Issued by: Technical University of Denmark / Sebastian B. Simonsen
Date:
Ref: C3S2_312a_Lot4.WP2-FDDP-IS-v1_202212_GMB_PUGS-v4_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): also known as post-glacial rebound, is the gradual rise of land in regions previously covered by ice sheets during glaciations. As the ice melts and retreats, the Earth's crust rebounds back to its original position over thousands of years. GIA affects sea levels, coastlines, and geological processes, and is essential for understanding Earth's history and predicting future changes.
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.
Leakage: for the GRACE mission, leakage refers to unwanted signal interference between twin satellites, impacting the precise gravity field measurements. This interference can arise from factors like Earth's tides, atmospheric drag, and variations in spacecraft orientation or position.
Zwally Basins: the basins are widely used glaciological basin definitions based on ice flow. This has become a de facto standard with the IMBIE project: http://imbie.org/imbie-3/drainage-basins/.
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 the Greenland ice sheet in product WP2-FDDP-SEC-CDR-GrIS
This document is the Product User Guide and Specification for Gravimetric Mass Balance (GMB) as part of the Copernicus Ice Sheets and Ice Shelves service. It describes the datasets produced and their specifications.
Executive summary
This document deals with gravimetric mass balance for Greenland and Antarctic ice sheets. This dataset is a brokered dataset from the ESA CCI, and a complete overview of the data generation can be found in the relevant documentation available at:
- Antarctic Icesheet (AIS): https://climate.esa.int/en/projects/ice-sheets-antarctic/key-documents/
- Greenland Icesheet (GrIS): https://climate.esa.int/en/projects/ice-sheets-greenland/key-documents/
This document provides a guide to usage and specifications for the two GMB polar region products. The first section of the document describes the product itself including the target requirements and data usage information, whereas section 2 provides the data access information. It should be highlighted that section 1 contains key information related to the sensors used in the production of the brokered dataset by the ESA CCI teams and insights into the C3S generated netCDF file which are available at the CDS.
Product Change Log
Version | Product Changes |
V1 | Initial product brokering the CCI GMB products. |
V2 | Added GRACE-FO data for the Greenland ice sheet |
V3 | Updating the Greenland time series and adding the Antarctica GRACE-FO |
| V4 | Updating the time series |
1. Product description
The GMB relies solely on remote sensing data from the Gravity Recovery And Climate Experiment (GRACE) mission and its follow-on mission (GRACE-FO) to provide estimates of mass balance changes of the major drainage basins of Greenland and Antarctica. The GRACE-FO mission was launched on May 22, 2018, and the GRACE mission ended in October 2017, this resulted in a data gap in the GMB record. The GRACE solution provided for the major drainage basins is brokered from the European Space Agency (ESA) Greenland and the Antarctic ice sheet Climate Change Initiative (CCI) projects. For both processing algorithms and uncertainty estimates, we refer to Barletta, Sørensen, and Forsberg (2013) and Groh and Horwath (2016). In Climate Data Record (CDR) v4.0 GMB products solutions for the GRACE-FO data are brokered from the ESA Antarctic ice sheets CCI and the ESA Greenland ice sheets CCI projects.
Specification summary:
- Sensors: GRACE and GRACE-FO
- Grid: major drainage basins
- Time range:
- Antarctic 2002 to June 2017 and June 2018 to the end of 2020
- Greenland 2002 to June 2017 and June 2018 to the end of 2020
- Time intervals: Monthly
- Validation frequency: N/A
- Quality flagging: N/A
In the following, we will use the term GRACE to mean GRACE and GRACE-FO, unless GRACE-FO needs to be explicitly mentioned.
1.1. Target requirements
The target requirements for the GMB are based on recommendations of both GCOS and C3S.
- Basin-level accuracy: 10km3/yr
- Stability: 10km3/yr
The requirements are given in terms of volume change, whereas what is measured is mass, a conservative volume-to-mass conversion in terms of target requirements is ice densities (917 kg/m3). It should be noted that the requirements on basin-scale accuracy cannot be reached in Antarctica, due to the large errors in the GIA (glacial isostatic adjustment) correction, which is at the level of 25-30 Gt/yr for all of Antarctica.
