Attenuation coefficients of the cosmic-ray nucleonic component in the lower atmosphere

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.

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“…Thus, neutron counting rates can be corrected by accounting for fluctuations of atmospheric pressure as follows (e.g. Bachelet et al, 1965):…”

Section: Quantitative Soil Moisture Estimation By Ground Albedo Neutrmentioning

confidence: 99%

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

Villarreyes

Baroni

Oswald

2011

Hydrol. Earth Syst. Sci.

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“…On the average the higher energy nucleons produce events of greater multiplicity. Indication of such a correlation has also been obtained from observations of the multiplicity distribution as a function of geomagnetic latitude by Bachelet et al [1965] and Drying and Sporre [1965,1966]. In general these authors found that the relative numbers of highmultiplicity events increased with geomagnetic cutoff rigidity, as expected from the association of higher multiplicity events with greater incident energy.…”

Section: Introductionmentioning

confidence: 61%

“…where N is the observed intensity at pressure p, Nois the intensity at some standard pres- sure po, and a is the pressure or barometric coefficient. Pressure coefficients as a function of multiplicity have been determined for the multiplicity monitor using the method of successive differences described by Lapointe and Rose [1962] and by Bachelet et al [1965]. This method also gives a realistic estimate of the probable errors based on the residuals between the actual data and the least-squares fit.…”

Section: N --Nocamentioning

confidence: 99%

Neutron multiplicity monitor observations during 1965

Nobles¹,

Alber²,

Hughes³

et al. 1967

J. Geophys. Res.

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The multiplicity, i.e. the average number of neutrons m produced per incident particle in a neutron monitor increases with the energy of the producing radiation. A monitor designed to take maximum advantage of the information contained in this effect has been used to study the characteristics of the cosmic radiation at White Mountain (3800‐meters elevation) and at Palo Alto (sea level) during 1965. The energy dependence of the incident differential nucleonic flux was found to be N(E) ∼ E−γ, with γ, = 1.96 at 3800 meters and 2.20 at sea level. Barometric pressure coefficients for the total neutron counting rate were found to be −1.022 and −0.958% per mmHg at the mountain and sea‐level locations, respectively. These values are in good agreement with results previously reported for other neutron monitors. The pressure coefficients for the multiplicity m = 1 counting rates were found to be −0.97% per mmHg at 3800 meters and −0.89% per mmHg at sea level. At both elevations the coefficients increased with multiplicity to the same median value of about −1.13% per mmHg at m ≥ 7. The relatively lower values found for the pressure coefficients for the sea‐level total count and low multiplicity rates are attributed to a contribution by µ‐meson capture neutrons. Aside from the meson effect, the variation of the pressure coefficients with multicplicity is in qualitative agreement with the observed altitude variation of the spectral index γ.

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“…La Pointe and Rose [1962] reported no change in the mass absorption coefficient at four Canadian high-latitude stations during 1958-1960, though there was some recovery of cosmicray intensity below 3 bey during that time [Kondo et al, 1965a]. The primary spectrum below 3 bey was quite different in 1962-1963 when Bachelet et al [1964] recomputed the mass absorption coefficient at these same Canadian stations (among 21 others) and found that the changes in mass absorption there since 1958-1960 were negligible (within the statistical accuracy of about 0.01%/mm Hg for the sea level stations, and only 0.03%/mm Hg at Sulphur Mountain). This evidence corroborates the constancy of the mass absorption coefficient at Chicago and Climax, but disagrees with the results of Kamphouse [1963], who, from calculations of the mass absorption coefficent at College, Alaska, on a total of 34 days from 1956 to 1962, reports an 11-year variation of 0.07%/mm Itg.…”

Section: Discussion Of Results the Increase In Thementioning

confidence: 99%

Neutron monitor mass absorption coefficients at Chicago and climax during solar cycle 19 (1954-1963)

Forman¹

1965

J. Geophys. Res.

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The dependence of the neutron monitor mass absorption coefficient on 11‐year changes in the primary cosmic‐ray spectrum was investigated for the monitors at Chicago, Illinois, and Climax, Colorado, using a modified single regression method. The analysis of hourly intensity and pressure values for 733 days at Chicago and 1000 days at Climax during the period 1954–1963 revealed no significant variation at either station. The mean value of the coefficient at Chicago is −0.938±0.007%/mm Hg; at Climax it is −1.010 ± 0.006%/mm Hg. This difference is significant and depends on the altitude characteristics of the nucleonic component. These results are compared with earlier work.

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Attenuation coefficients of the cosmic-ray nucleonic component in the lower atmosphere

Cited by 31 publications

References 12 publications

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

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

Neutron multiplicity monitor observations during 1965

Neutron monitor mass absorption coefficients at Chicago and climax during solar cycle 19 (1954-1963)

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