Download or read book Analysis of Ice Types Along the Northern Coast of Ellesmere Island Nunavut Canada and Their Relationship to Synthetic Aperture Radar SAR Backscatter written by Miriam Richer McCallum and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Determination of Backscatter Characteristics of Sea Ice Using Synthetic Aperture Radar Data written by Richard W. Larson and published by . This book was released on 1981 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: This final report presents results obtained from an analysis of multi-channel synthetic aperture radar (SAR) data obtained from imaging flights over areas of sea ice. The SAR system operated simultaneously at 3 cm and 23 cm wavelengths, with two orthagonal-polarization receivers, horizontal and vertical, for each wavelength. Two SAR data sets were used, one from sea ice test sites in the Beaufort Sea region with data flights conducted during March 1979 as a part of the Canada SURSAT program, and the other data obtained during March 1977 as a part of the Canadian SAR-77 program conducted in Labrador, Newfoundland. Ground truth information was provided by consultants from INTERA, Ottawa, Ontario, Canada, for the Beaufort Sea sites and from REMOTEC, St. John's, Newfoundland, Canada, for the Labrador sites. The SAR data were converted into digital image format and four basic measurements made on the data from each test site: (1) mean value, (2) standard deviation, (3) histogram, and (4) relative power scans at constant range lines. The results are presented in several formats: (1) cluster plots, (2) variance versus ice type, (3) coefficient of variation, and (4) two measures of the polarization ratio. Relative values of backscatter coefficients for several ice types are compared, but absolute values cannot be obtained. (Author).

Download or read book On the Estimation of Physical Roughness of Sea Ice in the Canadian Arctic Archipelago Using Synthetic Aperture Radar written by Silvie Cafarella and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Sea ice surface roughness is a geophysical property which can be defined and quantified on a variety scales, and consequently affects processes across various scales. The sea ice surface roughness influences various mass, gas, and energy fluxes across the ocean-sea ice-atmosphere interface. Utilizing synthetic aperture radar (SAR) data to understand and map sea ice roughness is an active area of research. This thesis provides new techniques for the estimation of sea ice surface roughness in the Canadian Arctic Archipelago using synthetic aperture radar (SAR). Estimating and isolating sea ice surface properties from SAR imagery is complicated as there are a number of sea ice and sensor properties that influence the backscattered energy. There is increased difficulty in the melting season due to the presence of melt ponds on the surface, which can often inhibit interactions from the sensor to the sea ice surface as shorter microwaves cannot penetrate through the melt water. An object-based image analysis is here used to quantitatively link the winter first-year sea ice surface roughness to C-band RADARSAT-2 and L-band ALOS-2 PALSAR-2 SAR backscatter measured at two periods: winter (pre-melt) and advanced melt. Since the sea ice in our study area, the Canadian Arctic Archipelago, is landfast, the same ice can be imaged using SAR after the surface roughness measurements are established. Strong correlations between winter measured surface roughness, and C- and L-band SAR backscatter acquired during both the winter and advanced melt periods are observed. Results for winter indicate: (1) C-band HH-polarization backscatter is correlated with roughness (r=0.86) at a shallow incidence angle; and (2) L-band HH- and VV-polarization backscatter is correlated with roughness (r=0.82) at a moderate incidence angle. Results for advanced melt indicate: (1) C-band HV/HH polarization ratio is correlated with roughness (r=-0.83) at shallow incidence angle; (2) C-band HH-polarization backscatter is correlated with roughness (r=0.84) at shallow incidence angle for deformed first-year ice only; and (3) L-band HH-polarization backscatter is correlated with roughness (r=0.79) at moderate incidence angle. Retrieval models for surface roughness are developed and applied to the imagery to demonstrate the utility of SAR for mapping roughness, also as a proxy for deformation state, with a best case RMSE of 5 mm in the winter, and 8 mm during the advanced melt.

