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Astroparticelle.it

OBSERVATION OF THE LYS GLACIER AND COSMIC RAYS TREND

Marco Arcani1,2

Abstract

Looking at the data of cosmic rays obtained by the neutron detector of the Sphinx (IGY NM Jungfraujoch - JUNG) [1,3], and comparing them to the data of glaciers at a global level and also at local level (WGMS 2012, updated and earlier issues) [2] it is evident that follow the same trend. At a glance this may not prove a direct link between cosmic rays and climate, but a more close observation can provide additional support to recent cosmo-climatological theories.

Keywords: glaciers, cosmic rays, climate change

1Astroparticle Physics Section, FOAM 13 Astronomical Observatory, Tradate-VA, Italy2Cosmic Rays Physics Section, GAT Astronomical Center, Tradate-VA, Italy e-mail: marco.arcani@astroparticelle.it

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1 INTRODUCTION

Cosmic rays are subatomic particles coming from the space and produced by several cosmic sources, included our Sun. The cosmic ray particles travelling into space are named primary particles, when they enter in the Earth’s atmosphere they collide with atoms of the air. The first interaction usually occurs between 20 and 30 km of altitude and it causes a cascade of other particles that extend till the ground, the particles that are created in the atmosphere are named secondary particles. This mechanism explains why ionizing radiation in the atmos-phere increases progressively from sea level up to about 10-15 km, where mainly the sec-ondary particles are produced. For example, a measurement made at about 3700 masl shows a particle flux, on average, three times than at sea level and a value of radioactivity at least twice, always compared from that at sea level (Figure 1). At high altitude it is also clearly visible the geomagnetic effect: since the primary particles of cosmic rays (protons or ions) are electrically charged, they are subject to magnetic forces, indeed the magnetic field of the Earth deviates their trajectory from west to east. Furthermore at equatorial latitudes the mag-netic Earth’s dipole rejects particles with energy below 15 GeV, while towards the earth’s poles the only shield against cosmic particles is made only by the atmosphere itself that cuts off or rather dissolves particles up to 2 GeV. To get the general trend of cosmic rays over the years, muon and neutron detectors are used. Despite the flux of secondary cosmic rays is mainly composed by charged particles such as muons, neutrons are used as a reference because they do not interact electromagnetically and thanks to this feature it is possible to obtain a trend for a broader spectrum of energies (500 MeV - 20 GeV [1]), in addition neutron detectors, also called neutron monitors, seem to be more reliable and stable over the years. All neutron monitor’s data are collected on the NMDB web site, this portal is a database that hosts data from all neutron monitors spread around the World.

Figure 1: Measure of cosmic rays intensity at the Lys glacier, from the author (near the Gnifetti hut at 3700 masl AO - Italy), very impressive the west/east ratio of cosmic rays with a value of 1.46.

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Over the years all the neutron monitors have been standardized to the NM-64 (or IQSY) detec-tor. This model uses the well proven BF3 (boron trifluoride) method; typically when a cosmic neutron reaches the boron atom, it decay and an alpha particle and an lithium ion (7Li) are pro-duced, these create other couple of ions that are analysed with a spectrometer. NM-64 means Neutron Monitor 1964, indeed the year 1964 was designated by cosmic ray investigators as the International Quiet Year Of the Sun, hence IQSY; the standardization leads to very affordable data. Nevertheless the neutron count rate, in the detector, change according to the altitude, as seen before the more is the altitude and the more is the particle flux. The count rate also change in relation to the local magnetic rigidity; since every detector is placed at different location of the Earth, its geomagnetic features are different from each other. At the Earth’s poles the magnetic rigidity is in theory null (it is the reason why cosmic radiation is shielded only by the atmosphere), instead at equatorial latitudes there are some 17GV as value for the magnetic rigidity, which corresponds to 15GeV of energy for the primary particle. This difference in the geomagnetic position of each detector is useful to define the incoming direction of cosmic rays. Indeed all together the detectors must be considered as a whole instrument used for space weather forecast, for instance to forecast dangerous solar blasts (solar cosmic rays).

