Shipborne sea-ice field mapping using a LiDAR

AbstractTo observe the distribution of pack ice off the coast of the Okhotsk Sea coast of Hokkaido, a radar network consisting of three radar stations was constructed during 1967-69. It covers an area about 70 km wide and 250 km long. The stations are remote-controlled by radio from the Sea Ice Research Laboratory and the information obtained is transmitted back to the laboratory and observed there. Radar has the great advantage of being able to make continuous observations of ice. Usually several special features can be seen on the radar screen, and they are used as markers for the observation of movement. It is ascertained that the average pattern of drift in this area is from north to south-east along the coast line and the ice field undergoes internal deformation during its drift. To get some information on the surface topography of ice from A-scope radar, the intensity of echo signals is classified into 16 steps by computer. To obtain the movement of an ice field from the numerical radar information, a modified two-dimensional cross-correlation method was tested.

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An Antarctic field study of the rheology and movement of a sea-ice floe aggregate

Annals of Glaciology ◽

10.3189/1991aog15-1-261-264 ◽

1991 ◽

Vol 15 ◽

pp. 261-264

Author(s):

T.H. Jacka ◽

R. Thwaites ◽

J.C Wilson

Keyword(s):

Wind Speed ◽

Sea Ice ◽

Drift Rate ◽

Small Strain ◽

Local Conditions ◽

Scientific Investigations ◽

Ice Drift ◽

Sea Ice Drift ◽

Ice Field ◽

Meteorological Observations

M.V. Nella Dan was beset in ice near 66°S, 51°Ε from 27 October to 15 December 1985. The scientific investigations planned for the voyage into the sea-ice zone included ice thickness, concentration and extent measurements, aerial photography of the ice, a core drilling project and meteorological observations. Once beset, the programme was expanded to include repeat measurements of a small strain grid and measurements of the sea-ice drift rate. Strongly convergent local conditions had led to the initial besetment of the ship. Analysis of measurements of the strain grid area over an 11 d period shows that, although there is some indication that the ice field may have been divergent, opening by approximately 3.4% over this period, there are large errors in the measurements and some doubt must be placed on the reliability of this estimate. The drift speed and direction were found to be highly dependent on wind speed and direction, the drift rate being approximately 2.7% of the wind speed at an angle of about 29° to the left of the wind direction.

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Sea-ice motion in the Weddell Sea from drifting-buoy and AVHRR data

Journal of Glaciology ◽

10.3189/s002214300000410x ◽

1996 ◽

Vol 42 (141) ◽

pp. 249-254 ◽

Cited By ~ 1

Author(s):

David Crane ◽

Peter Wadhams

Keyword(s):

Sea Ice ◽

Time Lag ◽

Ice Cover ◽

Weddell Sea ◽

Coherent Motion ◽

Meteorological Forcing ◽

Differential Motion ◽

Ice Field ◽

High Concentrations ◽

Ice Floes

AbstractA study of sea ice in the northern Weddell Sea was done, relating the ice motion, determined using an array of satellite-tracked drifters, deployed into ice floes, to parameters describing the nature of the ice cover, obtained from an analysis of Advanced Very High Resolution Radiometer (AVHRR) imagery. It was found that the ice motion was predominantly wind-driven, responding to the passage of low-pressure systems across the area. The correlation length of the strain field over the entire measurement period was around 200 km. At high concentrations the ice responded as a rigid body with coherent motion, but below a concentration of around 93%, differential motion occurred. The nature of the ice motion was found to depend upon the lead parameters, with low values of pure convergence and divergence and larger values of vorticity and deformation of the ice field. The vorticity was found to be well correlated with the atmospheric pressure, with a time lag of less than 3 h, implying an almost instantaneous response of the ice cover to meteorological forcing.

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Salinity profiles of Antarctic sea ice: Field data and model results

Journal of Geophysical Research Atmospheres ◽

10.1029/92jc01588 ◽

1992 ◽

Vol 97 (C10) ◽

pp. 15545 ◽

Cited By ~ 103

Author(s):

Hajo Eicken

Keyword(s):

Sea Ice ◽

Field Data ◽

Antarctic Sea Ice ◽

Ice Field

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An Antarctic field study of the rheology and movement of a sea-ice floe aggregate

Annals of Glaciology ◽

10.1017/s0260305500009836 ◽

1991 ◽

Vol 15 ◽

pp. 261-264

Author(s):

T.H. Jacka ◽

R. Thwaites ◽

J.C Wilson

Keyword(s):

Wind Speed ◽

Sea Ice ◽

Drift Rate ◽

Small Strain ◽

Local Conditions ◽

Scientific Investigations ◽

Ice Drift ◽

Sea Ice Drift ◽

Ice Field ◽

Meteorological Observations

M.V.Nella Danwas beset in ice near 66°S, 51°Ε from 27 October to 15 December 1985. The scientific investigations planned for the voyage into the sea-ice zone included ice thickness, concentration and extent measurements, aerial photography of the ice, a core drilling project and meteorological observations. Once beset, the programme was expanded to include repeat measurements of a small strain grid and measurements of the sea-ice drift rate. Strongly convergent local conditions had led to the initial besetment of the ship. Analysis of measurements of the strain grid area over an 11 d period shows that, although there is some indication that the ice field may have been divergent, opening by approximately 3.4% over this period, there are large errors in the measurements and some doubt must be placed on the reliability of this estimate. The drift speed and direction were found to be highly dependent on wind speed and direction, the drift rate being approximately 2.7% of the wind speed at an angle of about 29° to the left of the wind direction.

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Different Ways of Modeling Ice Drift Scenarios in Basin Tests

Volume 6: Polar and Arctic Sciences and Technology; Offshore Geotechnics; Petroleum Technology Symposium ◽

10.1115/omae2013-10793 ◽

2013 ◽

Cited By ~ 2

Author(s):

Andrea Haase ◽

Peter Jochmann

Keyword(s):

Sea Ice ◽

Relative Motion ◽

Development Project ◽

Model Tests ◽

Contact Forces ◽

Second Phase ◽

Offshore Structure ◽

Ice Drift ◽

Ice Field ◽

Ice Model

One known scenario from full scale sea ice investigations is a drifting managed ice field. This ice field may be driven by winds or currents or both and may eventually hit a vessel or an offshore structure. In case of a moving vessel the relative motion between vessel and ice may be determined by the vessels direction of motion or even its ambition to hold position against the drifting ice. All the above described scenarios deal with relative motions between several bodies. Along with the relative motion come the contact forces between the interacting bodies and last but not least the question of the failure of either of the bodies. As ice model tests are in general state of the art procedures to investigate the behavior of a vessel and the related loads in sea ice the question of how to model drift scenarios is of relevance here. Typically in ice model tests a drifting managed ice field is simulated by moving a model ship through a resting ice field. This paper addresses the differences in modeling the ice drift as described above and when moving the floes against a stationary vessel. For this purpose ice model tests of each kind are investigated and theoretical efforts are made to enlighten the topic. Also it is distinguished between the vessel being driven by its own propulsion system or by an external force. In summer 2011 and 2012 a comprehensive set of ice model tests was performed in the large ice tank of the Hamburg Ship Model Basin (HSVA). The tests are related to the research and development project DYPIC — Dynamic Positioning in Ice. Within the project two phases of model tests have been performed. The first phase has been documented and presented in [1] while the second phase is presented in [2]. The model setups described and analyzed in this paper all relate to tests performed within the scope of DYPIC.

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