Session GI4.4

GI4.4 | Cosmic rays across scales and disciplines: the new frontier in environmental research

Cosmic rays across scales and disciplines: the new frontier in environmental research

Co-organized by HS13/PS4/ST1

Convener: Martin Schrön | Co-conveners: Daniel RascheECSECS, Lena ScheiffeleECSECS, Cosimo BrogiECSECS, Jannis WeimarECSECS

Orals

| Thu, 01 May, 10:45–12:30 (CEST)

Room -2.15

Posters on site

| Attendance Thu, 01 May, 08:30–10:15 (CEST) | Display Thu, 01 May, 08:30–12:30

Hall X4

Cosmic rays carry information about space and solar activity, and, once near the Earth, they produce isotopes, influence genetic information, and are extraordinarily sensitive to water. Given the vast spectrum of interactions of cosmic rays with matter in different parts of the Earth and other planets, cosmic-ray research ranges from studies of the solar system to the history of the Earth, and from health and security issues to hydrology, agriculture, and climate change.
Although research on cosmic-ray particles is connected to a variety of disciplines and applications, they all share similar questions and challenges regarding the physics of detection, modeling, and the influence of environmental factors.

The session brings together scientists from all fields of research that are related to monitoring and modeling of cosmogenic radiation. It will allow the sharing of expertise amongst international researchers as well as showcase recent advancements in their field. The session aims to stimulate discussions about how individual disciplines can share their knowledge and benefit from each other.

We solicit contributions related but not limited to:
- Health, security, and radiation protection: cosmic-ray dosimetry on Earth and its dependence on environmental and atmospheric factors
- Planetary space science: satellite and ground-based neutron and gamma-ray sensors to detect water and soil constituents
- Neutron and Muon monitors: detection of high-energy cosmic-ray variations and its dependence on local, atmospheric, and magnetospheric factors
- Hydrology and climate change: low-energy neutron sensing to measure water in reservoirs at and near the land surface, such as soil, snowpack, and vegetation
- Cosmogenic nuclides: as tracers of atmospheric circulation and mixing; as a tool in archaeology or glaciology for dating of ice and measuring ablation rates; and as a tool for surface exposure dating and measuring rates of surficial geological processes
- Detector design: technological advancements in the detection of cosmic rays and cosmogenic particles
- Cosmic-ray modeling: advances in modeling of the cosmic-ray propagation through the magnetosphere and atmosphere, and their response to the Earth's surface
- Impact modeling: How can cosmic-ray monitoring support environmental models, weather and climate forecasting, agricultural and irrigation management, and the assessment of natural hazards

Orals: Thu, 1 May | Room -2.15

Chairpersons: Martin Schrön, Daniel Rasche, Cosimo Brogi

10:45–10:50

5-minute convener introduction

10:50–11:00

EGU25-3395

On-site presentation

A 10ka Holocene record of cyclic precipitation in a closed catchment in SE Australia, associated with episodes of solar Grand Minima and variations in galactic cosmic ray flux

Michael Asten, Ken McCracken, and Kathryn Fitzsimmons

Lake George is a closed basin located 50 km north-east of Canberra, in southeastern Australia. Historical records indicate that lake levels directly reflect precipitation; eight cycles of high water levels (up to 7m depth), interspersed with dry lake conditions, have occurred since 1820 CE. Over longer time scales, shoreline sediments also record phases of high water up to 14m depth in Lake George during the past 15000 years. Optically stimulated luminescence (OSL) chronologies show multiple high lake phases extending through the Holocene, with a dominant cyclic pattern of c. 2300 y.

Here we compare the Holocene lake-level data with astronomical and solar phenomena over the same time period. In particular, we calculate a cyclicity in the Grand Alignments (GAs) of the four Jovian planets of 4628 y and near GAs occurring at 2314 y intervals, the timing of which is coeval with the Lake George filling events. GAs have been observed to align with Grand Minima (GMs) (eg Maunder and Spoerer Minima) in solar activity (sunspots) which produce phases of high galactic cosmic ray flux on Earth. The timing of GMs is obtained by reconstruction of ¹⁰Be and ¹⁴C fluxes as recorded in terrestrial sediments. These high fluxes also appear to show a temporal relationship with occurrence of the lake level highs.

The recognition of cosmic ray flux episodes, rather than individual GMs, strongly indicates an association between observed solar activity and the high lake levels as preserved in the Lake George sediment archive. The time span 0-9.4ka contains four GM episodes and 13 OSL dated lake levels. Of the latter, 69% date within the episodes of GM. The evidence suggests that precipitation in the Lake George basin has been associated with Jovian planet grand alignments and near GAs for at least the past 15000 years, and with phases of reduced solar and interplanetary magnetic field strength and increased GCR flux in the vicinity of the Earth.

The study supports the hypothesis that solar activity exhibits the well -known Hallstatt cycle periodicity (2300 yr). Mechanisms for cause and effect remain subjects for further study.

How to cite: Asten, M., McCracken, K., and Fitzsimmons, K.: A 10ka Holocene record of cyclic precipitation in a closed catchment in SE Australia, associated with episodes of solar Grand Minima and variations in galactic cosmic ray flux, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3395, https://doi.org/10.5194/egusphere-egu25-3395, 2025.

Discussion Post a comment

11:00–11:10

EGU25-12050

ECS

On-site presentation

The Role of Aerosol Types in Mediating the Impact of Galactic Cosmic Rays on Climate Variability Over the Past Two Decades

Faezeh Karimian Sarakhs, Fabio Madonna, and Salvatore De Pasquale

Galactic Cosmic Rays (GCRs), high-energy particles originating from supernovas, have been hypothesized to influence Earth's climate by ionizing atmospheric aerosols and accelerating the formation of cloud condensation nuclei (CCN). This mechanism leads to increasing the cloud cover and enhances the cooling effect at the Earth’s surface. However, the magnitude of this natural forcing remains a subject of debate. This study proposes the use of multivariate linear regression to model monthly anomalies in near-surface air temperatures as a function of anomalies in GCR flux and other solar and climate variables, including sunspot number, geomagnetic indices, greenhouse gas concentrations (CO₂ and CH₄), cloud effective radius (CER), cloud liquid water, radiation, and aerosol optical depth (AOD) across different latitudes. Monthly data collected over the past 20 years from a variety of instruments, surface-based and satellite on board, and networks monitoring the atmosphere and from three neutron monitoring stations at different latitudes: in Hermanus (South Africa, low-latitude), Newark (USA, mid-latitude), and Oulu (Finland, high-latitude) have been considered, being the location of three neutron monitor stations. CER and AOD emerged as the most significant predictors across all stations. Incorporating GCR flux as a covariate for AOD improved model performance, with adjusted R-squared values increasing from 0.22 to 0.31 in Oulu, 0.37 to 0.52 in Newark, and 0.69 to 0.78 in Hermanus. Further analysis using ECMWF atmospheric composition reanalysis indicated that sea salt aerosols, particularly in the 5–20 µm size range, dominate across all locations, suggesting their potential role to the mechanisms enhanced by the GCRs ionization power, such as CCN formation and particle aggregation. A next step would be to investigate the impact of GCRs on cloud characteristics, such as cloud cover, cloud fraction and cloud top properties like pressure and temperature, to gain a clearer understanding of their influence on climate variability.

