scholarly journals Wind Speed Inversion in High Frequency Radar Based on Neural Network

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Yuming Zeng ◽  
Hao Zhou ◽  
Hugh Roarty ◽  
Biyang Wen
Keyword(s):  
Neural Network ◽  
Wind Speed ◽  
High Frequency ◽  
Dynamic Parameter ◽  
Hf Radar ◽  
Data Sets ◽  
High Frequency Radar ◽  
Wide Range ◽  
Radar Echo ◽  
Buoy Data

Wind speed is an important sea surface dynamic parameter which influences a wide variety of oceanic applications. Wave height and wind direction can be extracted from high frequency radar echo spectra with a relatively high accuracy, while the estimation of wind speed is still a challenge. This paper describes an artificial neural network based method to estimate the wind speed in HF radar which can be trained to store the specific but unknown wind-wave relationship by the historical buoy data sets. The method is validated by one-month-long data of SeaSonde radar, the correlation coefficient between the radar estimates and the buoy records is 0.68, and the root mean square error is 1.7 m/s. This method also performs well in a rather wide range of time and space (2 years around and 360 km away). This result shows that the ANN is an efficient tool to help make the wind speed an operational product of the HF radar.

scholarly journals Wind Speed Dependence of Single-Site Wave-Height Retrievals from High-Frequency Radars

2010 ◽  
Vol 27 (8) ◽  
pp. 1381-1394 ◽  
Author(s):  
Brian K. Haus ◽  
Lynn K. Shay ◽  
Paul A. Work ◽  
George Voulgaris ◽  
Rafael J. Ramos ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wave Height ◽  
High Frequency ◽  
Hf Radar ◽  
Single Site ◽  
Scale Separation ◽  
Peak Energy ◽  
Wave Heights ◽  
Acoustic Doppler Profiler ◽  
Buoy Data

Abstract Wave-height observations derived from single-site high-frequency (HF) radar backscattered Doppler spectra are generally recognized to be less accurate than overlapping radar techniques but can provide significantly larger sampling regions. The larger available wave-sampling region may have important implications for observing system design. Comparison of HF radar–derived wave heights with acoustic Doppler profiler and buoy data revealed that the scale separation between the Bragg scattering waves and the peak energy-containing waves may contribute to errors in the single-site estimates in light-to-moderate winds. A wave-height correction factor was developed that explicitly considers this scale separation and eliminates the trend of increasing errors with increasing wind speed.

scholarly journals METHOD OF FORMULATING INPUT PARAMETERS OF NEURAL NETWORK FOR DIAGNOSING GAS-TURBINE ENGINES

Aviation ◽  
2013 ◽  
Vol 17 (2) ◽  
pp. 52-56 ◽  
Author(s):  
Mykola Kulyk ◽  
Sergiy Dmitriev ◽  
Oleksandr Yakushenko ◽  
Oleksandr Popov
Keyword(s):  
Neural Network ◽  
Gas Turbine ◽  
Gas Turbine Engine ◽  
Training Data ◽  
Turbine Engines ◽  
Data Sets ◽  
Gas Turbine Engines ◽  
Turbine Engine ◽  
Wide Range ◽  
And Training

A method of obtaining test and training data sets has been developed. These sets are intended for training a static neural network to recognise individual and double defects in the air-gas path units of a gas-turbine engine. These data are obtained by using operational process parameters of the air-gas path of a bypass turbofan engine. The method allows sets that can project some changes in the technical conditions of a gas-turbine engine to be received, taking into account errors that occur in the measurement of the gas-dynamic parameters of the air-gas path. The operation of the engine in a wide range of modes should also be taken into account.

scholarly journals Shortwave Direction and Spreading Measured with HF Radar

2012 ◽  
Vol 29 (2) ◽  
pp. 286-299 ◽  
Author(s):  
Lucy R. Wyatt
Keyword(s):  
Wind Direction ◽  
Hf Radar ◽  
Wave Direction ◽  
Linear Dispersion ◽  
Low Wind Speed ◽  
Wide Range ◽  
Radar Measurements ◽  
Buoy Data ◽  
Common Application ◽  
Better Than

Abstract The accuracy of wave direction and spreading at the Bragg-matched wavelength measured with HF radar over a wide range of HF operating frequencies is demonstrated by comparison with buoy data. The agreement for shortwave direction is better than that obtained for wind direction, which has been the more common application of this measurement, because these waves are not always aligned with the wind direction, particularly in short fetch and low wind speed situations. The method assumes a model of shortwave directionality and the validity of this is explored by using the buoy Fourier coefficients, with inconclusive results. The radar measurements do not use the linear dispersion relationship, but the comparison with buoy data does, and the implications of this are discussed.

