Global Soil Moisture Anomalies (SMA Z-score) from the EUMETSAT - TU Wien ASCAT-SSM-CDR-12.5km version 8 (H121) surface soil moisture product (dekad=10days, SWI T=10d filtered) 2007-2024

• General Description

The dekad Soil Moisture Anomalies (SMA) dataset provides z-score soil moisture anomalies from the EUMETSAT – TU Wien ASCAT-SSM-CDR-12.5km version 8 (H121) surface soil moisture product. The dataset spans March 2007 to December 2024 for the entire globe (without Antarctica). Before computing the anomalies, the surface soil moisture observations from Metop-A, -B and -C were propagated to a representative sub-surface layer (approx. 5–15 cm) by applying the Soil Water Index (SWI) exponential filter (Albergel et al., 2008) with a characteristic time length of T = 10 days, aggregated into dekads, and averaged across the three satellites. Z-scores are computed per pixel and per dekad against the 2007–2024 mean and standard deviation. The dataset is directly applicable to analysing soil moisture changes from regional to global scales, as well as to evaluating other processes dependent on soil moisture evolution in the hydrosphere, atmosphere and biosphere. The dataset includes:

• 10-day (dekad) time-series:

SMA of soil moisture aggregated to 10-day periods ('dekads': days 1–10, 11–20 and 21 to the end of each month), following the approach defined in the European and Global Drought Observatories.

Data Details

• Time period: March 2007 – December 2024
• Type of data: Soil Moisture Anomaly (z-score) of soil moisture data aggregated to dekads (10-day periods)
• How the data was collected or derived: ASCAT-SSM-CDR-12.5km version 7 (H120) with all processing computed using Python packages.
• Statistical methods used: z-scores per pixel and per dekad against the 2007–2024 climatology (mean and standard deviation).
• Units: dimensionless (standard deviations)
• Coordinate reference system: EPSG:4326
• Bounding box (Xmin, Ymin, Xmax, Ymax): (-180, -60, 180, 90)
• Spatial resolution: COG TIFFs at 1/120 d.d. = 0.00833333 (~1 km), spatial sampling 12.5 km, spatial resolution 25km
• Image size: 43200 x 18000
• File format: Cloud Optimised GeoTIFF (COG), grouped into yearly uncompressed ZIP archives (store mode).

Support

If you discover a bug, artefact, or inconsistency, or if you have a question, please contact: jaime.gaonagarcia@cnr.it

Reference

Gaona, J., Bavera, D., Fioravanti, G., Hahn, S., Stradiotti, P., Filippucci, P., ... & Brocca, L. (2024). Soil moisture products consistency for operational drought monitoring in Europe. Hydrology and Earth System Sciences Discussions, 2024, 1-36. Preprint available at: https://doi.org/10.5194/hess-2024-182

Albergel, C., et al. (2008). From near-surface to root-zone soil moisture using an exponential filter: an assessment of the method based on in-situ observations and model simulations. Hydrology and Earth System Sciences, 12, 1323–1337.

Name convention

To ensure consistency and ease of use across and within the projects, we follow the standard Open-Earth-Monitor file-naming convention. The convention works with 10 fields that describe important properties of the data. In this way, users can search files, prepare data analysis etc., without needing to open files. The fields are:

1. Generic variable name: ssma= Surface Soil Moisture Anomaly (SMA)
2. Variable procedure combination: Satellite Application Facility on Support to Operational Hydrology and Water Management (H SAF) active Advanced SCATterometer (ASCAT)-derived dataset.
3. Statistical methods used: m = mean of SMA at dekad (10-day period)
4. Spatial support: 1km = ~1 km
5. Depth reference: sT10swi = soil moisture of approx. 5–15 cm depth layer, as applied with the SWI exponential filter of Albergel et al. (2008), which, depending on the T value, determines a representative depth.
6. Time reference begin time: first day of the dekad (e.g. 20070301 = 2007-03-01)
7. Time reference end time: last day of the dekad (e.g. 20070310 = 2007-03-10); the full dataset spans 20070301–20241231
8. Bounding box: go = global (without Antarctica)
9. EPSG code: epsg.4326 = EPSG:4326
10. Version code: v20261001 = 2026-10-01 (creation date)