Ice floe collision under wave action in the marginal ice zone

Gao, Longjun (1991) Ice floe collision under wave action in the marginal ice zone. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (16MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

This thesis describes a research program to study ice floe collisions under wave action in the Marginal Ice Zone ( MIZ ). The primary objective of this program was to develop a new interpretation approach for the phenomenon of ice floe collisions in the MIZ and to obtain the floe collision frequency. -- The ice floe field was considered to be random while the floe motion was modelled as a stochastic process. A new concept of floe spacing distributions was developed in order to study collision behavior by probability theory. From the aerial photographs of the LIMEX'89 field experiments, and by using probability plot test, ice floe edge distance distributions and centre distance distributions were derived. Both were shown to display Lognormal Distributions. -- By analysing water particle displacements in a wave field, a floe collision criterion was obtained. With this criterion, floe collisions were related to floe centre distance, floe edge distance, wave amplitude, and wave period. The floe spacing distributions were introduced into this criterion and the collision probability for a floe during one wave cycle was obtained. Valuable results such as the frequency of collision events within an ice floe field and the number of collisions of one floe during a time period could be derived from this collision probability. -- The same procedures were repeated to obtain floe spacing distributions and collision probabilities in different horizontal directions. The results showed that in two different horizontal directions only small differences existed between the floe spacing distributions, and between the collision probabilities. Ice floe collisions, as well as wave scattering mechanism, made the ice floe field evenly distributed. Eccentric collisions made the collision events happened without dominant directions. -- The acceleration data from the LIMEX'89 were analysed to find the number of collision events of the measured ice floes. Predictions of collision frequencies from floe-wave conditions and from acceleration data were significantly different. However, the difference became smaller after the dimensional effects of the floes were considered. The influences of winds were discussed and shown as the primary contribution to the results of higher wave amplitude with smaller collision frequency during a time period obtained from the acceleration data of LIMEX'89.

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