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Vocabulary collections

Methodology

A working group on harmonization of the glider data format was set up in September 2020 at the request of the OceanGliders steering team. All members of the OceanGliders data management team were invited to join. The three existing formats (at the time) were analysed and compared by the group. Regular technical meetings occurred and the format harmonization process was managed via a Google doc. In late 2021 the group decided to move the document to GitHub to better manage the issues, work asynchronously and contribute to the open source community. The GitHub repository is open to any comments from the community and validation rules were created by the working group (see the governance document). From there the working group organized regular meetings to validate the evolution of the format, discuss issues and reach a consensus on the OG1.0 format. It is envisaged that the format will continually evolve with contributions from the community.

Authorship

Authors

Contributors

Acknowledgements

Several organisations were instrumental in the development of this format. OceanGliders, UG2, and EGO provided encouragement and forums for initial discussion. Some authors received support from, amongst others, EuroSEA, AtlantOS, GOMO, EMODnet Physics, NERC, VOTO and GROOM II.

Background

The OceanGliders program brings together marine scientists and glider operators from all over the world who observe the long-term physical, biogeochemical, biological ocean processes, and phenomena relevant for societal applications. It allows active coordination and strengthening the roles of gliders in the ocean observation programs worldwide and contributes to the present international efforts for ocean observation for climate, ocean health and real-time services.

The program oversees the monitoring of global glider activity, a prerequisite for active coordination. By sharing requirements, efforts and scientific knowledge needed for glider data collection OceanGliders aims to continuously develop the network by supporting the dissemination of glider data in global databases, in real-time and delayed mode, for a wider community.

The OceanGliders program was created about 10 years after the popularization of the use of gliders by ocean scientists. With no common rules on format, data managers from Australia (IMOS), the USA (IOOS), and Europe (Coriolis) processed 3 regional formats that are not interoperable.

Harmonization toward interoperability within the existing formats and many national/regional glider networks is a recommendation from the OceanGliders steering team to strengthen the program and reach the FAIR principles (Findable, Accessible, Interoperable, Reusable) adopted by GOOS (Global Ocean Observing System), and better monitor the program activity.

Objectives

This document defines the common OceanGliders data format, hereafter OG1.0.

OG1.0 General conventions

  • The required granularity of the data set is the glider mission, starting from deployment at sea to recovery.

  • Data are recorded as a trajectory Discrete Geometry, using NetCDF[1] system and following CF 1.10[2] (Climate and Forecast) specifications. Each data file contains a series of dive cycles representing the mission of the glider. It can be produced in near real time after every glider transmission and revised later into a recovery-mode (when glider on shore and any data gaps filled in) or a delayed-mode (after rigorous QC) version.

  • Format follows the ACDD 1.3[3] convention where possible.

  • Vocabulary collections will be hosted in different places (NERC Vocabulary Server - NVS, OceanOPS, ICES, etc). The OceanGliders data management team will manage (additions, updates, etc.) the collections. Treatment of vocabularies is detailed in the vocabularies document.

  • OG1.0 defines some variables and definitions, as described in this document. Other types of measurements (e.g. intermediate parameters, technical measurements, other variables) not framed by OG1.0 can be included in OG1.0 data files. No control will be applied to those measurements.

  • Geospatial variables and along-track positioning variables are mandatory.

  • Methodologies used to interpolate data, compute along-track positioning variables, apply QC etc. Should be linked and, where possible, follow community best practices. It is encouraged to use unique resource identifiers (uris) to link to these resources.

  • 3 recommendations level have been defined for OG1.0:

    • Mandatory: Minimum metadata set to be compliant with OG1.0 requirement.

    • Highly desirable: Worth having for complete use of the data set.

    • Suggested: If the information is available.

DOI management

  • A DOI can be minted at any level (PI, Reference Data Center, Data Assembly Center, Global Data Assembly Center) following the internal policy of data curation.

  • A DOI can be minted for a single glider mission or multiple glider missions (i.e. project, reference lines).

