Contributors: Jacqueline Bannwart (University of Zurich), Inés Dussailan (University of Zurich), Frank Paul (University of Zurich), Michael Zemp (University of Zurich)
Issued by: UZH / Frank Paul
Date: 23/03/2024
Ref: C3S2_312a_Lot4.WP3-SQAD-GL-v2_202401_A_System_Quality_Assurance_i1.1
Official reference number service contract: 2021/C3S2_312a_Lot4_EODC/SC1
History of modifications
List of datasets covered by this document
Related documents
Acronyms
General definitions
Brokered Product: A brokered product is a pre-existing dataset to which the Copernicus Climate Change Service (C3S) acquires a license, for the purpose of including it in the Climate Data Store (CDS).
For the glacier area product, we define the Randolph Glacier Inventory (RGI) as a Climate Data Record (CDR) and the regionally and temporarily constrained improvements or updates submitted to the Global Land Ice Measurements from Space (GLIMS) database as Interim Climate Data Records (ICDRs). Several of them have been integrated in the new releases of the CDR (i.e. RGI version 7.0).
GLIMS database: Stores (after a quality check) all multi-temporal glacier outlines along with their attribute information as provided by the community. All datasets can be freely downloaded (CC BY 4.0 License). Hosted by NSICD in Boulder, CO.
Randolph Glacier Inventory (RGI): Spatio-temporal subset of the GLIMS database, contains for each glacier one outline. The selection is currently performed by an IACS Working Group. Hosted by NSICD in Boulder, CO.
Fluctuations of Glaciers (FoG) database: Contains information on glacier fluctuations (length, area, volume/mass) collected by Principle Investigators and provided by National Correspondents to WGMS. The FoG database is hosted by WGMS in Zurich, Switzerland.
Scope of the document
This document is the System Quality Assurance Document (SQAD) for the Copernicus glacier distribution service. It describes how the data processing system is organised in general and how product updates are implemented in the Global Land Ice Measurements from Space (GLIMS) and Climate Data Store (CDS) databases. The relevant products are glacier area and glacier mass change. The focus of this document is on the glacier area product, but due to the joint set-up of the work, the mass change product is included in the figures (see related SQAD for the mass change product [RD1]). This document also describes the difference between the datasets (ICDRs - Interim Climate Data Records) produced by the service and the dataset (CDR - Climate Data Record) provided to the CDS.
Executive summary
After presenting the general set-up of data production and provision, we describe the specifics of data production for the glacier area product. In contrast to other Essential Climate Variable (ECV) products, glacier outlines are manually created from individual satellite scenes by an analyst on a desktop computer and datasets usually have a time stamp and are spatially restricted. These spatio-temporal subsets are named ICDRs. The related products (glacier outlines / inventories and elevation / mass changes) are created by the science community and the C3S team and provided to the established databases of GLIMS and World Glacier Monitoring Service (WGMS), respectively. From here, the datasets are extracted and composed to new products with global coverage (the RGI and a global mass change grid) and shared with the community. Both products are then brokered for the Climate Data Store (CDS). We also describe the upgrade cycle and implementation procedure for the Copernicus Climate Change Service (C3S), highlighting the differences between datasets produced by us (ICDRs) and those provided as a CDR to the CDS. At the end of this document, the procedures for CDR reprocessing, system maintenance and user support are given.
1. System overview
1.1. System elements and interfaces
This section describes the set-up for both the glacier area and mass change products, as it is the same system that is used to produce both products. Both products are provided by the Copernicus Climate Change Service (C3S) via the Climate Data Store (CDS) and are created by the University of Zurich (UZH) team (green circles) and the global science community (light blue cloud in Figure 1).
The latter consists of (a) dedicated contributors to Global Land Ice Measurements from Space (GLIMS) and the Randolph Glacier Inventory (RGI), (b) independent scientists creating glacier outlines and elevation change products within their science projects who are willing to share their results, and (c) national correspondents as well as principal investigators of the World Glacier Monitoring Service (WGMS) network providing glacier change measurements to the Fluctuations of Glaciers (FoG) database. These three groups either provide their data directly to the two databases (blueish arrows pointing to the GLIMS and FoG data bases) or the UZH team asks authors to share their data and integrate them in one or other of these databases. The Interim Climate Data Records (ICDRs) created by the UZH team for the area product is provided to the GLIMS database as well as the Earth Observation Data Centre (EODC) server for inspection by the C3S team. These ICDRs are not forwarded to the CDS. This is only done for the RGI (grey arrow), which is a spatio-temporal subset of the multi-temporal GLIMS database and providing exactly one outline for each glacier. The dataset from the FoG is converted to a grid before it is provided to the EODC server and the CDS.
Figure 1: Schematic overview of the C3S Data Production System for glaciers. The glacier inventory and glacier change production systems are green, existing data repositories are blue and forwarding of CDRs to the EODC database from where the datasets are accessed by the CDS is shown in grey.
As dissemination of the latest FoG database is performed by WGMS, the update (with ICDRs) and redistribution of a new dataset is performed by the UZH team and will be provided once per year (as a reprocessed Climate Data Record (CDR)) to the Climate Data Store (CDS).
