Contributors: S. B. Simonsen (Technical University of Denmark), J. Wuite (ENVEO IT GmbH)
Issued by: Technical University of Denmark / Sebastian B. Simonsen
Date: 16/08/2023
Ref: C3S2_312a_Lot4.WP3-SQAD-IS-v1_202301_GMB_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).
Generated Product: A generated product is a dataset made specifically for C3S, for the purpose of including it in the CDS.
Glacial Isostatic Adjustment (GIA): Glacial isostatic adjustment describes the response of the gravitational field, solid Earth, and the ocean to the growth and decay of the global ice sheets.
Gravimetric Mass Balance (GMB): The mass balance of an ice sheet is the net difference between mass gained from snow deposition and mass lost by melting or iceberg calving. This is essentially the same as the mass change of the ice sheet. When mass balance is derived from measured changes in the Earth's gravitational field, this is referred to as a gravimetric mass balance.
Scope of the document
The Copernicus Ice Sheets and Ice Shelves service addresses three essential climate variables (ECVs) by providing four separate products.
- Ice velocity is given for Greenland in product WP2-FDDP-IV-CDR
- Gravimetric mass balance is given for Greenland and Antarctica in product WP2-FDDP-GMB-CDR
- Surface elevation change is given for:
- Antarctica in product WP2-FDDP-SEC-CDR-AntIS
- Greenland in product WP2-FDDP-SEC-CDR-GrIS
This document is the System Quality Assurance Document for Gravimetric Mass Balance (GMB) as part of the Copernicus Ice Sheets and Ice Shelves service. It describes the organization of the data processing system and how product updates are implemented.
Executive summary
We document here the production and support systems for the Climate Data Record (CDR) v4 for Gravimetric Mass Balance (GMB).
The GMB CDR (WP2-FDDP-GMB-CDR) is a brokered product from the European Space Agency (ESA) Climate Change Initiative (CCI) program. For details, the reader is referred to the GMB sections of the ESA Greenland_Ice_Sheet_cci and Antarctic_Ice_Sheet_cci products documentation. The focus within the CCI project has been to ensure a seamless continuation of data across the transition from the Gravity Recovery and Climate Experiment (GRACE) to the GRACE follow-on (FO) mission. Hence, limited research and development (R&D) have been conducted within the CCI project in terms of GMB processing algorithms for this version v4 product. The main update within this C3S product is an update of the observational time series coverage until December 2022.
This System Quality Assurance Document is only regarding the brokering of the data record from the ESA CCI program. Hence, it only covers the processing chain from acquiring of the data from the CCI project until delivery of the CDR to CDS which is provided in Section 1. Procedures for reprocessing the CDRs are described in Section 3 and Section 5 details the user support provided for the GMB product by the C3S. Section 2, describing the upgrade cycle implementation procedure is not applicable for a brokered product as well as Section 4 which describes the system maintenance and failures.
1. System Overview
1.1. System elements and interfaces
The gravimetric mass balance is brokered from the Antarctica and Greenland CCI projects. The C3S-processing chain consists of the following steps:
- Acquire the CCI GMB data from:
- The two individual datasets are combined into a common NetCDF file with the tailored C3S-processer.
- The common NetCDF file, with data from both hemispheres is then made available for the end-users of the C3S products.
The CCI-project websites are:
- Antarctica: https://climate.esa.int/en/projects/ice-sheets-antarctic/
- Greenland: https://climate.esa.int/en/projects/ice-sheets-greenland/
which both have public documentation sections that include their product user guides, algorithm theoretical basis documents, and other useful information of the brokered data provided.
1.2. Hardware, supercomputers, and cloud computing
Not applicable to the brokered GMB data, as the creation of the final NetCDF product is done in a python environment on a laptop. The details of the hardware and software used for the GMB generation is described in the System Specification Document (SSD) of the CCI projects. The SSD can be found at:
- Antarctica: https://climate.esa.int/en/projects/ice-sheets-antarctic/key-documents/
- Greenland: https://climate.esa.int/en/projects/ice-sheets-greenland/key-documents/ 1
2. Upgrade cycle implementation procedure
Not applicable to the brokered GMB data. This is a complete, finished product of the Gravity Recovery and Climate Experiment (GRACE) mission and its follow-on mission GRACE-FO.
3. Procedures for reprocessing CDRs
The GMB has been processed for the initial data release, at the beginning of the data brokering in 2019. With the release of the Greenland and Antarctica GRACE-FO data, this initial data release has been updated and now the time series for both GRACE and GRACE-FO is present. New data releases are monitored and will be incorporated annually. We follow the R&D intensively and once reliable and validated data are available then brokering of updated GRACE-FO GMB time series for Greenland and Antarctica will be implemented. The latest release, brokered in June 2023, extends the time series up to December 2022.
4. System maintenance and system failures
Not applicable to this brokered dataset.
5. User support
The Ice Sheets and Ice Shelves 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 website2.
Once a request is sent, the Copernicus User Support 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 Copernicus User Support 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 channelled 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 GMB product, are handled by the same system.
References
Forsberg, R. et al, 2015, System Specification Document (SSD) for the Greenland Ice Sheet CCI Project of ESA's Climate Change Initiative, version v2.1. Available at https://climate.esa.int/en/projects/ice-sheets-greenland/key-documents/ (last accessed : 05/06/2023)
