On the imaging of exposed intertidal flats by single- and dual-co-polarization Synthetic Aperture Radar

Gade, Martin; Wang, Wensheng; Kemme, Linnea

doi:10.1016/j.rse.2017.12.004

Cited by 27 publications

(28 citation statements)

References 19 publications

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“…Gade et al [23] found evidence of mapping characteristics of seagrass beds in SAR data from the Schleswig-Holstein Wadden Sea, whereas in the present study, no general detection of seagrass is proven. In some cases, areas of which seagrass vegetation is known from the field surveys, were characterized by diffusely elevated backscatter values, which may be due to elevated structures of the sediment surface induced by the seagrass cover.…”

Section: Visual Analysis and Classificationcontrasting

confidence: 77%

“…Further research is needed to investigate to what extent polarimetric information can be used for the detection of other surface types in the tidal area. Geng et al [21] identified different surface cover types (i.e., seawater, mud flats, and aquaculture algae farms) through polarimetric decomposition, and Ref [39], and recently Ref [23] pointed to the potential of fully polarimetric interpretation of SAR imagery for classification purposes in tidal areas.…”

Section: Visual Analysis and Classificationmentioning

confidence: 99%

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Remote Sensing Intertidal Flats with TerraSAR-X. A SAR Perspective of the Structural Elements of a Tidal Basin for Monitoring the Wadden Sea

et al. 2018

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Spatial distribution and dynamics of intertidal habitats are integral elements of the Wadden Sea ecosystem, essential for the preservation of ecosystem functions and interlocked with geomorphological processes. Protection and monitoring of the Wadden Sea is mandatory and remote sensing is required to survey the extensive, often inaccessible tidal area. Mainly airborne techniques are carried out for decades. High-resolution satellite-borne sensors now enable new possibilities with satellite synthetic aperture radar (SAR) offering high availability of acquisitions during low water time due to independence from daylight and cloud cover. More than 100 TerraSAR-X images from 2009 to 2016 were used to examine the reproduction of intertidal habitats and macrostructures from the flats south of the island of Norderney and comparative areas in the Lower Saxony Wadden Sea. As a non-specific, generic approach to distinguish various and variable surface types continuously influenced by tidal dynamics, visual analysis was chosen which was supported by extensive in situ data. This technically unsophisticated access enabled us to identify mussel beds, fields of shell-detritus, gully structures, mud fields, and bedforms, the latter detected in the upper flats of every East Frisian island. Based on the high frequency of TerraSAR-X recordings for the Norderney area, a bedform shift was observed in a time-series from 2009 to 2015. For the same period, the development of a mud field with an adjoining depression was traced. Beside seasonal variations of the mud field, the formation of a mussel bed settling in the depression was imaged over the years. This study exemplifies the relevance of TerraSAR-X imagery for Wadden Sea remote sensing. Further development of classification methods for current SAR data together with open access availability should contribute to large-scale surveys of intertidal surface structures of geomorphic or biogenic origin and improve monitoring and long-term ecological research in the Wadden Sea and related tidal areas.

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Section: Visual Analysis and Classificationcontrasting

confidence: 77%

Section: Visual Analysis and Classificationmentioning

confidence: 99%

Remote Sensing Intertidal Flats with TerraSAR-X. A SAR Perspective of the Structural Elements of a Tidal Basin for Monitoring the Wadden Sea

et al. 2018

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“…The other advantage is that these SAR sensors have polarimetric capabilities of acquiring data in different polarization combinations of VV, HH, VH and HV. These SAR polarimetric data are widely exploited for oil spill detection or classification [12][13][14], analysis of objects scattering or their classification in coastal intertidal flats [15][16][17], and sea ice detection and classification [18][19][20]. In addition to the general advantages of the aforementioned high spatial resolution and polarimetry, advanced SARs have constellation configuration design.…”

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confidence: 99%

Capabilities of Chinese Gaofen-3 Synthetic Aperture Radar in Selected Topics for Coastal and Ocean Observations

