Operational oil spill trajectory modelling using HF radar currents: A northwest European continental shelf case study

Abascal, Ana J.; Sánchez, Jorge Pérez; Chiri, Helios; Ferrer, M.I.; Cárdenas, Mar; Gallego, Alejandro; Castanedo, Sonia; Medina, Raúl; Alonso-Martirena, Andrés; Berx, Barbara; Turrell, W.R.; Hughes, Sarah L.

doi:10.1016/j.marpolbul.2017.04.010

Cited by 40 publications

(17 citation statements)

References 46 publications

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“…The HFR exploits the Doppler shift in Bragg backscatter from the ocean surface waves (Barrick et al, ). Attractive spatial and temporal resolution (around 3–6 km and 1 hr) and spatial coverage (up to 220 km) make these observations essential for time‐critical operations such as oil spill tracking (Abascal et al, ) and search‐and‐rescue operations (Breivik et al, ). These HFR‐based surface current observations can also be assimilated in ocean circulation models (e.g., Sperrevik et al, ).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Radial Ocean Surface Currents Derived From Sentinel‐1 IW Doppler Shift Using Coastal Radar and Lagrangian Surface Drifter Observations

Moiseev¹,

Johnsen

Hansen

et al. 2020

JGR Oceans

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Ocean surface radial velocities (RVLs) derived from the Sentinel-1 A/B Interferomic Wide (IW) mode Doppler frequency shift observations are regularly acquired over the Norwegian coastal zone. These data can be used to complement existing ocean observation systems with high-resolution (up to 1.5 × 1.5 km) spatial ocean surface current (OSC) maps. In this study, Sentinel-1 IW Level 2 OSC retrievals were obtained from 2 months (October-November 2017) of raw Doppler shift observations acquired over the Norwegian Coastal Current (NCC). The results were evaluated using coastal high-frequency radar (HFR) and Lagrangian ocean surface drifter observations. The analysis shows that distinct patterns of the NCC, with range directed currents reaching up to 0.7 m/s, can be detected in the SAR data. The mean bias between Synthetic Aperture Radar (SAR) and HFR observations was −0.08 m/s and the root mean square deviation (RMSD) was 0.25 m/s. In comparison, the agreement between the SAR-derived OSC and the trajectories from Lagrangian surface drifters showed a mean bias of 0.02 m/s and an RMSD of 0.24 m/s. The accuracy of the SAR OSC retrievals rely on precise wind-wave bias correction. Hence, the accuracy of the model wind field (speed and direction) is crucial. The sea state contribution must also be taken into account during the bias correction. A typical required accuracy of the OSC velocity is on the order of 0.1 m/s. Therefore, the comparisons demonstrate that the use of SAR for OSC retrieval is promising.Plain Language Summary Knowledge of ocean surface currents is crucial for tracking oil spills and marine debris (e.g., plastic), search and rescue operations, and fisheries. Traditionally, surface currents are studied using shipboard measurements or trajectory of buoys drifting within the water flow. Despite their accuracy, these measurements are also costly to collect and therefore irregular in time and space. The Doppler shift recorded by a radar placed on board of a satellite can be used for providing systematic snapshots of surface currents over vast areas of the ocean. However, these observations must be evaluated before application. In this study, we evaluated observations of the Norwegian Coastal Current acquired by the Sentinel-1 satellite in October-November 2017. Satellite observations were compared with collocated coastal radar and ocean surface drifters data. The analysis shows that distinct patterns of the surface current can be systematically detected in the Sentinel-1 data. The accuracy of the observations is within the range of user requirements. We underlined the importance of accurate information about wind field and ocean waves for analysis of the radar observation. The performed study demonstrates that the use of Sentinel-1 observations for the ocean surface current retrieval is promising.

