On the size distribution of Antarctic icebergs

Neshyba, Steve

doi:10.1016/0165-232x(80)90052-x

Cited by 19 publications

(21 citation statements)

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“…We note also that the data discussed by Neshyba [1980] include observations made close to the Antarctic continent where the icebergs are young and wave-induced fracture has had little opportunity to occur; this may explain the difference between his distribution and our own. The sparseness of the data set and the fact that these are apparent (radar) diameters rather than real maximum diameters imply that the application of the lognormal distribution should be treated with caution.…”

Section: F(x) = Xa(2roa/• Exp [--(In X --/1)2/2•7 2]mentioning

confidence: 67%

“…It can be seen that the modal diameter lies in the range 400-500 m; the mean diameter is 459 m and the median diameter 418 m. Neshyba [1980] suggested that the distribution of iceberg diameters in a given region can be fitted by a Rayleigh distribution. It can be seen that the modal diameter lies in the range 400-500 m; the mean diameter is 459 m and the median diameter 418 m. Neshyba [1980] suggested that the distribution of iceberg diameters in a given region can be fitted by a Rayleigh distribution.…”

Section: Iceberg Sizesmentioning

confidence: 99%

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Winter observations of iceberg frequencies and sizes in the south Atlantic Ocean

Wadhams¹

1988

J. Geophys. Res.

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The numbers and apparent sizes of icebergs in the South Atlantic Ocean in midwinter were measured by radar and visually from F. S. Polarstern during the 1986 Winter Weddell Sea Project cruise. Results show that in a heavy sea (sea state 7–8), icebergs have to be at least 115 m in diameter to be detected at all and that detectability falls off severely for all bergs at ranges exceeding 8 n. mi. (15 km); that most bergs had diameters of less than 1 km with a preferred size of 400–500 m; and that a high density of icebergs in the latitude band 53°–56°S at longitude 19°–30°W contrasted with a virtual absence of bergs in the same latitude band at longitude 1°–9°E. The latter effect is ascribed to melt and wave–induced deterioration causing the disappearance of this iceberg population between the two sets of longitudes.

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Section: F(x) = Xa(2roa/• Exp [--(In X --/1)2/2•7 2]mentioning

confidence: 67%

Section: Iceberg Sizesmentioning

confidence: 99%

Winter observations of iceberg frequencies and sizes in the south Atlantic Ocean

Wadhams¹

1988

J. Geophys. Res.

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“…However, fragmentation at the time of calving probably has a role in producing the relatively large numbers of small icebergs at the stations closest to Daugaard-Jensen Gletscher (Figure 8). Finally, we can compare the overall size-frequency distribution of the 1440 independent iceberg observations in East Greenland (Figure 7) with observations from Antarctic waters [e.g., Neshyba, 1980;Wadhams, 1988]. Neshyba, summarizing evidence for almost 2000 icebergs from several sources, notes a modal size of 200-600 m for Antarctic iceberg width.…”

Section: Discussionmentioning

confidence: 97%

“…A relatively large data set of reports on iceberg sizes and frequencies has been obtained from Antarctic waters during both summer and, more recently, winter voyages [e.g., Orheirn, 1985; Wadhams, 1988]. Functional forms have also been derived for iceberg size distributions aro •und Antarctica [Neshyba, 1980;Wadhams, 1988].…”

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confidence: 99%

The sizes, frequencies, and freeboards of East Greenland icebergs observed using ship radar and sextant

