153 research outputs found
Variations of geomagnetic cutoff rigidities during the series of geomagnetic storms in January 2005: observations and modelling
Coupling functions for lead and lead-free neutron monitors from the latitudinal measurements performed in 1982 in the research station Academician Kurchatov
The latitudinal behavior of intensities and multiplicities was registered by the neutron monitor 2 NM and the lead-free neutron monitor 3 SND (slow-neuron detector) in the equator-Kaliningrad line in the Atlantic Ocean. Coupling coefficients for 3 SND show the sensitivity of this detector to primary particles of cosmic rays of energies on the average lower than for 2 NM. As multiplicities increase, the coupling coefficients shift towards higher energies
Cutoff rigidity and particle trajectories online calculator
Over the years, many authors have developed unique software packages for calculating the geomagnetic cut-
off rigidities and the asymptotic directions of particle arrival. Such programs are used for mass calculations
and require some skill. However, it is often necessary to carry out single calculations with the same accu-
racy. For this purpose, calculator programs have been created on the basis of already developed software
packages. One of such programs, a calculator, is described in this work
About long term modulation of cosmic rays in the 23-24 solar activity cycles
Recently, there has been a significant trend in magnetic fields on the Sun. The total magnetic field of the Sun
from the end of the 22nd cycle of solar activity (SA) has more than halved and this decrease continues. Chan-
ges in the magnetic field are the key to all the active phenomena occurring on the Sun and in the heliosphere
and, accordingly, to processes in cosmic rays. In long-term CR variations in 23-24 cycles of SA the attenuation
of the solar magnetic field is displayed and these variations turned out to be the smallest for the entire time of
CR observations. Model calculations of CR modulation for 21-22 and 23-24 cycles of SA showed: with a slight
difference in the regression characteristics obtained, the distribution of contributions to the generated CR
modulation from the effects of various SA indices is strongly varies in the analyzed periods. Possible reasons
for the features of the last two CA cycles are discussed
Ground increase of cosmic ray intensity on February 16, 1984
The event of February 16, 1984 is one of the two largest ground increases of solar cosmic rays (CR) in the last two cycles of solar activity. This event happended at a decrease of the 21-st cycle against a quiet background. Although at the beginning of 1984 the observed indices of solar activity were higher than those at the end of 1983, the day of February 16 16 may be characterized as very quiet. On that day the geomagnetic perturbance (Sigma F sub p = 14, A sub p = 7) was the lowest in February. After a small Forbush decrease due to the magnetic storm of February 12-13, the CR intensity almost completely recovered by February 16. Thus, the solar particles that came to the Earth on February 16 got into a practically unperturbed magnetosphere, and the variations of secondary CR induced by these particles were not superimposed on any other substantial variations of extraterrestrial or magnetospheric origin
Comparison of long-term variations of the cosmic ray flux from the network of ground-based detectors, PAMELA and AMS-02 data
The paper presents preliminary results of a comparison of long-term variations of the cosmic ray flux using
data from the network of ground-based detectors with direct flux measurements on the PAMELA and AMS-02
magnetic spectrometers and a series of balloon stratospheric soundings. The analysis showed good agreement
for the entire period of continuous ground-based monitoring of cosmic ray variations
Relationship of the characteristics of large Forbush decreases and the heliolongitude of their sources
In this investigation the different features and characteristics of Forbush decreases, with emphasis on large For-
bush decreases (â„4%) and their association to solar sources, are being examined. According to the heliolongitude
of the solar source, the events under study were separated into three subcategories: western (21Âș †heliolongitude
†60Âș), eastern (-60Âș †heliolongitude †-21Âș) and central (-20Âș †heliolongitude †20Âș). The selected events cover
the time period 1967 - 2017. The âGlobal Survey Methodâ was used for analyzing the Forbush decreases, along with
data on solar flares, solar wind speed, geomagnetic indices (Kp and Dst), and interplanetary magnetic field. In ad -
dition, the superimposed epoch method was applied in order to plot the time profiles for the aforementioned group
of events. This detailed analysis reveals interesting results concerning the features of cosmic ray decreases in re-
gard to the heliolongitude of the solar sources. Moreover, it is also shown that large Forbush decreases, regardless
of the heliolongitude of the solar source, are accompanied by increased geomagnetic activity and increased aniso-
tropy, including anisotropy before the events, which can serve as a typical precursor of Forbush decreases
Unusual decrease of the cosmic ray intensity in May 2019 on the background of the minima solar activity
In May 2019 there was a long and sloping decreasing of cosmic rayâs intensity (up to ~4%), which was observed
on neutron monitors. Despite this was a small decreasing compared to quasi-eleven-period variation, it stands
out well in 24th cycle of solar activity.
According to LASCO/SOHO and STEREO-A data from spectrometer in different UHF bands and from coronograph,
there was a series of CMEs which affected on modulation of cosmic rays by creating a series of Forbush decrea -
sing, which didnât restore. This series was connected to two active regions on sun and began on April 30 from
âreversed haloâ CME. This CME didnât reach the earth, but led to significant additional modulation of cosmic rays,
mostly on east side. Later there was a series of smaller CMEs on May 1-6, which also didnât reach the earth, but
were gradually approaching to Earth. Recent CMEs on 8-9 and 12-13 created a normal Forbush decreasing.
In May 2019, cosmic rays shown again, that they can collect information about distant objects of geliosphere and
transmit it to Earth. The ground-level detectors sometimes can observe an interaction of interplanetary distur-
bances, which didnât reach the earth. East CMEs are especially effective, because they closing magnetic field
lines beyond the orbit of earth and can interfere the restoring of cosmic rayâs intensity
Snow effect on the neutron monitor network for 2018-2019
In this article, the influence of the surrounding snow cover on the neutron monitors count rate of the world network of neutron monitors was estimated using the method of reference stations. The applied technique also makes it possible to estimate the snow cover thickness at the observation point, which was done for more than two dozen stations. A comparison of the data correction results for snow is carried out for the case of automatic correction, based on the developed algorithm, and for manual one, with an error estimate
The new Athens center on data processing from the neutron monitor network in real time
International audienceThe ground-based neutron monitors (NMs) record galactic and solar relativistic cosmic rays which can play a useful key role in space weather forecasting, as a result of their interaction with interplanetary disturbances. The Earth's-based neutron monitor network has been used in order to produce a real-time prediction of space weather phenomena. Therefore, the Athens Neutron Monitor Data Processing Center (ANMODAP) takes advantage of this unique multi-directional device to solve problems concerning the diagnosis and forecasting of space weather. At this moment there has been a multi-sided use of neutron monitors. On the one hand, a preliminary alert for ground level enhancements (GLEs) may be provided due to relativistic solar particles and can be registered around 20 to 30 min before the arrival of the main part of lower energy particles responsible for radiation hazard. To make a more reliable prognosis of these events, real time data from channels of lower energy particles and X-ray intensity from the GOES satellite are involved in the analysis. The other possibility is to search in real time for predictors of geomagnetic storms when they occur simultaneously with Forbush effects, using hourly, on-line accessible neutron monitor data from the worldwide network and applying a special method of processing. This chance of prognosis is only being elaborated and considered here as one of the possible uses of the Neutron Monitor Network for forecasting the arrival of interplanetary disturbance to the Earth. The achievements, the processes and the future results, are discussed in this work
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