Recent moored current meter and SOFAR float observations in the eastern Atlantic near 32N

Author： Schmitz Jr. William J. Price James F. Richardson Philip L.

Publisher： Sears Foundation for Marine Research

ISSN： 1543-9542

Source： Journal of Marine Research, Vol.46, Iss.2, 1988-05, pp. : 301-319

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Abstract

Basic flow statistics from the two-year deployment of a mooring in the vicinity of 32N and 24W are presented, along with intercomparisons between SOFAR float results concurrent with the first year of moored instrument data. Current-temperature meters were deployed in the main thermocline (∼500 m depth), in Mediterranean Water (1000–1100 m depth) along with the SOFAR floats, and at an abyssal (∼3000 m) level. The float and current meter averages over a common time interval are at least roughly the same, with eddy field intercomparisons being better than those for mean flow.Strong year-to-year variability in the time-averaged flow and eddy statistics at thermocline depths is observed. The two-year based eddy kinetic energies (K_E) are about the same as found using a variety of data taken nearby, whereas zonal mean speeds exhibit strong, comparatively short horizontal scale variability. It is pointed out that all measurements available exhibit a significant (perhaps dominant) but relatively unexplored interannual variability, not yet explicitly connected to variations in the gyre-scale circulation. Frequency distributions of K_E are peaked at the (temporal) mesoscale at abyssal depth, and K_E increases with increasing period in the thermocline. The distribution of K_E with frequency at thermocline depths is also temporally inhomogeneous, although not at mesoscale and shorter periods. Meridonal frequency distributions of K_E are peaked at the mesoscale and zonal distributions are more “red.” The eddy field characteristics at this site are shown to be similar to those from other low energy regions in the North Atlantic and the North Pacific.