TEMPORAL VARIATIONS OF BEAM ATTENUATION COEFFICIENT ON THE CONTINENTAL RISE OFF NOVA SCOTIA.

Two separate time series observations of light transmission in the bottom water on the Continental Rise off Nova Scotia show fluctuations of light transmission in a wide range, 0-50% transmission at lambda equals 660 nm. The range corresponds approximately to SPM concentrations of 12 mg/l to 150 mu g/l. The former is the maximum value determined by filtration (Biscaye, 1980), and the latter is determined by an empirical relation between beam attenuation coefficient and particle volume determined by a particle counter. Nepheloid layers of significant turbidity, called benthic storms, were observed in 30 and 10% of the time, respectively, for the two observations, and each storm lasted 2-5 days. High frequency fluctuations represented by pulse lengths less than 10 min were observed superimposed on the low frequency fluctuations during 16 and 4% of the time. Both the major storms and the high frequency pulses are interpreted to be a result of resuspension of bottom sediments at varying distances from the instrument.