2 COSMIC RAYS TREND

This research is aimed to study a local area, so it was considered only the Sphinx detector (IGY NM Jungfraujoch - JUNG) because it is one of the first built neutron monitor and so is pos-sible go back to the cosmic rays data since 1958. The Sphinx was also chosen because it is the nearest cosmic rays station (about 70 Km and at the same altitude) to the glacier that has been analysed that is the Lys glacier, which extends in the region of Valle d’Aosta in Italy.

The graph of cosmic rays from 1958 to 2014 is shown in Figure 2, for comparison was made a second graph using data from the second detector of Sphinx (NM64 NM Jungfraujoch - JUNG1) and the detector of Rome (20-NM64 SVIRCO Observatory), in which it is evident that they follow the same trend, even if the last two are in operation for more recent times (Fig-ure 3). From Figure 2 it comes out an oscillation period, this period corresponds to the cycle of energetic activity of our Sun. Using the NMDB online tool to plot the number of sunspots1, indeed we get the graph in Figure 4 where one can see the solar cycle in comparison with that of cosmic rays. The inverse correlation between solar activity and cosmic rays is well known from long time. Since the Sun is a variable star, its activity has a swing with a period of 11 years; when the Sun is very active its magnetic field acts as a shield to galactic cosmic rays, while when its activity reaches a minimum, the number of cosmic rays that reach the Earth is greater. To highlight the general trend of cosmic rays over the whole period, was used the linear regression. Using NMDB data relating to Sphinx was found that cosmic rays since 1958 have gradually decreased (Figure 5), the curve was fitted with the equation: I(c.r. count) = sqrt(-44822.5 + 1.37832E8/Year), with a R-squared = 5.23 percent and adjusted R-squared = 3.5 percent.

Anyway the reasons for the general decrease of cosmic rays will not be discussed in this text.

1 The sunspot number is a measure directly proportional to solar activity..

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Figure 2: Cosmic rays trend since 1958, from the Sphinx Observatory Jungfrau-joch - Switzerland).

Figure 3: Comparison of cosmic rays trend among four neutron monitors (see text), in a second time was also added the 8-SNM15 Lomnicky stit, Slovakia (LMKS).

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Figure 4: The solar cycle superimposed to the cosmic rays curve from 1958 to 2014.

Figure 5: Evidence of the decrease in cosmic rays intensity during the years.

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3 GLOBAL GLACIERS VS COSMIC RAYS

As it now in evidence, the current climatic period of the Earth is undergoing a warming, one of the most direct effects on the climate is the melting of glaciers. Making a comparison of the data of cosmic rays with those of glaciers immediately appears a correlation (Figure 6), this is only a first clue that alone can not prove that the reduction of cosmic rays is the cause of global warming and thus of glaciers retreat, but it seems a good support to modern theories of the cosmo-climatology. In particular, we must take into account that the theory proposed by Svensmark [5] underline two effects that have emerged from his researches, the first is that the effects of the change in cosmic rays flux are not immediate, namely that as a result of a decrease or an increase in cosmic rays the climatic effects may also occur after some time, the second is that the effects appear to be localized and therefore different for different areas, this is the rea-son why the count of the cosmic rays has been evaluated through a neutron monitor, the more possible close to the considered glacier.

4 COSMIC RAYS AND CLOUDS

By now Svensmark [5,6] has proved how cosmic rays are able to modulate the production of clouds at low altitude: generally the clouds of high altitude as the cirrus clouds tend to warm the planet by greenhouse effect, while those at low altitude as the cumulus clouds tend to cool the planet. Svensmark remarked that in the periods in which the cosmic rays increases, the low-lying clouds rise then the temperatures decrease and rainfalls are more abundant; vice versa when there are fewer cosmic rays, few clouds are formed and the temperatures rise. These effects are global but also local, probably as a function of the local magnetic rigidity that can brake or deflect the cosmic rays. At present there are some investigations about the effects of

Figure 6: Graphic correlation between World’s glaciers and cosmic rays drop.

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cosmic rays on the clouds, as the CLOUD experiment at CERN [7]. The mechanism of produc-tion of clouds by the cosmic particles is related to the production of aerosols, water molecules need a support to be able to condense into droplets and form clouds, this support is provided by aerosols. Experiments such as the Danish SKY [5] and CLOUD are trying to figure out how cosmic rays are able to increase the production of aerosols and so far the results have been positive.