  • A DOI if included in OG1.0 files needs to be preserved. The DOI must remain unchanged if there is no valuable modification. If valuable information is aggregated/added or a new product produced, a new DOI should be created and the new DOI should link to the original DOI to acknowledge as the source

  • The most effective way of preserving the integrity of the source citation is to preserve the initial DOI added in the OG1.0 file.

OG1.0 file naming convention

  • Data files should be named as follows:

    • "<id>.nc" (ex : "sp065_20210616T143025_R.nc")

Where <id> = "<platform_serial>_<start_date>_<data_mode>" (ex : "sp065_20210616T143025_R")

In this case:

  • <platform_serial> = "sp065" a Spray glider number 065

  • <start_date> = "20210616T143025" The datetime in seconds precision 2021-06-16 14:30:25 formatted following ISO 8601

  • <data_mode> = "R" for near real time data

Global attributes

The global attribute section is used for data discovery. The following global attributes should appear in the global section. The NetCDF Climate and Forecast (CF) Metadata Conventions are available from: http://cfconventions.org/Data/cf-conventions/cf-conventions-1.10/cf-conventions.html#trajectory-data. It is recommended that extra global attributes follow ACDD convention".

Global attribute Definition Requirement status Format, fixed value or example

title

A short phrase or sentence describing the dataset.

mandatory

ex.: “OceanGliders trajectory file”

platform

Name of the platform(s) that supported the sensors data used to create this data set or product.

mandatory

ex.: "sub-surface gliders"

platform_vocabulary

Controlled vocabulary for the names used in the "platform" attribute.

mandatory

ex.: https://vocab.nerc.ac.uk/collection/L06/current/27/

id

Formatted mission name: <platform_serial>_<start_date>_<data_mode>

mandatory

ex.:

  • unit_1032_20230512T001245_delayed

  • sea008_20180715T012451_delayed

  • sp032_20150923T150451_R

  • sg041_20381221T000032_R

naming_authority

A unique name that identifies the institution who provided the id. ACDD-1.3 recommends using reverse-DNS naming.

highly desirable

ex.:

  • IOOS

  • IMOS

  • Coriolis

  • edu.ucsd.spray

institution

The name of the institution where the original data was produced.

highly desirable

ex.:

  • Texas A-M University

  • IMOS

  • PLOCAN

internal_mission_identifier

The mission identifier used by the institution principally responsible for originating this data

highly desirable

ex.:

  • sverdrup_20200512_delayed

  • Forster20201109

  • Estoc_2015_01

geospatial_lat_min

Describes a simple lower latitude limit

suggested

format: decimal degree

geospatial_lat_max

Describes a simple upper latitude limit

suggested

format: decimal degree

geospatial_lon_min

Describes a simple longitude limit

suggested

format: decimal degree

geospatial_lon_max

Describes a simple longitude limit

suggested

format: decimal degree

geospatial_vertical_min

Describes the numerically smaller vertical limit.

suggested

format: meter depth

geospatial_ vertical_max

Describes the numerically larger vertical limit

suggested

format: meter depth

time_coverage_start

Datetime of the first measurement in this dataset

highly desirable

format: Formatted string: YYYYmmddTHHMMss ex.: 20240425T145805

time_coverage_end

Datetime of the last measurement in this dataset

highly desirable

format: Formatted string: YYYYmmddTHHMMss ex.: 20240425T145805

site

The name of the regular sample line or area.

highly desirable

ex.: MOOSE_T00, MOOSE_02

site_vocabulary

Controlled vocabulary of the names used in the “site” attribute

highly desirable

To be defined

program

The overarching program(s) of which the dataset is a part. A program consists of a set (or portfolio) of related and possibly interdependent projects that meet an overarching objective.

Highly desirable

ex.: MOOSE glider program

program_vocabulary

Controlled vocabulary of the program attribute

highly desirable

To be defined

project

The name of the project(s) principally responsible for originating this data. Multiple projects can be separated by commas

suggested

ex.: SAMBA

network

A network is a group of platforms crossing the boundaries of a single program. It can represent a mutual scientific objective, a geographical focus, an array and/or a project. Multiple networks shall be separated by commas.

suggested

ex.: Integrated Ocean Observing System (IOOS), Southern California Coastal Ocean Observing System (SCCOOS), Boundary Ocean Observing Network (BOON)

contributor_name

Name of the contributors to the glider mission. Multiple contributors are separated by commas.