Keywords: galactic cosmic ray, near surface temperature, aerosol type, sea salt aerosol, cloud condensation nuclei, climate natural variability

How to cite: Karimian Sarakhs, F., Madonna, F., and De Pasquale, S.: The Role of Aerosol Types in Mediating the Impact of Galactic Cosmic Rays on Climate Variability Over the Past Two Decades, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12050, https://doi.org/10.5194/egusphere-egu25-12050, 2025.

11:10–11:20

EGU25-13265

On-site presentation

Cosmic ray energy spectrum in the atmosphere measured with a novel balloon-carried detector

Karen Aplin and Justin Tabbett

Evaluating the effects of galactic cosmic rays (GCR) and space weather throughout the atmosphere has motivated development of new instruments. A 1 x 1 x 0.8 cm³ and 30g microscintillator detector was flown on a meteorological radiosonde over the UK, reaching an altitude of 32 km. The flight was intended as a technology demonstrator for an improved version of the microscintillator that interfaces with the industry standard Vaisala RS41 radiosonde. GCR neutrons are regularly measured at the surface and assumed to be an indicator of ionisation above. However, neutrons are not ionising, and there are known discrepancies between surface neutrons and ionising radiation aloft. Our microscintillator is sensitive to ionising radiation with energies from 25keV-10MeV. Each pulse is recorded and pre-processed on the balloon into 17 energy channels for real-time radio transmission to a ground station.

The flight, on the afternoon of 9^th July 2024, occurred during minimal solar and space weather activity, therefore the measurements are almost entirely from the cosmic ray background. The system also recorded count rates from two Geiger counters, both independently and as “coincidences” from simultaneous triggering from higher energy particles. As anticipated, the background count rate in the microscintillator and Geigers increased as the balloon ascended, reaching the Regener-Pfotzer maximum, in this case at 22 km. Peaks in the energy spectrum occurred at 1.8 MeV, likely to be due to the gamma rays produced through de-excitation of atmospheric nitrogen nuclei excited by secondary GCR neutrons. Detection of gamma rays from neutron interactions offers the possibility of a direct comparison to neutron monitors. There were also peaks at 300keV which may be from secondary electrons created by GCR. Unlike previous flights of this detector during space weather activity, no bremsstrahlung X rays at ~100keV were observed. The Geiger and coincidence counter results were consistent with the medium and high- energy channels from the microscintillator, respectively. This combination of altitude and energy resolution is highly unusual for such a small and light weight detector.

How to cite: Aplin, K. and Tabbett, J.: Cosmic ray energy spectrum in the atmosphere measured with a novel balloon-carried detector, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13265, https://doi.org/10.5194/egusphere-egu25-13265, 2025.

11:20–11:30

EGU25-13563

On-site presentation

Observation of the Forbush decrease during the May 2024 solar storms with different muon and neutron detectors in the high-latitude site of the Svalbard archipelago

Ombretta Pinazza, Lasse Hertle, Francesco Riggi, and Martin Schrön and the EEE Collaboration

During the series of intense solar flares that occurred in May 2024, a remarkable Forbush decrease in the cosmic ray flux was observed on the Earth by particle detectors around the world. The Svalbard archipelago, which is located at polar latitudes, is particularly exposed to geomagnetic storms because the Earth's magnetic field provides a particularly weak shielding and is therefore a privileged observation point. In this contribution, we report an analysis of the Forbush decrease event using data from a unique combination of muon and neutron detectors installed in Ny-Ålesund, on Svalbard: three scintillator-based muon telescopes of the Extreme Energy Events (EEE) Project, 14 channels of a Bonner Sphere neutron Spectrometer (BSS), thermal and epithermal neutron sensors used for hydrological monitoring, and a high-energy neutron monitor located in Barentsburg and operated by the Polar Geophysical Institute. We found that most sensors showed significant responses and correlation during the event. The observed magnitude of the Forbush decrease depended on the detector’s energy sensitivity and was ≈ 10% for thermal neutrons, ≈ 8% for high-energy neutrons, and ≈ 3% for muons. The uncertainty of these results strongly depends on factors like the count rate, which ranged from 10 to 105 cph and resulted in low signal-to-noise ratio, particularly for the BSS. A detailed correlation analysis was carried out among the various time series originated from the different detectors in the “quiet” period (before the Forbush decrease) and during the Forbush event. Multi-particle and multi-energy observations provide an unprecedented view on the Earth’s exposure to cosmic rays during solar events.

How to cite: Pinazza, O., Hertle, L., Riggi, F., and Schrön, M. and the EEE Collaboration: Observation of the Forbush decrease during the May 2024 solar storms with different muon and neutron detectors in the high-latitude site of the Svalbard archipelago, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13563, https://doi.org/10.5194/egusphere-egu25-13563, 2025.

11:30–11:40

EGU25-17136

ECS

On-site presentation

Bonner Sphere Spectrometer at the Environmental Research Station Schneefernerhaus: Measuring Cosmic Radiation and Facilitating Data Accessibility

Jonas Marach, Thorsten Klages, Vladimir Mares, Marcel Reginatto, Till Rehm, Werner Rühm, and Miroslav Zboril

In 2024, Germany’s national metrology institute, the Physikalisch-Technischne Bundesanstalt (PTB), signed a sponsorship agreement with the Operational Company of the Environmental Research Station Schneefernerhaus (Umweltforschungsstation, UFS) for the operation, maintenance and upgrade of the Bonner sphere-based neutron spectrometer located at the UFS. The UFS Schneefernerhaus was established in 1999 and is Germany’s highest research station at an altitude of 2650 meters, just below the summit of Mt. Zugspitze, where it houses a wide range of scientific instruments for observing weather, climate and climate change.

The Bonner Sphere Spectrometer (BSS) system at the UFS Schneefernerhaus has been in operation since 2005, thanks to the cooperation between the UFS Operational Company and the German Research Center for Environmental Health of the Helmholtz Center Munich. The system is used for continuous measurements of the neutron component of secondary cosmic radiation. With an extensive set of polyethylene sphere moderators and spheres with metal shells, the BSS at Schneefernerhaus can detect neutrons with energies ranging from 10^-9 MeV to 10³ MeV. Thanks to its spectrometric capabilities, the system can provide neutron energy spectra, which is an advantage over the classical neutron monitors used worldwide.

The Neutron Radiation Department of PTB is currently working on upgrading the data acquisition hardware and software, data storage, workflow and data analysis of the BSS system towards an automated and robust operation.

This presentation introduces methods for error correction and data preparation, incorporating historical data (years 2013 to 2024) from the former team of the Helmholtz Center Munich, and discusses possibilities for disseminating the data to scientific communities.

How to cite: Marach, J., Klages, T., Mares, V., Reginatto, M., Rehm, T., Rühm, W., and Zboril, M.: Bonner Sphere Spectrometer at the Environmental Research Station Schneefernerhaus: Measuring Cosmic Radiation and Facilitating Data Accessibility, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17136, https://doi.org/10.5194/egusphere-egu25-17136, 2025.

