Nature's neutron probe: Land surface hydrology at an elusive scale with cosmic rays

Desilets, Darin; Zréda, Marek; Ferré, T. P. A.

doi:10.1029/2009wr008726

Cited by 308 publications

(539 citation statements)

References 22 publications

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“…The corrected neutron flux is negatively and nonlinearly proportional to SWC. The shape-defining function developed by Desilets et al (2010) was widely used to determine h (m 3 m À3 ) (Desilets et al, 2010):…”

Section: Correction and Calibrationmentioning

confidence: 99%

“…The N 0 method is the simplest for estimating SWC because it requires only one parameter. Desilets et al (2010) obtained the generalized SWC calibration equation by fitting the neutron flux obtained from the MCNPX radiation transport code and reported the values of the parameters in the equation. Franz et al (2012) derived an equation for calculating the depth of SWC measurements.…”

Section: Introductionmentioning

confidence: 99%

“…Several methods are available to estimate SWC from the measured neutron intensity. The N 0 -method (Desilets et al, 2010), the hydrogen molar fraction method and the COSMIC operator method were calibrated by the Monte Carlo Neutron-Particle eXtended (MCNPX) radiation transport code. Baatz et al (2014) compared the three methods and found that they all performed similarly well during validation.…”

Section: Introductionmentioning

confidence: 99%

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Application of cosmic-ray neutron sensing to monitor soil water content in an alpine meadow ecosystem on the northern Tibetan Plateau

Zhu

Shao

Zeng

et al. 2016

Journal of Hydrology

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Keywords: CRNS Soil moisture Alpine meadow Tibetan Plateau s u m m a r y Cosmic-ray neutron sensing (CRNS) is a new method for continuously monitoring mean soil water content (SWC) on a hectometer scale. To evaluate the application and accuracy of the method for SWC observation in an alpine meadow ecosystem (AME), we installed the CRNS in a flat meadow near the Naqu prefecture on the northern Tibetan Plateau. We collecting soil samples and applying the system by the oven-drying method. A weather station was also installed near the CRNS for monitoring basic meteorological variables and the soil temperature and water content at various depths. Three Em-50 instruments for monitoring SWC and soil temperature were buried in three sub-quadrats northwest, northeast and southeast of the CRNS at distances of 460, 370 and 373 m, respectively, to observe the variation of SWC at the various depths. The footprint of the CRNS for SWC observation in the meadow was about 580 m, and the mean measuring depth was about 31 cm according to the general calculation equations. The reference neutron flux for dry soil (N 0 ) had a mean and coefficient of variation of 8686 and 3%, respectively, and remained substantially invariant throughout the measuring period. The five SWCs from the independent field samples almost passed through the SWC trend of the CRNS, the root mean square error (RMSE) was 0.011 m 3 m À3 for the CRNS and oven-drying method. The time series of SWC measured by the CRNS agreed well with the mean SWC series to a depth of 20 cm measured by the weather station. The trend of SWC measured by the Em-50s generally agreed with the trend of SWC measured by the CRNS, but some values and variations of SWC differed between the Em-50s and CRNS data. Because of the good agreement between the CRNS and independent field samples, we suspect that this disagreement is due to an insufficient representativeness of point observations and the distances of the points from the CRNS. The diurnal variation of hourly SWC from the CRNS was sinusoidal during a dry period, peaking at 11:00 and was minimum at 18:00 (Beijing time), with a range of 1%. Overall, the CRNS measured SWC in the AME with an acceptable accuracy, providing a scientific basis for the promotion and application of the CRNS in high, cold ecosystems.

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Section: Correction and Calibrationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Application of cosmic-ray neutron sensing to monitor soil water content in an alpine meadow ecosystem on the northern Tibetan Plateau

Zhu

Shao

Zeng

et al. 2016

Journal of Hydrology

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“…The cosmic-ray soil moisture probe (CRP) is a relatively new instrument that was primarily developed for measuring average soil water content at the landscape scale (Zreda et al, 2008) but also has the potential to be a useful tool for measuring SWE (Desilets et al, 2010). The CRP measures neutrons in the fast to epithermal range, which are emitted from soil and inversely related to soil water content due to the neutron moderating characteristic of hydrogen (H).…”

mentioning

confidence: 99%

Calibration of a non-invasive cosmic-ray probe for wide area snow water equivalent measurement

