Computing Ocean Surface Currents Over the Coastal California Current System Using 30-Min-Lag Sequential SAR Images

Qazi, Waqas A.; Emery, William J.; Fox‐Kemper, Baylor

doi:10.1109/tgrs.2014.2314117

Cited by 57 publications

(39 citation statements)

References 46 publications

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“…This allows the observation of such slicks in MSS images provided by SAR and use the MCC technique to retrieve currents. This approach was successfully tested by Qazi et al (2014), who used SAR data from Envisat and ERS-2 separated by only 30 min. Although the use of SAR data allows the limitation imposed by cloud coverage to be overcome, the interpretation of MSS is strongly dependent on weather conditions (Robinson, 2004;Kudryavtsev et al, 2005), implying that it can only be applied for winds within the range 2-7 m s −1 (Qazi et al, 2014).…”

Section: Currents From a Sequence Of Tracer Imagesmentioning

confidence: 99%

“…This approach was successfully tested by Qazi et al (2014), who used SAR data from Envisat and ERS-2 separated by only 30 min. Although the use of SAR data allows the limitation imposed by cloud coverage to be overcome, the interpretation of MSS is strongly dependent on weather conditions (Robinson, 2004;Kudryavtsev et al, 2005), implying that it can only be applied for winds within the range 2-7 m s −1 (Qazi et al, 2014). Marcello et al (2008) proposed improvement of the MCC approach using a twostep procedure: in the first step, image segmentation is used to unveil the patterns present in the image, which are tracked in the second step.…”

Section: Currents From a Sequence Of Tracer Imagesmentioning

confidence: 99%

See 1 more Smart Citation

Remote sensing of ocean surface currents: a review of what is being observed and what is being assimilated

Isern‐Fontanet

Ballabrera-Poy

Turiel

et al. 2017

Nonlin. Processes Geophys.

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Abstract. Ocean currents play a key role in Earth's climate -they impact almost any process taking place in the ocean and are of major importance for navigation and human activities at sea. Nevertheless, their observation and forecasting are still difficult. First, no observing system is able to provide direct measurements of global ocean currents on synoptic scales. Consequently, it has been necessary to use sea surface height and sea surface temperature measurements and refer to dynamical frameworks to derive the velocity field. Second, the assimilation of the velocity field into numerical models of ocean circulation is difficult mainly due to lack of data. Recent experiments that assimilate coastal-based radar data have shown that ocean currents will contribute to increasing the forecast skill of surface currents, but require application in multidata assimilation approaches to better identify the thermohaline structure of the ocean. In this paper we review the current knowledge in these fields and provide a global and systematic view of the technologies to retrieve ocean velocities in the upper ocean and the available approaches to assimilate this information into ocean models.

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Section: Currents From a Sequence Of Tracer Imagesmentioning

confidence: 99%

Section: Currents From a Sequence Of Tracer Imagesmentioning

confidence: 99%

Remote sensing of ocean surface currents: a review of what is being observed and what is being assimilated

Isern‐Fontanet

Ballabrera-Poy

Turiel

et al. 2017

Nonlin. Processes Geophys.

View full text Add to dashboard Cite

show abstract

“…This method has been used to measure a variety of ocean surface currents over the past several decades [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Its effectiveness for retrieving ocean surface currents from Advanced Very High Resolution Radiometer (AVHRR) thermal infrared (IR) images has been repeatedly demonstrated [6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

“…Also, ocean color (OC) images collected from Coastal Zone Color Scanner (CZCS) [12], Moderate-Resolution Imaging Spectroradiometer (MODIS) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) [9], and Geostationary Ocean Color Imager (GOCI) [13][14][15] have been used successfully to compute the space-time variability of the surface currents. More recently, sequential synthetic aperture radar (SAR) images derived from ERS-2, Envisat [16], TerraSAR-X (TSX) [17], TanDEM-X (TDX) and COSMO-SkyMed (CSK) [18] have also been used with the MCC method to map the space-time variations of coastal currents. Moreover, this MCC method is not region-specific, and has been used to study the current structure in diverse regions such as the California Current [9,11], the Gulf Stream [7,10], the East Australian Current [8,19], the Tsushima Currents [14] and the Kuroshio Current [15].…”

Section: Introductionmentioning

confidence: 99%

Computing Coastal Ocean Surface Currents from MODIS and VIIRS Satellite Imagery

Liu

Emery

et al. 2017

Remote Sensing

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Abstract:We explore the potential of computing coastal ocean surface currents from ModerateResolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) satellite imagery using the maximum cross-correlation (MCC) method. To improve on past versions of this method, we evaluate combining MODIS and VIIRS thermal infrared (IR) and ocean color (OC) imagery to map the coastal surface currents and discuss the benefits of this combination of sensors and optical channels. By combining these two sensors, the total number of vectors increases by 58.3%. In addition, we also make use of the different surface patterns of IR and OC imagery to improve the tracking performance of the MCC method. By merging the MCC velocity fields inferred from IR and OC products, the spatial coverage of each individual MCC field is increased by 65.8% relative to the vectors derived from OC images. The root mean square (RMS) error of the merged currents is 18 cm · s −1 compared with coincident HF radar surface currents. A 5-year long time serious of merged MCC computed currents was used to investigate the current structure of the California Current (CC). Weekly, seasonal, and 5-year mean flows provide a unique space-time picture of the oceanographic variability of the CC.

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“…Among these, are ocean surface currents which can be derived from fully polarimetric SAR images [6][7][8]. Moreover, some studies suggest that ocean surface currents also have significant effects on the electromagnetic backscattering signals per se, and therefore on the retrievals of associated ocean surface parameters [9,10].…”

Section: Introductionmentioning

confidence: 99%

Ocean Wind and Current Retrievals Based on Satellite SAR Measurements in Conjunction with Buoy and HF Radar Data

et al. 2017

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A total of 168 fully polarimetric synthetic-aperture radar (SAR) images are selected together with the buoy measurements of ocean surface wind fields and high-frequency radar measurements of ocean surface currents. Our objective is to investigate the effect of the ocean currents on the retrieved SAR ocean surface wind fields. The results show that, compared to SAR wind fields that are retrieved without taking into account the ocean currents, the accuracy of the winds obtained when ocean currents are taken into account is increased by 0.2-0.3 m/s; the accuracy of the wind direction is improved by 3-4 • . Based on these results, a semi-empirical formula for the errors in the winds and the ocean currents is derived. Verification is achieved by analysis of 52 SAR images, buoy measurements of the corresponding ocean surface winds, and high-frequency radar measurements of ocean currents. Results of the comparisons between data obtained by the semi-empirical formula and data measured by the high-frequency radar show that the root-mean-square error in the ocean current speed is 12.32 cm/s and the error in the current direction is 6.32 • .

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Computing Ocean Surface Currents Over the Coastal California Current System Using 30-Min-Lag Sequential SAR Images

Cited by 57 publications

References 46 publications

Remote sensing of ocean surface currents: a review of what is being observed and what is being assimilated

Remote sensing of ocean surface currents: a review of what is being observed and what is being assimilated

Computing Coastal Ocean Surface Currents from MODIS and VIIRS Satellite Imagery

Ocean Wind and Current Retrievals Based on Satellite SAR Measurements in Conjunction with Buoy and HF Radar Data

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