5 COSMIC RAYS ON THE LYS GLACIER

The data of the Lys glacier and the nearby Indren glacier were provided by WGMS (World Glacier Monitoring Service) [2], in the analysis was also considered the Indren glacier, but its historical data are fragmentary so than it was excluded. The main parameter that influences changes in a glacier is the temperature; rainfalls during the year and solar irradiation can also produce effects but are considered minimal. The parameters to measure the advance or retreat of glaciers are mass balance, volume and frontal variation. However all historical data are related to the frontal variation (Figure 7A) and also the Lys glacier is in gradually retreating (Figure 7B). The comparison between the variation of cosmic rays and the variation of glaciers is shown in the graph of Figure 8. At a first glance seems that there is not a direct correlation between cosmic rays and glaciers, but we must keep in mind the effect of delayed response in front variation of glaciers to climate change. As shown by previous researches (Pelfini et al. [4]) glaciers respond to climate change first varying their mass and volume and later the front,

however, the latter is in some manner also sensitive to precipitation of each year. Through dendrogeomorphological assessments, the response time of the Lys glacier was estimated to be in 5 years [4]. As mentioned before, effects of cosmic rays on the climate conditions are not immediate, this may lead to a further delay in the manifestation of the effects in terms of frontal variations of the glacier. The relationship between cosmic rays and the Lys glacier was searched using the statistical method of the cross correlation. The result shows a correlation with a delay of about 5 ÷ 7 years (Figure 9). Indeed playing with the graph of Figure 8 it can be seen that by moving the curve of cosmic rays to the right, starting from 4 years is obtained

Figure 7: A) The advancing front trend by the Lys glacier since 1900. B) Simple regression, also the Lys Glacier is in progressive retreating.

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a trend matched to the curve of the Lys glacier (Figure 10). The best value found for the cross-correlation coefficient is 0.406157 corresponding to 7 years of delay (Table 1). This value does not reach the threshold of 0.582971 considered statistically significant at 95% confidence level, however, it exceed the value of 0.3, a value usually considered good.

Lag Crosscorrelation Stnd. Error Prob limit 95%0 -0.161628 0.277867 0.5446111 -0.0717541 0.280428 0.549632 0.0174267 0.283061 0.5547913 0.140955 0.28577 0.56014 0.293484 0.288558 0.5655655 0.378195 0.29143 0.5711926 0.388088 0.294388 0.5769917 0.406157 0.297439 0.5829718 0.372784 0.300587 0.58914

To evaluate how much good is the correlation number 0.406157 more analyses were done. The two variables (cosmic rays data and glaciers data) were been correlated in several manner but this time with their data shifted by a lag of 7 years (i.e. so that the first data correspondent to 1958 for cosmic rays were related to the first data for the glacier, 7 years later in 1965 and so on). All the statistical results have shown a P-values below 0.05, this mean a statistically

Figure 8: Cosmic rays versus Lys glacier from 1958 to 2012.

Table 1: Cross-correlations data for Lys with Cosmic Rays, in the first column the lag in years, in the second column the coefficient of cross-correlation, in the third column the standard error and in the last column the limit for 95% of confidence level.

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Figure 9: Graph of the crosscorrelations, since is thought that cosmic rays cause the behaviour of the glacier only positive Lag values must be considered and since the glacier and cosmic rays are posi-tively correlated, only positive crosscorrelations coefficients must be taken.

Figure 10: Moving the cosmic rays curve on the right (e.g. by five years), one can see several matched points.

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significant correlation at the 95.0% confidence level (see Table 2). So we can say not only that the cross-correlation coefficient 0.406157 is a good value, but also that cosmic rays and glacier variations are really correlated by a late of 7 years.

Analysis Lys - C.R. +7y Features N value P-value

Simple RegressionLys=-63.3329 + 0.00226129*(C.R)^2

Correlation Coefficient = 0.445996R-squared = 19.8912 percent

R-squared (adjusted) = 18.1497 percent48 0.0015

Pearson product moment correlations

Correlation Coefficient = 0.4371 48 0.0019

Canonical Correlations Correlation Coefficient = 0.43715Chi-squares = 9.64964 48 0.0019

Knowing that the Lys glacier varies its front with a delay of five years for climate change, it can be assumed that the two-year difference is the time needed for cosmic rays to seeding the clouds. Finally it was made a comparison between solar activity and the years in which the Lys glacier has had an advance or an arrest in contraction, the years in which the front of the glacier has not retreated are for example: between 1950÷1953, 1958÷1960 and 1969÷1972 whereas in recent years does not seem to show long periods of retreating pause.