Sigouin

Bing

2016

The Cryosphere

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Abstract. Measuring snow water equivalent (SWE) is important for many hydrological purposes such as modelling and flood forecasting. Measurements of SWE are also crucial for agricultural production in areas where snowmelt runoff dominates spring soil water recharge. Typical methods for measuring SWE include point measurements (snow tubes) and large-scale measurements (remote sensing). We explored the potential of using the cosmic-ray soil moisture probe (CRP) to measure average SWE at a spatial scale between those provided by snow tubes and remote sensing. The CRP measures above-ground moderated neutron intensity within a radius of approximately 300 m. Using snow tubes, surveys were performed over two winters (2013/2014 and 2014/2015) in an area surrounding a CRP in an agricultural field in Saskatoon, Saskatchewan, Canada. The raw moderated neutron intensity counts were corrected for atmospheric pressure, water vapour, and temporal variability of incoming cosmic-ray flux. The mean SWE from manually measured snow surveys was adjusted for differences in soil water storage before snowfall between both winters because the CRP reading appeared to be affected by soil water below the snowpack. The SWE from the snow surveys was negatively correlated with the CRP-measured moderated neutron intensity, giving Pearson correlation coefficients of −0.90 (2013/2014) and −0. 87 (2014/2015). A linear regression performed on the manually measured SWE and moderated neutron intensity counts for 2013/2014 yielded an r 2 of 0.81. Linear regression lines from the 2013/2014 and 2014/2015 manually measured SWE and moderated neutron counts were similar; thus differences in antecedent soil water storage did not appear to affect the slope of the SWE vs. neutron relationship.The regression equation obtained from 2013/2014 was used to model SWE using the moderated neutron intensity data for 2014/2015. The CRP-estimated SWE for 2014/2015 was similar to that of the snow survey, with an root-mean-square error of 8.8 mm. The CRP-estimated SWE also compared well to estimates made using snow depths at meteorological sites near (< 10 km) the CRP. Overall, the empirical equation presented provides acceptable estimates of average SWE using moderated neutron intensity measurements. Using a CRP to monitor SWE is attractive because it delivers a continuous reading, can be installed in remote locations, requires minimal labour, and provides a landscape-scale measurement footprint.

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“…Other applications of neutron detectors use above ground measurements of natural slow neutrons emitted upwards from the soil water under influence of cosmic rays. These measurements have a footprint of 10-100 m and are sensitive to moisture at a depth of 10-100 cm [50,51].…”

Section: Neutron Probesmentioning

confidence: 99%

Soil Moisture & Snow Properties Determination with GNSS in Alpine Environments: Challenges, Status, and Perspectives

et al. 2013

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Moisture content in the soil and snow in the alpine environment is an important factor, not only for environmentally oriented research, but also for decision making in agriculture and hazard management. Current observation techniques quantifying soil moisture or characterizing a snow pack often require dedicated instrumentation that measures either at point scale or at very large (satellite pixel) scale. Given the heterogeneity of both snow cover and soil moisture in alpine terrain, observations of the spatial distribution of moisture and snow-cover are lacking at spatial scales relevant for alpine hydrometeorology. This paper provides an overview of the challenges and status of the determination of soil moisture and snow properties in alpine environments. Current measurement techniques and newly proposed ones, based on the reception of reflected Global Navigation Satellite Signals (i.e., GNSS Reflectometry or GNSS-R), or the use of laser scanning are reviewed, and the perspectives offered by these new techniques to fill the current gap in the instrumentation level are discussed. Some key enabling technologies OPEN ACCESSRemote Sens. 2013, 5 3517 including the availability of modernized GNSS signals and GNSS array beamforming techniques are also considered and discussed.

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Nature's neutron probe: Land surface hydrology at an elusive scale with cosmic rays

Cited by 308 publications

References 22 publications

Application of cosmic-ray neutron sensing to monitor soil water content in an alpine meadow ecosystem on the northern Tibetan Plateau

Application of cosmic-ray neutron sensing to monitor soil water content in an alpine meadow ecosystem on the northern Tibetan Plateau

Calibration of a non-invasive cosmic-ray probe for wide area snow water equivalent measurement

Soil Moisture & Snow Properties Determination with GNSS in Alpine Environments: Challenges, Status, and Perspectives

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