Zhang

Huang

et al. 2018

Remote Sensing

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Gaofen-3 (GF-3), the first Chinese spaceborne synthetic aperture radar (SAR) in C-band for civil applications, was launched on August 2016. Some studies have examined the use of GF-3 SAR data for ocean and coastal observations, but these studies generally focus on one particular application. As GF-3 has been in operation over two years, it is essential to evaluate its performance in ocean observation, a primary goal of the GF-3 launch. In this paper, we offer an overview demonstrating the capabilities of GF-3 SAR in ocean and coastal observations by presenting several representative cases, i.e., the monitoring of intertidal flats, offshore tidal turbulent wakes and oceanic internal waves, to highlight the GF-3's full polarimetry, high spatial resolution and wide-swath imaging advantages. Moreover, we also present a detailed analysis of the use of GF-3 quad-polarization data for sea surface wind retrievals and wave mode data for sea surface wave retrievals. The case studies and statistical analysis suggest that GF-3 has good ocean and coastal monitoring capabilities, though further improvements are possible, particularly in radiometric calibration and stable image quality.kilometers. Wide-swath or ScanSAR images generally have a spatial resolution of tens of meters and, more importantly, can map a large area of the open sea and coast, which makes them particularly suitable for studying meso-scale oceanic and atmospheric processes, e.g., by mapping the distribution of internal ocean waves [2], observing atmospheric solitons [3], estimating the wind speed of tropical cyclones [4], and measuring sea surface velocity [5].The year 2007 marks an important advance in the development of spaceborne SAR; two X-band spaceborne SAR, the TerraSAR-X (TSX) and Cosmo-SkyMed and the C-band SAR, Radarsat-2 (R2), were launched. Compared with previous spaceborne SAR missions, the new generation of SAR sensors has several advantages. One advantage is that the new generation can acquire images with a high spatial resolution of up to 1 m in spotlight mode [6][7][8]. This offers a unique opportunity to detect targets in the ocean and coast, e.g., for ship detection [9][10][11]. The other advantage is that these SAR sensors have polarimetric capabilities of acquiring data in different polarization combinations of VV, HH, VH and HV. These SAR polarimetric data are widely exploited for oil spill detection or classification [12][13][14], analysis of objects scattering or their classification in coastal intertidal flats [15][16][17], and sea ice detection and classification [18][19][20]. In addition to the general advantages of the aforementioned high spatial resolution and polarimetry, advanced SARs have constellation configuration design. The Cosmo-SkyMed, TSX/TanDEM-X (TDX) and Sentinel-1A/1B missions, as well as the forthcoming Radarsat Constellation Mission (RCM), all operate in constellations, which significantly reduces the temporal intervals of SAR data acquisition and therefore enhances the capture of dynamic sea surface information ...

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“…Therefore, further research is still needed to determine to what extent our new parameters can be used for such purposes. In addition, different water levels and seasonal changes can influence the backscattering characteristics of bare sediments [29] and bivalve beds. Therefore, future work will also include the sensitivity of Kennaugh elements to water levels and seasonal changes, e.g., the coverage by brown algae or Fucus.…”

Section: Discussionmentioning

confidence: 99%

Detection of Bivalve Beds on Exposed Intertidal Flats Using Polarimetric SAR Indicators

2017

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Abstract:We propose new indicators for bivalve (oyster and mussel) beds on exposed intertidal flats, derived from dual-copolarization (HH + VV) TerraSAR-X, Radarsat-2, and ALOS-2 images of the German North Sea coast. Our analyses are based upon the Kennaugh element framework, and we show that different targets on exposed intertidal flats exhibit different radar backscattering characteristics, which manifest in different magnitudes of the Kennaugh elements. Namely, the inter-channel correlation's real (K 3 ) and imaginary (K 7 ) part can be used to distinguish bivalve beds from surrounding sandy sediments, and together with the polarimetric coefficient (i.e., the normalized differential polarization ratio, K 0 /K 4 ) they can be used as indicators for bivalve beds using multi-frequency dual-copolarization SAR data. Our results show that continuous bivalve bed monitoring is possible using dual-copolarimetric SAR acquisitions at all radar wavelengths.

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On the imaging of exposed intertidal flats by single- and dual-co-polarization Synthetic Aperture Radar

Cited by 27 publications

References 19 publications

Remote Sensing Intertidal Flats with TerraSAR-X. A SAR Perspective of the Structural Elements of a Tidal Basin for Monitoring the Wadden Sea

Remote Sensing Intertidal Flats with TerraSAR-X. A SAR Perspective of the Structural Elements of a Tidal Basin for Monitoring the Wadden Sea

Capabilities of Chinese Gaofen-3 Synthetic Aperture Radar in Selected Topics for Coastal and Ocean Observations

Detection of Bivalve Beds on Exposed Intertidal Flats Using Polarimetric SAR Indicators

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