11:40–11:50

EGU25-11397

ECS

On-site presentation

Improving neutron spectrometry measurement methodology to better understand soil moisture variability: application to an area subject to strong seasonal and daily variations

Anaïs Tilhac, Guillaume Hubert, Markus Köhli, and Fabienne Lohou

Secondary cosmic rays (CRs) are produced when primary CRs interact with atmospheric atoms, leading
to the formation of a cascade of secondary particles such as neutrons, pions, protons, and muons, with
energies ranging from a few dozen meV to over 1 GeV. Neutrons produced during the extensive air
shower spreading is characterized by a high elastic scattering cross section with hydrogen nuclei. This
latter effectively moderates neutrons by slowing them down, and composes different media in the
atmosphere, such as water vapor, ice and liquid vapor.
Neutron spectrometry is based on this singular ability of hydrogen to moderate neutrons. In addition of
interacting with the atmosphere, cosmic neutrons also interact with the Earth’s surface. Some of them
are scattered back to the surface and are referred to as albedo neutrons. This phenomenon is crucial for
studying soil moisture with a Bonner sphere spectrometer. Indeed, previous studies on both neutrons
monitors and Bonner spheres spectrometers highlighted the impact of soil water content on neutron fluxes,
validating the use of these methods to monitor soil moisture. However, it has been established that
atmospheric water vapor induces a significant decrease in neutron counts that requires consideration.
For this study, an experimental platform was deployed at the Atmospheric Research Center in
Lannemezan, France. This platform includes instruments monitoring the atmospheric column
hygrometry (precipitations, mixing ratio) and pressure -provided by a 60 m high mast- and soil moisture
variations measured by refractometric probes in a 120 cm depth pit. In addition, a BSS extended to high
neutron energies is constantly measuring the neutronic natural environment near the pit and mast since
September 2023. The Bonner sphere spectrometer consists of three high-density polyethylene spheres
(3, 5, and 8 inches) and two polyethylene spheres with inner high-density metal shells (8 and 9 inches),
each equipped with a 2-inch proportional counter. This instrument provides a valuable information about
the detected neutrons by allowing the reconstruction of the full spectrum, from meV to GeV. Thus, this
approach enables the study of the impact of different hydrogen pools across the four main energy
domains (thermal, epithermal, evaporation, and cascade neutrons).
To complement these experimental data, a simulation work was necessary. The URANOS (Ultra Rapid
Neutron Only Simulation) code has been a reference for several years in the field of simulating the
transport of atmospheric neutrons in the atmosphere and soils. It is based on the application of the Monte
Carlo method, and allows to calculate physical quantities such as energy distribution, spatial distribution,
and neutron interaction processes. To meet more accurately the needs of this study, a module
specifically designed for Bonner Spheres has been developed, providing key information on the impact
of the atmosphere on neutron counts measured by each sphere.
In this study, we apply a new methodology to a set of experimental time series in order to reduce the
impact of the atmosphere on neutron counts from the Bonner sphere spectrometer. We will finally
compare the results to the same uncorrected time series.

How to cite: Tilhac, A., Hubert, G., Köhli, M., and Lohou, F.: Improving neutron spectrometry measurement methodology to better understand soil moisture variability: application to an area subject to strong seasonal and daily variations , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11397, https://doi.org/10.5194/egusphere-egu25-11397, 2025.

11:50–12:00

EGU25-4551

On-site presentation

Atmospheric effect on cosmic ray produced neutron: mini neutron monitor experimental results

Juan Jose Blanco, Du Toit Strauss, Juan Ignacio García-Tejedor, África Barreto, Pablo Cerviño-Solana, David Arrazola, Alberto Regadío, Carlo Luis Guerrero Contreras, Pablo Gonzalez-Sicilia, David Moure, Victor Cabrera, Stepan Poluianov, and Óscar García-Población

Primary cosmic rays (PCRs) interact with atmospheric nuclei producing a myriad of secondary particles known as secondary cosmic rays (SCRs) that can be measured with ground-based detectors such as neutron monitors. Neutrons, protons, pions or muons are some of the particle species of these SCRs. Their flux is related to the kinetic energy of the PCRs and shows a strong dependence on the pressure level at the observation site reflecting their dependence on the amount of matter they have to pass through the atmosphere. In addition, the air column above the observation point evolves continuously introducing temporal changes in the SCR flux due to atmospheric conditions. This atmospheric effect is taken into account by the β factor, which is the exponent of the exponential relationship between the atmospheric pressure and the SCR count rate, being mostly neutrons in the case of neutron monitors. On the other hand, pressure shows an inverse dependence with height above sea level and this should be reflected in the neutron monitor count rate as it is measured at different altitude levels. Altitude surveys with a mobile neutron monitor are essential for understanding how the atmosphere affects SCR production and for cross-checking models describing the interaction between cosmic rays and atmospheric atoms. From October 2023 to September 2024, one such survey was carried out with a mini neutron monitor on the island of Tenerife. Four sites were visited at the altitudes of 20, 868, 2390 and 3355 meters above sea level, respectively. A control point to monitor solar activity during altitude sounding has been established at the 2390 m site where a standard 3NM64 neutron monitor has been operating since early 2023 at the Izaña Atmospheric Observatory. The results of the experiment are presented and discussed and the dependence of the β factor on the multiplicity in the mini neutron monitor is noted, suggesting an energy dependence of the β factor.

How to cite: Blanco, J. J., Strauss, D. T., García-Tejedor, J. I., Barreto, Á., Cerviño-Solana, P., Arrazola, D., Regadío, A., Guerrero Contreras, C. L., Gonzalez-Sicilia, P., Moure, D., Cabrera, V., Poluianov, S., and García-Población, Ó.: Atmospheric effect on cosmic ray produced neutron: mini neutron monitor experimental results, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4551, https://doi.org/10.5194/egusphere-egu25-4551, 2025.

12:00–12:10

EGU25-15027

On-site presentation

Scaling Cosmic Ray Neutron Flux for Enhanced Environmental Monitoring

Roland Baatz, Patrick Davies, Paolo Nasta, Paul Schattan, Emmanuel Quansah, Leonard Amekudzi, and Heye Bogena

Cosmic Ray Neutron Sensors (CRNS) are pivotal in measuring field-scale soil moisture, but uncertainties persist due to traditional methods of scaling parameter estimation, which often fail to consider site- and sensor-specific factors. This study integrates novel, data-driven approaches to refine scaling parameters for atmospheric pressure, air humidity and incoming cosmic ray intensity (β, ψ, ω) using measurement data. We demonstrate the strong potential for considerable improvents in the accuracy of CRNS-derived soil moisture estimates. Additionally, barometric correction in CRNS but also in neutron monitors is critical to account for local atmospheric density variations to minimize errors in soil moisture estimation and incoming cosmic ray intensity. Our analysis of CRNS and Neutron Monitor data from global stations reveals significant variability in barometric coefficients (β), influenced by geographical and atmospheric factors. The findings underscore the necessity for tailored scaling and correction methods to optimize CRNS applications in hydrology, agriculture, and climate research. Enhanced parameter estimation reduced RMSE by up to 25%, demonstrating potential for improved environmental decision-making and modeling accuracy.

