595 research outputs found
The influence of the Earth's magnetosphere on the high-energy solar protons
In the Earth's polar regions the intensity of the solar protons with the energy above the critical energy of geomagnetic cutoff is the same as in the interplanetary space. The penumbra in the polar regions is small and the East-West effect is also small. However the geomagnetic cutoff rigidity R sub c in polar regions is difficult to calculate because it is not sufficient to include only the internal sources of the geomagnetic field. During the magneto-quiescent periods the real value of R sub c can be less by 0.1 GV than the calculated value because of the external sources. During the geomagnetic storms the real value of R sub c is still lower
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Balloon measurements of the vertical ionization profile over southern Israel and comparison to mid-latitude observations
Airborne measurements using meteorological balloons were conducted for the first time from southern Israel
(geographic 30°35’N, 34°45’E geomagnetic 27°6’N 112°23’E) for measuring the vertical ionization profile during solar cycle 24. The results show the differences (increase of ~30%) in count rates as we proceed from solar maximum toward solar minimum. The observed altitude of maximum ionization (the Regener-Pfotzer maximum) was between 17–20 km, and it agrees well with results from other simultaneous measurements conducted at different latitudes (Reading, UK and Zaragoza-Barcelona, Spain). When compared with predictions of an analytical model, we find a highly significant correlation (R2=0.97) between our observations and the computed ionization profiles. The difference in count rates can be attributed to the height of the tropopause due to the model using a US standard atmosphere that differs from the measured atmospheric parameters above Israel
Analysis of cosmic ray variations observed by the CARPET in association with solar flares in 2011-2012
The CARPET cosmic ray detector was installed on April 2006 at CASLEO (Complejo Astronmico El Leoncito) at the Argentinean Andes (31.8S, 69.3W, 2550 m, Rc=9.65 GV). This instrument was developed within an international cooperation between the Lebedev Physical Institute RAS (LPI; Russia), the Centro de Radio Astronomia e Astrofsica Mackenzie (CRAAM; Brazil) and the Complejo Astronmico el Leoncito (CASLEO; Argentina). In this paper we present results of analysis of cosmic ray variations recorded by the CARPET during increased solar flare activity in 2011-2012. Available solar and interplanetary medium observational data obtained onboard GOES, FERMI, ISS, as well as cosmic ray measurements by ground-based neutron monitor network were also used in the present analysis.Fil: Makhmutov, V.. Lebedev Physical Institute; Rusia. Universidade Presbiteriana Mackenzie; BrasilFil: Raulin, J. P.. Universidade Presbiteriana Mackenzie; BrasilFil: De Mendonca, R. R. S.. National Institute for Space Research; BrasilFil: Bazilevskaya, G. A.. Lebedev Physical Institute; RusiaFil: Correia, E.. Universidade Presbiteriana Mackenzie; Brasil. National Institute for Space Research; BrasilFil: Kaufmann, Pierre. Universidade Presbiteriana Mackenzie; BrasilFil: Marun, Adolfo Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Complejo Astronómico "El Leoncito". Universidad Nacional de Córdoba. Complejo Astronómico "El Leoncito". Universidad Nacional de la Plata. Complejo Astronómico "El Leoncito". Universidad Nacional de San Juan. Complejo Astronómico "El Leoncito"; ArgentinaFil: Fernandez, German Enzo Leonel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Complejo Astronómico "El Leoncito". Universidad Nacional de Córdoba. Complejo Astronómico "El Leoncito". Universidad Nacional de la Plata. Complejo Astronómico "El Leoncito". Universidad Nacional de San Juan. Complejo Astronómico "El Leoncito"; ArgentinaFil: Echer, E.. National Institute for Space Research; Brasi
Latitudinal dependence of low cloud amount on cosmic ray induced ionization
A significant correlation between the annual cosmic ray flux and the amount
of low clouds has recently been found for the past 20 years. However, of the
physical explanations suggested, none has been quantitatively verified in the
atmosphere by a combination of modelling and experiment. Here we study the
relation between the global distributions of the observed low cloud amount and
the calculated tropospheric ionization induced by cosmic rays. We find that the
time evolution of the low cloud amount can be decomposed into a long-term trend
and inter-annual variations, the latter depicting a clear 11-year cycle. We
also find that the relative inter-annual variability in low cloud amount
increases polewards and exhibits a highly significant one-to-one relation with
inter-annual variations in the ionization over the latitude range
20--55S and 10--70N. This latitudinal dependence gives strong
support for the hypothesis that the cosmic ray induced ionization modulates
cloud properties.Comment: GRL, in pres
On the correlation between cosmic ray intensity and cloud cover
Various aspects of the connection between cloud cover (CC) and cosmic rays
(CR) are analysed. Many features of this connection indicate that there is no
direct causal connection between low cloud cover (LCC) and CR in spite of the
evident long-term correlation between them. However, most of these features are
indirect. If only some part of the LCC is connected and varies with CR, then
its value, obtained from the joint analysis of their 11-year variations, and
averaged over the globe, should be most likely less than 20%.
The most significant argument against a causal connection of CR and LCC is
the anticorrelation between LCC and the medium cloud cover (MCC). The scenario
of the parallel influence of the solar activity on the global temperature and
CC on one side and CR on the other, which can lead to the observed
correlations, is discussed and advocated.Comment: 30 pages, 10 figures, accepted for publication in Journal of
Atmospheric and Solar-Terrestrial Physics, acknowledgements replace
Time Variations of Solar Neutrino Signals and the RSFCN Hypothesis
Resonant spin--flavour conversion of neutrinos (RSFCN) in twisting magnetic
fields might be at the origin of the apparent anticorrelation between the
Ar production--rate in the Homestake solar neutrino detector and the
solar activity. Moreover, it can account for the results of all solar neutrino
experiments reported so far including the recent results of GALLEX and SAGE.Comment: 10 pages and 4 figures (not included), CERN--TH.6648/92 and
IFP--458--UN
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