Download or read book Sea Ice Classification Using Synthetic Aperture Radar written by and published by . This book was released on 1990 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study employs Synthetic Aperture Radar (SAR) imagery from the Marginal Ice Zone Experiment (MIZEX) 1987 to identify an optimal set of statistical descriptors that accurately classify three types of ice (first-year, multiyear, odden) and open water. Two groups of statistics, univariate and texture, are compared and contrasted with respect to their skill in classifying the ice types and open water. Individual statistical descriptors are subjected to principal component analysis and discriminant analysis. Principal component analysis was of little use in understanding features of each ice and open water group. Discriminant analysis was valuable in identifying which statistics held the most power. When combined, univariate and texture statistics classified the groups with 89.5% accuracy, univariate alone with 86.8% accuracy and texture alone with 75.4% accuracy. Range and inertia were the strongest univariate and texture discriminators with 74.6% and 50.8% accuracy, respectively. Despite the use of a non-calibrated SAR, univariate statistics were able to classify the images with greater accuracy than texture statistics.

Download or read book Towards Automated Lake Ice Classification Using Dual Polarization RADARSAT SAR Imagery written by Junqian Wang and published by . This book was released on 2018 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lake ice, as one of the most important component of the cryosphere, is a valuable indicator of climate change and variability. The Laurentian Great Lakes are the world's largest supply of freshwater and their ice cover has a major impact on regional weather and climate, ship navigation, and public safety. Monitoring detailed ice conditions on large lakes requires the use of satellite-borne synthetic aperture radar (SAR) data that provide all-weather sensing capabilities, high resolution, and large spatial coverage. Ice experts at the Canadian Ice Service (CIS) have been manually producing operational Great Lakes image analysis charts based on visual interpretation of the SAR images. Ice services such as the CIS would greatly benefit from the availability of an automated or semi-automated SAR ice classification algorithm. We investigated the performance of the unsupervised segmentation algorithm “glocal” iterative region growing with semantics (IRGS) for lake ice classification using dual polarized RADARSAT-2 imagery. Here, the segmented classes with arbitrary labels are manually labelled based on visual interpretation. IRGS was tested on 26 RADARSAT-2 scenes acquired over Lake Erie during winter 2014, and the results were validated against the manually produced CIS image analysis charts. Analysis of various case studies indicated that the “glocal” IRGS algorithm can provide a reliable ice-water classification using dual polarized images with a high overall accuracy of 90.2%. The improvement of using dual-pol as opposed to single-pol images for ice-water discrimination was also demonstrated. For lake ice type classification, most thin ice types were effectively identified but thick and very thick lake ice were often confused due to the ambiguous relation between backscatter and ice types. Texture features could be included for further improvement. Overall, our “glocal” IRGS classification results are close to visual interpretation by ice analysts and would have expected to be closer if they could draw ice charts at a more detailed level.

Download or read book The Analysis of Sea Ice Cover with the Use of Synthetic Aperture Radar SAR Imagery written by Martin Ouellet and published by . This book was released on 1996 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Identification of sea ice types in spaceborne synthetic aperture radar data written by R. KWOK and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dual polarization HH HV RADARSAT 2 ScanSAR Observations of New Young and First year Sea Ice written by John Alexander Casey and published by . This book was released on 2010 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: Observations of sea ice from space are routinely used to monitor sea ice extent, concentration and type to support human marine activity and climate change studies. In this study, eight dual-polarization (dual-pol) (HH/HV) RADARSAT-2 ScanSAR images acquired over the Gulf of St. Lawrence during the winter of 2009 are analysed to determine what new or improved sea ice information is provided by dual-pol C-band synthetic aperture radar (SAR) data at wide swath widths, relative to single co-pol data. The objective of this study is to assess how dual-pol RADARSAT-2 ScanSAR data might improve operational ice charts and derived sea ice climate data records. In order to evaluate the dual-pol data, ice thickness and surface roughness measurements and optical remote sensing data were compared to backscatter signatures observed in the SAR data. The study found that: i) dual-pol data provide improved separation of ice and open water, particularly at steep incidence angles and high wind speeds; ii) the contrast between new, young and first-year (FY) ice types is reduced in the cross-pol channel; and iii) large areas of heavily deformed ice can reliably be separated from level ice in the dual-pol data, but areas of light and moderately ridged ice cannot be resolved and the thickness of heavily deformed ice cannot be determined. These results are limited to observations of new, young and FY ice types in winter conditions. From an operational perspective, the improved separation of ice and open water will increase the accuracy of ice edge and total ice concentration estimates while reducing the time required to produce image analysis charts. Further work is needed to determine if areas of heavily ridged ice can be separated from areas of heavily rafted ice based on knowledge of ice conditions in the days preceding the formation of high backscatter deformed ice. If rafted and ridged ice can be separated, tactical ridged ice information should be included on image analysis charts. The dual-pol data can also provide small improvements to ice extent and concentration data in derived climate data records. Further analysis of dual-pol RADARSAT-2 ScanSAR data over additional ice regimes and seasons is required.

