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Welcome to the gncutils wiki!

Contents

• Glider Background & Terminology
• Slocum Glider Data Primer
• Deployment Configuration
• Source Glider File Parser Format
• Writing Trajectory NetCDF Files
• Writing Profile NetCDF Files

Background

Supported Glider Types

Currently, the only raw data file reader and variable definitions contained in this package are for the Slocum glider DBA format. I hope to add data file readers for both the Seaglider and Spray glider soon.

Trajectory Terminology

The following diagram illustrates the concepts and terms used for ocean glider trajectories, segment, dives and profiles and the definitions follow. These terms are used throughout the rest of the wiki documentation.

• Profile: A single vertically oriented track of a glider, either upward or downward through the water column. A profile is one-half of a dive. The profile is the fundamental atomic data type used by the NGDAC. All data submitted to the NGDAC is submitted as individual profiles, containing the various water column properties or sensor values.
• Dive: A single vertical profile to depth followed by a vertical profile towards the surface. A dive does not necessarily begin with or terminate with a surfacing and/or GPS fix.
• Segment: The set of data collected between 2 GPS fixes obtained while the glider is on the surface of the water. The first GPS fix is acquired prior to the beginning of a dive and the second GPS fix is acquired following the completion of at least one dive. Glider segments always consist of at least one, and possibly many dives.
• Deployment: A series of one or more segments completed by a glider between the time of deployment and the time of recovery. A glider writes multiple data files during a deployment.
• Trajectory: The National Centers for Environmental Information (NCEI) defines a trajectory as “A series of data points along a path through space with monotonically increasing times.” A glider deployment, consisting of multiple data files, is analogous to a trajectory. Each individual profile-based NetCDF file submitted by the user includes a trajectory variable of the form glider-YYYYmmddTHHMM. This trajectory name contains the name of the glider and the start date of the deployment, as specified by the data provider when registering a deployment with the NGDAC. All files containing the same trajectory value are deemed to be from the same deployment and are aggregated by ERDDAP into an aggregated TrajectoryProfile dataset.

Slocum Glider Data Primer

An in-depth discussion of the Slocum glider native file format and conversion process can be found here