How to cite: Baatz, R., Davies, P., Nasta, P., Schattan, P., Quansah, E., Amekudzi, L., and Bogena, H.: Scaling Cosmic Ray Neutron Flux for Enhanced Environmental Monitoring, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15027, https://doi.org/10.5194/egusphere-egu25-15027, 2025.

12:10–12:20

EGU25-12782

ECS

On-site presentation

On the use of geophysics to support and connect soil sensors and cosmic ray neutron sensing: a case study highlighting the relevance of soil heterogeneity

Luca Peruzzo, Mirko Pavoni, Viola Cioffi, Matteo Censini, Francesca Manca, Ilaria Barone, Matteo Verdone, Jacopo Boaga, and Giorgio Cassiani

Precision agriculture directly points at both spatial and temporal variabilities, to be mapped and monitored with relevant technologies. With regard to the subsurface, soil sensors remain the foremost driver of precision agriculture. These sensors provide high temporal resolution information on key soil variables, including volumetric water content. However, their limited representativeness and high sensitivity to local and installation factors are intrinsic and well known issues. Cosmic ray neutron sensing (CRNS) is a newer technology that addresses these issues, with the water content information being integrated over a footprint of several tens of meters. Nonetheless, the integrated water information remains a one-dimensional time series. The interplay of different spatial scales of the measurements and unknown subsurface heterogeneity ultimately hinders the correct interpretation of the individual time series, and their discrepancies.

In this work we explore how geophysics-based soil heterogeneity supports the interpretation of time series from soil water sensors and cosmic ray neutron sensing. We present a case study from a vineyard in the Chianti region (Siena, Italy). We focus on the joint use of electrical resistivity tomography and frequency-domain electromagnetic induction. Two field campaigns, conducted in April and November 2024, highlight significant differences in both soil composition (clay content) and soil depth over the vineyard. Before the geophysical campaign, the soil water sensors were installed in a region with particularly deep and clayey soil. On the contrary, the cosmic ray was installed at the center of the vineyard and thus responds to regions with dominant water dynamics. The results show that the differences in water dynamics between the clay-rich area (with the soil sensors) and the surrounding areas coupled with the larger CRNS sensitivity to faster-draining regions lead to significant discrepancies. The geophysics-based spatial information qualitatively explains these discrepancies and supports CRNS numerical simulations (Uranos) that aim to provide a more quantitative understanding.

How to cite: Peruzzo, L., Pavoni, M., Cioffi, V., Censini, M., Manca, F., Barone, I., Verdone, M., Boaga, J., and Cassiani, G.: On the use of geophysics to support and connect soil sensors and cosmic ray neutron sensing: a case study highlighting the relevance of soil heterogeneity, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12782, https://doi.org/10.5194/egusphere-egu25-12782, 2025.

12:20–12:30

EGU25-15979

On-site presentation

Validation of rail based CRNS-roving: underpinning the large-scale root zone soil moisture monitoring concept

Daniel Altdorff, Solveig Landmark, Merlin Schiel, Sascha E. Oswald, Steffen Zacharias, Peter Dietrich, Hannes Mollenhauer, Sabine Attinger, and Martin Schrön

Root zone soil moisture (RZSM) is a critical parameter for various environmental, agricultural, and hydrological applications. The recently proposed rail based Cosmic Ray Neutron Sensing monitoring method (Rail-CRNS) offers an innovative solution for soil moisture measurement by enabling continuous, large-scale RZSM measurements across extensive railway networks. By 2024, Germany established a fleet of five Rail-CRNS systems, covering up to hundreds of kilometers daily and marking thus a transformative step in soil moisture monitoring. Yet, questions remained regarding the reliability of Rail-CRNS data: did they accurately capture RZSM, or were they overly influenced by confounding factors such as land use and rail track conditions?

This study addresses these questions by analyzing 16 months of Rail-CRNS data collected along a pilot route in Rübeland, Low Harz Mountain, Germany. Time series from two stationary CRNS sites, located in forested and grassland areas, were compared with corresponding Rail-CRNS data segments. Additionally, soil moisture measurements from buried sensor nodes in the forest provided for parts of the period another independent reference dataset. The results demonstrated a strong correlation between the stationary CRNS measurements, the Rail-CRNS-derived RZSM values, and the soil moisture node data. This alignment indicates that Rail-CRNS data reliably captures not only spatial but also temporal variability in soil moisture. These findings provide robust support for the Rail-CRNS concept, emphasizing its potential to generate accurate and high-resolution RZSM data for regional and national-scale monitoring.

However, the pilot study was conducted under specific and well-monitored conditions, with frequent train passages and a well-instrumented route. Applying the Rail-CRNS method to longer, less-instrumented tracks, combined with higher train speed variability and fewer repeated passes, will likely introduce greater uncertainties. To address this, the deployment of a CRNS station cluster near railways was proposed. Such clusters would enable ongoing validation of Rail-CRNS data, ensuring their reliability across diverse environmental and operational conditions.

This study underscored the transformative potential of Rail-CRNS in overcoming the long-standing challenges of sparse and incomplete RZSM measurements. However, further instrumentation and research is planned to develop strategies for mitigating potential uncertainties in less-controlled environments. Integrating Rail-CRNS data with satellite-based products and RZSM estimates from hydrological modeling for example could further enhance the accuracy and applicability of soil moisture monitoring on a national scale.

How to cite: Altdorff, D., Landmark, S., Schiel, M., Oswald, S. E., Zacharias, S., Dietrich, P., Mollenhauer, H., Attinger, S., and Schrön, M.: Validation of rail based CRNS-roving: underpinning the large-scale root zone soil moisture monitoring concept, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15979, https://doi.org/10.5194/egusphere-egu25-15979, 2025.

Posters on site: Thu, 1 May, 08:30–10:15 | Hall X4

Display time: Thu, 1 May, 08:30–12:30

Chairpersons: Lena Scheiffele, Jannis Weimar, Martin Schrön

X4.80

EGU25-17007

ECS

A Gamma Ray and Neutron Spectrometer (GRNS) for mapping lunar surface composition and water abundance on the SER3NE mission

Rebecka Wahlén, Ramsey Al Jebali, Luis Teodoro, and Anja Kohfeldt

Selene’s Explorer for Roughness, Regolith, Resources, Neutrons and Elements (SER3NE) is a lunar orbiter mission designed to map the topmost composition of the lunar surface, including elemental composition and water abundance. Planned instruments include a Gamma Ray and Neutron Spectrometer (GRNS) for elemental composition, including hydrogen indicating water, a Laser Altimeter (LA) for surface roughness and albedo observations, and a near-infrared spectrometer (LIPS) to determine water forms.

