Table of Contents

Introduction top

The Slocum Coastal Electric Glider is an Autonomous Underwater Vehicle (AUV) which propels itself through the water column by adjusting it's internal volume to weight ratio. The glider is powered by alkaline battery packs and is nominally equipped with a SeaBird 41CP CTD sensor for recording Conductivity, Temperature and Depth (pressure) at 0.5Hz. The glider may also be outfitted with a suite of additional instrumentation for measure in situ water properties.

Terminology

The following concepts and terms are defined to make the following discussion more transparent:

Native Data Filetypes top

The glider stores all measured parameters (sensors) in 3 native binary filetypes:

Addendum: Science data logging was implemented in GliderDOS release 7.0 (February 2010) and has resulted in significant improvements in the overall data logging quality by the glider. Any glider running GliderDOS 7.0 or higher now logs only the glider engineering and flight parameters in the files mentioned above. All science sensors (prefixed with 'sci_') are logged onboard the science computer in the following new set of files:

Once the individual files are transferred back to shore, they must be converted from binary to ascii and merged with their corresponding analog file (ie: an sbd file from a particular segment must be merged with it's tbd counterpart in order to get the engineering, flight and science sensors into a single file.)

All filetypes store data in binary format, which must be converted to ASCII via a few linux or windows shore-side executables. Technical documentation and further information on the nature of the binary format as well as utilties for converting them to ascii data can be found here.

Shore-Side Data Processing top

Once transmitted to shore, the raw slocum binary data files are converted to ASCII data and stored on our local fileserver, where they pass through a number of processing steps/levels, prior to being made publicly available. The goals of organizing the data processing into a series of processing levels are:

Filetypes and APIs top

This section describes the various processing stages of raw slocum glider datasets. A full description of slocum glider native raw data filetypes and their structure is located here. The majority of this processing is done with the Matlab programming language. As such, many of the intermediate processing level data structures are Matlab native (.mat). However, as of this writing (2009-March), we have also chosen to store the data in the NetCDF file format to allow for machine and platform independent data access through a number of APIs including, but not limited to:

Processing Levels top

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