Environmental Conditions on the Continental Shelf Off West Greenland

Abstract

This paper describes the meteorological, hydrographical, and ice conditions of the Davis Strait, with particular emphasis on the west Greenland continental shelf, located from 630 to 680 N latitude. An analysis is presented of existing information and environmental data obtained during presented of existing information and environmental data obtained during intensive data-collection programs conducted during the summer and fall of 1975 and 1976. Introduction Until offshore petroleum exploration began in the Davis Strait of west Greenland, little attention had been devoted to environmental conditions of the area. Only limited hydrographic data existed for concession areas located up to 160 km from Greenland's coast, between latitudes 63 degrees and 68 degrees N. Data on ice conditions, the most critical factor of offshore operations in northern waters, also were scarce.To obtain data on currents, icebergs, ice drift, and weather conditions, comprehensive environmental data collection programs were conducted during 1975-76, both by the concessionaires (with Chevron Petroleum of Greenland as operator) and by the Danish Ministry for Greenland. The programs performed by the concessionaires were intended primarily to provide performed by the concessionaires were intended primarily to provide sufficient data for planning and executing drilling operations. These programs were concentrated on the concession areas. The Ministry's test programs were concentrated on the concession areas. The Ministry's test programs also included the possible effects of oil spills on the sensitive programs also included the possible effects of oil spills on the sensitive arctic environment.The government programs for 1975-76 were executed by the Danish Hydraulic Institute (DHI), which also was commissioned to perform the industry's Weathership program in 1976. Special iceberg profiling equipment was used in 1976, in addition to seven wave-rider buoys and 35 "Aanderaa" recording current meters, which were deployed in water up to 600 m deep. The areas involved are shown in Figs. 1 and 2.In addition to these programs, reconnaissance flights and comprehensive analysis of existing "vestis" (west ice) data have been performed by the Danish Meteorological Institute (DMI). Also, wave hindcasting studies and analysis of existing hydrographic data were conducted by DHI.This paper presents a general description of the area's environmental conditions, as well as examples of the data collected during the 1975-76 programs. Environmental programs also were performed for the Ministry for programs. Environmental programs also were performed for the Ministry for Greenland in 1977 and 1978, but are not reported here. Meteorological Conditions General Weather conditions in the Davis Strait are governed by the interaction between the polar high-pressure field over Greenland and cyclones, which normally move eastward from the east coast of Canada and the U.S. Most cyclones pass south of Greenland, but some propagate northward along the east coast of Canada, or through the Davis Strait. Fig. 3 shows examples from pilot charts (U.S. Navy) of cyclone tracks during September and October of 1955 to 1960, inclusive.The barometric polar high pressure is created by cooling air masses over the ice cap in the polar region and Greenland; thus, its extent shows seasonal variations. Because of the polar high pressure over Greenland, the isobars in the Davis Strait often are compressed and aligned north-south along the west coast of Greenland. JPT P. 1381