Now, knowing the relationship between the Sun and cosmic rays we should expect a minimum of solar activity between 1943÷1946, between 1951÷1953 and between 1962÷1965. As previ-ously mentioned, the Sun had an historical minimum in 1964 and also in 1953 its activity was minim, this is in perfect agreement with the above, while seem that there is a longer delay time for the arrest of the glacier between 1950÷1953, as the Sun was at a minimum in 1942 and not between 1943÷1946 as expected.

6 DISCUSSION AND CONCLUSIONS

From the data on cosmic rays available through the Sphinx neutron monitor, we seen that cosmic rays are decreasing progressively and the worldwide glaciers are retreating too, indeed their average thickness is gradually decreasing. Data analysis of the Lys glacier also shows a period of progressive regression since the far 1900.

It was found a correlation between the trend of cosmic rays and the Lys glacier from 1958 to 2012. Statistical analyses pointed out a lag of seven years for frontal vari-ations of the Lys glacier to changes in cosmic rays. The delay for the front varia-tion of the Lys glacier compared to climate change was found to be five years in aver-age, therefore it seems that cosmic rays require two years to induce climate change. Even if the cross-correlation coefficient is good, does not reach statistically significant values to allow us to make predictions, however from the data shifted by 7 years the relationship be-tween cosmic rays and changes in the Lys glacier seems to be clear, the correlation coefficients

Table 2: Analysis of the two variables, C.R. as independent variable and Lys as dependent variable, the results show how the relation between the variables is linear, a P-value below 0.05 means statisti-cally significant correlation at the 95.0% confidence level.

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of further analyses are around values of 0.4 (Table 2).We must also consider that in this survey were not taken into account the meteorological data of precipitations for each year, that could produce some changes in the frontal variations of the glacier, independent from the general trend, this could faking the correlation coefficient both for positive and for negative values.

In conclusion, the found clues seem to be much more than circumstantial evidences, according to the latest and clear relationships between cosmic rays and climate. Further investigations of this type can therefore bring a good contribution to modern cosmo-climatological theories and shed light to climatological models.

Acknowledgements

Thank you to:

Rolf Bütikofer - Jungfraujoch neutron monitors - Physikalisches Institut, University of Bern, Switzerland.

Samuel Nussbaumer - World Glacier Monitoring Service (WGMS) Department of Geography University of Zurich.

Jungfraujoch neutron monitor data were kindly provided by the Cosmic Ray Group, Physika-lisches Institut, University of Bern, Switzerland.

NMDB database (www.nmdb.eu), founded under the European Union’s FP7 programme (contract no. 213007).

References[1] NMDB: real-time database for high resolution neutron monitor measurements - (http://www.nmdb.eu/).[2] WGMS (2012): Fluctuations of Glaciers 2005-2010 (Vol. X): Zemp, M., Frey, H., Gärt-ner-Roer, I., Nussbaumer, S.U., Hoelzle, M., Paul, F. & W. Haeberli (eds.), ICSU (WDS)/ IUGG (IACS)/ UNEP/ UNESCO/ WMO, World Glacier Monitoring Service, Zurich, Swit-zerland. Data based on database version doi:10.5904/wgms-fog-2014-09.[3] Jungfraujoch neutron monitor data - Cosmic Ray Group, PhysikalischesInstitut, University of Bern, Switzerland.[4] Manuela Pelfini et al. Geografia Fisica e Dinamica Quaternaria 329-338, 1997.[5] Henrik Svensmark, Nigel Calder - The chilling stars - Totem books 2008.[6] Nigel D. Marsh, Henrik Svensmark - Low Cloud Properties Influenced by Cosmic Rays, Phys. Rev. Lett. 85, 5004 – Published 4 December 2000. [7] http://home.web.cern.ch/about/experiments/cloud.