Image quality and calibration of RADARSAT-2

Luscombe, A.P.

doi:10.1109/igarss.2009.5418201

Cited by 36 publications

(23 citation statements)

References 2 publications

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“…The 2009 grounding line is indicated for reference. In addition to the 12-yr difference in speed, dv, we provide the difference in % of the glacier speed at the grounding line in the text below to provide some context One of the reasons is that the quality of the orbit information for RADARSAT-2 is better than that of RADARSAT-1 due to improvements in the satellite design (Luscombe, 2009 Slessor Glacier, we also indicate the erroneous MOA-based grounding line portion (purple line) discussed earlier. In the region indicated by a black dashed circle in Fig.…”

Section: Resultsmentioning

confidence: 99%

Ice velocity changes in the Ross and Ronne sectors observed using satellite radar data from 1997 and 2009

2012

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Abstract. We report changes in ice velocity of a 6.5 million km 2 region around South Pole encompassing the Filchner-Ronne and Ross Ice Shelves and a significant portion of the ice streams and glaciers that constitute their catchment areas. Using the first full interferometric synthetic aperture radar (InSAR) coverage of the region completed in 2009 and partial coverage acquired in 1997, we processed the data to assemble a comprehensive map of ice speed changes between those two years. On the Ross Ice Shelf, our results confirm a continued deceleration of Mercer and Whillans Ice Streams with a 12-yr velocity difference of −50 m yr −1 (−16.7 %) and −100 m yr −1 (−25.3 %) at their grounding lines. The deceleration spreads 450 km upstream of the grounding line and more than 500 km onto the shelf, beyond what was previously known. Ross and Filchner Ice Shelves exhibit signs of pre-calving events, representing the largest observed changes, with an increase in speed in excess of +100 m yr −1 in 12 yr. Other changes in the Ross Ice Shelf region are less significant. The observed changes in glacier speed extend on the Ross Ice Shelf along the ice streams' flow lines. Most tributaries of the Filchner-Ronne Ice Shelf show a modest deceleration or no change between 1997 and 2009. Slessor Glacier shows a small deceleration over a large sector. No change is detected on the Bailey, Rutford, and Institute Ice Streams. On the Filchner Ice Shelf itself, ice decelerated rather uniformly with a 12-yr difference in speed of −50 m yr −1 , or −5 % of its ice front speed, which we attribute to a 12 km advance in its ice front position. Our results show that dynamic changes are present in the region. They highlight the need for continued observation of the area with a primary focus on the Siple Coast. The dynamic changes in Central Antarctica between 1997 and 2009 are generally second-order effects in comparison to losses on glaciers in the Bellingshausen and Amundsen Seas region and on the Antarctic Peninsula. We therefore conclude that the dynamic changes shown here do not have a strong impact on the mass budget of the Antarctic continent.

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Section: Resultsmentioning

confidence: 99%

Ice velocity changes in the Ross and Ronne sectors observed using satellite radar data from 1997 and 2009

2012

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“…Each acquisition comprises a fully polarimetric (HH + VV + HV + VH and inter-channel phase information) data set, with a nominal 5.2 m × 7.7 m resolution in range and azimuth, and a 25 km × 25 km image size (MDA, 2009). The absolute calibration accuracy of the quad-pol images, not provided, is typically reported to be < 1 dB (Luscombe, 2009). The low noise equivalent sigma zero (NESZ) of the quad-pol mode, nominally −36.5 ± 3 dB, makes it an essential tool for experimental studies of low intensity targets such as level FYI.…”

