Spatial aspects of pressure ridge statistics

Mock, S. J.; Hartwell, Allan D.; Hibler, W. D.

doi:10.1029/jc077i030p05945

Cited by 60 publications

(32 citation statements)

References 5 publications

(2 reference statements)

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“…In the measurement of ridge height (or depth), there is usually some uncertainty in the initial height; that is, there may be some consistent error in the ridge height or depth in the form of an additive constant. This hypothesis is tested in detail by Mock et al [1972] with reasonable agreement, To test the Potsson distribution, data from and so we do not feel it is necessary to carry laser profiles and photographs were used. use errors of 0.5 to 1.0 meter in the true water level are small compared to the mean ridge depth.…”

Section: Samples Passes the X • Test At The 5% Levelmentioning

confidence: 98%

Statistical aspects of sea-ice ridge distributions

Hibler¹,

Weeks²,

Mock³

1972

J. Geophys. Res.

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A theoretical distribution function for pressure‐ridge, sail heights and keel depths is derived from fundamental assumptions about the randomness of the ridges. It is shown that the distribution function for ridge spacings (distance between ridges) can also be predicted from the assumption of spatially random occurrence. The suggested distribution functions are, in form, negative exponentials of the ridge height (or depth) squared and the ridge spacing, respectively. Extremely good fits were achieved to extensive data collected from sonar profiles of the lower surface of the pack ice and to laser profiles, as well as visual roughness data from the upper ice surface. Using these models, it is possible to completely characterize the ridging, in a one‐dimensional sense, by two parameters: 〈N〉, the mean number of ridges per unit length, and 〈h〉, the mean ridge height (or depth). In addition, there is a linear correlation between 〈N〉 and 〈h〉. This suggests that maps showing the distribution of 〈N〉 or 〈h〉 over an ocean covered with pack ice can be used to statistically characterize both the spacing and the height distribution of the ridges.

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Section: Samples Passes the X • Test At The 5% Levelmentioning

confidence: 98%

Statistical aspects of sea-ice ridge distributions

Hibler¹,

Weeks²,

Mock³

1972

J. Geophys. Res.

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“…Castellani et al, 2014) simply measure the spacing between unique surface features along the linear profile, assuming that the features are randomly orientated and sufficiently sampled for this assumption to be valid. Mock et al (1972) showed that for randomly oriented ridges, the average ridge frequency, µ, and the average ridge density (the ratio of the total length of ridges per unit area), R D , are related via µ = (2/π )R D . In contrast to linear profiling studies, R D can be calculated directly with these data as R D = i L i / A tot = L tot / A tot , where the sum is over all features within the total ice/swath area (given a fully concentrated ice pack).…”

Section: Feature Geometry and The Potential For Additional Feature Chmentioning

confidence: 99%

Characterizing Arctic sea ice topography using high-resolution IceBridge data

et al. 2016

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Abstract. We present an analysis of Arctic sea ice topography using high-resolution, three-dimensional surface elevation data from the Airborne Topographic Mapper, flown as part of NASA's Operation IceBridge mission. Surface features in the sea ice cover are detected using a newly developed surface feature picking algorithm. We derive information regarding the height, volume and geometry of surface features from 2009 to 2014 within the Beaufort/Chukchi and Central Arctic regions. The results are delineated by ice type to estimate the topographic variability across first-year and multi-year ice regimes.The results demonstrate that Arctic sea ice topography exhibits significant spatial variability, mainly driven by the increased surface feature height and volume (per unit area) of the multi-year ice that dominates the Central Arctic region. The multi-year ice topography exhibits greater interannual variability compared to the first-year ice regimes, which dominates the total ice topography variability across both regions. The ice topography also shows a clear coastal dependency, with the feature height and volume increasing as a function of proximity to the nearest coastline, especially north of Greenland and the Canadian Archipelago. A strong correlation between ice topography and ice thickness (from the IceBridge sea ice product) is found, using a square-root relationship. The results allude to the importance of ice deformation variability in the total sea ice mass balance, and provide crucial information regarding the tail of the ice thickness distribution across the western Arctic. Future research priorities associated with this new data set are presented and discussed, especially in relation to calculations of atmospheric form drag.