scholarly journals A Quality Control Method for Broad-Beam HF Radar Current Velocity Measurements

2019 ◽  
Vol 7 (4) ◽  
pp. 112 ◽  
Author(s):  
Lipa ◽  
Barrick ◽  
Whelan
Keyword(s):  
Quality Control ◽  
High Frequency ◽  
Control Method ◽  
Doppler Frequency ◽  
Hf Radar ◽  
Velocity Measurements ◽  
Poor Agreement ◽  
Broad Beam ◽  
Radar Echo ◽  
Basic Equations

This paper describes a method to provide quality control for radial velocity maps derived from radar echo voltage cross spectra measured by broad-beam high frequency radars. The method involves the comparison of voltage cross spectra measured at Doppler frequencies in the Bragg region with values predicted from basic equations defining the complex voltage cross spectra in terms of the measured antenna patterns and the radar cross section. Poor agreement at a given Doppler frequency indicates contamination of the spectra, usually due to interference; velocity results from that Doppler frequency are then eliminated. Examples are given of its application to broad-beam radars operating at four sites.

Lagrangian dynamics in the Gulf of Trieste from high resolution HF-Radar

2020 ◽  
Author(s):  
Nydia Catalina Reyes-Suarez ◽  
Ismael Hernandez-Carrasco ◽  
Matjaz Licer ◽  
Vanessa Cardin ◽  
Miroslav Gacic ◽  
...  
Keyword(s):  
High Frequency ◽  
Oil Spills ◽  
Hf Radar ◽  
Time Data ◽  
High Frequency Radar ◽  
Gulf Of Trieste ◽  
Radar Network ◽  
Marine Traffic ◽  
Surface Variability ◽  
Lagrangian Descriptors

<p>The Gulf of Trieste (GoT) is shared by Italy, Slovenia and Croatia, with most of its coasts belonging to Italy and Slovenia, along with the two main harbours; the Harbour of Trieste (Italy) and Koper (Slovenia). Both are subject to heavy marine traffic and exposed to different threats including oil spills, maritime accidents and SAR operations. The GOT High frequency radar network provides near-real time data of sea surface currents and waves since 2016. In this work we provide a statistical description of surface variability in terms of Lagrangian descriptors in order to elucidate the transport and retention in the GoT as well as to provide the seasonal evolution of the residence time. Among the most widely used Lagrangian techniques, we focus the study on Lagrangian Coherent Structures and Path-integrated topological variables like Lagrangian divergence and Lagrangian vorticity. </p>

Performance Evaluation of SeaSonde High-Frequency Radar for Vessel Detection

2011 ◽  
Vol 45 (3) ◽  
pp. 14-24 ◽  
Author(s):  
Hugh J. Roarty ◽  
Erick Rivera Lemus ◽  
Ethan Handel ◽  
Scott M. Glenn ◽  
Donald E. Barrick ◽  
...  
Keyword(s):  
High Frequency ◽  
Processing Parameters ◽  
Hf Radar ◽  
High Frequency Radar ◽  
Detection And Tracking ◽  
Surface Vessels ◽  
Wave Radar ◽  
Vessel Detection ◽  
Track Surface ◽  
Maritime Domain Awareness

AbstractHigh-frequency (HF) surface wave radar has been identified to be a gap-filling technology for Maritime Domain Awareness. Present SeaSonde HF radars have been designed to map surface currents but are able to track surface vessels in a dual-use mode. Rutgers and CODAR Ocean Sensors, Ltd., have collaborated on the development of vessel detection and tracking capabilities from compact HF radars, demonstrating that ships can be detected and tracked by multistatic HF radar in a multiship environment while simultaneously mapping ocean currents. Furthermore, the same vessel is seen simultaneously by the radar based on different processing parameters, mitigating the need to preselect a fixed set and thereby improving detection performance.

scholarly journals Joint analysis of coastal altimetry and high-frequency (HF) radar data: observability of seasonal and mesoscale ocean dynamics in the Bay of Biscay

Ocean Science ◽  
2018 ◽  
Vol 14 (5) ◽  
pp. 1265-1281 ◽  
Author(s):  
Ivan Manso-Narvarte ◽  
Ainhoa Caballero ◽  
Anna Rubio ◽  
Claire Dufau ◽  
Florence Birol
Keyword(s):  
Coastal Area ◽  
High Frequency ◽  
Ocean Dynamics ◽  
Hf Radar ◽  
Global Ocean ◽  
Joint Analysis ◽  
Data Sets ◽  
Altimetry Data ◽  
Geostrophic Currents ◽  
Temporal Sampling

