Disaggregated Metop ASCAT NRT SSM at 1 km NRT

The disaggregated Surface Soil Moisture (SSM) product (H08) derived from the global ASCAT NRT product (H16) is limited to the H SAF area (Europe) and maps the soil moisture content in the surface layer (0-2 cm) at spatial sampling of 1 km.

• Coverage: Strips of 1000 km swath crossing the H SAF area [25-75°N lat, 25°W-45°E long]
• Cycle: 36 hours
• Resolution: Basic 25 km, constant through the field of view; sampling 1 km
• Accuracy: 0.05 m³ m-³, degrading in dependence of the presence of vegetation, topographic complexity
• Timeliness: 135 min (potentially 35 min using the EARS service)
• Dissemination: By dedicated lines to centres connected by GTS - By EUMETCast to most other users, especially scientific ones
• Formats: Values in grid points in the orbital projection or fixed latitude-longitude grid (BUFR) and NetCDF

The product is derived by disaggregating the global ASCAT NRT product (H16), which is generated at the EUMETSAT H/Q and disseminated via EUMETCast. The disaggregation process is performed based on a pre-computed fine-mesh scaling layer derived from statistical analysis of C-band SAR imagery. A linear relationship is established between the local (fine-scale) and the regional (coarse-scale) backscatter information and derived from a multi-annual image-analysis. The downscaling parameter database is then used to disaggregate the scatterometer pixels to the fine mesh in near real-time. The SAR imagery used for generating the database is ENVISAT ASAR in ScanSAR Global Mode (years 2004-2012) and, planned for future, imagery from the upcoming Sentinel-1. The disaggregated product, sampled at km-scale, enables better fitting of local information to better suite hydrological requirements.