Current, Pressure and Temperature data from the Gulf Stream; IES Data in the Central and Inlet Array from SYNOP Experiment

The Synoptic Ocean Prediction Experiment (SYNOP) was a major
observational and modeling program designed to understand
the physics governing large amplitude meandering of the Gulf
Stream and the shedding and interactions of rings east of Cape
Hatteras to the Grand Banks. The moored instrumentation program
included the small Inlet Array near Cape Hatteras, the Central
Array near 68W, the East Array near 55W, and the 50W Array.
Observations in the different arrays were made between 1987
and 1990 with some overlapping periods between arrays.

The URI, UNC and UM groups maintained the Inlet and Central
Arrays. The Inlet Array, consisting of 9 inverted echo
sounders (IESs) and 5 deep current meters, was designed
to monitor the inflow conditions as the Gulf Stream leaves
the continental margin. These instruments were in place from
October 1987 to September 1990. The Central Array had two different
deployment configurations, but the largest and longest configuration
consisted of 24 IESs, 12 of which included bottom pressure gauges.
The Central Array also included 12 tall current meter moorings, each
with four levels (400, 700, 1000, and 3500 m) instrumented. Three of
the moorings had upward-looking acoustic doppler current profilers
with pressure and temperature sensors mounted above the topmost
current meter. This configuration remained in place from May 1988
to August 1990.

One of the most interesting findings of this experiment was the
presence of strong deep cyclones and anitcyclones beneath the
Gulf Stream. The spin-up of the deep flow field occurred during
the passage of steep meander crests and troughs of the Gulf Stream.
The velocities at 3500 m depth often were as high as 35-40 cm/s during
these strong events. While strong velocities had previously been
observed under the Gulf Stream, the association of these strong velocities
with an organized deep flow field was not understood prior to the SYNOP
observations.