HR: 1340h
AN: OS33B-1269    [Abstracts]
TI: Fish Effects on Ocean Current Observations in the Cariaco Basin
AU: * Virmani, J I
EM: jyotika@marine.usf.edu
AF: College of Marine Science, University of South Florida, 140 Seventh Avenue S., St. Petersburg, FL 33701, United States
AU: Weisberg, R H
EM: weisberg@marine.usf.edu
AF: College of Marine Science, University of South Florida, 140 Seventh Avenue S., St. Petersburg, FL 33701, United States
AB: Multiple years of moored current meter observations from the Cariaco Basin imply the persistent diurnal movement of fish species known to populate the basin. In agreement with short-term observations from 1979, the more recent observations with acoustic Doppler current profilers provide evidence of the multi-decadal presence and behavior of these species. An unwanted corollary however, is a bias in both the vertical and horizontal components of velocity due to the fish movements. Removal of this fish-bias results in large data loss (approximately 72%); however, an interpolated, non-biased data set is developed with depth-averaged horizontal velocities comparable to the observations, demonstrating successful elimination of the bias. Further comparisons show that the interpolated data results in minimal variance density loss at low frequencies and a reduction of variance density at high frequencies such that the interpolated data fits Kolmogorov's 5/3 law for turbulence at subinertial frequencies. A net downward velocity of 0.18cm s^-1 is a reflection of a biogenic particle flux and some residual fish contamination. The mean settling speed of particles in the Cariaco Basin is calculated, via Stokes Law, to be smaller than 0.04 cm s^-1. Velocity observations from acoustic current meters at depths greater than 400m are impacted by the water clarity, therefore alternate methods should be used to make velocity measurements at depth.
DE: 4223 Descriptive and regional oceanography
DE: 4227 Diurnal, seasonal, and annual cycles (0438)
DE: 4273 Physical and biogeochemical interactions
DE: 4568 Turbulence, diffusion, and mixing processes (4490)
DE: 4594 Instruments and techniques
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting