Intense Shipping Research Articles

Summer Distribution of Bowhead Whales, <i>Balaena mysticetus</i>, Relative to Oil Industry Activities in the Canadian Beaufort Sea, 1980-84

Aerial surveys in 1980-84 showed that summer distribution of bowheads in the Beaufort Sea varied markedly between years. Distribution varied both outside and within the main industrial (MIA), the area of island construction, drilling and intensive ship and helicopter traffic. Numbers of bowheads in the MIA were high in 1980, lower in 1981, near zero in 1982 and very low in 1983-84. The few whales in the MIA in 1983-84 were mainly near its edges, contrary to 1980-81. These data, plus limited evidence from 1976-79, indicate that bowheads were numerous in the centre of the MIA in 3 of 5 years from 1976-80 (1976-77, 1980) vs. 0 of 4 years from 1981-84. One hypothesis is that progressively increasing industrial activities affected bowhead distribution after 1980. However, bowheads probably also react to variations in their zooplankton prey, which may be affected by year-to-year changes in oceanography and weather. Influences of natural factors on zooplankton and bowheads need to be better understood in order to assess whether oil exploration caused any of the observed changes in bowhead distribution. Key words: bowhead whale, Balaena mysticetus , Beaufort Sea, oil exploration, seismic exploration, aerial surveys

A Case Study of West Atlantic Cloud Clusters: Part 2. Dynamic Structure and Environment

Abstract We describe the behavior, dynamics and setting of three cloud clusters. The clusters occurred in the western Atlantic Ocean between 21 and 24 July 1969. Wind and cloud analyses made from intensive ship and satellite observations of the Barbados Oceanographic and Meteorological Experiment (BOMEX) were supplemented by analyses of thermodynamic structure (temperature, moisture and stability) from Martin and Sikdar (1975). Each of the clusters moved west to northwest. In each cluster high-energy near-surface air was ingested on the front or right flank and vented in the upper troposphere toward the right flank or rear. The clusters were distinguished by a range of speeds (6–15 m s−1), maximum areas (30 000–200 000 km2) and lifetimes (<1 to ∼3 days). Downdrafts in the first cluster were weak. The second cluster was without significant downdrafts as it formed, but gradually assumed the appearance of tropical squall lines. Massive squall-line downdrafts were observed in the third cluster. Conditions fav...