Compilation of a new version of the RGI (the CDR of the area product) and the related update cycle, is performed by the International Association for Cryospheric Sciences (IACS) working group on the Randolph Glacier Inventory1 [IACS WG-RGI]. We will, thus, provide new versions of the RGI to the CDS when the working group makes new releases available.
In particular, the GLIMS database ishosted at the National Snow and Ice Data Center (NSIDC) in Boulder (CO) and is continuously assimilating new datasets from contributors all over the world. Thus the C3S contribution to this database might be small. However, as a member of the GLIMS executive board and the IACS working group on the RGI we have a direct link to key stakeholders (GLIMS director and RGI co-leads) and thus data production or service needs of the community. This will lead to a very efficient and targeted data production and provide an important contribution. The key media for information exchange between the different groups are email, telecons, and meetings at conferences or dedicated workshops. Overall coordination of the international data centres and services (NSDIC, WGMS) and the different working groups (GLIMS, RGI) will be done within the framework of the Global Terrestrial Network for Glaciers (GTN-G2) during its periodic executive board meetings.
1.2. Hardware, supercomputers and cloud computing
Data processing for the glacier area product is performed by individual analysts on standard desktop computers or servers (see Figure 2). There is no need for special hardware, supercomputers or cloud computing. There is, however, need for specific (typically commercial) image processing and/or Geographic Information System (GIS) software to create the products out of the raw satellite data or from digital elevation models (DEMs), for example drainage divides and topographic parameters for each glacier. Also conversion of the glacier outlines in vector format to a gridded version is performed with such software. We mostly use the ArcGIS software from ESRI and various MS Office software products.
Figure 2: Main differences between data production for the Glacier ECV (right) and most other ECVs (left). Whereas most other ECVs work with a large amount of data processed at the same time on a supercomputer (or mainframe) to create global scale products (left part of the image), glacier outlines are derived from individual satellite images on a desktop computer at a regional scale and are merged to a global product by integrating results from numerous analysts (right).
2. Upgrade cycle and implementation procedure
To better understand the differences of the implementation procedure for the two products (glacier area and mass changes), we also show in Figure 3 both products collectively. The area product created by UZH (an ICDR, orange arrow) is submitted to the GLIMS database and to the EODC server (for inspection). Vector and raster versions of the RGI are extracted from GLIMS and are also provided to EODC from where they are forwarded to the C3S CDS (grey arrows below Jan23 and Jan24). Whereas the update cycle for the FoG database is every 12 months, a new version of the RGI is provided when new releases become available. The related datasets are brokered from the respective repositories (area from the RGI in vector format). To also have measureable progress for the glacier area product, we will provide the generated ICDRs to both the GLIMS database and the Earth Observation Data Centre (EODC) server. However, these spatio-temporal extensions will not be forwarded to the CDS.
Figure 3: Principle set up and timeline of data production (ICDRs – orange arrows), data integration in the respective databases (blue) and forwarding of the CDRs to the C3S Climate Data Store (grey).
In summary, we have two data streams:
(1) One consisting of the two CDRs (RGI and gridded mass change product) that are provided to the climate data store (CDS) once per year, and
(2) New and improved glacier outlines ICDRs that will be provided to GLIMS and elevation and mass change ICDRs that will be provided to the FoG database at WGMS.
3. Procedures for reprocessing CDR's
Our targeted ICDR data production for the RGI (replacing regions with poor quality and adding regions with outlines from different dates) is intended to contribute to new versions of the RGI. The specific regions that are to be updated depends on data availability and user requirements. User requirements are discussed and coordinated by the IACS working group for the RGI. They are also in charge of the contents of future RGI versions.
4. System maintenance and system failures
The chance of system failure is small, as the system is globally distributed rather than centralised. A global community is providing glacier outlines and for long-term maintenance the GLIMS and RGI databases are now hosted at the National Aeronautics and Space Administration (NASA) Distributed Active Archive Centers (DAAC). Moreover, key processing algorithms to create glacier outlines are very simple (band ratio) and can be used in a wide range of processing environments, including free software.
5. User support
The Glaciers service has a team account with the Copernicus User Support (CUS) Jira Service Desk System, to provide level 2 user support, i.e. to answer enquiries specific to their products, by direct interaction with the user through the Jira helpdesk. The request to the CUS can be sent via tag “Scientific or technical question about our products (create ticket)” on the Support Portal Home webpage3.
Once a request is sent, the CUS Service team at the European Centre for Medium-Range Weather Forecasts (ECMWF) will handle the requests within 8 hours (level 1).
For any scientific and special enquiries that cannot be answered by the CUS team at ECMWF or addressed to the Knowledge Base, the request will be forwarded to the Copernicus User Support Specialists (level-2).
Enquiries forwarded to the CUS Specialist team will be acknowledged within 3 working days (target 100%) and a notification sent to the user. In case of specific scientific issues, the enquiries will be channeled to the ECV and data specialist of the C3S2_312a_Lot4 project and should be resolved within 3 working weeks (target 85%). In each quarter, we aim for User Support satisfaction scoring 3 in 90% of all voluntary based feedbacks by users, with 1 (very unsatisfied) to 5 (very satisfied). We will also list the number of tickets in the Quarterly Report.
All products made by the team, including the Glacier Area product, are handled by the same system.
