Quick Guide: NCAS General Data Standard
What is the NCAS General Data Standard?
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The NCAS General Standard (previously known as NCAS-AMF and NCAS-AMOF standard) is designed to capture all the information needed to make sure the data in the files are self-describing, and contain details about the people, projects, and instruments responsible for taking the measurements. Based on the CF Conventions, NCAS-General uses the global and variable attributes within the netCDF classic data model to record the relevant information, and forms the basis for the other NCAS data standards. |
When to Use it
The NCAS General data standard should be used for all NCAS observational data intended to be archived with CEDA or shared with other people for use, provided that the instrument is not covered by another of the NCAS data standards (e.g. radar). The basis of this standard can also be used for non-NCAS observational data, with some adjustments needed to account for any differences in licence or required acknowledgements.
How to use it
As data files using the NCAS General standard are of netCDF format, there are many tools available to use that can produce NCAS-General compliant files, in the majority of programming languages. Examples of these tools include the netCDF4 and xarray modules for Python programming.
Built on top of the netCDF4 module, ncas-amof-netcdf-template is a Python module designed specifically to aid in making NCAS-General netCDF files, creating the overall structure for the netCDF file for a given instrument and data product, and pulling in as many of the values for the required attributes as possible, while providing easy options for adding and changing attribute values and for adding data into the netCDF variables.
The data files will have the following key sections:
Common global attributes that cover:
- standards being used in the file
- project details
- instrument details
- geo-temporal bounds
- instrument and processing software used
- associated people
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IF on a moving platform:
- variables covering the platform characteristics (pitch, yaw, bearing)
Geo-spatial variable attributes
- With date-time provided in a variety of ways to meet a range of end-user needs
Data Products variable attributes
- variables (and quality control info) for the data themselves
- These are defined in 'Data Products' common to all instruments of a given type, regardless of the manufacturer
Each of these elements are defined within the standard in their attribute names and also the way the attribute values and data arrays are provided.
To help with constructing data files that follow the standards the ncas-amof-netcdf-template Python module and the 'checksit' compliance checker tool have been provided.
Tools
netCDF libraries for C, C++, Fortran and Java
ncas-amof-netcdf-template Python module
Further Details
You can see the full NCAS General Standard at:
https://sites.google.com/ncas.ac.uk/ncasobservations/home/data-project/ncas-data-standards/ncas-amof
For further details contact the NCAS Data manager: Joshua Hampton