The GRNS detector is designed for both in situ utilization as well as remote sensing. It has a core of CLLBC and LaBr₃ crystal scintillators in a chessboard pattern for high-resolution gamma-ray detection (30 keV-8MeV) and thermal to epithermal neutron sensitivity. Gd foil on CLLBC allows separation of thermal and epithermal neutrons, while LaB3 and CLLBC enable advanced neutron detection analysis. Encapsulated by EJ-248M plastic scintillators, the detector includes anti-coincidence detector for charged particle rejection. With gamma-ray spectroscopy, rock-forming elements as well as KREEP and trace elements can be detected in the shallow surface of the moon. The local count rates of thermal and epithermal neutrons allow for the analysis of the distribution of hydrogen on the lunar surface, as well as for estimation of neutron lifetime from the lunar orbit.

A demonstrator of the GRNS instrument has been successfully tested in the lab. A prototype of this lunar GRNS instrument will fly on the CENSSat-1 Bifrost CubeSat mission, scheduled for launch 2027.

In this presentation, the GRNS instrument concept will be presented, focusing on the detector design and suitability for elemental composition analysis on a lunar orbiter.

How to cite: Wahlén, R., Al Jebali, R., Teodoro, L., and Kohfeldt, A.: A Gamma Ray and Neutron Spectrometer (GRNS) for mapping lunar surface composition and water abundance on the SER3NE mission, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17007, https://doi.org/10.5194/egusphere-egu25-17007, 2025.

X4.81

EGU25-19534

ECS

Mars Radiation Environment and Water-ice Prospecting through a Distributed Swarm of Tumbleweed Rovers

Mário de Pinto Balsemão, Abhimanyu Shanbhag, James Kingsnorth, Gergana Bounova, Luka Pikulić, Cristina Moisuc, Daan Molhuijsen, and Julian Rothenbuchner

The Tumbleweed mission aims to revolutionize Mars exploration by leveraging the unique capabilities of wind-driven, spheroidal rovers. The use of modular design strategies, off-the-shelf components, and mass production will significantly reduce costs, making Mars exploration more accessible. Designed for rapid and extensive surface exploration, Tumbleweed rovers offer an affordable and efficient method for gathering crucial data across large areas of the Martian terrain. By deploying a swarm of more than 90 rovers equipped with various scientific instruments, this mission will significantly enhance our understanding of Mars, facilitating future human exploration and settlement.

The search for water in various forms is the common thread that binds the science goals of Mars exploration missions over the past few decades. For large scale water extraction (aimed at producing propellant and potable water in sizable quantities), a coordinated prospecting and characterisation campaign is required to arrive at maps of exploitable reserves.

Unfortunately, current architectures rely primarily on large, complex, and expensive rovers. While these platforms provide invaluable data, they are limited in their spatio-temporal coverage. Consequently, optimal Exploration Zones (EZs) for human exploration of Mars are yet to be defined.

Based on current priorities in Mars science and exploration, as well as the technical constraints of the Tumbleweed rover, a preliminary list of instruments was drafted. Exploring the synergies amongst these instruments, we arrived at the opportunity to use radiation-focused instrumentation to simultaneously achieve high-resolution mapping of hydrogen in the near-surface environment. Measuring the flux of epithermal neutron emissions is one of the best approaches towards estimating water equivalent hydrogen (WEH) abundance. Thermal and epithermal neutron measurements from instruments such as FREND, HEND and DAN have indicated the presence of WEH in the near-surface. This would represent the prime target for ISRU operations in the near future. However, the resolution of existing orbital maps of water ice is insufficient to direct and execute robotic/human operations on ground.

This suite of radiation detection instruments will be consolidated in the future through the addition of a miniaturized Gamma Ray Spectrometer, providing the ability to perform elemental mapping along the rover traverse. Beyond neutron spectrometers, patch permittivity sensors may also be deployed on the Tumbleweed Rovers, enabling cross-confirmation of WEH mapping.

This instrumentation and our mission architecture enable high-resolution mapping of Martian environments, combining radiation scouting with WEH prospecting, thus identifying low-radiation and high-WEH regions ideal for crewed missions.

To aid further maturation and design of the mission, a conceptual study is proposed herein. Starting from a simulation of the individual rover’s trajectories on the surface of Mars, we shall geospatially compute the probable intersections with the already identified EZs on Mars. Based on these intersections we can infer thresholds for the controlled navigation of individual rovers (assessing intersections per trajectory buffer size) and classify candidate EZs according to known topography and available WEH mapping. This classification would enable more precise GEANT4 modelling of individual rovers and their instrumentation, resulting in probable neutron counts and dose/flux readings, leading to mission-specific requirements for our spacecrafts and their payloads.

How to cite: de Pinto Balsemão, M., Shanbhag, A., Kingsnorth, J., Bounova, G., Pikulić, L., Moisuc, C., Molhuijsen, D., and Rothenbuchner, J.: Mars Radiation Environment and Water-ice Prospecting through a Distributed Swarm of Tumbleweed Rovers , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19534, https://doi.org/10.5194/egusphere-egu25-19534, 2025.

X4.82

EGU25-3490

ECS

Simulation of Cosmic Rays Trajectories and Neutron Transport generated on the Sun and observed on Earth

Rocío Fuente, Carlo Luis Guerrero, Juan José Blanco, and Pablo Cerviño

The study of Cosmic Rays (CRs) and Solar Energetic Particles (SEPs) is key in analyzing the effect of solar activity on the terrestrial environment. Changes in the properties of the medium they pass through until their detection profoundly affect the intensity and the propagation direction of the CR flux.

Our starting point is that accurate measurements of CR and SEP flux can allow us to infer the conditions of the medium they pass through on their way to Earth, particularly the interplanetary medium, the magnetosphere and the atmosphere. The development of a CR simulation code helps us perform such analysis, which may contribute to future predictions of solar events and prevent potential damage and disturbances in the global technological system and the human environment. Computational simulation of these phenomena allows us to interpret the data and obtain a vision that will facilitate, for instance, explaining the generation and transport of solar neutrons to Earth’s atmosphere and their interaction with the atmosphere and the detectors installed in different geographical locations.

The Space Research Group of the University of Alcala (SGR – UAH) has extensive experience in the design, construction, control and maintenance of neutron measurement systems, distributed in different regions of the world. Among these, we can mention: CALMA, ORCA, ICaRO and the EPD aboard on the Solar Orbiter Mission. These instruments generate a large amount of data that must be analyzed and modeled for understanding and study. It is at this point where computational simulation techniques and data management are crucial for the SGR-UAH group.

In this work we present the code we developed to study the trajectory and rigidity of charged particles entering Earth’s magnetic field. The simulation code TOROS (Trajectories of cOsmic Rays Observed Simulator) is based on numerically calculating the trajectories of charged particles and their interaction with Earth’s magnetic field before reaching the atmosphere. The code uses the magnetic dipole model and various approximations of Tsyganenko’s magnetic field model. Our goal is to use this simulation tool and the data it generates as input for well known simulation codes in the research field, such as GEANT-4 and CORSIKA, to validate, simulate and propose models based on experimental measurements from detectors of the SGR-UAH group and others worldwide. Comparing our results with other simulation codes is also part of the validation and testing process for the “TOROS” code.

How to cite: Fuente, R., Guerrero, C. L., Blanco, J. J., and Cerviño, P.: Simulation of Cosmic Rays Trajectories and Neutron Transport generated on the Sun and observed on Earth, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3490, https://doi.org/10.5194/egusphere-egu25-3490, 2025.