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“…Mock and others (1972) tested this relationship for surface ridges using aerial photographs, and found good agreement except for an excess of ridges at small spacings. On a purely random theory, however, we expect a deficit of ridges or keels at small spacings, on account of the so-called "ridge shadowing" effect (Wadhams,[CI980], in press) .…”

Section: Theory Of Spacingsmentioning

confidence: 99%

An Analysis Of Ice Profiles Obtained By Submarine Sonar In The Beaufort Sea

1980

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ABSTRACT. A profile of the ice cover in the southern Beaufort Sea was obtained by the submarine U.S.S. Gurnard in April 1976, using a narrow-beam upward-looking sonar. The I 400 km profile consisted of three legs, of which the long south-north and east-west legs intersected near the Caribou camp of the AIDJEX experiment. A statistical analysis was carried out over contiguous 50 km sections to yield probability-density functions of the drafts of ice and of level ice, the distributions of keel spacings and drafts, and the frequencies and widths of leads. Two distinct types of ice cover were found in the profile. The first, nearest the coast in the south and west of the experimental area, consisted of heavily ridged ice with mean drafts of up to 5. I m. The rest of the track (I 200 km) consisted of a homogeneous ice cover with a mean draft of 3.7 m. The percentage of thin ice varied greatly from section to section, with a range of 0.4 to 12.3% for ice of 0-1 m draft. Level ice, defined as ice with a local gradient of less than I in 40, made up 56% of the homogeneous cover, with a preferred draft of2.7 to 2.9 m. Keel spacings obeyed a negative exponential distribution, with a deficit at small spacings due to a keel shadowing effect and a surfeit at very large spacings due to the contribution of polynyas. The draft distribution of keels was a negative exponential of form P (h) dh = B exp ( -bh) dh, with Band b as parameters. This differs from the distribution of Hibler and others (1972), probably because the narrow beam records a complex structure for every keel. The homogeneous cover had a lower keel frequency and mean draft than the ice nearest the coast. Maximum keel draft was 31.12 m. The average separation of leads was 2 12 m, with almost all leads being less than 50 m in width. REsuME. AnalYse de projils de glace obtenus par sonar sous-marin dans la mer de Beaufort. Un profil de la couverture de glace du sud de la mer de Beaufort a ete obtenu par le sous-marin U.S.S. Gurnard en avril 1976 en utilisant un sonar dirige vers le haut a faisceau etroit. Les I 400 km de profil se composent de trois branches dont les longues branches sud-nord et est-ouest se coupent pres du camp Caribou de I'experience AIDJEX. On a pratique une analyse statistique sur des sections contigues de 50 km pour obtenir les fonctions de densite de probabilite des tirants d'eau de glace et des glaces a fond plat, les distributions des espacements entre cretes de pression sous-glace et des tirants d'eau, et les frequences et la largeur des chenaux. On a trouve deux types distincts de couverture de glace dans le profil. La premiere, la plus proche de la cote dans le sud et dans I'est de la zone exploree consistait en une glace fortement plissee avec des tirants moyens d'eau de plus de 5,1 m. Le reste de I'itineraire (I 200 km ), consistait en une couverture de glace homogene avec des tirants moyens de 3,7 m d'epaisseur. Le pourcentage de glace mince variait beaucoup d'une section a I'autre avec une proportion allant de 0,4 a 12,3 % pour la glace...

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Spatial aspects of pressure ridge statistics

Cited by 60 publications

References 5 publications

Statistical aspects of sea-ice ridge distributions

Statistical aspects of sea-ice ridge distributions

Characterizing Arctic sea ice topography using high-resolution IceBridge data

An Analysis Of Ice Profiles Obtained By Submarine Sonar In The Beaufort Sea

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