1.2. Data usage information
The product provides summed estimates at major drainage basins for both ice sheets. The basin definition is also provided in the file, in order to make the product more transparent for the end user. The resolution of the GRACE measurement results in difficulties in separating mass changes across drainage boundaries.
1.2.1. Product Data Format and Content
The product is provided as a NetCDF file with separate layers for the individual drainage basins of the two ice sheets on Earth. For both hemispheres, the drainage basin definition is included in the file. In Table 1 below we list the most important variables in the product files.
Table 1: GMB main data variables
Variable name | Variable description | Type |
AntBasin | Definition of the major Antarctic drainage basins, given by the latitude longitude and basin number [degree, degree, ~] | 3*32-bit floating-point |
AntIS_x | Gravimetric mass balance of Antarctic basin X [Gt] | 32-bit floating-point |
GrISBasin | Definition of the major Greenland drainage basins, given by the latitude longitude and basin number [degree, degree, ~] | 3*32-bit floating-point |
GrIS_x | Gravimetric mass balance of Greenland basin X [Gt] | 32-bit floating-point |
time | Central time of gravimetric mass balance, in hours since 1990.0 | 32-bit floating-point |
1.2.2. Product known limitations
Limitations to the GRACE product include:
- Spatial resolution. The real GRACE spatial resolution is around 200-250 km, but maps are provided at 50 km resolution. The higher resolution in the grid product is needed to properly reflect and compare to the mass domains solved for the "drainage basin" products. The GRACE mass measurements for Greenland are also given as 8 "Zwally Basins", using a subdivision going back in time to early satellite altimetry estimates. See Zwally et al. (2012). In addition, a total mass change product for all of Greenland, including outlying ice caps and glaciers, is given. The GRACE measurements for Antarctica are given similarly for the 27 Zwally basins.
- Solution space: the GRACE mass change product is derived by two different methods: direct inversion and spectral estimation. The "leakage" of mass change from glaciers and ice caps from Canada is treated differently in these methods, and therefore the total Greenland mass change is different, as GRACE minute differences in the processing aproches are able to redistbute of mass changes between North-West Greenland and ice caps on the Canadian side. Furthermore, the spectral method estimates drainage basins independently, meaning that the mass loss sum of all basins does not sum to the best estimate for all of Greenland. Since signal leakage is one of the largest error sources in GRACE mass loss estimates, both methods are retained in C3S and provide a measure of method-related errors.
- Time resolution: The C3S GRACE data are based on monthly averages. The time stamp refers to the centre of the month.
- For the first GRACE mission, the solution after 2014 is relatively degraded and the temporal resolution is also affected. That means that some solutions are actually for more than one month. This is not the case when the time series is continued by GRACE-FO
1.2.3. Product Nomenclature
The dataset filename as provided by CDS is of the format
C3S_GMB_versx.nc, where:
- C3S is the overall project
- GMB is the ECV addressed, ie gravimetric mass balance
- versx is the version number of the processing code
1.2.4. Structure of netcdf files
The header data for an example NetCDF data file is given in Table 2.
