scholarly journals Calibration approaches of cosmic-ray neutron sensing for soil moisture measurement in cropped fields

2013 ◽  
Vol 10 (4) ◽  
pp. 4237-4274 ◽  
Author(s):  
C. A. Rivera Villarreyes ◽  
G. Baroni ◽  
S. E. Oswald
Keyword(s):  
Soil Moisture ◽  
Cosmic Ray ◽  
Fast Neutrons ◽  
Winter Rye ◽  
Moisture Profile ◽  
Hill Slope ◽  
Vadose Zone Hydrology ◽  
Classical Point ◽  
Soil Moisture Measurement ◽  
Single Set

Abstract. Measurement of soil moisture at the plot or hill-slope scale is an important link between local vadose-zone hydrology and catchment hydrology. This study evaluates the applicability of the cosmic-ray neutron sensing for soil moisture in cropped fields. Measurements of cosmic-ray neutrons (fast neutrons) were performed at a lowland farmland in Bornim (Brandenburg, Germany) cropped with sunflower and winter rye. Three field calibration approaches and four different ways of integration the soil moisture profile to an integral value for cosmic-ray neutron sensing were evaluated in this study. The cosmic-ray sensing (CRS) probe was calibrated against a network of classical point-scale soil moisture measurements. A large CRS parameter variability was observed by choosing calibration periods within the different growing stages of sunflower and winter rye. Therefore, it was not possible to identify a single set of parameters perfectly estimating soil moisture for both sunflower and winter rye periods. On the other hand, CRS signal and its parameter variability could be understood by some crop characteristics and by predicting the attenuated neutrons by crop presence. This study proves the potentiality of the cosmic-ray neutron sensing at the field scale; however, its calibration needs to be adapted for seasonal vegetation in cropped fields.

The Effect of Atmospheric Water Vapor on Neutron Count in the Cosmic-Ray Soil Moisture Observing System

2013 ◽  
Vol 14 (5) ◽  
pp. 1659-1671 ◽  
Author(s):  
R. Rosolem ◽  
W. J. Shuttleworth ◽  
M. Zreda ◽  
T. E. Franz ◽  
X. Zeng ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Vapor ◽  
Neutron Transport ◽  
Cosmic Ray ◽  
Atmospheric Water Vapor ◽  
Fast Neutrons ◽  
Atmospheric Conditions ◽  
Atmospheric Water ◽  
Neutron Measurement ◽  
Neutron Intensity

Abstract The cosmic-ray method for measuring soil moisture, used in the Cosmic-Ray Soil Moisture Observing System (COSMOS), relies on the exceptional ability of hydrogen to moderate fast neutrons. Sources of hydrogen near the ground, other than soil moisture, affect the neutron measurement and therefore must be quantified. This study investigates the effect of atmospheric water vapor on the cosmic-ray probe signal and evaluates the fast neutron response in realistic atmospheric conditions using the neutron transport code Monte Carlo N-Particle eXtended (MCNPX). The vertical height of influence of the sensor in the atmosphere varies between 412 and 265 m in dry and wet atmospheres, respectively. Model results show that atmospheric water vapor near the surface affects the neutron intensity signal by up to 12%, corresponding to soil moisture differences on the order of 0.10 m3 m−3. A simple correction is defined to identify the true signal associated with integrated soil moisture that rescales the measured neutron intensity to that which would have been observed in the atmospheric conditions prevailing on the day of sensor calibration. Use of this approach is investigated with in situ observations at two sites characterized by strong seasonality in water vapor where standard meteorological measurements are readily available.

scholarly journals Soil moisture observation in a forested headwater catchment: combining a dense cosmic-ray neutron sensor network with roving and hydrogravimetry at the TERENO site Wüstebach

