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This document describes the PMEL-EPIC convention for writing netCDF data files with the EPS library, for use with the EPIC software package for oceanographic data.

Documentations located at ftp://ftp.unidata.ucar.edu/pub/netcdf/Conventions/PMEL-EPIC describe the Conventions common to all PMEL-EPIC style netCDF data files. Please see the accompanying documents describing Conventions specific to specific data types:

• EPIC netCDF General Conventions
• Conventions for Profile Type Data
• Conventions for Time Series Type Data

This document is an addendum to the PMEL-EPIC Conventions document in the Unidata /pub/netcdf/Conventions/PMEL-EPIC directory, describing those characteristics which are specific to shipboard ADCP data.

This is a tentative guideline for this particular type of data. Files compliant with the rules described in this document can be analyzed with the EPIC functions: trackav, mapadcp, and conadcp (as of summer 1996). Later efforts might incorporate shipboard ADCP data with other more general track-type data to be managed by the EPIC system.

Shipboard ADCP data (in the scope of this project) consists of processed acoustic data collected along the shiptrack. The shipboard instrumentation records average measurements, derived from individual acoustic ping "events". The time interval over which an "ensemble" of individual pings are processed is fixed. Current velocities (and some other measurements) are calculated for some number of depth bins during each ensemble interval, representative of the time between the start and end of the interval, and therefore of the section that spans the ship's initial and final positions. Thus, the resulting data is a mix of 1-D fields spanned by time (e.g. position of one ensemble) and 2-D fields spanned by time and depth (e.g. velocities). This structure needs to be reflected by the netCDF data files. Please refer to this example shipboard ADCP file for detailed information. The original netCDF file can be found here. For further information look on PMEL's anonymous ftp server:

ftp://www.epic.noaa.gov/epic/adcp/

No further global attributes in addition to those defined in the general conventions document are neccessary.

• Example ADCP transect and track plots
• Example programs using Shipboord ADCP data