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Section: Introductionmentioning

confidence: 99%

Evaluation of Radial Ocean Surface Currents Derived From Sentinel‐1 IW Doppler Shift Using Coastal Radar and Lagrangian Surface Drifter Observations

Moiseev¹,

Johnsen

Hansen

et al. 2020

JGR Oceans

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“…Comparing Figure 3b with Figure 3a, we can clearly see that the simulation results are almost the same as the theoretical calculated results. Divergences for β = 2.5 at the DOA near ±30 • are owing to the approximation in Equation (7). This result suggests that the quantitative relationship is valid.…”

Section: Problem Formulationmentioning

confidence: 84%

“…Additionally, the current mapping results are provided in real time with a variety of temporal resolutions (normally around one hour) and spatial resolutions (from hundreds of meters to kilometers). These results are invaluable in many fields, including oceanographic and meteorological research [2][3][4], tsunami warning [5], search and rescue support [6], and monitoring of oil spills in real time [7].…”

Section: Introductionmentioning

confidence: 98%

Quantifying and Reducing the DOA Estimation Error Resulting from Antenna Pattern Deviation for Direction-Finding HF Radar

et al. 2017

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High-frequency (HF) radars are routinely used for remotely sensing ocean surface currents. However, the performance of the most widely used direction-finding HF radar is degraded due to the effect of the inevitable deviations of actual antenna pattern on the direction of arrival (DOA) estimation. In this paper, we quantify the DOA estimation error resulting from the deviation of the actual antenna pattern from the ideal one. Theoretical analysis and field experiment results suggest that the ratio of the deviations for the two loops dominates the DOA estimation error. Thus, eliminating the effect of the antenna pattern deviations on DOA estimation error is transformed into eliminating the effect of this ratio. From this, a calibration method based on the time-averaged local spatial coverage rate (TLSCR) is proposed to reduce the effect of the antenna pattern deviations on current extraction, which uses the ideal antenna pattern to estimate the DOA of the echoes. To validate this proposed calibration method, we assess the radar-derived radial velocities by comparing with in situ observations. The comparison results indicate that the proposed TLSCR calibration method can effectively reduce the DOA estimation error and improve the performance of the direction-finding HF radar in current observation.

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“…HFR systems usually average current measurements for one hour, although some average currents for shorter periods, such as 30 minutes. Due to their high spatio-temporal resolution, HFR data are commonly used in real time for search and rescue (Ullman et al, 2006) or oil spill prediction/mitigation emergency response (Abascal et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

A new Lagrandian based short term prediction methodology for HF radar currents

Solabarrieta

Hernández‐Carrasco

Rubio

et al. 2020

Preprint

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Abstract. The use of High Frequency Radar (HFR) data is increasing worldwide for 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 hours of ocean currents from HFR data. The method is based on the finding of historical gridded analogues of Lagrangian trajectories obtained from HFR surface currents. Then, assuming that the present state will follow the same temporal evolution as did the historical analogue, we obtain a short-term prediction of the surface currents. 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. The L-STP improves on previous prediction systems implemented for the SE Bay of Biscay and provides good results for the Red Sea study area. A comparison of the L-STP methodology with predictions based on persistence and reference fields has been performed in order to quantify the error introduced by this Lagrangian approach. Furthermore, a temporal sensitivity analysis has been addressed 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 to identify 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.

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Operational oil spill trajectory modelling using HF radar currents: A northwest European continental shelf case study

Cited by 40 publications

References 46 publications

Evaluation of Radial Ocean Surface Currents Derived From Sentinel‐1 IW Doppler Shift Using Coastal Radar and Lagrangian Surface Drifter Observations

Evaluation of Radial Ocean Surface Currents Derived From Sentinel‐1 IW Doppler Shift Using Coastal Radar and Lagrangian Surface Drifter Observations

Quantifying and Reducing the DOA Estimation Error Resulting from Antenna Pattern Deviation for Direction-Finding HF Radar

A new Lagrandian based short term prediction methodology for HF radar currents

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