Environmental Conditions on the Continental Shelf off West Greenland

Abstract

ABSTRACT Petroleum exploration activities started on the Greenland Continental Shelf in 1975 and intensive data collection programs on hydrographic, metrological and ice conditions have been carried out during the summer and fall seasons 1975 and 1976. The paper describes the environmental conditions in the Davis Strait with emphasis on the concession areas between latitudes 63°and 68°N The wave climate which is strongly correlated with the storm conditions was found to vary with the location and the seasons with the most severe conditions occurring late fall. During 1975–76 the maximum recorded wave heights was 6,8 m with corresponding wave periods of Tz = 9,5 sec. The currents on the shelf were found to be governed by a general northward circulation of water and tidal current. The tidal currents vary geographically from weak diurnal currents to strong semidiurnal currents. Variations in currents were also found with the depths. Maximum current velocities were in 1975–76 measured at 80 cm/sec and the daily net drift speed was typically 10–20 cm/sec. The ice conditions are governed by the "Vestis" and icebergs of glacial origin. The app. one meter thick Vestis" moves southwards during the fall and covers large parts of the Davis Strait during winter and spring. Icebergs are found in many sizes through out the year. They originate mainly from the east and south coasts and from the Disco Bay in the north. The maximum size and draught of the measured icebergs were 8.5 Mt and 50 m, respectively. INTRODUCTION Until offshore petroleum exploration began in 1975 only little attention had been paisa to the environmental conditions on the continental shelf in the Davis Strait off West Greenland Only very limited hydrographic data was found to exist at the concession areas located up to 160 km off the coast between latitudes 63° and 68°N, and data on ice conditions which as the most critical factor for offshore operations in Ghese areas, was also found to be scarce. In order to provide data on currents, icebergs, ice drift and weather conditions comprehensive environmental data collection programs were therefore carried out in 1975 and 1976 both by the Concessionaires (with Chevron Petroleum of Greenland as operator) and by the Ministry for Greenland. The Programs of the Concessionaires aimed primarily at providing sufficient data for planning and execution of drilling operations and was concentrated on the concession Ares while the programs of the Ministry also emphasized the effects of possible oil spills upon the sensitive arctic environment. The Ministry's program in 1975 and 1976 was executed by the Danish Hydraulic Institute (DRI) and in 1976 DRI also performed the Industry's Weather ship program. Special iceberg profiling equipment was used in 1976 and a total number of 7 wave rider buoys and 35 Andrea recording current meters were deployed in water depths up to 600 m. The area involve in the 1975 and 1976 measuring programs are shown on Figs. 1-2.