COSMOS: the COsmic-ray Soil Moisture Observing System

By Marek Zreda, W. James Shuttleworth, X. Zeng, C. Zweck, Darin Desilets, Trenton Franz, Rafael Rosolem. 2012

591 citations recorded by the source corpus.

The newly-developed cosmic-ray method for mea- suring area-average soil moisture at the hectometer horizon- tal scale is being implemented in the COsmic-ray Soil Mois- ture Observing System (or the COSMOS). The stationary cosmic-ray soil moisture probe measures the neutrons that are generated by cosmic rays within air and soil and other materials, moderated by mainly hydrogen atoms located pri- marily in soil water, and emitted to the atmosphere where they mix instantaneously at a scale of hundreds of meters and whose density is inversely correlated with soil moisture. The COSMOS has already deployed more than 50 of the even- tual 500 cosmic-ray probes, distributed mainly in the USA, each generating a time series of average soil moisture over its horizontal footprint, with similar networks coming into exis- tence around the world. This paper is written to serve a com- munity need to better understand this novel method and the COSMOS project. We describe the cosmic-ray soil moisture measurement method, the instrument and its calibration, the design, data processing and dissemination used in the COS- MOS project, and give example time series of soil moisture obtained from COSMOS probes.

Subfields: Civil and Structural Engineering, Environmental Engineering, Ocean Engineering

View Paper: https://www.semanticscholar.org/paper/5f84365df2e1f7ac32f4899e22033ce609e44d87

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Citations in the corpus

Evaluation of the ESA CCI soil moisture product using ground-based observations (2015, unknown): “Rangeland, wheat, crops, forest Zreda et al. (2012)”
The Effect of Atmospheric Water Vapor on Neutron Count in the Cosmic-Ray Soil Moisture Observing System (2013, methodology): “…area of a cosmic-ray probe (the radius within which 86% of the neutrons originate) is approximately 300– 350m and independent of soil moisture (Zreda et al. 2008, 2012; Desilets et al. 2010; Desilets 2011), while the depth of influence of the probe (similarly defined) varies between 76 cm in…”
A universal calibration function for determination of soil moisture with cosmic-ray neutrons (2012, methodology): “The influence of additional sources of hydrogen is evident from the wide range ofN0 values computed for COSMOS sites using the Desilets et al. (2010) calibration function: θ(N) = 0.0808( N N0 ) − 0.372 − 0.115 (1) where θ is the volumetric pore water content (m3 −3), N is the neutron counting rate/f”
Measurement depth of the cosmic ray soil moisture probe affected by hydrogen from various sources (2012, methodology): “From multiple calibration data sets, at a single site, over a range of water contents and horizontal heterogeneity [Zreda et al., 2008; Zreda et al., 2012], we find that horizontal heterogeneity likely plays a minor role but the issue remains to be fully validated.”
The International Soil Moisture Network: serving Earth system science for over a decade (2021, methodology): “The Cosmic-ray Soil Moisture Observing System (COSMOS; Zreda et al., 2012) started in 2009 with a grant from the U.”
Footprint characteristics revised for field‐scale soil moisture monitoring with cosmic‐ray neutrons (2015, methodology): “The accepted method equally weights point measurements from three distinct radii [Zreda et al., 2012; Franz et al., 2012a] which correspond to an exponential weighting function (see section 2.4).”
Toward Global Soil Moisture Monitoring With Sentinel-1: Harnessing Assets and Overcoming Obstacles (2019, methodology): “The cosmic-ray soil moisture observing system (COSMOS) is a network of stations that measure soil moisture through a newly developed cosmic-ray method [86].”
Improving calibration and validation of cosmic-ray neutron sensors in the light of spatial sensitivity (2017, methodology): “These calculations were based on a simple exponential sensitivity function (Zreda et al., 2008) and presented by Franz et al.”