The main technical characteristics of the GFM product are summarized below. The eleven output layers of worldwide flood information are continuously and automatically generated in near real-time by the GFM product based on the latest Synthetic Aperture Radar (SAR) image data acquired by the Sentinel-1 satellites.
| Input satellite data | |
| Satellite sensor | S-1 - Synthetic Aperture Radar (SAR) |
| Acquisition mode | Interferometric Wide Swath (IW) |
| Data product | Level-1 - Ground Range Detected (GRD) |
| Spatial sampling | 20 x 22 metres |
| Global revisit frequency | Europe: ~1-3 days. Rest of the world: ~3-14 days, depending on location |
| SAR polarisation scheme | VV + VH |
| General product specifics | |
| Geographic coverage | Global |
| Pixel size | 20 metres |
| Timeliness | <8 hours after S-1 image acquisition. |
| Thematic accuracy | Target threshold of >70-80%, based on the Critical Success Index |
The eleven GFM product output layers are briefly described in the following sub-sections. For a more detailed technical description of the GFM product output layers, please refer to the GFM Product Definition Document (PDD).
| Output layers | Description | Data formats | Availibility in beta version of GFM product |
¶ 1. S-1 Observed Flood Extent |
Flooded areas mapped using S-1 SAR backscatter intensity | raster (geotiff) |
yes |
| vector(shapefile) |
not yet |
||
¶ 2. S-1 Observed Water Extent |
Open and calm water mapped as the union of the output layers S-1 Observed Flood Extent and S-1 Reference Water Mask | raster (geotiff) |
yes |
| vector (shapefile) |
not yet |
||
¶ 3. S-1 Reference Water Mask |
Normal (i.e. permanent, seasonal) water mapped using S-1 SAR backscatter intensity. | raster (geotiff) |
yes |
| vector (shapefile) |
not yet |
||
¶ 4. Exclusion Mask |
Unclassified areas (e.g., urban areas; dense vegetation, flat and impervious areas, sandy surfaces, topographic effects). | raster (geotiff) |
yes |
¶ 5. Likelihood Values |
Estimated uncertainty of flood mapping, for all areas outside exclusion mask | raster (geotiff) |
yes |
¶ 6. Advisory Flags |
Flags indicating potential reduced quality of flood mapping, due to meteorological conditions or degraded input data quality |
raster (geotiff) |
not yet |
¶ 7. S-1 Metadata |
Information on the acquisition parameters of the S-1 data used |
json |
yes |
¶ 8. S-1 Footprint |
Image boundaries of the S-1 data used |
geojson |
yes |
¶ 9. S-1 Schedule |
Next scheduled S-1 data acquisition |
geojson |
yes |
¶ 10. Affected Population |
Number of people in flooded areas, mapped by a spatial overlay of observed flood extent and gridded population | raster (geotiff) |
yes |
¶ 11. Affected Land Cover |
Land cover type flooded | raster (geotiff) |
yes |