Mechanical current meter gridding

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Four moorings along the Equator at 156E, 165E, 140W, and 110W have had between four and seven mechanical current meters deployed at any given time. The number of instruments and their depths have varied with time because of changing scientific priorities, especially for the 140W and 110W sites which have been occupied the longest.

The depths (m) at which currents have been measured are:

156E (TRITON site): 10, 50, 100, 200
165E: 10, 50, 100, 150, 200, 250, 300
140W: 3, 10, 25, 45, 80, 120, 160, 200, 250, 300
110W: 10, 15, 20, 25, 45, 50, 75, 80, 100, 120, 150, 160, 200, 250

These and other current velocity data and their temporal distribution are described in Current Meter Moorings. In fall 1983 the location of most instruments at 110W changed by 5 m to 20 m. In fall 1987 the location and number of instruments below 150 m changed at both 110W and 140W. For display purposes data at 110W have been interpolated or extrapolated (where vertical correlation was high) to a common grid of 10 m, 25 m, 45m, 80m, 120m, 160m, 200m, 250m. The regridding was performed using either linear interpolation between daily mean data or linear regression relationships based upon monthly mean data. These methods were also used to fill some data gaps at 110W, 140W and 165E. In some cases, vertical coherence was high for the zonal component, but not so for the meridional component. In these cases, interpolation or extrapolation was performed for the zonal component only.