Download or read book The Ice Environment of Eastern Lancaster Sound and Northern Baffin Bay written by J. R. Marko and published by Indian and Northern Affairs Canada. This book was released on 1982 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report integrates recent data on sea ice and icebergs in Lancaster Sound and western Baffin Bay, with data collected in the 1978-1979 Petro-Canada-EAMES studies (Eastern Arctic Marine Environmental Studies), as a basis for assessing sea ice, icebergs and ice cover in relation to offshore drilling activities and possible oil spills.

Download or read book A Correlation based Approach to Modeling Interferometric Radar Observations of the Greenland Ice Sheet written by E. Weber Hoen and published by . This book was released on 2001 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Interferometric synthetic aperture radar (InSAR) phase observations have greatly increased our understanding of the topography and motion of ice sheets, but yield little information on the sub-surface structure, a needed description for mass-balance estimates. Inversion of a diffuse volume scatter model shows that InSAR correlation values, p, can be related to radiowave penetration depths, d, which depend on characteristics of the snow/ice volume. Application to European Research Satellite (ERS) images (VV, 5.6 cm, 23 ̊incidence angle) of the Greenland ice sheet imply C-band d of 0 m along the rocky coast, 10-20 m in the bare ice zone, and 20-35 m in the percolation zone and dry snow zone, consistent with in situ results. Moreover, volume scattering reduces the ERS critical baseline from about 1100 m to 300 m. Correlation and backscatter power (ơ0) observations can be combined for further understanding of the snow/ice volume. In particular, p and ơ0 data of 15 km-long, 50 m-high topographic undulations in the dry snow zone arc minimum on the windward side and maximum on the lee side, with 1 to 3 dB variation typical. These spatial variations in the scattering medium appear to follow from differences in snow accumulation due to prevailing winds. Assuming that snow-grains are the dominant source of backscatter, the classical independent-scatterer model is physically implausible at firn densities; a second-order dense-medium radiative transfer model also is unable to explain both the observed d and ơ0. A modified Born approach provides a better match to ơ0 and p separately, but leads to different grain size solutions for each measurement type. A buried layer model based on the incoherent addition of echoes from hoar layer interfaces, in which scattering from a single layer is derived from small-perturbation methods, reconciles the ERS ơ0 and p data, with variations in hoar layer spacing of 12-17 cm providing the needed structural fluctuations for the observed range of ơ0 and p. Translation of layer spacing into accumulation rates predicts a 40% variability in accumulation rate from the windward to lee side and, more importantly, addresses high-resolution mapping of continental accumulation rates"--Leaves iv-v.

