slocum-glide 0.1.0

Process Slocum glider data

glide

Slocum underwater glider processing command line interface.

glide produces quality controlled L2 and L3 datasets from real-time and delayed Slocum glider data. It can generate datasets that meet IOOS Glider DAC standards. It requires that data are first converted to netCDF or csv using dbd2netcdf (or dbd2csv), a very fast Dinkum binary conversion tool.

Our definitions of data processing levels are guided by NASA, the Spray data, and our own experiences working with gliders. We define the following levels:

• L0: Binary files produced by Slocum gliders include .dbd, .sbd, .ebd, .tbd or their compressed counterparts .dcd, ... etc.
• L1: NetCDF or csv timeseries of flight and science data generated using dbd2netcdf. Usually named glidername.dbd.nc and glidername.ebd.nc or something similar. No quality control is performed. Data have the same units as in masterdata.
• L2: Variable units are converted to oceanographic/CF standards. Quality controls are applied. Some missing data are interpolated. Dead reckoned GPS positions are adjusted using surface GPS fixes; valid GPS fixes are also written on a dedicated time_gps dimension. Thermodynamic variables, such as potential density, are derived. Profiles are identified and tagged with profile_id. Depth-averaged velocity is reported on a time_uv dimension. Science and flight variables specified in the configuration file are merged into a single file.
• L3: The L2 data are binned in depth and separated into profiles. Ancillery datasets may be merged, such as MicroRider data processed using q2netcdf.

Additionally, we provide the following intermediate processing outputs that may be useful for debugging issues:

• L1B: The L1 data are parsed and quality control is performed but science and flight data are not merged.

Installation

Use pipx:

pipx install git+https://github.com/OSUGliders/glide

Usage

flowchart TD;
    sbd[L0 flight: .sbd /.dbd] -->|dbd2netcdf| l1sbd[L1 flight: .sbd.nc];
    tbd[L0 science: .tbd /.ebd] -->|dbd2netcdf| l1tbd[L1 science: .tbd.nc];
    l1sbd --- C[ ]:::empty;
    l1tbd --- C;
    config[config.yml] --- C;
    C -->|glide l2| l2[L2: .l2.nc];
    l2 --- D[ ]:::empty;
    config --- D;
    q[Ancillery: .q.nc] --- D;
    D -->|glide l3| l3[L3: .l3.nc];
    
classDef empty fill:none,stroke:none,color:transparent,width:1px,height:1px;

glide requires a configuration file to properly process glider data. If you do not provide a file, the default file will be used. The configuration file specifies which variables to extract from the L1 data and provides flags for unit conversion and quality controls. Variables that are not listed will not be extracted.

Assuming that you have already run dbd2netcdf over a directory of files (e.g. dbd2netcdf -o glider.tbd.nc *.tbd) you can apply the l2 processing using,

glide l2 glidername.sbd.nc glidername.tbd.nc -o glidername.l2.nc -c glidername.config.yml

The two file arguments also accept shell-style glob patterns, so you can let glide concatenate per-segment L1 files for you instead of pre-merging with dbd2netcdf:

glide l2 "glidername-*.sbd.nc" "glidername-*.tbd.nc" -o glidername.l2.nc

Quote the patterns to keep the shell from expanding them. Each flight file must have a science file with the same basename stem (e.g. glider-2025-056-0-27.sbd.nc pairs with glider-2025-056-0-27.tbd.nc); the command aborts on any unpaired file. Pass --skip-unpaired to drop unmatched files with a warning instead.

To perform level 3 processing with a specific bin size, use:

glide l3 glidername.l2.nc -o glidername.l3.nc -c glidername.config.yml -b 10

To view the help for the package, or a specific command, use:

glide --help
glide l2 --help

To create a hotel file

glide hot glidername.l2.nc -o glidername.hot.mat

To extract location data to CSV (interpolated, dense) or just the surface fixes (sparse, raw):

glide gps glidername.l2.nc -o glidername.gps.csv
glide gps glidername.l2.nc -o glidername.fixes.csv --fixes

Real-time workflow and the national glider DAC

For real-time applications, especially the production of DAC files, glide is designed to be run on the full concatenated dataset for a deployment, not on individual segment files as they arrive. Re-running glide l2 on real-time data is relatively cheap and fast. This avoids the gaps that arise when velocity, GPS, or other state is reported only at the next surfacing and also ensures consistent profile numbering. You can either pre-merge files with dbd2netcdf and pass the resulting single file to glide l2, or pass glob patterns directly to glide l2 and let it concatenate the per-segment L1 files itself (every flight file must have a science file with the same basename stem).

IOOS Glider DAC submission

Add --ioos to glide l2 to additionally emit one NGDAC v2-compliant NetCDF file per profile (one descent or one ascent) into the given directory:

glide l2 glider.sbd.nc glider.tbd.nc -o glider.l2.nc \
    --ioos ./dac/ -g glidername -c glidername.config.yml

A profile is emitted only when its containing surface-to-surface segment has a finite depth-averaged velocity — i.e., the closing surfacing has reported. Profiles still awaiting that surfacing are skipped and will be emitted on a future re-run with more concatenated data. Existing files are skipped (the filename encodes the profile start time); pass --force to overwrite.

Per-deployment instrument metadata (CTD make/model/serial, calibration dates, etc.) goes in the instruments: section of config.yml and is placed as scalar variables in each profile file.

Quality control

During L1 → L2 processing we currently:

• Drop missing or repeated timestamps.
• Check data are within valid_min and valid_max limits from the config.
• Interpolate missing dead-reckoned position and linearly adjust the dead-reckoned position to align with surface fixes.
• Identify behavioral states such as dive, climb, surface, and drift, and assign profile numbers. This relies on profinder
• Track per-variable QC flags (*_qc) for variables tagged track_qc in core.yml, including for variables interpolated across the science/flight merge.

We plan to implement more of the standard IOOS QC methods in the future.

Development

This package is developed with uv.

After cloning this repository, genereate the virtual environment:

uv sync

Run tests:

uv run pytest -v

Format code:

uv run ruff format src tests
uv run ruff check --select I --fix

Type checking:

uv run mypy src tests

Try out glide on the test data:

uv run glide --log-level=debug l2 tests/data/osu684.sbd.csv tests/data/osu684.tbd.csv

By default this will produce a file slocum.l2.nc.

Contributing

Collaboration is highly encouraged, and contributions from the community are always welcome. To ensure a productive and respectful development process, please follow these guidelines.

Before submitting any code, please open an issue to describe the problem you're addressing or the feature you'd like to implement. This allows for discussion around the proposed changes, helps align efforts, and ensures that contributions are in line with the project's goals. When creating an issue, be as detailed as possible. Include relevant context, your motivation, and any initial ideas you may have.

Once an issue has been discussed and agreed upon, feel free to fork the repository and begin working on a solution in a separate branch. When you're ready, submit a pull request that references the related issue and clearly outlines the changes you've made. Try to keep your pull requests focused and limited to a single concern to make the review process smoother. Please ensure your code follows the existing style and structure of the project. If you're unsure about conventions or need guidance, don't hesitate to ask. Contributions should be well-tested.