Randolph Glacier Inventory (RGI) and its role in future glacier monitoring and GLIMS
(2020 – 2023)
Fabien Maussion, University of Innsbruck, Austria
Regine Hock, University of Alaska Fairbanks, USA
Frank Paul, University of Zurich, Zurich, Switzerland
Philipp Rastner, University of Zurich, Zurich, Switzerland
Bruce Raup, National Snow and Ice Data Center, Boulder, USA
Michael Zemp, World Glacier Monitoring Service, Zurich, Switzerland
Liss Andreassen (Norway), Tobias Bolch (UK), Nicolas Champollion (France), Matthias Dusch (Austria), Koji Fujita (Japan), Ajanta Goswami (India), Matthias Huss (Switzerland), James M Lea (UK), Akiko Sakai (Japan), Antoine Rabatel (France), David Rounce (US), David Shean (US), Thorsten Seehaus (Germany)
Har Amrit Singh Sandhu, Iestyn Barr, Etienne Berthier, Wilson Cheung, Luke Copland, Bethan Davies, Amaury Dehecq, Ankur Dixit, Tatiana Khromova, Russia, Peter Kirchner, Jack Kohler, Lukas Krieger, Rohit Kumar, India, Kirsty Langley, Emilio Mateo, Dan McGrath, Francisco Navarro, Ben Roberts-Pierel, Dirk Scherler, Christoph Schneider, Levan Tielidze, Hendrik Wulf
The Randolph Glacier Inventory (RGI) is a globally complete collection of digital glacier outlines, excluding the polar ice sheets. It was created with limited resources to meet the needs of the assessment reports of the Intergovernmental Panel on Climate Change (IPCC). It has become a pillar of glaciological research at global and regional scales, for estimates of recent and future glacier changes, glacier mass balance, and glacier contribution to sea-level rise. After its creation in 2012, the dataset’s further development has been coordinated by an earlier IACS Working Group.
The latest RGI version (V6) was released in July 2017. In the past, the RGI was produced with an ad-hoc manual process, which was effective but labor-intensive. One of the main objectives of the WG is to automate this process as much as possible by incorporating RGI generation tools into the Global Land Ice Measurements from Space (GLIMS) database. Furthermore, the RGI (as of version 6) needs further improvements to remain useful to the wider scientific community. Examples include data quality (wrong/outdated outlines, ice divides) but also the quality and availability of glacier attributes (hypsometry, glacier type…). Additionally, there is also a demand for consistent historic glacier outlines (e.g. from the mid-1980s or earlier) to facilitate validation of glacier evolution models or transient mass balance calculations. In this WG, we strive to continuously improve and update the RGI, as well as to lay out a long-term plan for sustainable continuation of the RGI beyond the end of this WG.
The WG will have the following general objectives:
- Make GLIMS the single entry point to access future RGI versions
- Develop tools in GLIMS to allow outline selection by date and possibly other attributes (e.g. analyst) at the global level.
- Automate the process of glacier attribute generation and data formatting, so that future RGI versions can be generated semi-automatically.
- Discuss and propose a way to implement a sustainable release cycle for the various RGI products, which will depend on long-term institutional funding.
- Extend the RGI with more attributes.
- Provide different “snapshots” of the RGI by date: e.g. around 2000, 2015, 1985, or select glacier outlines by proximity to given date, i.e. to match that of a reference elevation model (SRTM, Arctic DEM, TanDEM-X, national DEMs).
- Provide glacier outlines in various levels of data precision and geometrical complexity (i.e. including ice divides, or ‘merged’ entities).
- Continue to extend the RGI with new and improved attributes such as debris cover, ice thickness (i.e. incorporate the output of the now finished IACS WG “Glacier ice thickness estimation”), snow line altitudes, snow cover fractions, glacier length, bathymetry of calving glaciers, surface flow velocities, etc.
- Engage a sustainable community around the open development of the RGI
Whenever possible, provide the tools used to achieve objectives A and B in open online repositories, in order to encourage code reviews and improvements from the community.
- Open a discussion platform for users and developers to come together and discuss issues around the RGI. This platform should be inclusive and ideally replace private e-mails for all discussions related to the RGI dataset itself: it can take the form of open meetings, open meeting notes, and a low-maintenance online forum (e.g. GitHub issues).
- Regularly invite members of the broader glaciological community to contribute to the RGI with improvement to either data or tools.
- Provide educational material about the RGI and related products.
- Communicate with universities, research centres, employers, funding agencies and scientific journals to raise awareness about the usefulness of the RGI and to encourage its sustainable development.
- Publication of an updated version of the RGI based on a new, semi-automated extraction and attribute generation workflow (Version 7).
- Publication of an online platform for open discussions related to the RGI based on existing tools such as GitHub or GitLab or may be hosted at GLIMS.
- Publication of open-source tools for automated glacier attribute generation (where possible). A prototype is already available (rgitools).
- Updated technical notes to accompany each release of a new RGI version which is hosted at GLIMS.
- Glacier mapping guidelines to increase the consistency in interpretation.
- Educational material about the RGI in the form of online tutorials and workshops.
- Publication of new RGI products (RGI-2015 and RGI-1985) as unprecedented time-dependent global inventories to be extracted from the GLIMS database.
- A long-term plan for sustainable continuation of the RGI beyond the end of this WG in partnership with GLIMS.
Membership and contribution to the RGI
The RGI is a community product. Its future development depends on broad involvement. Participation in the Working Group (WG) is open; we welcome broad international participation and aim for diversity with regard to gender, geographic spread and career stage. We welcome two levels of WG participation, WG Members and/or WG Contributors:
WG members are expected to contribute actively to the goals of the WG and strategic decisions and to participate in annual WG meetings (mostly held at conferences; remote participation via telecon can be arranged) and possible telecons in between. WG members must be IACS Member.
WG Contributors are all individuals who have contributed or will contribute to any outlines to GLIMS that will be used in the next RGI to be released by the end of 2020. All contributors will be part of the RGI Consortium and named and acknowledged in the next RGI release.
If you are interested in joining and contributing to the WG (as Member or Contributor), please contact Fabien Maussion (fabien.maussion @ uibk.ac.at) and Regine Hock (rehock @ alaska.edu), and let us know (latest by 20 February 2020) how you intend to contribute to the goals of the WG and/or for which regions you are able to provide outlines for consideration for the next RGI version (any new outlines must be submitted through GLIMS – a specific call for data will follow). We also welcome any feedback you might have about the RGI and the goals of the WG: we aim to make the RGI as useful as possible for anyone!
RGI or GLIMS outlines ?
The RGI was developed to provide glacier outlines for large-scale (regional to global) assessments of recent glacier mass changes and glacier projections, not for small-scale studies. In particular, the dataset is often not adequate for area change detection. For change detection of specific regions multi-temporal outlines from GLIMS should be used and GLIMS should be acknowledged as the source.
All outlines used in the RGI are taken from GLIMS at the National Snow and Ice Data Center (NSIDC) which remains the data center for hosting, archiving and glacier outlines and through which new outlines should be submitted.