X4.83

EGU25-19126

ECS

Reduced ERA-I forecasting skill during Forbush decreases

(withdrawn)

Jacob Svensmark

X4.84

EGU25-18374

Approaches and Challenges of the Neutron Monitor based Incoming Flux Correction for Cosmic-Ray Neutron Sensing

Lasse Hertle, Steffen Zacharias, Nicholas Larsen, Daniel Rasche, and Martin Schrön

Cosmic Ray Neutron Sensing (CRNS) is a technique to measure water content, for example soil moisture, on the hectare scale through the measurement of epithermal neutrons. The neutrons are results of particle showers in the earth's atmosphere caused by cosmic rays impinging on it. The abundance and global distribution of neutrons is changed in time through different factors. On the largest scale, the heliosphere and therefore the solar cycle greatly affect the amount of galactic cosmic rays that are able to reach earth. Large solar events, such as Forbush decreases, also cause rapid changes in the cosmic ray flux. The aim of any incoming neutron flux correction method is ultimately to account for these heliospheric changes. Any neutron monitor based correction method has to overcome the uneven distribution of neutrons across latitudes, due to the earth's magnetic field. There have been multiple, neutron monitor based, approaches developed, all of them based upon the assumption of linearity between the CRNS and the neutron monitor measurement. This assumption is challenged by multiple factors, most importantly geomagnetic and local conditions. Understanding the challenges and limitations of the linearity assumption is crucial to reliably correct CRNS measurements and produce a robust soil moisture product. Multiple correction methods have been evaluated and compared, with consideration towards the impact of different geomagnetic and local conditions.

How to cite: Hertle, L., Zacharias, S., Larsen, N., Rasche, D., and Schrön, M.: Approaches and Challenges of the Neutron Monitor based Incoming Flux Correction for Cosmic-Ray Neutron Sensing, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18374, https://doi.org/10.5194/egusphere-egu25-18374, 2025.

X4.85

EGU25-5935

Site-specific incoming correction based on muons: a comparison with cosmic neutrons measurements at JUNG at OULU.

Carlotta Bonvicini, Gianmarco Cracco, Barbara Biasuzzi, Stefano Gianessi, Marcello Lunardon, Mario Zara, Marco Zanetti, Luca Stevanato, and Enrico Gazzola

Cosmic Rays Neutron Sensing (CRNS) opened the possibility to measure water content in the environment by neutrons absorption overcoming the need of an artificial radioactive source of neutrons. While the exploitation of a naturally available source of radiation is a fundamental feature that allows the widespread deployment of permanent sensors on-field, it intruduces the need of monitoring the natural variation of the incoming radiation to correct the signal accordingly.

This so-called “incoming correction” for CRNS is usually obtained by referring to the public data provided by the Neutron Monitor DataBase (NMDB) observatories, with the Jungfraujoch (JUNG) often being the preferred one, due to its position in central Europe on the Swiss Alps. In fact, a critical factor affecting the incoming flux of cosmic rays at the ground is the geomagnetic cutoff rigidity parameter, which is site-specific with a strong dependence on the latitude. The site-specificity of the incoming correction, together with the need to rely on an external source of data, makes it a crucial topic for the CRNS community.

Finapp developed a patented detection technology with the feature of contextually detecting neutrons and muons. Muons are also generated by cosmic rays, but they are not backscattered by the soil like neutrons, which makes them suitable for monitoring the incoming flux itself. In order to provide a fair, site-specific comparison between the variations of muons counts by Finapp and cosmic neutrons counts by NMDB observatories, we installed a sensor at the NMDB-JUNG site in January 2024 and one at the NMDB-OULU site in Finland in October 2024. In this presentation we will report preliminary results of this project and its impact on CRNS applications.

We acknowledge the NMDB database (www.nmdb.eu), founded under the European Union's FP7 programme (contract no. 213007) for providing data. Jungfraujoch neutron monitor data were kindly provided by the Physikalisches Institut, University of Bern, Switzerland. Oulu neutron monitor data were kindly provided by the Sodankyla Geophysical Observatory (https://cosmicrays.oulu.fi).

How to cite: Bonvicini, C., Cracco, G., Biasuzzi, B., Gianessi, S., Lunardon, M., Zara, M., Zanetti, M., Stevanato, L., and Gazzola, E.: Site-specific incoming correction based on muons: a comparison with cosmic neutrons measurements at JUNG at OULU., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5935, https://doi.org/10.5194/egusphere-egu25-5935, 2025.

X4.86

EGU25-12351

Irrigation Management and Soil Moisture Monitoring with Cosmic-Ray Neutron Sensors: Lessons Learned and Future Opportunities

Heye Bogena, Cosimo Brogi, Felix Nieberding, Andre Daccache, Lena Scheiffele, and Salar Saeed Dogar

Cosmic Ray Neutron Sensing (CRNS) is attracting attention in irrigation management. CRNS can non-invasively and accurately measure soil moisture (SM) in the root zone at the field scale, thus addressing scale and logistics issues typical of point-scale sensor networks. CRNS are effectively used to inform large pivot irrigation systems but most agricultural landscapes in Europe and elsewhere consist of highly diversified and small fields. These are challenging for CRNS as the measured signal integrates an area of ~200m radius where multiple fields, soil heterogeneities, or variable amount of water applications can be found.

In this work, we present results from three case studies, and we develop and test solutions to improve CRNS accuracy in irrigated contexts. In 2023, a potato field in Leerodt (Germany) where strip irrigation is practiced was equipped with three CRNS (with moderators and thermal shielding), three meteorological stations, and six profile SM probes measuring at six different depths (up to 60 cm). In the same year, in Davis (California, USA), two CRNS with a 15 mm moderator, one of which also had a thermal shielding, were installed in an alfalfa field where flood irrigation is practiced. These were supported by meteorological measurements and point-scale TDR sensors. Similarly, a CRNS installed in a winter wheat field in Oehna (Germany) where pivot irrigation is applied. As the origin and propagation of neutrons detected by a CRNS cannot be inferred from the measured signal, we used the URANOS model to analyze neutron transport in the three case studies under varying soil moisture scenarios. To account for soil heterogeneity in the Leerodt study, we assessed the spatial distribution of soil characteristics by integrating soil sampling and Electromagnetic Induction (EMI) measurements in a machine-learning framework.

The Leerodt study showed that CRNS outperformed point-scale sensors, which were strongly affected by soil erosion in the top 10 cm. However, CRNS was unexpectedly sensitive only to nearby irrigation. Here, key insights on sub-footprint heterogeneity and soil roughness were gained through the analysis of URANOS simulations. In the Davis study, CRNS effectively monitored irrigation but also showed unexpected sensitivities to the irrigation of distant fields. Again, important insights were gained thanks to URANOS simulations. In the Oehna study, large quantitative differences between the CRNS and point-scale sensors were observed. However, the CRNS provided clear responses to irrigation that can outperform the information provided by the point-scale devices. Overall, the limitations of CRNS-based irrigation management in complex agricultural environments can generally be overcome through a synergetic use of measurements and modelling. Nonetheless, more efforts are needed to improve the understanding of the underlying processes and to standardize measurement procedures, which ultimately requires the involvement not only of researchers but also of manufacturers and stakeholders.

