Deriving Ocean Surface Drift Using Multiple SAR Sensors

Liu, Antony K.; Hsu, Meng−Kai

doi:10.3390/rs1030266

Cited by 18 publications

(8 citation statements)

References 22 publications

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“…Such techniques mainly involve applications related to ship detection, land mask estimation in those situations where geographic maps cannot be used (natural disasters, marshlands and wetlands) and oil-spill detection, among others. Furthermore, maritime applications have become one of the SAR major fields of study in recent years [19][20][21][22][23][24]. All in all, the absence of studies of this particular issue along with the difference it can make in automatic processing, make this topic an interesting one to cover.…”

Section: Introductionmentioning

confidence: 99%

Statistical Analysis of SAR Sea Clutter for Classification Purposes

et al. 2014

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Statistical analysis of radar clutter has always been one of the topics, where more effort has been put in the last few decades. These studies were usually focused on finding the statistical models that better fitted the clutter distribution; however, the goal of this work is not the modeling of the clutter, but the study of the suitability of the statistical parameters to carry out a sea state classification. In order to achieve this objective and provide some relevance to this study, an important set of maritime and coastal Synthetic Aperture Radar data is considered. Due to the nature of the acquisition of data by SAR sensors, speckle noise is inherent to these data, and a specific study of how this noise affects the clutter distribution is also performed in this work. In pursuit of a sense of wholeness, a thorough study of the most suitable statistical parameters, as well as the most adequate classifier is carried out, achieving excellent results in terms of classification success rates. These concluding results confirm that a sea state classification is not only viable, but also successful using statistical parameters different from those of the best modeling distribution and applying a speckle filter, which allows a better characterization of the parameters used to distinguish between different sea states.

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Section: Introductionmentioning

confidence: 99%

Statistical Analysis of SAR Sea Clutter for Classification Purposes

et al. 2014

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“…However, the results of eye location from both techniques are close and will not have too much effect on our final results of separation distance between eye centers from SAR and IR. Therefore in this study, due to the high spatial resolution of limited SAR images, the typhoon eyes are derived based on the wavelet analysis to track ocean features [25].…”

Section: Issues and Discussionmentioning

confidence: 99%

“…A two dimensional wavelet transform is a highly efficient band-pass data filter, which can be used to separate various scales of processes [23]. For effective identification and tracking of common features in a chosen image, such as typhoon eyes, a two dimensional Mexican hat wavelet transform is applied to extract features with corresponding spatial scales from the image and to filter out noise [24,25].…”

Section: Approachmentioning

confidence: 99%

Comparison of Typhoon Locations over Ocean Surface Observed by Various Satellite Sensors

Pan

Liu

et al. 2013

Remote Sensing

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Abstract:In this study, typhoon eyes have been delineated using wavelet analysis from the synthetic aperture radar (SAR) images of ocean surface roughness and from the warm area at the cloud top in the infrared (IR) images, respectively. Envisat SAR imagery, and multi-functional transport satellite (MTSAT) and Feng Yun (FY)-2 Chinese meteorological satellite IR imagery were used to examine the typhoons in the western North Pacific from 2005 to 2011. Three cases of various typhoons in different years, locations, and conditions have been used to compare the typhoon eyes derived from SAR (on the ocean surface) with IR (at the cloud-top level) images. Furthermore, the best track data from the Joint Typhoon Warning Center (JTWC), Chinese Meteorological Administration (CMA), and the Japan Meteorological Agency (JMA) are checked for the calibration. Because of the vertical wind shear, which acts as an upright tilt, the location of the typhoon eye on the ocean surface differs from that at the top of the clouds. Consequently, the large horizontal distance between typhoon eyes on the ocean surface and on the cloud top implies that the associated vertical wind shear profile is considerably more complex than generally expected. This result demonstrates that SAR can be a useful tool for typhoon monitoring study over the ocean surface.

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“…Visible and thermal data have provided a starting point for understanding sill-induced turbulence. Synthetic aperture radar imagery, which can measure the surface roughness pattern and the surface current field at high spatial resolution [32][33][34], might be used to quantify the wave-current interaction and kinetic energy associated with the surface turbulence; and multi-look satellite imagery might be used to measure the boil growth rate.…”

Section: Discussionmentioning

confidence: 99%

Surface Imprints of Water-Column Turbulence: A Case Study of Tidal Flow over an Estuarine Sill

2013

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Turbulent mixing in the ocean can, in some cases, be so intense as to leave surface imprints, or "boils", that are detectable from space. Examples include turbulent flow over a submerged obstacle and instability of large-amplitude internal waves. In this paper we examine the particular case of tidal flow over a ~60-m-deep sill, which forms a barrier for the flow of dense water from the Pacific Ocean into the Strait of Georgia. The flow response during flood tide is illustrated using visible and thermal-band satellite and airborne imagery, the latter having high-resolution multi-looks that capture the formative stage of the boils. The image examples capture aspects of the expected flow response based on in situ measurements reported in the literature, but they also suggest differences, and they reveal the level of complexity of the surface structure. A new result is that, after the front is pushed well off the sill, boils emerge several hundred meters downstream from the sill crest, grow at a rate of ~60 m 2 /s, and attain a size of 3,800 m 2 (an equivalent diameter of 70 m) after one minute. These boils appear to arise from vorticity generated by vertical shear at the sill crest, and provide an additional source of vertical mixing and (through wave breaking) air-sea gas exchange.

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Deriving Ocean Surface Drift Using Multiple SAR Sensors

Cited by 18 publications

References 22 publications

Statistical Analysis of SAR Sea Clutter for Classification Purposes

Statistical Analysis of SAR Sea Clutter for Classification Purposes

Comparison of Typhoon Locations over Ocean Surface Observed by Various Satellite Sensors

Surface Imprints of Water-Column Turbulence: A Case Study of Tidal Flow over an Estuarine Sill

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