Download or read book Eastern Arctic SURSAT SAR Ice Experiment Radar Signatures of Sea Ice Features written by R. D Ketchum (Jr) and published by . This book was released on 1980 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: Evaluation of X- and L-band steep angle synthetic aperture radar (SAR) sea ice imagery taken in Baffin Bay and Davis Strait in April 1979 has shown that description and discrimination of first-season ice types can be difficult because of ambiguous radar returns. Ambiguous returns seen on X-band radar imagery are attributed to snow cover. The data have indicated that changes in snow properties due to melting and refreezing cause development of a highly reflective medium to the 3 cm X-band radar. The 25 cm L-band radar is not noticeably affected by the observed phenomena, thus correlation of coincident X- and L-band imagery often resolves interpretation ambiguities on the X-band imagery caused by the snow effects. The data suggest that L-band radar energy often penetrates the ice and that subsurface returns are received. These returns also produce ambiguities in interpretation. Apparent smooth surfaces do not show this effect, but rough surfaces which have widely different roughness densities may produce apparently equal backscatter of L-band radar. Ice ridge identification and discrimination was often poor due to the obscuring effects of background clutter associated with the above-suggested backscattering phenomena. Small ridge sizes versus system resolution and steep angles of incidence also reduce ridge identification capabilities. Some icebergs produced time-delayed L-band signals, indicating internal reflections within the iceberg. Iceberg/water interface reflections rather than volume scattering are indicated. L-band radar cannot be depended upon for iceberg identification, since icebergs may be only partially imaged or not imaged at all by this frequency.

Download or read book Ice Conditions Off the North Coast of Ellesmere Island written by G. Hattersley-Smith and published by . This book was released on 1962 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthetic Aperture Radar SAR Study of Beaufort and Chukchi Sea Ice 1981 written by Intera Environmental Consultants and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Toward Automated Ice water Classification on Large Northern Lakes Using RADARSAT 2 Synthetic Aperture Radar Imagery written by Marie Hoekstra and published by . This book was released on 2018 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: Changes to ice cover on lakes throughout the northern landscape has been established as an indicator of climate change and variability. These changes are expected to have implications for both human and environmental systems. Additionally, monitoring lake ice cover is required to enable more reliable weather forecasting across lake-rich northern latitudes. Currently the Canadian Ice Service (CIS) monitors lakes using RADARSAT-2 SAR (synthetic aperture radar) and optical imagery through visual interpretation, with total lake ice cover reported weekly as a fraction out of ten. An automated method of classification would allow for more detailed records to be delivered operationally. In this research, the Iterative Region Growing using Semantics (IRGS) approach has been employed to perform ice-water classification on 61 RADARSAT-2 scenes of Great Bear Lake and Great Slave Lake over a three year period. This approach first locally segments homogeneous regions in an image, then merges similar regions into classes across the entire scene. These classes are manually labelled by the user, however automated labelling capability is currently in development. An accuracy assessment has been performed on the classification results, comparing outcomes with user-generated reference data as well as the CIS fraction reported at the time of image acquisition. The overall average accuracy of the IRGS method for this dataset is 92%, demonstrating the potential of this semi-automated method to provide detailed and reliable lake ice cover information.

Download or read book Arctic Ice Shelves and Ice Islands written by Luke Copland and published by Springer. This book was released on 2017-05-30 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an overview of the current state of knowledge of Arctic ice shelves, ice islands and related features. Ice shelves are permanent areas of ice which float on the ocean surface while attached to the coast, and typically occur in very cold environments where perennial sea ice builds up to great thickness, and/or where glaciers flow off the land and are preserved on the ocean surface. These landscape features are relatively poorly studied in the Arctic, yet they are potentially highly sensitive indicators of climate change because they respond to changes in atmospheric, oceanic and glaciological conditions. Recent fracturing and breakup events of ice shelves in the Canadian High Arctic have attracted significant scientific and public attention, and produced large ice islands which may pose a risk to Arctic shipping and offshore infrastructure. Much has been published about Antarctic ice shelves, but to date there has not been a dedicated book about Arctic ice shelves or ice islands. This book fills that gap.

Download or read book Four Channel Synthetic Aperture Radar Imagery Results of Freshwater Ice and Sea Ice in Lake Melville written by Memorial University of Newfoundland. Centre for Cold Ocean Resources Engineering and published by St. John's : Centre for Cold Ocean Resources Engineering, Memorial University of Newfoundland. This book was released on 1978 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: Four Channel Synthetic Radar (SAR) imagery of sea ice and lake ice along a traverse from the western end of Lake Melville, Labrador, to a point approximately 8 km off the coast, giving a variety of returns with reversal in tonal contrast between X- and L- band imagery for some features.