How to cite: Bogena, H., Brogi, C., Nieberding, F., Daccache, A., Scheiffele, L., and Dogar, S. S.: Irrigation Management and Soil Moisture Monitoring with Cosmic-Ray Neutron Sensors: Lessons Learned and Future Opportunities, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12351, https://doi.org/10.5194/egusphere-egu25-12351, 2025.

X4.87

EGU25-19713

ECS

Understanding the influence of landscape heterogeneities on the signal of cosmic-ray neutron sensors by means of site-specific neutron transport simulation

Jannis Weimar, Markus Köhli, Martin Schrön, Sascha Oswald, and Miroslav Zboril

Monitoring soil moisture is a challenging task due to its complex spatial patterns. In recent years, cosmic-ray neutron sensing has gained popularity for its ability to provide integral measurements over a few hectares horizontally and a few decimeters vertically, covering a representative volume for many research questions in various landscapes. However, interpreting signals using averaging methods becomes increasingly difficult as the heterogeneity of the observable increases.
As part of the SoMMet project, three field sites in Germany and Italy equipped with cosmic-ray neutron sensors are analyzed in detail using the Monte Carlo code URANOS. The virtual representation of these sites in the code allows for removing and adding structures. Thereby, all features of the landscape of the three different sites can be examined separately with respect to their impact on the local neutron field. These include general landscape heterogeneities, buildings, land use, and biomass. While this study focuses on three specific, although relatively common, site setups, it also offers general insights that can enhance the understanding of signal and footprint dynamics at other locations.

How to cite: Weimar, J., Köhli, M., Schrön, M., Oswald, S., and Zboril, M.: Understanding the influence of landscape heterogeneities on the signal of cosmic-ray neutron sensors by means of site-specific neutron transport simulation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19713, https://doi.org/10.5194/egusphere-egu25-19713, 2025.

X4.88

EGU25-3236

ECS

Challenges and Opportunities with Soil Moisture Measurement in Ireland using Cosmic-Ray Neutron Sensing: Examples from an agriculture and a forest site

Haleh Karbala Ali, Klara Finkele, Rafael Rosolem, Jonathan Evans, Martin Schrön, Brian Tobin, and Eve Daly

Field-scale Soil Moisture (SM) is an important variable to derive and study agriculture, plant growth, nutrient management, water quality and management, soil carbon sequestration, groundwater availability, flood forecasting, forest fire risk, land surface models and is an Essential Climate Variable (ECV). Field-scale SM estimates are vital due to small scale soil heterogeneities and can fill the gap between the traditional in-situ point measurements and products derived from remote sensing.

The Cosmic-Ray Neutron Sensor (CRNS) technology detects and counts naturally occurring fast neutrons (generated by cosmic-rays) after they are slowed primarily by hydrogen atoms in soil water and biomass. The CRNS can measure the root-zone SM at field-scale in a non-invasive way to an effective depth of 10 to 70 cm depending on soil water content and over a footprint of around 300 m diameter.

The AGMET group (Working Group of Applied Agricultural Meteorology in Ireland) instigated the Irish Soil Moisture Observation Network (ISMON) in 2021 and installed ten CRNS stations across Ireland, covering a range of soil types, with a view to estimating regional soil moisture conditions more accurately.

In this study, we present the SM estimates recorded since 2021 at two different ISMON sites in Ireland. In each of these sites, the CRNS sensor is co-located with arrays of Time-Domain Reflectometry (TDR) in-situ sensors. The first site is an agricultural grazing system on a mineral soil at the ISMON Farmer’s Journal farm site in Tullamore, County Offaly. The second site locates in a forest setting at the ISMON Dooray forest in County Laois. The CRNS measurements are calibrated based on soil sampling campaigns and the CRNS derived SM products are compared with TDR measurements for validation. The effect of the soil types and vegetation cover on the final SM estimates are investigated.

How to cite: Karbala Ali, H., Finkele, K., Rosolem, R., Evans, J., Schrön, M., Tobin, B., and Daly, E.: Challenges and Opportunities with Soil Moisture Measurement in Ireland using Cosmic-Ray Neutron Sensing: Examples from an agriculture and a forest site, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3236, https://doi.org/10.5194/egusphere-egu25-3236, 2025.

X4.89

EGU25-11935

ECS

Adverse conditions for cosmic-ray neutron sensing: high water content low bulk density – can we still infer soil moisture over the full moisture range?

Peter Grosse, Lena Scheiffele, Sophia Dobkowitz, Katya Dimitrova-Petrova, Daniel Rasche, and Sascha Oswald

Near-surface soil moisture variation is an important variable in peatlands, controlling chemical processes and peat development or degradation. Cosmic-ray neutron sensing (CRNS) provides an area average soil moisture over a support volume of > 150 m radius and down to 50 cm depth by relating the abundance of secondary fast neutrons above ground to soil moisture. However, standard calibration and weighting functions for CRNS were developed and tested for mineral soils with dry bulk densities above 1 g cm^-³ and only up to 55 % of volumetric soil moisture. Peat soils, in contrast, are characterized by high organic matter content, low bulk densities, and high soil moisture when saturated. This makes peatlands a challenging environment for any soil moisture monitoring, including CRNS. In such adverse conditions, questions remain on the appropriate CRNS calibration approach and therefore the accurate determination of soil moisture.

This study presents lessons learned from operating a CRNS at a fen site with extensively used grassland in Northeast Germany (nature conservation area “Kremmener Luch”) for 3.5 years. The CRNS was complemented with point-scale soil moisture sensor profiles down to 1 m (FDR and TDR) in several locations of its footprint as well as groundwater level observations to identify periods of ponding that occur frequently at the site. Measuring soil moisture with the dielectric point-scale sensors showed challenges on its own. We increased the precision of point-scale data by a local soil specific calibration relating sensor permittivity to soil moisture. However, strong jumps and unreliable values remained, presumably due to swelling and shrinking of the organic-rich soil and loss of contact with the sensor. FDR and TDR time series showed large differences in absolute values as well as spatially different soil moisture regimes due do effects of microtopography. This is opposed to the CRNS, which senses average water content independent of small-scale heterogeneities. To derive a CRNS soil moisture time series we tested calibrating the CRNS using data from dedicated soil moisture sampling campaigns or the point-scale time series. We obtained unrealistically high CRNS-soil moisture regardless of which calibration function we chose – the standard “Desilets’ equation” or the recently proposed advanced “Universal Transport Solution”. Following the suggestion in previous CRNS studies conducted at peaty sites, we adjusted the parameters of the Desilets’ equation, which lead to a more realistic soil moisture range. However, the estimation of the CRNS integration depth with the standard procedures is very sensitive to the low bulk density of the organic soil and remains largely uncertain. This data set serves as a valuable testbed for extending the validity of existing calibration and weighting functions, and we will utilize neutron simulations to enhance our understanding of the vertical footprint of CRNS under conditions of low bulk density and high soil moisture.

