Monday, April 20, 2020

How to find CMIP6 Data Citations (machine-access)?

The last post on April 2, 2020, explained how a human user can find CMIP6 data citations. For use cases where the data citation information was not stored during ESGF data download and many datasets have been analyzed, a script-based data citation access is required.

There are different options available:

1. Direct access using DRS_id

The content of the CMIP6 DOI landing pages is provided in two additional machine-readable formats: JSON and XML. The underlying metadata standard is that of DataCite 4 (see documentation:; schema definition:

For possible values of the DRS (Data Reference Syntax) components, please check the CMIP6 Controlled Vocabulary at:

Example calls for json format:

a. Model/MIP granularity:

b. Experiment granularity:

It is possible to use the ESGF Search API to collect these JSON urls for the 'experiment granularity' from the ESGF index. These 'citation_url's are part of every dataset information. More information on the ESGF Search API is available at:

2. API to list data citations based on DRS components

A list of available CMIP6 data citations in a simple JSON response can be requested via an API:

Available attributes are combined as logical AND: institutionId, sourceId, complete (true|false), drsId.

3. DataCite RestAPI to list data citations based on DRS components

DataCite also provides a RestAPI for the access of CMIP6 citation information with a registered DOI. It is documented at: . Examples for DataCite RestAPI requests are:
    1. Access of all CMIP6 DOIs:
    2. Search through the entries in the JSON response to identify them by their DRS under 'attributes/subjects/subject' with subjectScheme='DRS', e.g.


References and Links:
CMIP6 Citation Service:
CMIP6 Registration/CV:

Thursday, April 2, 2020

How to find CMIP6 Data Citations?

The IPCC AR6 Part 1 is in its Second Order Draft review. Publications to be included in the AR6 are published. The question about how to find a CMIP6 data reference comes up more frequently. The data citation recommendation is part of the DOI landing page for each data collection. But how to find that?

The different options are discussed in this post. A second blog post discusses machine-accessible options.


The best and least time-consuming option is to check the CMIP6 data citation at the time of data download in the ESGF CoG portal, e.g.
Use 'Show Citation' and follow the provided link to the landing page.

2. CMIP6 Citation Service search interface

In case the CMIP6 data citations were not stored at the time of data download, the CMIP6 Citation Service offers a dedicated search interface at: A detailed documentation with use cases is available here.

The result list includes data references for both granularities offered. For filtering a simple search using the magnifying glass and an advanced search under 'Actions' > 'Filter' are offered. Please choose the appropriate granularity for your use case. Each result gives the complete data citation recommendation. Results can be exported in csv, html and PDF formats. To reduce the downloaded information, it is possible to hide individual columns, e.g. via 'Actions' > 'Selected Columns'. Please read the 'Actions' > 'Help' for information on further functionalities.

In case a machine readable version of the complete metadata is required, it is possible to make a link to the json formatted metadata visible via: 'Actions' > 'Select Columns'.

3. DataCite Search interface

Another source with a complete record of all CMIP6 data citations is DataCite's search interface at
The search syntax is not very intuitive. An example search for MPI-M's CMIP6 data is:

A documentation of DataCite's Search is available at:

4. Google Dataset Search

CMIP6 Data Citations appear in Google Dataset Search with an unknown delay. Auto-completion supports DRS_ids.




















5. FurtherInfoUrl link

Based on the 'furtherInfoUrl' global attribute provided in each NetCDF file header, the CMIP6 Data Citation information can be accessed via a page hosted by ES-DOC, e.g.

6. OpenAIRE's Explore portal

An alternative to DataCite's Search offers OpenAIRE's Explore portal The search functionality of the Explorer is similar to that of DataCite but easier to use. However, a temporal delay has to be taken into account when using this portal, as the CMIP6 Citation information is harvested by OpenAIRE from DKRZ's OAI server.

To search through CMIP6 data citation information, please use this link as entry point.

References and Links:
CMIP6 Citation Service:
Google Dataset Search:
OpenAIRE Explore:

Monday, December 23, 2019

CMIP6 Citation Service in context of data citation principles and IPCC's 6th assessment cycle and its uncertain future

The CMIP6 Citation Service as part of the infrastructure for CMIP6 (Coupled Model Intercomparison Project Phase 6) enable the citation of CMIP data for the first time. Data references are planned to compliment paper references in the next IPCC (Intergovernmental Panel on Climate Change) assessment report AR6 (Stockhause et al., 2019). More specific IPCC author guidelines are about to be sent to the authors in early 2020. The goal is twofold:
  • to improve the transparency of the AR6 by an increased traceability of its key results, and
  • to give credit to the providers of source data analysed by the authors.
The IPCC author guidelines implement the general author guidelines for data citation developed within the 'Enabling FAIR data project' (Stall et al., 2017). Many publishers and repositories have subscribed these guidelines. Apart from FAIR (Findable, Accessible, Interoperable, Reusable), the long-term preservation and curation of the AR6 data in the trusted (TRUST: Transparency, Responsibility, Users, Sustainability, Technology) repository of the IPCC Data Distribution Centre (DDC) is part of IPCC's new author guidance.

The CMIP6 Citation Service itself recommends to cite input4MIPs (Durack et al., 2019) data as well as papers underpinning the CMIP6 data.

Implementation and maintenance as well as documentation and support for the CMIP6 Citation Service relies on institutional resources and an increasing share of my spare time. As many other infrastructure components for international projects, the service has no substantial nor long-term funding. Thus my institution has to be convinced that investing in the CMIP6 citation service is worthwhile, which requires

  • usage numbers and
  • user stories / feedback.
Thus, I cordially invite you to leave comments to share your opinion about the CMIP6 Citation Service - its value, your usage and experiences of it as well as your ideas for its further development and sustainable funding or anything else you want to share.

References and Links:
Durack et al. (2018). Toward standardized data sets for climate model experimentation, Eos, 99, Published on 02 July 2018.
Stall et al. (2017). Enabling FAIR data across the Earth and space sciences, Eos, 98, Published on 08 December 2017.
Stockhause et al. (2019). Data Distribution Centre Support for the IPCC Sixth Assessment. Data Science Journal, 18(1), p.20.
Coupled Model Intercomparison Project Phase 6 (CMIP6):
CMIP6 Citation Service: 

CMIP6 Citatin Service Statistics:
Coalition for Publishing Data in the Earth and Space Sciences (COPDESS):
Intergovernmental Panel on Climate Change (IPCC):
IPCC Data Distribution Centre (DDC):