ABSTRACT

A new operational iceberg forecasting model is under development at the Canadian Ice Service (CIS). The model deals with iceberg drift, deterioration, and calving. One of the main features of the new model is the utilization of detailed environmental conditions. In particular, the vertical distribution of water current is used to calculate water drag forces. An accurate description of keel geometry is, therefore, needed in order to take advantage of the detailed water current information. This paper describes the analyses done to determine the geometry of iceberg keels and sails. The objective was to provide refined input for the iceberg drift section of the forecasting model. Available iceberg data were used to create empirical equations which describe keel crosssectional areas at different depth intervals from a given waterline length. The equations also determine sail area, draft, and mass as functions of waterline length. This is the first investigation that determines geometry in detail.

INTRODUCTION

The development of the Grand Banks of Canada for oil and gas production requires reliable forecasting of iceberg and bergy bit drift and deterioration, to ensure the safety of offshore structures and shipping operations. A new operational model has been developed at the Canadian Ice Service (CIS) in response to emerging forecasting requirements. The model deals with the drift, deterioration, and calving of icebergs. One of the main features of the model is employing detailed environmental forcing information in order to improve accuracy of the forecasts. In particular, detailed vertical profiles of water current are used to calculate water drag forces, which lead to significant improvements in predicted drift tracks. Previous prediction models assumed a uniform current independent of depth. Naturally, an estimate of keel area variation with depth is needed for appropriate evaluation of drag forces.

This content is only available via PDF.
You can access this article if you purchase or spend a download.