PI name is mandatory

ex.: "Victor Turpin, Callum Rollo"

contributor_email

Email of the contributors to the glider mission. Multiple contributors' emails are separated by commas.

PI email is mandatory

ex.: "victor@eample.com, callum@example.com"

contributor_id

Unique id of the contributors to the glider mission. Multiple contributors’ ids are separated by commas.

highly desirable

contributor_role

Role of the contributors to the glider mission. Multiple contributors’ roles are separated by commas.

PI vocabulary is mandatory

contributor_role_vocabulary

Controlled vocabulary for the roles used in the "contributors_role". Multiple contributors’ roles and vocabularies are separated by commas.

PI vocabulary is mandatory

ex.: http://vocab.nerc.ac.uk/search_nvs/W08/

contributing_institutions

Names of institutions involved in the glider mission. Multiple institutions are separated by commas.

Operator is mandatory

contributing_institutions_vocabulary

url to the repository of the id

highly desirable

ex.: https://edmo.seadatanet.org/report/544, https://ror.org/012tb2g32

contributing_institutions_role

Role of the institutions involved in the glider mission. Multiple institutions' roles are separated by a comma.

Operator role is mandatory

contributing_institutions_role_vocabulary

The controlled vocabulary of the role used in the institution’s role. Multiple vocabularies are separated by commas.

Operator vocabulary is mandatory

ex.: https://vocab.nerc.ac.uk/collection/W08/current/

uri

Other universal resource identifiers relevant to be linked to this dataset. Multiple uris are separated by a comma.

suggested

ex.: EDIOS, CSR, EDMERP, EDMED, CDI, ICES, etc.

data_url

url link to where the OG1.0 data file is hosted

highly desirable

ex.: https://linkedsystems.uk/erddap/files/Public_OG1_Data_001/Kelvin_20231205/Kelvin_620_R.nc

doi

The digital object identifier of the OG1.0 data file

highly desirable

ex.: https://doi.org/10.17882/56366

rtqc_method

The method used by DAC to apply real-time quality control to the data set

mandatory

ex.: "Quality control performed with IOOS QARTOD toolbox v2.1", "No QC applied"

rtqc_method_doi

The digital object identifier of the methodology used to apply real-time quality control to the data set.

highly desirable

ex.: "n/a"

web_link

url that provides useful information about anything related to the glider mission. Multiple urls are separated by commas.

suggested

ex.: https://observations.voiceoftheocean.org/SEA078/M25

comment

Miscellaneous information about the glider mission, data or methods used to produce it.

suggested

ex.: "glider recovered after 5 days due to leak"

start_date

Datetime of glider deployment

mandatory

format: Formatted string: YYYYmmddTHHMMss ex.: 20240425T145805

date_created

date of creation of this data set

mandatory

format: Formatted string: YYYYmmddTHHMMss ex.: 20240425T145805

featureType

Description of a single feature with this discrete sampling geometry

mandatory

fixed value: "trajectory"

Conventions

A comma-separated list of the conventions that are followed by the dataset.

mandatory

ex.: "CF-1.10, ACDD-1.3, OG-1.0"

Dimension and definition

Name Definition Comment

N_MEASUREMENTS

N_MEASUREMENTS = unlimited;

Number of recorded measurements.

Location variables

Coordinates

OG1.0 requirements cover positioning variables and geolocation of any scientific measurements made by the glider during its mission, described in the table below.

