This page will contain the answers for the most frequently asked questions.
Initially the partner repositories (IMR, NERSC, NILU, NPI, MET) are integrated. However, the system is still under development and full integration of partner repositories with daily updates are not expected until 2019. As it is now partner repositories and e.g. NSIDC and PANGAEA are harvested regularly, but not all records harvested are ingested. The quality assurance in the harvest process is still under development.
Yes, NorDataNet would like to extend with more data repositories. The requirements are that data repositories offer discovery metadata using OAI-PMH serving either GCMD DIF or ISO19115 (including GCMD Science Keywords). For best functionality data should be served using OPeNDAP which allows streaming of data through a generic data model which is capable to handling most types of data. Please contact the project if interested in integration.
No, NorDataNet is currently under development. NorDataNet is neither intended to be an operational service in the sense that operational agencies define this. It is intended as a research infrastructure supporting scientific work flows. Operational agencies may use data and services offered through NorDataNet, but in the current situation, no Service Level Agreements will be offered for NorDataNet services. Please ask the contributing data repositories if you need such services on data found through NorDataNet.
NorDataNet is not hosting data centrally. Data archiving is done by the partners through their repositories. Further information on how to contribute data will be available through the Data Submission page. This page will be updated and eventually a central upload service will be supported. NorDataNet also plan to integrate with the Norwegian Infrastructure for Research Data (NIRD).
Once the system is fully functional, the NorDataNet hub will harvest disovery metadata from each contributing data centre and make these searchable in a unified catalogue. Data will be served from the host data centre and will not be harvested. However, bundling of data from different data centres is a functionality that will be supported as well as combination of data that are available through OPeNDAP from the host data centre.
The basic search supports search by keywords (GCMD Science Keywords), spatial and temporal extent as well as a freetext search in all available discovery metadata. The search interface will be extended with more support for faceted search and ranking. NorDataNet is following the Research Data Alliance activities in this area.
NorDataNet will offer unified search across a number of data repositories/catalogues allowing the user to search one location for information. depending on the interoperability interfaces (access protocols and data encoding/formatting) for the data served, NorDataNet will offer:
- Direct download of full datasets in the native format.
- Visualisation of gridded datasets if OGC WMS is supported for that dataset.
- Visualisation of timeseries if OPeNDAP is supported for that dataset (this functionality is limited currently) and the dataset is identified as a timeseries using the global attribute featureType set to timeSeries.
- Data reduction on the contributing data centre if the dataset is served through OPeNDAP. This implies subsetting in parameter space, as well as spatial and temporal subsetting.
- Transformations of data if data are served through OPeNDAP. This implies reformatting (changing file formats) and repojecting (changing map projections) of gridded data. For timeseries, data dump to comma separated files is supported (limited functionality currently).
Metadata are data about data. In general there are two types of metadata that scientists should be concerned about. That is Discovery metadata that are used as index cards in a library and used to search for and find relevant data. Once data have been found, data consumers needs standardised information to tell them about the content of the data and how to interpret these. This is what is understood by use metadata. For further information please check https://www.nordatanet.no/en/node/71.
The NorDataNet compliance checker tells me that I don’t have a Conventions attribute present that clarifies that it follows ACDD-1.3 standard, but I have a Conventions attribute containing "ACDD-1.3, CF-1.8"?
The reason for this issue is that the Conventions attribute is an attribute of both ACDD and CF. It can be a bit confusing as:
- acdd wants comma separated
- cf wants either space (preferred) or comma separated
According to CF:
"It is possible for a netCDF file to adhere to more than one set of conventions, even when there is no inheritance relationship among the
conventions. In this case, the value of the Conventions attribute may be a single text string containing a list of the convention names separated by blank space (recommended) or commas (if a convention name contains blanks). This is the Unidata recommended syntax from NetCDF Users Guide, Appendix A. If the string contains any commas, it is assumed to be a comma-separated list."
Thus, you should format youyr Conventions attribute with comma as the separator.