November 9, 2022 Dataset Open Access

ASCAT Global Maps of monthly mean surface soil moisture

Kern, Stefan

Data curator(s)

Abstract: The globally gridded daily 5-day running mean surface soil moisture product derived at ICDC (https://www.cen.uni-hamburg.de/en/icdc/data/land/ascat-soilmoisture.html , https://doi.org/10.25592/uhhfdm.10467) from soil moisture time series data of the EUMETSAT H-SAF product H119 and its extension H120 based on MetOp-A, -B, and -C ASCAT data, processing version v7 (https://doi.org/10.15570/EUM_SAF_H_0009), are averaged to obtain monthly means of the surface soil moisture (SM) distribution separately for ascending and descending overpasses. The monthly mean SM values include the nominally computed SM values as well as those SM values which were negative (down to -25%, correction flag = 1) or larger than 100% (up to 125%, correction flag = 2) but set to 0% and 100%, respectively. The threshold for the monthly average is (the number of days per Month) 10. If there are fewer values per month, the value is set to the missing_value. For more information see the respective global attribute in the netCDF file.

TableOfContents: mean soil moisture extended; mean soil moisture extended noise; number of valid soil moisture extended values per month; mean number of overpasses per grid cell; mean historic probability of snow cover; mean historic probability of frozen land; inundation and wetland fraction; topographic complexity; soil porosity LDAS; soil porosity HWSD; soil moisture status flag

Technical Info: dimensions: 3207 columns x 1599 rows x unlimited; temporalExtent_startDate: 2007-01-01; temporalExtent_endDate: 2021-12-31; temporalResolution: monthly; spatialResolution: 0.1125; spatialResolutionUnit: degrees; horizontalResolutionXdirection: 0.11225; horizontalResolutionXdirectionUnit: degrees; horizontalResolutionYdirection: 0.1125; horizontalResolutionYdirectionUnit: degrees; verticalResolution: none; verticalResolutionUnit: none; verticalStart: none; verticalEnd: none; instrumentName: Advanced SCATterometer (ASCAT); instrumentType: C-band microwave_scatterometer; instrumentLocation: Meteorological Operational Satellite (MetOp-A, MetOp-B, MetOp-C); instrumentProvider: EUMETSAT, ESA

Methods: For a description of the methods used to obtain the daily 5-day running mean / composite data on which these monthly data are based, we refer to the global attributes of the netCDF files. For the methods used for the native soil moisture time series please see:  [1] Wagner, W., et al.: A method for estimating soil moisture from ERS scatterometer and soil data, Rem. Sens. Environ., 70(2), 191-207, 1999. doi: 10.1016/S0034-4257(99)00036-X; [2] Naeimi, V., et al.: An Improved Soil Moisture Retrieval Algorithm for ERS and METOP Scatterometer Observations, IEEE Trans. Geosci. Rem. Sens., 47(7), 1999-2013, 2009. doi: 10.1109/TGRS.2008.2011617; [3] Naeimi, V., et al.: ASCAT Surface State Flag (SSF): Extracting Information on Surface Freeze/Thaw Conditions From Backscatter Data Using an Empirical Threshold-Analysis Algorithm, IEEE Trans. Geosci. Rem. Sens., 50(7), 2566-2582, 2012. doi: 10.1109/TGRS.2011.2177667; [4] Product User Manual: H SAF, Product User Manual (PUM) Metop ASCAT Surface Soil Moisture Climate Data Record v7 12.5 km sampling (H119) and Extension (H120), v0.2, 2022; [5] Algorithm Theoretical Basis Document: H SAF, Algorithm Theoretical Baseline Document (ATBD) Metop ASCAT Surface Soil Moisture Climate Data Record v7 12.5 km sampling (H119) and Extension (H120), v0.1, 2021; [6] Product Validation Report: H SAF, Product Validation Report (PVR) Metop ASCAT Surface Soil Moisture Climate Data Record v7 12.5 km sampling (H119) and Extension (H120), v1.1, 2022.

Units: Units for all variables (see TableOfContents): percent, percent, 1, 1, percent, percent, percent, percent, m³/m³, m³/m³, 1

geoLocations: westBoundLongitude: -180.0 degrees East; eastBoundLongitude: 180.0 degrees East; southBoundLatitude: -90.0 degrees North; northBoundLatitude: 90.0 degrees North; geoLocationPlace: global on land

Size: 24 files per year [12 for ascending, 12 for descending overpasses]; ~56.439 MegaByte per file; ~19.873 GigaByte in total (data are packed into two zip-archives per year, one for the ascending, one for the descending data)

Format: netCDF

DataSources:

Gridded daily 5-day running mean surface soil moisture maps: https://doi.org/10.25592/uhhfdm.10467; see also https://www.cen.uni-hamburg.de/en/icdc/data/land/ascat-soilmoisture.html

Original time-series of the surface soil moisture: https://hsaf.meteoam.it/Products/Detail?prod=H119 and https://hsaf.meteoam.it/Products/Detail?prod=H120

Contact: stefan.kern (at) uni-hamburg.de

Web page: https://www.cen.uni-hamburg.de/en/icdc/data/land/ascat-soilmoisture.html