VARIABLE NAME variable attributes requirement status

TIME

  • data type: double

  • dimension: N_MEASUREMENTS

  • long_name = “Time elapsed since 1970-01-01T00:00:00Z”;

  • calendar = "gregorian" ;

  • units = “seconds since 1970-01-01T00:00:00Z”;

  • _FillValue = -1.0 ;

  • valid_min = 1e9 ;

  • valid_max = 4e9 ;

  • ancillary_variables = “TIME_QC”;

  • interpolation_methodology = “”;

  • time_vocabulary = “https://vocab.nerc.ac.uk/collection/OG1/current/TIME/”;

mandatory

LONGITUDE

  • data type: double

  • dimension: N_MEASUREMENTS

  • long_name = “longitude of each measurement and GPS location”;

  • standard_name = “longitude”;

  • units = “degrees_east”;

  • _FillValue = -9999.9;

  • valid_min = -180.0;

  • valid_max = 180.0;

  • ancillary_variables = "LONGITUDE_QC";

  • interpolation_methodology = “”;

  • longitude_vocabulary = “https://vocab.nerc.ac.uk/collection/OG1/current/LON/”;

mandatory

LATITUDE

  • data type: double

  • dimension: N_MEASUREMENTS

  • long_name = “Latitude north (WGS84)”;

  • standard_name = “latitude”;

  • units = “degrees_north”;

  • _FillValue = -9999.9;

  • valid_min = -90.0;

  • valid_max = 90.0;

  • ancillary_variables = "LATITUDE_QC"

  • interpolation_methodology = “”;

  • latitude_vocabulary = “https://vocab.nerc.ac.uk/collection/OG1/current/LAT/”;

mandatory

DEPTH

  • data type: double

  • dimension: N_MEASUREMENTS

  • long_name = “Depth below surface of the water body by unknown instrument and correction to zero at sea level using unspecified algorithm.”;

  • standard_name = “depth”;

  • units = “metres”;

  • _FillValue = -9999.9;

  • valid_min = 0.0;

  • valid_max = 10000.0;

  • ancillary_variables = "DEPTH_QC"

  • interpolation_methodology = “”;

  • depth_vocabulary = “https://vocab.nerc.ac.uk/collection/OG1/current/DEPTH/”;

mandatory

See parameters section for guidance on attributes and conventions on _QC channels.

GPS variables

OG1.0 requirements cover the GPS variables delivered by the glider when at the sea surface, described in the table below.

VARIABLE NAME variable attributes requirement status

TIME_GPS

  • data type: double

  • dimension: N_MEASUREMENTS

  • long_name = “time of each GPS location”;

  • calendar = "gregorian" ;

  • units = “seconds since 1970-01-01T00:00:00Z”;

  • _FillValue = -1.0 ;

  • valid_min = 1e9 ;

  • valid_max = 4e9 ;

  • ancillary_variables = “TIME_GPS_QC”

mandatory

LONGITUDE_GPS

  • data type: double

  • dimension: N_MEASUREMENTS

  • long_name = “longitude of each GPS location”;

  • standard_name = “longitude”;

  • units = “degrees_east”;

  • _FillValue = -9999.9;

  • valid_min = -180.0;

  • valid_max = 180.0;

  • ancillary_variables = "LONGITUDE_GPS_QC"

mandatory

LATITUDE_GPS

  • data type: double

  • dimension: N_MEASUREMENTS

  • long_name = “latitude of each GPS location”;

  • standard_name = “latitude”;

  • units = “degrees_north”;

  • _FillValue = -9999.9;

  • valid_min = -90.0;

  • valid_max = 90.0;

  • ancillary_variables = "LATITUDE_GPS_QC"

mandatory

Trajectory Name

VARIABLE NAME variable attributes requirement status Format, fixed value or example

TRAJECTORY

  • data type: string

TRAJECTORY:cf_role = "trajectory_id"

TRAJECTORY:long_name = “trajectory name”;

Where the format is <platform_serial>_<start_date>

The format for platform_serial is described in the PLATFORM_SERIAL variable documentation.

