The Influence of Cosmic‐Ray Modulation at High Heliospheric Latitudes on the Solar Diurnal Variation Observed at Earth

Moraal, H.; Caballero─López, R. A.; McCracken, K. G.; Humble, J. E.

doi:10.1086/431480

Cited by 8 publications

(7 citation statements)

References 11 publications

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“…4) are measured using cosmic-ray neutron monitors which are designed to detect high-energy secondary neutrons while being insensitive to low-energy neutrons (Simpson, 2000). Removal of secular variations, for example due to the sunspot cycle or diurnal fluctuations (e.g., Moraal et al, 2005), is straightforward. The required correction factor, f i , is merely the ratio of the measured neutron monitor intensity, I m , at a given time to a specified baseline reference intensity, I 0 , and can be expressed as…”

Section: Computations Correctionsmentioning

confidence: 99%

COSMOS: the COsmic-ray Soil Moisture Observing System

Zréda

Shuttleworth

Zeng

et al. 2012

Hydrol. Earth Syst. Sci.

480

538

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Abstract. The newly-developed cosmic-ray method for measuring area-average soil moisture at the hectometer horizontal scale is being implemented in the COsmic-ray Soil Moisture Observing System (or the COSMOS). The stationary cosmic-ray soil moisture probe measures the neutrons that are generated by cosmic rays within air and soil and other materials, moderated by mainly hydrogen atoms located 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. The COSMOS has already deployed more than 50 of the eventual 500 cosmic-ray probes, distributed mainly in the USA, each generating a time series of average soil moisture over its horizontal footprint, with similar networks coming into 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 the COS-MOS project, and give example time series of soil moisture obtained from COSMOS probes.

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Section: Computations Correctionsmentioning

confidence: 99%

COSMOS: the COsmic-ray Soil Moisture Observing System

Zréda

Shuttleworth

Zeng

et al. 2012

Hydrol. Earth Syst. Sci.

480

538

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show abstract

“…The correction of influencing factors has also received much attention. The analysis and correction of the influences of atmospheric pressure, water vapor, solar activity and aboveground biomass on the neutrons have been studied (Desilets and Zreda, 2001;Moraal et al, 2005;Rosolem et al, 2013;Coopersmith et al, 2014;McJannet et al, 2014;Baatz et al, 2015) and can improve the accuracy of the CRNS. These studies have built the foundation for the application of the CRNS method (Rivera villarreyes et al, 2011;Bogena et al, 2013;Han et al, 2014;Wang et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

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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“…Schrijver & DeRosa 2003). At solar minimum, as the Sun's magnetic polarity reverses, there may be times when cosmic rays arrive much more easily at the solar surface (see Moraal et al 2005) and the escaping neutron population would be temporarily enhanced at these times. Seckel et al neglect incident and target species heavier than 4 He, even although these can make a non-negligible contribution to neutron production in flares (Hua & Lingenfelter 1987;Hua et al 2002).…”

Section: Discussionmentioning

confidence: 99%

Solar hard X-ray halo from decaying neutrons

MacKinnon¹

2006

A&A

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Aims. To quantify the solar X-ray halo resulting from inner bremsstrahlung in beta decay of neutrons generated by cosmic ray bombardment of the solar surface. Methods. We show analytically how the angular form of this X-ray halo directly reflects the energy distribution of neutrons escaping the Sun. Previous Monte Carlo calculations of solar albedo neutron production are used to normalise an assumed parametric form for the escaping neutron distribution and thus to estimate the halo's intensity. The main remaining assumptions, that neutrons escape radially and that gravitational deceleration may be neglected, affect a negligible fraction of all solar neutrons. Results. Observations of this halo would have clear diagnostic interest for cosmic ray propagation in the inner heliosphere. Unfortunately it is unlikely to be observable in competition with the cosmic X-ray background.

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The Influence of Cosmic‐Ray Modulation at High Heliospheric Latitudes on the Solar Diurnal Variation Observed at Earth

Cited by 8 publications

References 11 publications

COSMOS: the COsmic-ray Soil Moisture Observing System

COSMOS: the COsmic-ray Soil Moisture Observing System

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

Solar hard X-ray halo from decaying neutrons

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