Abstract. Land-based coastal high-frequency (HF) radar systems provide operational measurements of coastal surface currents (within 1–3 m depth) with high spatial (300 m–10 km) and temporal (≤1 h) sampling resolutions, while the near-continuous altimetry missions provide information, from 1993 until today, on geostrophic currents in the global ocean with typical along-track and temporal sampling resolutions of >7 km and >9 days, respectively. During the last years, the altimetry community has made a step forward in improving these data in the coastal area, where the data present lower quality than in the open ocean. The combination of HF radar and altimetry measurements arises as a promising strategy to improve the continuous monitoring of the coastal area (e.g. by expanding the measurements made by HF radars to adjacent areas covered by the altimetry or by validating/confirming improvements brought by specific coastal algorithms or new altimeter missions). A first step towards this combination is the comparison of both data sets in overlapping areas. In this study, a HF radar system and two Jason-2 satellite altimetry products with different processing are compared over the period from 1 January 2009 to 24 July 2015. The results provide an evaluation of the performance of different coastal altimetry data sets within the study area and a better understanding of the ocean variability contained in the HF radar and altimetry data sets. Both observing systems detect the main mesoscale processes within the study area (the Iberian Poleward Current and mesoscale eddies), and the highest correlations between radar and altimetry (up to 0.64) occur in the slope where the Iberian Poleward Current represents a significant part of the variability in the circulation. Besides, the use of an Ekman model, to add the wind-induced current component to the altimetry-derived geostrophic currents, increases the agreement between both data sets (increasing the correlation by around 10 %).

scholarly journals A new Lagrangian-based short-term prediction methodology for high-frequency (HF) radar currents

Ocean Science ◽  
2021 ◽  
Vol 17 (3) ◽  
pp. 755-768
Author(s):  
Lohitzune Solabarrieta ◽  
Ismael Hernández-Carrasco ◽  
Anna Rubio ◽  
Michael Campbell ◽  
Ganix Esnaola ◽  
...  
Keyword(s):  
Real Time ◽  
High Frequency ◽  
Skill Score ◽  
Hf Radar ◽  
Surface Currents ◽  
Short Term ◽  
High Frequency Radar ◽  
Term Prediction ◽  
Short Term Prediction ◽  
Temporal Horizon

Abstract. The use of high-frequency radar (HFR) data is increasing worldwide for different applications in the field of operational oceanography and data assimilation, as it provides real-time coastal surface currents at high temporal and spatial resolution. In this work, a Lagrangian-based, empirical, real-time, short-term prediction (L-STP) system is presented in order to provide short-term forecasts of up to 48 h of ocean currents. The method is based on finding historical analogs of Lagrangian trajectories obtained from HFR surface currents. Then, assuming that the present state will follow the same temporal evolution as the historical analog, we perform the forecast. The method is applied to two HFR systems covering two areas with different dynamical characteristics: the southeast Bay of Biscay and the central Red Sea. A comparison of the L-STP methodology with predictions based on persistence and reference fields is performed in order to quantify the error introduced by this approach. Furthermore, a sensitivity analysis has been conducted to determine the limit of applicability of the methodology regarding the temporal horizon of Lagrangian prediction. A real-time skill score has been developed using the results of this analysis, which allows for the identification of periods when the short-term prediction performance is more likely to be low, and persistence can be used as a better predictor for the future currents.

scholarly journals Accuracy of altimeter data in inner and coastal seas

Ocean Science ◽  
2019 ◽  
Vol 15 (2) ◽  
pp. 227-233 ◽  
Author(s):  
Luigi Cavaleri ◽  
Luciana Bertotti ◽  
Paolo Pezzutto
Keyword(s):  
Wind Speed ◽  
High Frequency ◽  
Adriatic Sea ◽  
Wave Model ◽  
Altimeter Data ◽  
Data Sets ◽  
Northern Adriatic Sea ◽  
Large Wave ◽  
Northern Adriatic ◽  
Wave Heights

Abstract. We carry out an inter-comparison of four different altimeters: Cryosat, Jason-2, Jason-3, and Sentinel-3. This inter-comparison is undertaken by checking the altimeter data against the wind and wave model results of a given area, the Mediterranean Sea, for a 1-year period. The four data sets are consistent for wind speed, but they show substantial differences with respect to wave heights. The verification of a Sentinel-3 pass close to the coast in the northern Adriatic Sea shows irregular, spiky, large, wave height values close to the coast. This problem worsens when using high-frequency altimeter data.

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