The format for start_date is the ISO 8601 representation of the deployment start UTC datetime with seconds precision.

mandatory

ex.: sp041_20210909T160556

Platform information

VARIABLE NAME variable attributes requirement status Format, fixed value or example

WMO_IDENTIFIER

  • data type: string

WMO_IDENTIFIER:long_name = “wmo id”;

mandatory

ex.: '6801706'

PLATFORM_MODEL

  • data type: string

PLATFORM_MODEL:long_name: “model of the glider”;

PLATFORM_MODEL:platform_model_vocabulary = “”;

mandatory

ex.: "Kongsberg Maritime Seaglider M1 glider"

PLATFORM_MODEL: platform_model_vocabulary = “https://vocab.nerc.ac.uk/ collection/B76/current/B7600002/”;

PLATFORM_SERIAL_NUMBER

  • data type: string

PLATFORM_SERIAL_NUMBER:long_name = “glider serial number”;

mandatory

The platform serial should be constructed from the manufacturer prefix and the platform serial number ex.: "sg001" (seaglider), "unit_001" (slocum), "sea001" (seaexplorer), "sp001" (spray). Where the serial number of the platform is not known, a local nickname can be used e.g. "orca", "sverdrup", "ammonite".

PLATFORM_NAME

  • data type: string

PLATFORM_NAME:long_name = “Local or nickname of the glider”;

highly desirable

a local nickname for the glider ex.: "orca", "sverdrup", "ammonite".

PLATFORM_DEPTH_RATING

  • data type: integer

PLATFORM_DEPTH_RATING:long_name = “depth limit in meters of the glider for this mission”;

PLATFORM_DEPTH_RATING:convention = “positive value expected - e.g. 100m depth = 100”;

highly desirable

ex.: 1000

ICES_CODE

  • data type: string

ICES_CODE:long_name = “ICES platform code of the glider”;

ICES_CODE:ices_code_vocabulary = “”;

highly desirable

ex.: "7460"

ICES_CODE:ices_code_vocabulary = “https://vocab.ices.dk/? codeguid=690d82e2 -b4e2-4e30-9772-7499c66144c6”;

PLATFORM_MAKER

  • data type: string

PLATFORM_MAKER:long_name = “glider manufacturer”;

PLATFORM_MAKER:platform_maker_vocabulary = “”;

suggested

ex.: "Teledyne Webb Research"

PLATFORM_MAKER: platform_maker_vocabulary = “https://vocab.nerc.ac.uk/ collection/B75/current/ORG01077/”;

Deployment information

VARIABLE NAME variable attributes requirement status

DEPLOYMENT_TIME

  • data type: double

DEPLOYMENT_TIME:long_name = “date of deployment”;

DEPLOYMENT_TIME:standard_name = "time";

DEPLOYMENT_TIME:calendar = "gregorian";

DEPLOYMENT_TIME:units = "seconds since 1970-01-01T00:00:00Z";

mandatory

DEPLOYMENT_LATITUDE

  • data type: double

DEPLOYMENT_LATITUDE:long_name = “latitude of deployment”;

mandatory

DEPLOYMENT_LONGITUDE

  • data type: double

long_name = “longitude of deployment”;

mandatory

Field comparison information

VARIABLE NAME variable attributes requirement status Format, fixed value or example

FIELD_COMPARISON_REFERENCE

  • data type: string

FIELD_COMPARISON_REFERENCE:long_name = “links (uri or url) to supplementary data that can provide field comparison for platform sensors.”;

FIELD_COMPARISON_REFERENCE:comment = “multiple links are separated by a comma”

highly desirable

Note: FIELD_COMPARISON_REFERENCE is applicable to deployment, recovery, and delayed versions.

Hardware information

VARIABLE NAME variable attributes requirement status Format, fixed value or example

GLIDER_FIRMWARE_VERSION

  • data type: string

GLIDER_FIRMWARE_VERSION:long_name = “version of the internal glider firmware”;

highly desirable

ex.: v1.3.22

LANDSTATION_VERSION

  • data type: string

LANDSTATION_VERSION:long_name = “version of the server onshore”;

highly desirable

ex.: "dockserver v3.42"

BATTERY_TYPE

  • data type: string

BATTERY_TYPE:long_name = “type of the battery”;

BATTERY_TYPE:battery_type_vocabulary = “https://github.com/OceanGlidersCommunity/OG-format-user-manual/blob/main/vocabularyCollection/battery_type.md”;

suggested

ex.: "lithium rechargeable"