Section: Data Collectionmentioning

confidence: 99%

First-year sea ice melt pond fraction estimation from dual-polarisation C-band SAR – Part 2: Scaling in situ to Radarsat-2

et al. 2014

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Abstract. Sea ice melt pond fraction (f p ), linked with lower sea ice surface albedo and increased light transmittance to the ocean, is inadequately parameterised in sea ice models due to a lack of observations. In this paper, results from a multiscale remote-sensing program dedicated to the retrieval of level first-year sea ice (FYI) f p from dual co-and crosspolarisation C-band synthetic aperture radar (SAR) backscatter are detailed. Models which utilise the dominant effect of free-water melt ponds on the VV/HH (vertical transmit and vertical receive/horizontal transmit and horizontal receive) polarisation ratio at high incidence angles are tested for their ability to provide estimates of the subscale f p . Retrieved f p from noise-corrected Radarsat-2 quad-polarisation scenes are in good agreement with observations from coincident aerial survey data, with root mean square errors (RMSEs) of 0.05-0.07 obtained during intermediate and late stages of ponding. Weak model performance is attributed to the presence of wet snow and slush during initial ponding, and a synoptically driven freezing event causing ice lids to form on ponds. The HV/HH (horizontal transmit and vertical receive/horizontal transmit and horizontal receive) ratio explains a greater portion of variability in f p , compared to VV/HH, when ice lids are present. Generally low HV channel intensity suggests limited applications using dual crosspolarisation data, except with systems that have exceptionally low noise floors. Results demonstrate the overall potential of dual-polarisation SAR for standalone or complementary observations of f p for process-scale studies and improvements to model parameterisations.

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“…The values obtained in the calibration of the R99B images were considered to be satisfactory by Mura et al [22] and the quality of the images was reinforced by crosstalk levels of less than −30 dB. On the other hand, the quality of the RADARSAT-2 polarimetric images is supported by the values of the 0.3 dB imbalance channel and −40 dB crosstalk [24]. The RADARSAT-2 images available for the investigation were provided under the Science and Operational Applications Research (SOAR) programme, and refer to a Fine Quad Pol mode (FQP) coverage in ascending orbit, acquired over the study area in November 2008.…”

Section: Methodsmentioning

confidence: 96%

“…Lee et al [33] presented a new classification system, in which the decomposition method developed by Freeman and Durden [24] is used initially to generate the training classes for the subsequent interactions of the Wishart K-mean classifier, grouping the pixels into three classes based on the predominant scattering mechanism (volumetric, double-bounce or surface). The advantage of this approach is that it preserves the characteristics of the pixel scattering mechanisms.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of Digital Classification of Polarimetric SAR Data for Iron-Mineralized Laterites Mapping in the Amazon Region

et al. 2013

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This study evaluates the potential of C-and L-band polarimetric SAR data for the discrimination of iron-mineralized laterites in the Brazilian Amazon region. The study area is the N1 plateau located on the northern border of the Carajá s Mineral Province, the most important Brazilian mineral province which has numerous mineral deposits, particularly the world's largest iron deposits. The plateau is covered by low-density savanna-type vegetation (campus rupestres) which contrasts visibly with the dense equatorial forest. The laterites are subdivided into three units: chemical crust, iron-ore duricrust, and hematite, of which only the latter two are of economic interest. Full polarimetric data from the airborne R99B sensor of the SIVAM/CENSIPAM (L-band) system and the RADARSAT-2 satellite (C-band) were evaluated. The study focused on an assessment of distinct schemes for digital classification based on decomposition theory and hybrid approach, which incorporates statistical analysis as input data derived from the target decomposition modeling. The results indicated that the polarimetric classifications presented a poor performance, with global Kappa values below 0.20. The accuracy for the identification of units of economic interest varied from 55% to 89%, albeit with high commission error values. In addition, the results using L-band were considered superior OPEN ACCESS Remote Sens. 2013, 5 3102 compared to C-band, which suggest that the roughness scale for laterite discrimination in the area is nearer to L than to C-band.

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Image quality and calibration of RADARSAT-2

Cited by 36 publications

References 2 publications

Ice velocity changes in the Ross and Ronne sectors observed using satellite radar data from 1997 and 2009

Ice velocity changes in the Ross and Ronne sectors observed using satellite radar data from 1997 and 2009

First-year sea ice melt pond fraction estimation from dual-polarisation C-band SAR – Part 2: Scaling in situ to Radarsat-2

Evaluation of Digital Classification of Polarimetric SAR Data for Iron-Mineralized Laterites Mapping in the Amazon Region

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