2021 ◽  
Author(s):  
Maik Heistermann ◽  
Heye Bogena ◽  
Till Francke ◽  
Andreas Güntner ◽  
Jannis Jakobi ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Sensor Network ◽  
Root Zone ◽  
Water Storage ◽  
Cosmic Ray ◽  
Water Dynamics ◽  
Catchment Scale ◽  
Small Catchment ◽  
Hill Slope ◽  
The Hill

Abstract. Cosmic Ray Neutron Sensing (CRNS) has become an effective method to measure soil moisture at a horizontal scale of hundreds of meters and a depth of decimeters. Recent studies proposed to operate CRNS in a network with overlapping footprints in order to cover root-zone water dynamics at the small catchment scale, and, at the same time, to represent spatial heterogeneity. In a joint field campaign from September to November 2020 (JFC-2020), five German research institutions deployed 15 CRNS sensors in the 0.4 km2 Wüstebach catchment (Eifel mountains, Germany). The catchment is dominantly forested (but includes a substantial fraction of open vegetation), and features a topographically distinct watershed. In addition to the dense CRNS coverage, the campaign featured a unique combination of additional instruments and techniques: hydro-gravimetry (to detect water storage dynamics also below the root zone); ground-based and, for the first time, airborne CRNS roving; an extensive wireless soil sensor network, supplemented by manual measurements; and six weighable lysimeters. Together with comprehensive data from the long-term local research infrastructure, the published dataset (available at https://doi.org/10.23728/b2share.afb20a34a6ac429ca6b759238d842765) will be a valuable asset in various research contexts: to advance the retrieval of landscape water storage from CRNS, wireless soil sensor networks, or hydrogravimetry; to identify scale-specific combinations of sensors and methods to represent soil moisture variability; to improve the understanding and simulation of land-atmosphere exchange as well as hydrological and hydrogeological processes at the hill-slope and the catchment scale; and to support the retrieval soil water content from airborne and spaceborne remote sensing platforms.

Understanding soil moisture dynamics through cosmic rays: a global analysis

2021 ◽  
Author(s):  
Daniel Power ◽  
Rafael Rosolem ◽  
Miguel Rico-Ramirez ◽  
Darin Desilets ◽  
Sharon Desilets
Keyword(s):  
Soil Moisture ◽  
Cosmic Rays ◽  
Cosmic Ray ◽  
Fast Neutrons ◽  
Field Scale ◽  
Hydrogen Atoms ◽  
Soil Moisture Dynamics ◽  
Large Sample ◽  
Wide Range ◽  
Moisture Dynamics

<p>Despite its importance in many hydrological and environmental applications, direct estimates of soil moisture at the field-scale is still challenging. The spatial gap between point scale sensors and satellite derived products is becoming increasingly important to consider in the push for hyper-resolution (sub)kilometre-hydrometeorological models. Cosmic-Ray Neutron Sensors (CRNS) can help to bridge this spatial gap. CRNS provide estimates of field-scale (sub-kilometre) root-zone integrated soil moisture typically at hourly intervals. They achieve this by counting fast neutrons which are produced in the atmosphere from incoming cosmic rays. Fast neutrons are mitigated primarily by hydrogen atoms, and it is this relationship that allows us to estimate field averaged soil moisture. National networks of CRNS are available in the USA, Australia, the UK, and Germany, along with individual sites across the globe. As these networks have expanded, so has our knowledge on best practices for calibration and correction of the sensor measurements. However, there continues to be a divergence and lack of harmonization in some processing data methods leading to an additional uncertainty when comparing sensors in different networks. This can undermine efforts to employ large-sample hydrological analysis of CRNS across a wide range of climate and biomes. To provide an easily accessible platform for multi-site comparison worldwide, we developed the Cosmic Ray Sensor Python tool (crspy). Crspy is an open-source Python package which is designed to process CRNS data from global networks in a uniform and harmonized way (https://www.github.com/danpower101/crspy). Additionally, crspy has been developed for multi-site ‘big-data’ analysis in hydrology. Our crspy tool produces detailed information in the form of metadata for each site, using both site specific data as well as global data products to give information on soil properties (SoilGridsv2), land cover/aboveground biomass (ESA CCI) and climate data (ERA5-land). Our preliminary analysis and tool development was carried out using data from more than 100 sites globally from the public domain. We will present an analysis of this large sample of data, utilising the harmonized soil moisture readings along with detailed metadata for each site. We aim to increase our understanding of the dominant mechanisms controlling soil moisture dynamics which will undoubtedly be useful in multiple areas of research such as catchment classification, agriculture and irrigation, and hydrological model development.</p>