BATTERY_TYPE:battery_type_vocabulary = “https://github.com/OceanGlidersCommunity/OG-format-user-manual/blob/main/vocabularyCollection/battery_type.md”

BATTERY_PACK

  • data type: string

BATTERY_PACK:long_name = “battery packaging”;

suggested

ex.: "2X24 12V battery"

Telecom information

VARIABLE NAME variable attributes requirement status Format, fixed value or example

TELECOM_TYPE

  • data type: string

TELECOM_TYPE:long_name = “types of telecommunication systems used by the glider, multiple telecom type are separated by a comma”;

TELECOM_TYPE:telecom_type_vocabulary = “https://github.com/OceanGlidersCommunity/OG-format-user-manual/blob/main/vocabularyCollection/telecom_type.md”;

highly desirable

ex.: iridium

TELECOM_TYPE:telecom_type_vocabulary = “https://github.com/OceanGlidersCommunity/OG-format-user-manual/blob/main/vocabularyCollection/telecom_type.md”

TRACKING_SYSTEM

  • data type: string

TRACKING_SYSTEM:long_name = “type of tracking systems used by the glider, multiple tracking system are separated by a comma”;

TRACKING_SYSTEM:tracking_system_vocabulary = “https://github.com/OceanGlidersCommunity/OG-format-user-manual/blob/main/vocabularyCollection/tracking_system.md”;

highly desirable

ex.: "gps, accoustic"

TRACKING_SYSTEM:tracking_system_vocabulary = "https://github.com/OceanGlidersCommunity/OG-format-user-manual/blob/main/vocabularyCollection/tracking_system.md, https://github.com/OceanGlidersCommunity/OG-format-user-manual/blob/main/vocabularyCollection/tracking_system.md"

Phase variable

PHASE describes the glider behaviors when at sea. The different behaviors are described in the phase vocabulary (ascent, descent, surfacing, parking, inflection, etc.)

Note that the vocabulary will be fully described and implemented in the control vocabulary tool during the implementation phase.

Phase calculation methodologies need publishing as a best practice document separately to the OG1.0 terms of reference.

VARIABLES NAME variable attributes requirement status

PHASE

  • data type: byte

  • dimension: N_MEASUREMENTS

PHASE:long_name = “behavior of the glider at sea”;

PHASE:phase_vocabulary: “https://github.com/OceanGlidersCommunity/OG-format-user-manual/blob/main/vocabularyCollection/phase.md”;

PHASE:_FillValue = 0b ;

PHASE:phase_calculation_method = “”;

PHASE:phase_calculation_method_vocabulary = “”;

PHASE: ancillary_variables = "PHASE_QC"

Highly desirable

PHASE_QC

  • data type: byte

  • dimension: N_MEASUREMENTS

PHASE_QC:long_name = "quality flag";

PHASE_QC:_FillValue = " ";

PHASE_QC:valid_range = 0b, 1b, 2b, 3b, 4b;

PHASE_QC:flag_values = 0b, 1b, 2b, 3b, 4b;

PHASE_QC:flag_meanings = "No QC has been applied, Good data, Probably good data, Probably bad data, Bad data" ;

Highly desirable

PHASE is used to derive data product (profile, trajectory profiles, gridded product) from OG1.0 data sets. It is recommended to include PHASE when possible.

Sensor information

Each geophysical variable to be recorded must be described with its sensor. Sensor information are stored in an empty and dimensionless variable filled with variable attributes.

Naming convention of the sensor variables

Sensor variables are named as follows: SENSOR_<sensor_type>_<sensor_serial_number>

Where <sensor_type> is a controlled vocabulary: see vocabulary guidelines

VARIABLE NAME variable attributes and requirement status example

SENSOR_<sensor_type>_ <sensor_serial_number>

string SENSOR_<sensor_type>_<sensor_serial_number>

attributes:

sensor_type_vocabulary: “” - mandatory

long_name: “” - mandatory

sensor_model: “” - mandatory

sensor_model_vocabulary: “” - mandatory

sensor_maker: “” - highly desirable

sensor_maker_vocabulary: “” - highly desirable

sensor_serial_number: “” - highly desirable

sensor_calibration_date: “” - highly desirable - Format iso8601 ("YYYY-MM-DD")