Table 2: Sample of the structure of the provided NetCDF file for the Gravimetric mass balance. This structure is the same for version 4 as here provided for version 2. The update is a prolongation of time series (the time dimension(t) in the netCDF-file)
netcdf C3S_GMB_GRACE_vers2.nc {
dimensions:
t = 180;
AntB = 901322;
GrisB = 272965;
N = 3;
variables:
float time(t=180);
:long_name = "Time";
:standard_name = "time";
:units = "hours since 1990-01-01T00:00:00Z";
float AntBasin(N=3, AntB=901322);
:long_name = "Antarctic_Basin_definition";
:column_meanings = "Latitude, Longitude, basin_number";
:units = "degrees_north degrees_east number";
:reference = "Zwally antarctic basins http://imbie.org/imbie-3/drainage-basins/";
float GrISBasin(N=3, GrisB=272965);
:long_name = "Greenland_Basin_definition";
:column_meanings = "Latitude, Longitude, basin_number";
:units = "degrees_north degrees_east number";
:reference = "Zwally Greenland basins http://imbie.org/imbie-3/drainage-basins/";
float GrIS_total(t=180);
:long_name = "Greenland_ice_sheet_total_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float GrIS_total_er(t=180);
:long_name = "Greenland_ice_sheet_total_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float GrIS_1(t=180);
:long_name = "Greenland_ice_sheet_basin_1_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float GrIS_1_er(t=180);
:long_name = "Greenland_ice_sheet_basin_1_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float GrIS_2(t=180);
:long_name = "Greenland_ice_sheet_basin_2_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float GrIS_2_er(t=180);
:long_name = "Greenland_ice_sheet_basin_2_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float GrIS_3(t=180);
:units = "Gt";
:long_name = "Greenland_ice_sheet_basin_3_GMB";
:_ChunkSizes = 180U; // uint
float GrIS_3_er(t=180);
:long_name = "Greenland_ice_sheet_basin_3_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float GrIS_4(t=180);
:units = "Gt";
:long_name = "Greenland_ice_sheet_basin_4_GMB";
:_ChunkSizes = 180U; // uint
float GrIS_4_er(t=180);
:long_name = "Greenland_ice_sheet_basin_4_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float GrIS_5(t=180);
:long_name = "Greenland_ice_sheet_basin_5_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float GrIS_5_er(t=180);
:long_name = "Greenland_ice_sheet_basin_5_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float GrIS_6(t=180);
:long_name = "Greenland_ice_sheet_basin_6_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float GrIS_6_er(t=180);
:long_name = "Greenland_ice_sheet_basin_6_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float GrIS_7(t=180);
:long_name = "Greenland_ice_sheet_basin_7_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float GrIS_7_er(t=180);
:long_name = "Greenland_ice_sheet_basin_7_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float GrIS_8(t=180);
:long_name = "Greenland_ice_sheet_basin_8_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float GrIS_8_er(t=180);
:long_name = "Greenland_ice_sheet_basin_8_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_1(t=180);
:long_name = "Antarctic_ice_sheet_basin_1_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_1_er(t=180);
:units = "Gt";
:long_name = "Antarctic_ice_sheet_basin_1_GMB_error";
:_ChunkSizes = 180U; // uint
float AntIS_2(t=180);
:long_name = "Antarctic_ice_sheet_basin_2_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_2_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_2_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_3(t=180);
:long_name = "Antarctic_ice_sheet_basin_3_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_3_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_3_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_4(t=180);
:long_name = "Antarctic_ice_sheet_basin_4_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_4_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_4_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_5(t=180);
:long_name = "Antarctic_ice_sheet_basin_5_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_5_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_5_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_6(t=180);
:long_name = "Antarctic_ice_sheet_basin_6_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_6_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_6_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_7(t=180);
:long_name = "Antarctic_ice_sheet_basin_7_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_7_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_7_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_8(t=180);
:long_name = "Antarctic_ice_sheet_basin_8_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_8_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_8_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_9(t=180);
:long_name = "Antarctic_ice_sheet_basin_9_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_9_er(t=180);
:units = "Gt";
:long_name = "Antarctic_ice_sheet_basin_9_GMB_error";
:_ChunkSizes = 180U; // uint
float AntIS_10(t=180);
:long_name = "Antarctic_ice_sheet_basin_10_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_10_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_10_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_11(t=180);
:long_name = "Antarctic_ice_sheet_basin_11_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_11_er(t=180);
:units = "Gt";
:long_name = "Antarctic_ice_sheet_basin_11_GMB_error";
:_ChunkSizes = 180U; // uint
float AntIS_12(t=180);
:long_name = "Antarctic_ice_sheet_basin_12_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_12_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_12_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_13(t=180);
:long_name = "Antarctic_ice_sheet_basin_13_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_13_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_13_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_14(t=180);
:long_name = "Antarctic_ice_sheet_basin_14_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_14_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_14_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_15(t=180);