scholarly journals Integral quantification of seasonal soil moisture changes in farmland by cosmic-ray neutrons

2011 ◽  
Vol 15 (12) ◽  
pp. 3843-3859 ◽  
Author(s):  
C. A. Rivera Villarreyes ◽  
G. Baroni ◽  
S. E. Oswald
Keyword(s):  
Soil Moisture ◽  
Snow Cover ◽  
Meteorological Data ◽  
Cosmic Ray ◽  
Winter Period ◽  
Agricultural Field ◽  
Substantial Impact ◽  
Hill Slope ◽  
Measurement Methodology ◽  
Crop Biomass

Abstract. Soil moisture at the plot or hill-slope scale is an important link between local vadose zone hydrology and catchment hydrology. However, so far only a few methods are on the way to close this gap between point measurements and remote sensing. One new measurement methodology that could determine integral soil moisture at this scale is the aboveground sensing of cosmic-ray neutrons, more precisely of ground albedo neutrons. The present study performed ground albedo neutron sensing (GANS) at an agricultural field in northern Germany. To test the method it was accompanied by other soil moisture measurements for a summer period with corn crops growing on the field and a later autumn-winter period without crops and a longer period of snow cover. Additionally, meteorological data and aboveground crop biomass were included in the evaluation. Hourly values of ground albedo neutron sensing showed a high statistical variability. Six-hourly values corresponded well with classical soil moisture measurements, after calibration based on one reference dry period and three wet periods of a few days each. Crop biomass seemed to influence the measurements only to minor degree, opposed to snow cover which has a more substantial impact on the measurements. The latter could be quantitatively related to a newly introduced field neutron ratio estimated from neutron counting rates of two energy ranges. Overall, our study outlines a procedure to apply the ground albedo neutron sensing method based on devices now commercially available, without the need for accompanying numerical simulations and suited for longer monitoring periods after initial calibration.

scholarly journals COSMOS-UK: National soil moisture and hydrometeorology data for empowering UK environmental science

2020 ◽  
Author(s):  
Hollie M. Cooper ◽  
Emma Bennett ◽  
James Blake ◽  
Eleanor Blyth ◽  
David Boorman ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Real Time ◽  
Land Surface ◽  
Large Scale ◽  
Environmental Science ◽  
Cosmic Ray ◽  
Fast Neutrons ◽  
High Temporal Resolution ◽  
Field Scale ◽  
Near Surface

Abstract. The COSMOS-UK observation network has been providing field scale soil moisture and hydrometeorological measurements across the UK since 2013. At the time of publication a total of 51 COSMOS-UK sites have been established, each delivering high temporal resolution data in near-real time. Each site utilises a cosmic-ray neutron sensor, which counts fast neutrons at the land surface. These measurements are used to derive field scale near-surface soil water content, which can provide unique insight for science, industry, and agriculture by filling a scale gap between localised point soil moisture and large-scale satellite soil moisture datasets. Additional soil physics and meteorological measurements are made by the COSMOS-UK network including precipitation, air temperature, relative humidity, barometric pressure, soil heat flux, wind speed and direction, and components of incoming and outgoing radiation. These near-real time observational data can be used to improve the performance of hydrological models, validate remote sensing products, improve hydro-meteorological forecasting and underpin applications across a range of other scientific fields. The most recent version of the COSMOS-UK dataset is publically available at https://doi.org/10.5285/37702a54-b7a4-40ff-b62e-d14b161b69ca (Stanley et al., 2020).

