Editing Soil moisture (volumetric)

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{| class="wikitable" style="float:right; clear:right; margin:0 0 1em 1em; width:320px;"
|+ SIGNAL Earth Structured Data
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! Object type
| Damage Signal
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! SIGNAL Earth ID
| DS-00147
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! Observable type
| Soil moisture (volumetric)
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! Unit
| % (%)
|-
! Temporal structure
| Daily
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! Monitoring backbone
| —
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{{SignalTerm|type=DS|id=DS-00147|label=Soil moisture (volumetric)}} is a critical environmental variable representing the volume percentage of water contained within the soil matrix. It influences a wide range of ecological, hydrological, and climatic processes, including plant growth, weather patterns, and water resource management. Accurate assessment of soil moisture is essential for understanding land surface conditions and their interactions with the atmosphere and biosphere.

This phenomenon is relevant globally, as soil moisture dynamics affect agricultural productivity, drought monitoring, and flood forecasting. Variations in soil moisture can indicate changes in precipitation, evaporation, and land use, making it a key indicator in environmental monitoring and climate studies.

Soil moisture is measured as a state condition within the terrestrial environment, reflecting the balance between water inputs and outputs in the soil. Its spatial and temporal variability is influenced by soil texture, vegetation cover, topography, and climatic factors, necessitating comprehensive observation methods to capture its dynamics effectively.

== Geographic / System Context ==
Soil moisture (volumetric) is observed across diverse geographic regions worldwide, encompassing various soil types, climates, and ecosystems. It is a fundamental component of the land domain, affecting areas from arid deserts to tropical rainforests and temperate grasslands. The global distribution of soil moisture is shaped by regional precipitation patterns, soil characteristics, vegetation, and land management practices.

In hydrological systems, soil moisture acts as a reservoir that modulates surface runoff and groundwater recharge. Its spatial heterogeneity is significant at multiple scales, from local agricultural fields to continental landscapes, influencing regional climate feedbacks and ecosystem productivity.

== Monitoring and Measurement ==
Soil moisture is monitored using a combination of in situ measurements, remote sensing technologies, and model-based estimations. Ground-based sensors provide direct volumetric water content measurements at specific locations, offering high temporal resolution data. Satellite missions, such as those contributing to the European Space Agency Climate Change Initiative (ESA CCI), utilize microwave radiometry and radar to estimate soil moisture over large spatial extents with global coverage.

These observations are often integrated with land surface models to improve spatial and temporal representation. Standard measurement conventions express soil moisture as a percentage of the soil volume occupied by water, enabling consistent comparisons across datasets and studies. Scientific institutions involved in soil moisture monitoring include space agencies and environmental research organizations that develop and maintain global soil moisture products.

Within the SIGNAL system, soil moisture (volumetric) is treated as a defined environmental signal whose boundaries and measurement conventions are described below.

== Signal Definition ==
The soil moisture (volumetric) signal quantifies the volumetric fraction of water present in the soil, expressed as a percentage (%). It represents the state condition of soil water content within the land domain, reflecting the balance of hydrological inputs and outputs. This signal is derived from the observable type 'Soil moisture (volumetric)' and is measured on a daily temporal structure to capture short-term variability and trends.

== Boundary Conditions ==
Boundary inclusions for this signal encompass all soil moisture contained within the root zone and near-surface soil layers that influence land-atmosphere interactions. It includes moisture in various soil textures and organic matter compositions across terrestrial ecosystems. Boundary exclusions involve soil water beyond the root zone depth that does not directly affect surface processes, as well as moisture contained in frozen or permafrost soils where liquid water content is negligible. Additionally, soil moisture in urban impervious surfaces and water bodies is excluded to maintain focus on terrestrial soil systems.

== Aggregation Semantics ==
Geographic aggregation of soil moisture data is performed at multiple scales, from local plot-level measurements to global gridded products, enabling analysis across spatial resolutions suitable for different applications. Temporal aggregation follows a daily cadence, allowing for the assessment of diurnal and seasonal variations as well as longer-term trends. Cross-signal aggregation may involve integrating soil moisture with related environmental signals such as precipitation, evapotranspiration, and vegetation indices to provide comprehensive insights into land surface and climate interactions. Aggregation methods account for spatial heterogeneity and temporal continuity to ensure meaningful interpretation of the soil moisture state.

== Observational Status ==
Current monitoring of soil moisture benefits from extensive satellite missions and ground networks, providing near-global coverage and continuous data streams. The ESA CCI Soil Moisture GAPFILLED dataset offers an independent, gap-free satellite climate record with uncertainty estimates, enhancing the reliability of soil moisture observations. Future SIGNAL releases may incorporate additional datasets, improved spatial resolution, and integration with complementary environmental signals to refine the understanding of soil moisture dynamics and their environmental implications.

== Related Signals ==
* None specified

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== Key Associated People ==
* '''Wolfgang Preimesberger''' (TU Wien) [Lead author]
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== Sources ==
* [https://essd.copernicus.org/articles/17/4305/2025/ ESA CCI Soil Moisture GAPFILLED: an independent global gap-free satellite climate data record with uncertainty estimates — 2025]
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