Dowdeswell¹,

Whittington²,

Hodgkins³

1992

J. Geophys. Res.

103

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The Scoresby Sund fjord system, East Greenland, contains the most productive fast‐flowing outlet glaciers draining east from the Greenland Ice Sheet, calving 18 km3 a−1 of icebergs. The sizes, frequencies, and freeboards of 1900 icebergs were measured from F.S. Polarstern, using ship X‐band radar and sextant. Radar beam spreading exaggerates iceberg width by 60 m per nautical mile of range beyond the first mile. Data sets on iceberg size (e.g., that collated for Antarctic icebergs) collected using ship radars which do not take this effect into account will overestimate iceberg dimensions significantly. The location and concentration of icebergs within the fjord complex can be explained by (1) the locations of the principal source glaciers and (2) fjord topography and bathymetry. Iceberg concentration (maximum 0.6 icebergs km−2) declines with distance from the major iceberg sources. We found that 69% of icebergs within the fjord system are <200 m in width. Only five are >1 km in length. The largest is 2.7 km long. Icebergs become spread more evenly over the range of size classes in the outer fjord and shelf. Modal iceberg keel depth, calculated from freeboard measurements, is 4–500 m in the inner fjords, shifting to lower values in the outer fjords, reflecting shallower bathymetry. Radar measurements of iceberg width cannot be used to infer keel depths accurately, because width and keel depth are only weakly correlated. Comparison between freeboards and keel depths for icebergs from East Greenland and the Barents Sea indicates that the iceberg source (i.e., floating or grounded) exerts a fundamental control on iceberg dimensions. The drift pattern of icebergs is from the head to the mouth of the fjord system, although fjord bifurcations, bathymetry, and currents provide additional complications. The trends in observed iceberg size and frequency, and in inferred keel depth, in the Scoresby Sund region are likely to be applicable to other fjords and shelves around Greenland.

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“…Icebergs present an important element of the Earth's cryosphere and an intrinsic part of Antarctic waters. Considerable efforts have been applied to monitor icebergs in the Southern Polar waters to establish their occurrence, distribution, morphometric characteristics, and drift patterns [ Jacka and Giles , ; Neshyba , ; Orheim , ; Romanov et al ., ; Schodlok et al ., ; Stuart and Long , ; Tournadre et al ., ]. These efforts were stimulated by practical and research needs that include improvement of navigational safety, estimating a potential iceberg impact on offshore drilling platforms, calculating the freshwater balance in polar regions, development of iceberg drift and deterioration models, and estimating the iceberg impact on the ecosystem of Southern Ocean [ Bigg et al ., ; Jacobs et al ., ; Lichey and Hellmer , ; Romanov , ; Smith et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Changing effect of El Niño on Antarctic iceberg distribution: From canonical El Niño to El Niño Modoki

2014

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Earlier studies indicate that during El Niño events the iceberg concentration increases in the east of the Pacific sector and in the west of the Atlantic sector of Southern Ocean, but decreases in the center of the Pacific sector. During La Niña the pattern of the iceberg concentration anomalies in these regions reverses. This iceberg redistribution is explained by anomalous winds and currents around an extensive positive atmospheric pressure anomaly that typically develops in the South-East Pacific during the warm El Niño-Southern Oscillation (ENSO) phase. In this study, the results of iceberg observations during two cruises of the r/v ''Akademik Fedorov'' in Antarctica in January-February 2008 (La Niña) and 2010 (El Niño) have been used to examine the consistency of changes in the iceberg distribution in the Southern Ocean related to El Niño events. The analysis of these observations has shown that in the Pacific Sector of Antarctica changes in the iceberg distribution between 2008 and 2010 followed the scenario outlined above and thus could be associated with the ENSO phase change. Contrary to earlier observations, the iceberg concentration in the Atlantic sector of Antarctica did not increase during 2010 El Niño. The latter is explained by a noncanonical type of 2010 El Niño, El Niño Modoki, and associated atmospheric circulation pattern different from the canonical El Niño. Further analysis has shown that a more frequent occurrence of El Niño Modoki in recent years have resulted in weaker links between El Niño events and the Antarctic iceberg distribution.

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On the size distribution of Antarctic icebergs

Cited by 19 publications

References 1 publication

Winter observations of iceberg frequencies and sizes in the south Atlantic Ocean

Winter observations of iceberg frequencies and sizes in the south Atlantic Ocean

The sizes, frequencies, and freeboards of East Greenland icebergs observed using ship radar and sextant

Changing effect of El Niño on Antarctic iceberg distribution: From canonical El Niño to El Niño Modoki

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