scholarly journals COSMOS: The COsmic-ray Soil Moisture Observing System

2012 ◽  
Vol 9 (4) ◽  
pp. 4505-4551 ◽  
Author(s):  
M. Zreda ◽  
W. J. Shuttleworth ◽  
X. Zeng ◽  
C. Zweck ◽  
D. Desilets ◽  
...  
Keyword(s):  
Time Series ◽  
Soil Moisture ◽  
Cosmic Ray ◽  
Hydrogen Atoms ◽  
Ray Method ◽  
Design Data ◽  
The World ◽  
The Usa ◽  
Novel Method ◽  
Soil Moisture Measurement

Abstract. Area-average soil moisture at the sub-kilometer scale is needed but until the advent of the cosmic-ray method (Zreda et al., 2008), it was difficult to measure. This new method is now being implemented routinely in the COsmic-ray Soil Moisture Observing System (or COSMOS). The stationary cosmic-ray soil moisture probe (sometimes called "neutronavka") measures the neutrons that are generated by cosmic rays within air and soil, moderated by mainly hydrogen atoms located primarily 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. COSMOS has already deployed 53 of the eventual 500 neutronavkas distributed mainly in the USA, each generating a time series of average soil moisture over its hectometer horizontal footprint, with similar networks coming into existence around the world. This paper is written to serve a community 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 COSMOS, and give example time series of soil moisture obtained from COSMOS probes.

scholarly journals Integral quantification of seasonal soil moisture changes in farmland by cosmic-ray neutrons

2011 ◽  
Vol 8 (4) ◽  
pp. 6867-6906 ◽  
Author(s):  
C. A. Rivera Villarreyes ◽  
G. Baroni ◽  
S. E. Oswald
Keyword(s):  
Soil Moisture ◽  
Snow Cover ◽  
Meteorological Data ◽  
Cosmic Ray ◽  
Winter Period ◽  
Agricultural Field ◽  
Substantial Impact ◽  
Hill Slope ◽  
First Time ◽  
Crop Biomass

Abstract. The measurement of soil moisture at the plot or hill-slope scale is an important link between local vadose zone hydrology and catchment hydrology. However, so far only a few methods are on the way to close this gap between point measurements and remote sensing. One method that could determine an integral soil moisture at this scale is the so called cosmic ray sensing that was introduced to soil hydrology very recently the first time. The present study performed cosmic ray sensing at an agricultural field in a Central European lowland. To test the method it was accompanied by other soil moisture measurements for a summer period with corn crops growing on the field and a later autumn-winter period without crops and a longer period of snow cover. Additionally, meteorological data and above-ground crop biomass was included into the evaluation. Hourly values of cosmic ray sensing showed a high statistical variability. Six-hourly values corresponded well with classical soil moisture measurements, after calibration based on one dry and three wet periods of a few days each. Crop biomass seemed to influence the measurements only to minor degree, opposed to snow cover which has a more substantial impact on the measurements. The latter could be quantitatively related to count rates in two different variants of cosmic ray counters. Overall, our study outlines a procedure to apply the cosmic ray sensing method based on devices now commercially available, without the need for accompanying numerical simulations and suited for longer monitoring periods after initial calibration.

scholarly journals The COsmic-ray Soil Moisture Interaction Code (COSMIC) for use in data assimilation

2013 ◽  
Vol 17 (8) ◽  
pp. 3205-3217 ◽  
Author(s):  
J. Shuttleworth ◽  
R. Rosolem ◽  
M. Zreda ◽  
T. Franz
Keyword(s):  
Soil Moisture ◽  
Data Assimilation ◽  
Fast Neutron ◽  
Land Surface ◽  
Soil Depth ◽  
Cosmic Ray ◽  
High Energy ◽  
Fast Neutrons ◽  
Surface Model ◽  
Neutron Intensity

