Two-Dimensional Deformation Patterns in Sea Ice

Erlingsson, Björn

doi:10.1017/s0022143000007061

Cited by 69 publications

(70 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Overall, however, the distribution shows peaks around 10 and around 150 . Curiously, this separation of approximately 40 (between 10 and 150 ) is consistent with Erlingsson's [4] citations of observations of leads crossing at 30 10 in the Beaufort Sea, with the fracture-pattern angle attributed to the internal angle of friction and the principal direction of stress. This is surprising since the orientation statistics are for six months, rather than a single point in time.…”

Section: Resultssupporting

confidence: 84%

“…Furthermore, there should be an approximately 30 angle for intersections between leads. This angle is a result of an angle of internal friction for sea ice of about 15 [4]. Here we will describe a method for identifying leads in SAR imagery that is based on Banfield's method [1] and will test its utility for obtaining lead statistics automatically by seeing if the above statements about lead-population characteristics hold true for our sample of SAR images.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Analyzing lead information from SAR images

Dyne

Tsatsoulis

Fetterer

1998

IEEE Trans. Geosci. Remote Sensing

View full text Add to dashboard Cite

Abstract-Leads are relatively linear features in the sea ice cover, which are composed of open water or new, thin ice. Because of their composition, leads impact the ocean/air heat exchange. Automated analysis of leads from sea ice imagery may provide a means of gathering important information about the sea ice cover and its climatic influence. This paper describes: 1) a method for extracting and analyzing leads from ERS-1 synthetic aperture radar (SAR) images classified by ice type and 2) the results of using this method on images of the Beaufort Sea. The methodology consists of identifying potential lead features in the image and measuring their characteristics both before and after using a thinning or skeletonization technique on the features. The measurements obtained using this method include lead area, average width, number of leads in an area, amount of branching, and linearity of the lead. These measurements were analyzed with respect to the time of year and the latitude of the images. Results indicate that the measurements produced by the methodology are consistent with lead measurement distributions that others have found. The results of the study suggest that the methodology is appropriate to study lead characteristics on a large scale.

show abstract

Section: Resultssupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Analyzing lead information from SAR images

Dyne

Tsatsoulis

Fetterer

1998

IEEE Trans. Geosci. Remote Sensing

View full text Add to dashboard Cite

show abstract

“…[61] Satellite observations of sea ice reveal that diamondshaped floes are common [Marko and Thomson, 1977;Erlingsson, 1988]. Calculations using diamond-shaped floes (with smaller apex angle of 30 degrees and boundary lengths 1000 m) yielded results similar to those with square floes.…”

Section: Results For Diamond and Random Geometriesmentioning

confidence: 99%

Continuum sea ice rheology determined from subcontinuum mechanics

Taylor¹,

Feltham²,

Sammonds³

et al. 2006

J. Geophys. Res.

View full text Add to dashboard Cite

[1] A method is presented to calculate the continuum-scale sea ice stress as an imposed, continuum-scale strain-rate is varied. The continuum-scale stress is calculated as the areaaverage of the stresses within the floes and leads in a region (the continuum element). The continuum-scale stress depends upon: the imposed strain rate; the subcontinuum scale, material rheology of sea ice; the chosen configuration of sea ice floes and leads; and a prescribed rule for determining the motion of the floes in response to the continuum-scale strain-rate. We calculated plastic yield curves and flow rules associated with subcontinuum scale, material sea ice rheologies with elliptic, linear and modified Coulombic elliptic plastic yield curves, and with square, diamond and irregular, convex polygon-shaped floes. For the case of a tiling of square floes, only for particular orientations of the leads have the principal axes of strain rate and calculated continuum-scale sea ice stress aligned, and these have been investigated analytically. The ensemble average of calculated sea ice stress for square floes with uniform orientation with respect to the principal axes of strain rate yielded alignment of average stress and strain-rate principal axes and an isotropic, continuum-scale sea ice rheology. We present a lemon-shaped yield curve with normal flow rule, derived from ensemble averages of sea ice stress, suitable for direct inclusion into the current generation of sea ice models. This continuum-scale sea ice rheology directly relates the size (strength) of the continuum-scale yield curve to the material compressive strength.

show abstract

“…Thomson [1975, 1977] explained lead pattems as the result of intemal waves and stress fields, with a characteristic crossing angle of the order of 30 ø or slightly greater. Expanding on their work, lead field geometry has been modeled [Erlingsson, 1988[Erlingsson, , 1991 …”

Section: Lead Orientationmentioning

confidence: 99%

“…In the common and closing at others [Thorndike, 1986]. This factor appears to case of crossing (rectilinear) leads, Erlingsson [1988Erlingsson [ , 1991 NDJ j' lead density.' …”

Section: Ice Divergence and Lead Occurrencementioning

confidence: 99%