Summary
The Atmospheric Composition Variable Standard Name Convention (ACVSNC) provides a convention and heuristic for creating common variable names for atmospheric composition and chemistry measurements acquired during suborbital field campaigns.
The development of this convention was motivated by the ubiquity of the ICARTT file format within the community of atmospheric composition and chemistry researchers. ICARTT V2.0 requires a standard variable name entry as part of the variable definition, which was introduced to mitigate challenges in dealing with an ever-increasing variety of variables from the NASA suborbital field campaigns.
Having a structured rules set, as outlined in this document, to create variable names is a critical step to meet the challenges of data discovery and interoperability, and to improve the usability of these data.
Status
The Atmospheric Composition Variable Standard Names Convention is an approved NASA Earth Science Data Systems convention.
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NASA Earth Science Community Recommendations for Use
Strengths
The Atmospheric Composition Variable Standard Name Convention provides a guideline and convention developed by subject matter experts for generating complex atmospheric variable names documenting a variety of measurement attributes such as chemical species, quantity and concentration, and acquisition method. It fulfills an immediate need to standardize variable names collected from an increasing array of NASA airborne campaigns investigating atmospheric composition, including trace gasses, where existing vocabularies such as CF Standard Names are not sufficient. The difficulty with CF conventions is that many of the data attributes captured by the ACVSNC are either optional or not included. The ACVSNC allows users to locate and interact with a particular variable across multiple data sets and is especially geared for atmospheric research use. The ACVSNC variable list is relevant for the standard name requirement in the ICARTT V2.0 file format, but could be extended to variable attributes (e.g., longname) in netCDF/HDF files.
This variable naming convention is in use in select existing NASA suborbital field studies (e.g., FIREX-AQ, CAMP2EX, ACTIVATE, and DCOTSS) and potential wider adoption will ensure future data products are generated using consistent variable names, reducing confusion and disparity, and increasing both human and machine-based consumption.
Weaknesses
The ACVSNC was established to provide a consistent approach to atmospheric variable names but it does not have any lineage or strong relationship with existing conventions. It is thus independent and there is a concern with its long-term governance and maintenance. One result is that it may end up siloed in a small community of atmospheric scientists with no uptake beyond NASA. This could limit interoperability with other data, or tools and services for accessing, processing, and analyzing data.
The rules for creating names with the ACVSNC are complex, and the prescribed vocabulary varies depending on the type of measurement being described. Consequently, the rules may be difficult to follow without significant domain expertise. Implementation at ESDIS DAACs may therefore be challenging.
Given the challenges of implementation, a well-defined governance structure is critical. However, the governance of proposed new variable names is not addressed. For example, the reference documentation containing the full list of current names and practical examples is maintained in a separate document. A well-defined process for proposing, vetting, accepting and maintaining variable names should be developed.
Applicability
To the extent that it is already in use within certain communities, the ACVSNC should be applied consistently, if possible, throughout NASA airborne and field campaign programs, and the relevant metadata, and documentation. The ACVSNC has been adopted within the Sub-Orbital Ordering Tool (SOOT) developed for expert users by the Atmospheric Science Data Center. However, we would urge adherents to this convention to use it in conjunction with other standards. For example, in addition to the names that adhere to the ACVSNC, SOOT should consider using UMM-Var metadata records to describe the data, in order to ensure that data are interoperable with a wider array of tools.
Limitations
The ACVSNC is limited to describing variables for atmospheric composition and chemistry, and in particular, focuses on data acquired in airborne campaigns. It is not intended for use with satellite observations or model outputs. Currently, the ACVSNC does not have broad community adoption, and implementation challenges and lack of a well-defined governance may hinder further uptake.