Abstract. Soil moisture status in land surface models (LSMs) can be updated by assimilating cosmic-ray neutron intensity measured in air above the surface. This requires a fast and accurate model to calculate the neutron intensity from the profiles of soil moisture modeled by the LSM. The existing Monte Carlo N-Particle eXtended (MCNPX) model is sufficiently accurate but too slow to be practical in the context of data assimilation. Consequently an alternative and efficient model is needed which can be calibrated accurately to reproduce the calculations made by MCNPX and used to substitute for MCNPX during data assimilation. This paper describes the construction and calibration of such a model, COsmic-ray Soil Moisture Interaction Code (COSMIC), which is simple, physically based and analytic, and which, because it runs at least 50 000 times faster than MCNPX, is appropriate in data assimilation applications. The model includes simple descriptions of (a) degradation of the incoming high-energy neutron flux with soil depth, (b) creation of fast neutrons at each depth in the soil, and (c) scattering of the resulting fast neutrons before they reach the soil surface, all of which processes may have parameterized dependency on the chemistry and moisture content of the soil. The site-to-site variability in the parameters used in COSMIC is explored for 42 sample sites in the COsmic-ray Soil Moisture Observing System (COSMOS), and the comparative performance of COSMIC relative to MCNPX when applied to represent interactions between cosmic-ray neutrons and moist soil is explored. At an example site in Arizona, fast-neutron counts calculated by COSMIC from the average soil moisture profile given by an independent network of point measurements in the COSMOS probe footprint are similar to the fast-neutron intensity measured by the COSMOS probe. It was demonstrated that, when used within a data assimilation framework to assimilate COSMOS probe counts into the Noah land surface model at the Santa Rita Experimental Range field site, the calibrated COSMIC model provided an effective mechanism for translating model-calculated soil moisture profiles into aboveground fast-neutron count when applied with two radically different approaches used to remove the bias between data and model.

scholarly journals Assimilation of near-surface cosmic-ray neutrons improves summertime soil moisture profile estimates at three distinct biomes in the USA

2014 ◽  
Vol 11 (5) ◽  
pp. 5515-5558 ◽  
Author(s):  
R. Rosolem ◽  
T. Hoar ◽  
A. Arellano ◽  
J. L. Anderson ◽  
W. J. Shuttleworth ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Land Surface ◽  
Mixed Forest ◽  
Land Surface Model ◽  
Cosmic Ray ◽  
Surface Model ◽  
Moisture Profile ◽  
The Usa ◽  
Moisture Profiles ◽  
Semi Arid

Abstract. Aboveground cosmic-ray neutron measurements provide an opportunity to infer soil moisture at the sub-kilometer scale. Initial efforts to assimilate those measurements have shown promise. This study expands such analysis by investigating (1) how the information from aboveground cosmic-ray neutrons can constrain the soil moisture at distinct depths simulated by a land surface model, and (2) how changes in data availability (in terms of retrieval frequency) impact the dynamics of simulated soil moisture profiles. We employ ensemble data assimilation techniques in a "nearly-identical twin" experiment applied at semi-arid shrubland, rainfed agricultural field, and mixed forest biomes in the USA The performance of the Noah land surface model is compared without and with assimilation of observations at hourly intervals and every 2 days Synthetic observations of aboveground cosmic-ray neutrons better constrain the soil moisture simulated by Noah in root zone soil layers (0–100 cm) despite the limited measurement depth of the sensor (estimated to be 12–20 cm). The ability of Noah to reproduce a "true" soil moisture profile is remarkably good regardless of the frequency of observations at the semi-arid site. However, soil moisture profiles are better constrained when assimilating synthetic cosmic-ray neutrons observations hourly rather than every 2 days at the cropland and mixed forest sites. This indicates potential benefits for hydrometeorological modeling when soil moisture measurements are available at relatively high frequency. Moreover, differences in summertime meteorological forcing between the semi-arid site and the other two sites may indicate a possible controlling factor to soil moisture dynamics in addition to differences in soil and vegetation properties.

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