OceanCurrent - Time-series

All data shown here are read directly from the IMOS EMII data portal into Matlab using opendap protocols, at the time shown on the graphic.

Australian National Moorings Network

ADCP - Acoustic Doppler Current Profiler. The ANMN have used several types: the RDI Workhorse, RDI Continental and Nortek AWAC units, all deployed as upward-looking units, either rigidly on the bottom, or in taut moorings.
U, V - Current velocity components along orthogonal axes. These estimates are at a number of equi-spaced vertical distances from the ADCP, i.e. the manufacturer's software has taken the tilt of the unit into account. For moorings that do not undergo large vertical displacement, these data can be used directly to estimate velocity at a range of depth levels. This is what we do here. For ADCPs that change their depth a lot, users will probably want to re-grid the velocity data from range coordinates to range+depth(t) coordinates.
ABSI - Acoustic Back-Scatter Intensity, without correction for the average range-dependent attenuation.
ADCP-T - Temperature at the depth of the ADCP.
ADCP-P - Pressure at the depth of the ADCP. This is a measure of both the mooring motion and the tidal elevation, and is shown to help trouble-shoot apparently spurious estimates of U and V. In some files this is a constant. Note that some instruments may suffer drift of the pressure data.
ADCP-D - Depth of the ADCP. For some files this is missing, so we use ADCP-P, or the 'nominal depth' in the global attributes.
ADCP-tilt - A combination of the ADCP Pitch and Roll data, which are in the ADCP instrumental coordinate system.
SurfaceBinKnockdown - This is a diagnostic calculation of the approximate depth anomaly of the nominal surface bin resulting from the instrument tilt, also shown just for trouble-shooting purposes.
Surface blanking interval - ADCP velocity estimates are contaminated by side-lobe interference with the surface for a significant distance beneath the surface. The thickness of this affected layer is about 12% of the nominal instrument depth but also depends on the instrument acoustic characteristics (frequency, beam width, etc), the tilt and the sea state. For an introductory discussion of some highlights of the data, see our 27 March 2013 and 2 July 2013 News Items.

For further information

IMOS Australian National Moorings Network (ANMN) Facility AIMS site CSIRO NRS site

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