[单项选择]Before 1965 many scientists pictured the circulation of the ocean’s water mass as consisting of large slow-moving currents, such as the Gulf Stream. That view, based on 100 years of observations made around the globe, produced only a rough approximation of the true circulation. But in the 1950s and the 1960s, researchers began to employ newly developed techniques and equipment including subsurface floats that move with ocean current and emit identification signals for months at fixed locations in the ocean. These instruments disclosed an unexpected level of variability in the’ deep ocean. Rather than being characterized by smooth, large-scale currents that change seasonally (if at all), the seas are dominated by what oceanographers (海洋研究者) call mesoscale fields (紊流): fluctuating, energetic flows whose velocity can reach ten times of the mean velocity of the majior currents.
Mesoscale phenomena--the oceanic analogue of weather terms--often extend to distances of 100 kilometers an
A. Nowadays, scientists pictured the circulation of ocean’s water mass as consisting of large slow-moving currents.
B. Before 1965 ,the concept of scientists produced only a rough approximation of the true circulation.
C. Researchers began to do research on the developed techniques and equipment.
D. These instruments disclosed an expected level of variability in the deep ocean.