SENSOR_CTD_206523

attributes:

sensor_type_vocabulary: "https://vocab.nerc.ac.uk/collection/L05/current/130”

long_name: “RBR Legato3 CTD”

sensor_model: “RBR Legato3 CTD”

sensor_model_vocabulary: “https://vocab.nerc.ac.uk/collection/L22/current/TOOL1745”

sensor_maker: “RBR”

sensor_maker_vocabulary: “https://vocab.nerc.ac.uk/collection/L35/current/MAN0049”

sensor_serial_number: “206523”

sensor_calibration_date: “2021-03-01”

Geophysical variables

Geophysical variables are measurements of a physical phenomenon (or an intermediate variable needed to measure a physical phenomenon); It is provided directly by a sensor (in sensor counts or in physical units) or computed (derived) from other parameters (i.e. intermediate parameters).

The fill value should have the same data type as the variable and be outside the range of possible data values.

VARIABLE NAME variable attributes requirement status example

<PARAM>

  • data type: float

  • dimension: N_MEASUREMENT

<PARAM>:long_name = "<X>"; <PARAM>:standard_name = "<X>";

<PARAM>:vocabulary = "";

<PARAM>:_FillValue = <X>; Note: The fill value should have the same data type as the variable and be outside the range of possible data values.

<PARAM>:units = "<X>";

<PARAM>:ancillary_variables = "<PARAM>_QC";

<PARAM>:coordinates = "TIME, LONGITUDE, LATITUDE, DEPTH"

<PARAM>:sensor = "SENSOR_<sensor_type>_<sensor_serial_number>"

mandatory

<PARAM> contains the values of a parameter listed in the control vocabulary related to OceanGliders parameters.

<X>: these fields are specified in the control vocabularies.

CNDC(N_MEASUREMENT);

attributes:

long_name = "Electrical conductivity of the water body by CTD"

standard_name = "<X>";

vocabulary = "https://vocab.nerc.ac.uk/collection/OG1/current/CNDC/";

_FillValue = NaNf

units = "mS cm-1"

ancillary_variables = "CNDC_QC";

coordinates = "TIME, LONGITUDE, LATITUDE, DEPTH"

sensor = "SENSOR_CTD_206523"

<PARAM>_QC

  • data type: byte

  • dimension: N_MEASUREMENT

<PARAM>_QC:long_name = "quality flag";

<PARAM>_QC:_FillValue = " ";

<PARAM>_QC:valid_range = 0b, 1b, 2b, 3b, 4b;

<PARAM>_QC:flag_values = 0b, 1b, 2b, 3b, 4b;

<PARAM>_QC:flag_meanings = "No QC has been applied, Good data, Probably good data, Probably bad data, Bad data" ;

<PARAM>_QC:RTQC_methodology = “”;

<PARAM>_QC:RTQC_methodology_vocabulary = “”;

<PARAM>_QC:RTQC_methodology_doi = “”;

higly desirable

Best practices

Methodologies used to produce files meeting the OG format should be published in the IODE Ocean Best Practice (OBP) repository (https://repository.oceanbestpractices.org/) under the community “OceanGliders” and the collection “data management”. The following methodologies are covered, among others:

  • Interpolation

  • PHASE computation

  • RTQC

Methodologies should describe the computation methods used (typically by Data Assembly Centers) to produce the data set. Ocean Best Practices are assigned a DOI and should be tagged as "OceanGliders" practices by the submitter. Additionally, OBP endorsed by the OceanGliders data management task team will be marked as such.

Evolution process, the inclusion of new variables.

Management of the evolution of the format will be organized by the OceanGliders data management team.

1. NetCDF-3 does not satisfy the requirements of OG1.0 format
2. http://cfconventions.org/Data/cf-conventions/cf-conventions-1.10/cf-conventions.html
3. https://wiki.esipfed.org/Attribute_Convention_for_Data_Discovery_1-3