Download or read book Spaceborne Monitoring of Arctic Lake Ice in a Changing Climate written by Cristina M. Surdu and published by . This book was released on 2015 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lake ice phenology (timing of ice-on and ice-off) and thickness are changing in response to generally warmer climate conditions at high northern latitudes observed during recent decades. Monitoring changes in the lake ice cover provides valuable evidence in assessing climate variability in the Arctic. To enhance our understanding of the role of lake ice in the Arctic cryosphere and to evaluate the extent to which Arctic lakes have been impacted by the contemporary changing climate, development of a lake ice monitoring system at pan-Arctic scale is needed. While large lakes across the Arctic are currently being monitored through satellite observations, there are extremely sparse and mostly non-existent records tracking the changes in small high-latitude lakes. Employing a combination of spaceborne observations from synthetic aperture radar (SAR) and optical sensors, and simulations from the Canadian Lake Ice Model (CLIMo), this researched aimed to investigate changes in winter ice growth and ice phenology of lakes across the Arctic, focus being given to smaller lakes on the North Slope of Alaska (NSA) and lakes of various sizes in the Canadian Arctic Archipelago (CAA). To determine the changes in the fraction of lakes that freeze to bed (grounded ice) in late winter on the NSA from 1991 to 2011, a time series of ERS-1/2 was analysed. Results show a trend toward increasing floating ice fractions from 1991 to 2011, with the greatest change occurring in April, when the grounded ice fraction declined by 22% ([alpha] = 0.01). This finding is in good agreement with the decrease in ice thickness simulated with CLIMo, a lower fraction of lakes frozen to the bed corresponding to a thinner ice cover. Model simulations over the same period as SAR acquisitions (1991-2011) indicate a trend toward thinner ice covers by 18-22 cm (no-snow and 53% snow depth scenarios, [alpha] = 0.01). The results emphasize the regime shifts that these lakes are currently undergoing, including shorter ice seasons. The longer-term trends (1950-2011) derived from model simulations show a decrease in the ice cover duration by ~ 24 days consequent to later freeze-up dates by 5.9 days ([alpha] = 0.1) and earlier break-up dates by 17.7-18.6 days ([alpha] = 0.001). The temporal evolution of backscatter ([sigma]0) from two C-band SAR sensors - Advanced Synthetic Aperture Radar (ASAR) Wide Swath and RADARSAT-2 ScanSAR Wide Swath - was then used to investigate the potential of high temporal-frequency SAR for determining lake ice phenological events (e.g. freeze onset, melt onset and water-clear-of-ice). Results show that combined SAR observations are generally suitable for detection of important lake ice events timing. However, the wide range of incidence angles and to a certain extent the orbit differences between the observations, the wind effect, particularly during fall freeze-up, the low differences in [sigma]0 during transition from a grounded-ice cover to melt onset of ice in early spring, complicate the detection of lake ice phenological events. In order to order to document the response of ice cover of lakes in the Canadian High Arctic to climate conditions during recent years, a 15-year time series (1997-2011) of RADARSAT-1/2 ScanSAR Wide Swath, ASAR Wide Swath and Landsat acquisitions were analyzed. Results show that earlier melt onset occurred earlier for all 11 polar-desert and polar-oasis lakes that were investigated. With the exception of Lower Murray Lake, all lakes experienced earlier ice-minimum and water-clear-of-ice dates, with greater changes being observed for polar-oasis lakes (9-23.6 days earlier water-clear-of-ice for lakes located in polar oases and 1.6-20 days earlier water-clear-of-ice for polar-desert lakes). Additionally, results suggest that some lakes may be transitioning from a perennial to a seasonal ice regime, with only a few lakes maintaining a perennial ice cover on occasional years. Aside Lake Hazen and Murray Lakes that preserved their ice cover during the summer of 2009, no residual ice was observed on any of the other lakes from 2007 to 2011. This research provides the foundation of a lake-ice monitoring network that can be built on with the newly launched and future SAR and multispectral missions. Additionally, this study shows that in response to warmer climate conditions, Arctic lakes are experiencing regime shifts with overall shorter ice seasons, thinner ice covers, fewer lakes that freeze to the bottom and more lakes that lose the perennial ice cover and experience a seasonal ice regime.