:long_name = "Antarctic_ice_sheet_basin_15_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_15_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_15_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_16(t=180);
:long_name = "Antarctic_ice_sheet_basin_16_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_16_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_16_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_17(t=180);
:long_name = "Antarctic_ice_sheet_basin_17_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_17_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_17_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_18(t=180);
:long_name = "Antarctic_ice_sheet_basin_18_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_18_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_18_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_19(t=180);
:long_name = "Antarctic_ice_sheet_basin_19_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_19_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_19_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_20(t=180);
:long_name = "Antarctic_ice_sheet_basin_20_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_20_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_20_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_21(t=180);
:long_name = "Antarctic_ice_sheet_basin_21_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_21_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_21_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_22(t=180);
:long_name = "Antarctic_ice_sheet_basin_22_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_22_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_22_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_23(t=180);
:long_name = "Antarctic_ice_sheet_basin_23_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_23_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_23_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_24(t=180);
:long_name = "Antarctic_ice_sheet_basin_24_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_24_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_24_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_27(t=180);
:long_name = "Antarctic_ice_sheet_basin_27_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_27_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_27_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_25_26(t=180);
:long_name = "Antarctic_ice_sheet_basin_25_and_26_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_25_26_er(t=180);
:long_name = "Antarctic_ice_sheet_basin_25_and_26_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntPeninsula_total(t=180);
:long_name = "Antarctic_Peninsula_total_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntPeninsula_total_er(t=180);
:long_name = "Antarctic_Peninsula_total_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float East_AntIS_total(t=180);
:long_name = "East_Antarctic_ice_sheet_total_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float East_AntIS_total_er(t=180);
:long_name = "East_Antarctic_ice_sheet_total_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float West_AntIS_total(t=180);
:long_name = "West_Antarctic_ice_sheet_total_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float West_AntIS_total_er(t=180);
:long_name = "West_Antarctic_ice_sheet_total_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_total(t=180);
:long_name = "Antarctic_ice_sheet_total_GMB";
:units = "Gt";
:_ChunkSizes = 180U; // uint
float AntIS_total_er(t=180);
:long_name = "Antarctic_ice_sheet_total_GMB_error";
:units = "Gt";
:_ChunkSizes = 180U; // uint
// global attributes:
:Title = "GMB for Greenland and Antarctica ice sheets from the GRACE missions";
:institution = "DTU Space - Geodesy and Earth Observations";
:reference = "Baratta et al. (2016), Groh and Horwart (2016)";
:file_creation_date = "Tue Nov 10 10:51:12 2020";
:region = "Greenland and Antarctica";
:missions_used = "For Antarctica GRACE only and for Greenland both GRACE and GRACE-FO";
:time_coverage_start = "2003";
:time_coverage_end = "2019 (2016 for Antarctica)";
:Tracking_id = "24398bcd-4138-4414-8f66-deb6dfc5c879";
:netCDF_version = "NETCDF4";
:product_version = "2.0";
:Summary = "This data set is prepared for the C3S project, and is brokered from the CCI+ projects of Antarctica and Greenland ice sheets";
}
2. Data access information
2.1. All products
Data is available through the Copernicus Climate Data Store (CDS), which is the sole data distributor. Registration (free) is required to access the CDS and its toolbox software suite. The CDS is a web-based service, with its homepage at https://cds.climate.copernicus.eu/cdsapp#!/home
Data can be downloaded from the website and used under the License to Use Copernicus Products (included on the download page). Data may also be viewed online.
All requests for information or further data should be channelled through the CDS Knowledge Base at https://confluence.ecmwf.int/display/CKB/
References
Barletta, V.R., Sørensen, L.S. and Forsberg, R. (2013). Scatter of mass changes estimates at basin scale for Greenland and Antarctica. The Cryosphere, 7, 1411-1432
Groh, A., and Horwath, M. (2016). The method of tailored sensitivity kernels for GRACE mass change estimates. Geophysical Research Abstracts, 18, EGU2016-12065.
Zwally, H.J., Giovinetto, M.B., Beckley, M.A. and Saba, J.L. (2012). Antarctic and Greenland drainage systems, GSFC cryospheric sciences laboratory. Available at https://earth.gsfc.nasa.gov/cryo/data/polar-altimetry/antarctic-and-greenland-drainage-systems
This document has been produced in the context of the Copernicus Climate Change Service (C3S).
The activities leading to these results have been contracted by the European Centre for Medium-Range Weather Forecasts, operator of C3S on behalf of the European Union (Contribution agreement signed on 22/07/2021). All information in this document is provided "as is" and no guarantee or warranty is given that the information is fit for any particular purpose.
The users thereof use the information at their sole risk and liability. For the avoidance of all doubt , the European Commission and the European Centre for Medium - Range Weather Forecasts have no liability in respect of this document, which is merely representing the author's view.