Improved understanding and precision of CRNS soil moisture in peatlands can support peatland restoration efforts by providing insights into near-surface soil moisture variations allowing the evaluation of water level management success.

How to cite: Grosse, P., Scheiffele, L., Dobkowitz, S., Dimitrova-Petrova, K., Rasche, D., and Oswald, S.: Adverse conditions for cosmic-ray neutron sensing: high water content low bulk density – can we still infer soil moisture over the full moisture range?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11935, https://doi.org/10.5194/egusphere-egu25-11935, 2025.

X4.90

EGU25-6803

ECS

A worst-case scenario? Exploring low-energy cosmic-ray neutron signal dynamics in wetlands

Daniel Rasche, Torsten Sachs, Aram Kalhori, Christian Wille, Markus Morgner, Andreas Güntner, and Theresa Blume

In the past 15 years, Cosmic-Ray Neutron Sensing (CRNS) has evolved to a useful tool for monitoring soil moisture at the field scale. Given the large measurement radius of up to 200 metres and measurement depth of 20 to 30 centimetres, it overcomes small-scale heterogeneities and allows to estimate soil moisture at spatio-temporal scales which are required to e.g., inform environmental models or validate soil moisture products from remote sensing data.

CRNS relies on the inverse relationship between soil moisture and observed low-energy cosmic-ray neutrons. Higher soil moisture results in lower neutron intensities but also a higher statistical noise in the data. In combination with the strongly non-linear relationship between soil moisture and observed low-energy cosmic-ray neutrons, this leads to larger uncertainties for soil moisture estimates when the soil moisture is high. Therefore, CRNS is expected to provide most accurate soil moisture estimates at monitoring sites with generally drier soils. Knowledge gaps remain with respect to the use of CRNS and the response of measured neutron intensities at observation sites with very wet soils and even partial water cover.

Against this background, we explore the signal dynamics of observed thermal and epithermal neutron intensities in a wetland in north-eastern Germany. Placing two identical neutron detectors at two different locations in the wetland and with different fractions of water cover in their respective measurement footprint allows for an investigation of the sensitivity of observed neutron signals to variations in partial water cover and soil moisture changes in water-free areas. Site-specific signal dynamics are modelled using neutron transport simulations conducted with the URANOS model code as well as simplified approaches to gain understanding on the influence of water cover and soil moisture on thermal and epithermal neutron signals. Ultimately, the possibility of deriving soil moisture information in water-free areas from observed neutron intensities is explored.

Our analyses shed additional light on the potential of CRNS for soil moisture estimation and its sensitive measurement footprint at extreme and unfavourable monitoring sites.

How to cite: Rasche, D., Sachs, T., Kalhori, A., Wille, C., Morgner, M., Güntner, A., and Blume, T.: A worst-case scenario? Exploring low-energy cosmic-ray neutron signal dynamics in wetlands, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6803, https://doi.org/10.5194/egusphere-egu25-6803, 2025.

X4.91

EGU25-8780

ECS

The additive value of multi-scale remote sensing snow products for alpine above-snow Cosmic Ray Neutron Sensing

Nora Krebs, Paul Schattan, Valentina Premier, Abraham Mejia-Aguilar, Christine Fey, Magnus Bremer, and Martin Rutzinger

Alpine snow cover is shaped by complex topography, wind and insulation patterns, causing strong lateral heterogeneity in snow water equivalent (SWE) within only a few meters distance. While common SWE observation methods are confined to a footprint area of a few square meters, above-snow cosmic ray neutron sensing (CRNS) detects secondary cosmogenic neutrons that can be translated to SWE from an area of several hectares. The large footprint size decreases the observation bias that is caused by the choice of measurement location in conventional methods. However, the large footprint size also decreases the control on other signal contributing factors. Cosmogenic neutrons are sensitive to all sources of ambient hydrogen, including soil moisture and vegetation. Partial snow cover poses an additional challenge, due to the dissimilar and non-linear contribution of snow-free and snow-covered areas. The predominant development of mountain snowpack into partial snow cover highlights the intricacy of the CRNS signal in the alpine domain. In this study, we explore the complementary value of close-range, mid-range and far-range remote sensing snow products for the characterization of alpine CRNS snow monitoring sites in Austria and Italy. Joined observations of satellite-based fractional snow cover (FSC) products of Sentinel-1 and -2 and MODIS, at a spatial resolution of 20 m, 60 m and 500 m, respectively, provide quasi-daily observations of the snow cover state within the CRNS footprint area. This allows us to identify site-specific snow season parameters and dynamics in the CRNS signal. Further, air-borne and terrestrial topographic lidar (ALS and TLS) campaigns under snow-free and snow-covered conditions provide detailed FCS, snow height distribution and topographic information at a high spatial resolution. The good compatibility of these products is shown by the overall low deviation between lidar derived FSC and Sentinel FSC products of ~11% and between lidar and MODIS FSC of ~13%. Paired with complementary, manual snow density measurements for the computation of distributed SWE and the calibration of the neutron count to SWE conversion, these observations allow us to evaluate the complexity and dynamics of the seasonal CRNS signal at alpine sites. The similarity in spatial resolution between CRNS and satellite-based remote sensing products points towards its high potential for bridging the gap between ground- and space-based snow observations. Dedicated neutron simulations and further investigations are needed to gain a better understanding of factors that contribute to neutron count dynamics in alpine terrain.

How to cite: Krebs, N., Schattan, P., Premier, V., Mejia-Aguilar, A., Fey, C., Bremer, M., and Rutzinger, M.: The additive value of multi-scale remote sensing snow products for alpine above-snow Cosmic Ray Neutron Sensing, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8780, https://doi.org/10.5194/egusphere-egu25-8780, 2025.

X4.92

EGU25-18234

ECS

neptoon: An extensible software package for processing CRNS data

Daniel Power, Steffen Zacharias, Fredo Erxleben, Rafael Rosolem, and Martin Schrön

The increasing adoption of Cosmic-Ray Neutron Sensors (CRNS), across research infrastructures and beyond, necessitates standardised and flexible processing tools. Such tools should be accessible to new users with little experience in CRNS, as well as support researchers investigating novel processing methodologies and developing new theoretical frameworks. Here we present neptoon; an open-source python tool, using a modular, expandable framework, to ensure long term viability and software sustainability. Building from previous CRNS processing tools, we will present the overall architecture of neptoon and how it implements established processing methodologies while maintaining extensibility for emerging approaches. We will demonstrate streamlined data processing workflows through our configuration system and graphical user interface. We will show how neptoon supports replicability when processing sensors, supporting rapid updates when needed. Furthermore, we will showcase how neptoon enables systematic testing of new processing theories for CRNS, such as alternative correction methods, leading to a software that supports both operational deployment and methodological research. Lastly we will outline our roadmap for neptoon, explaining features which will be implemented in the near future. By creating a fully documented software toolset for processing, we aim to support the growing community of CRNS users and researchers.

How to cite: Power, D., Zacharias, S., Erxleben, F., Rosolem, R., and Schrön, M.: neptoon: An extensible software package for processing CRNS data, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18234, https://doi.org/10.5194/egusphere-egu25-18234, 2025.