF or GRBF, or derived by a projection process. From there, the power contributions, namely the total power delivered by the feed, the radiated power, the SW power, and the Ohmic power losses in the dielectric are computed. Several efficiency metrics are presented and discussed: tapering efficiency, conversion efficiency, loss factor, and diffraction factor. Since the MTS apertures at hand are leaky-wave (LW) antennas, the designer must find a compromise between the aperture efficiency and the conversion efficiency. This requires accurate and fast computational techniques for the efficiency. The present paper demonstrates for the first time that the efficiency of MTS antenna devices can be accurately evaluated in a few minutes. The compromise that should be made during the design process between the tapering efficiency and the conversion efficiency is highlighted. The impact on the efficiency of isotropic versus anisotropic MTS, uniform versus non-uniform modulation index, is analyzed. An excellent agreement is obtained between both approaches, commercial software, and experimental data.

scholarly journals Application of HF Radar in Hazard Management

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Mal Heron ◽  
Roberto Gomez ◽  
Bernd Weber ◽  
Anna Dzvonkovskaya ◽  
Thomas Helzel ◽  
...  
Keyword(s):  
Real Time ◽  
Phased Array ◽  
Surface Current ◽  
Tohoku Earthquake ◽  
Suspended Sediments ◽  
Hf Radar ◽  
Coastal Hazards ◽  
Hazard Management ◽  
Measurement Capability ◽  
The Impact

A review is given of the impact that HF radars are having on the management of coastal hazards. Maps of surface currents can be produced every 10–20 minutes which, in real time, improve navigation safety in restricted areas commonly found near ports and harbours. The time sequence of surface current maps enables Lagrangian tracking of small parcels of surface water, which enables hazard mitigation in managing suspended sediments in dredging, in emergency situations where flotsam and other drifting items need to be found, and in pollution control. The surface current measurement capability is used to assist tsunami warnings as shown by the phased-array data from Chile following the Great Tohoku Earthquake in 2011. The newly launched Tsunami Warning Center in Oman includes a network of phased-array HF radars to provide real-time tsunami monitoring. Wind direction maps can be used to locate the position of cold fronts in the open ocean and to monitor the timing and strength of sea-breeze fronts in key locations.

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