Estimation of long-term cosmic ray intensity variation in near future and prediction of their contribution in expected global climate change

On the basis of results obtained in our paper [Dorman, L.I. Long-term cosmic ray intensity variation and part of global climate change, controlled by solar activity through cosmic rays, Paper D2.1/C2.2/E3.1-0097-04. Adv. Space Res., 2004 (accepted)], we determine: the dimension of the Heliosphere (modulation region), radial diffusion coefficient and other parameters of convection–diffusion; drift mechanisms of long-term variations of cosmic ray (CR) dependence on particle energy; level of solar activity (SA); and generally, the solar magnetic field. We obtain this important information on the basis of CR and SA data in the past, taking into account the theory of convection–diffusion and global drift modulation of galactic CR in the Heliosphere. By using these results and other regularly published predictions of expected SA variation in the near future, as well as predictions of the next SA cycle, we may make predictions of long-term cosmic ray intensity variation expected in the near future (up to 10–12 years). In [Dorman, L.I. Long-term cosmic ray intensity variation and part of global climate change, controlled by solar activity through cosmic rays, Paper D2.1/C2.2/E3.1-0097-04. Adv. Space Res., 2004 (accepted)], properties of connections between long-term variation in CR intensity and some part of a global climate change were estimated, controlled by solar activity through CR. We show that in this way we may make predictions of some part of a global climate change expected in the near future (up to 10–12 years and maybe more, depending upon the period during which definite predictions of SA can be made), controlled by solar activity through CR. In this case, estimations of expected long-term changes in the planetary distribution of cutoff rigidities, which also influence CR intensity, as well as CR-influenced effects on global climate variation, become important.     

On the 27-day variations of the galactic cosmic ray anisotropy and intensity for different periods of solar magnetic cycle

The average amplitude of the 27-day variation of the galactic cosmic ray anisotropy calculated based on the neutron monitors experimental data is larger in the qA > 0 period than in the qA < 0 period of solar magnetic cycle. The amplitudes of the 27-day variation of the galactic cosmic rays anisotropy do not depend on the tilt angles of the heliospheric neutral sheet for different the qA > 0 and the qA < 0 periods of solar magnetic cycle. A good correlation has been revealed between the changes of the amplitudes of the 27-day variations of the galactic cosmic ray anisotropy and intensity versus the qA > 0 and the qA < 0 periods of solar magnetic cycle.     

The structure of the solar cycle maximum phase in the galactic cosmic ray 11-year variation

Two phenomena connected with the maximum phase of the 11-year solar cycle in the galactic cosmic ray intensity – the change in the energy dependence of the intensity variations and the double-peak structure in the intensity modulation time profile – are considered for the last five solar cycles (Nos. 19–23). The distinct 22-year cycle in the magnitude of the so called energy hysteresis is observed.The periods of the solar cycle maximum phase in the galactic cosmic ray intensity, characterized by the specific energy dependence of the intensity, are estimated. It is found that the double-peak structures belonging to the solar cycle maximum phase and those around it are very similar both in the amplitude and in its energy dependence.     

Radiation environment induced by cosmic ray particle fluxes in the international space station orbit according to recent galactic and solar cosmic ray models

Radiation characteristics (particle fluxes, doses, and LET spectra) are calculated for spacecraft in the International Space Station orbit. The calculations are made in terms of the dynamic model for galactic cosmic rays and the probabilistic model for solar cosmic rays developed at the Institute of Nuclear Physics of Moscow State University.     

Features of the 11-year variation of galactic cosmic rays in different periods of solar magnetic cycles

Variations of galactic cosmic ray intensity have been studied based on the neutron monitors and interplanetary magnetic field experimental data for different ascending and descending epochs of solar activity. The dependence of the diffusion coefficient on the cosmic ray particles rigidity R is stronger in the maxima epoch than in the minima epoch of solar activity. For the period of 1977–1981 (qA > 0) the diffusion coefficient for the minimum epoch is, χ_min ∝ R^{0.7 ± 0.04} and for the maximum χ_max ∝ R^{1.3 ± 0.05}; for the period of 1987–1990 (qA < 0), χ_min ∝ R^{0.8 ± 0.05} and χ_max ∝ R^{1.1 ± 0.04}. The exponents ν_y and ν_z of the power spectral density of the B_y and B_z components of the IMF in the region of the frequencies (10⁻⁶– 4 × 10⁻⁶) Hz are larger for the minimum epoch of 1987 (ν_y ≈ 2.0 and ν_z ≈ 1.93) than for the maximum epoch of 1990 (ν_y ≈ 1.43 and ν_z ≈ 1.27).     

How does the global structure of the interplanetary magnetic field affect cosmic ray modulation?

Force-field theory is studied in 3-dimension using the full diffusion tensor incorporating drift effects. An analytical approximate solution is deduced under some assumptions which include a flat neutral sheet and a non-uniform density distribution at the outer boundary. By contrast with the usual force-field theory, our solution gives a large and charge dependent latitudinal gradient and near perfect isotropy, even corotation disappears. The results are in general agreement with the numerical calculations of Jokipii and Kopriva.     

Dependence of the 27-day variation of cosmic rays on the global magnetic field of the Sun

We show that the higher range of the heliolongitudinal asymmetry of the solar wind speed in the positive polarity period (A > 0) than in the negative polarity period (A < 0) is one of the important reasons of the larger amplitudes of the 27-day variation of the galactic cosmic ray (GCR) intensity in the period of 1995–1997 (A > 0) than in 1985–1987 (A < 0). Subsequently, different ranges of the heliolongitudinal asymmetry of the solar wind speed jointly with equally important corresponding drift effect are general causes of the polarity dependence of the amplitudes of the 27-day variation of the GCR intensity. At the same time, we show that the polarity dependence is feeble for the last unusual minimum epoch of solar activity 2007–2009 (A < 0); the amplitude of the 27-day variation of the GCR intensity shows only a tendency of the polarity dependence. We present a three dimensional (3-D) model of the 27-day variation of GCR based on the Parker’s transport equation. In the 3-D model is implemented a longitudinal variation of the solar wind speed reproducing in situ measurements and corresponding divergence-free interplanetary magnetic field (IMF) derived from the Maxwell’s equations. We show that results of the proposed 3-D modeling of the 27-day variation of GCR intensity for different polarities of the solar magnetic cycle are in good agreement with the neutron monitors experimental data. To reach a compatibility of the theoretical modeling with observations for the last minimum epoch of solar activity 2007–2009 (A < 0) a parallel diffusion coefficient was increased by ∼40%.     

The effect on cosmic ray modulation of a parker field modified by a latitudinal-dependent solar wind speed

We present a new two-dimensional divergence-free heliospheric magnetic field of which the radial component depends on latitudinal gradients in the solar wind speed. It is used in a two-dimensional numerical modulation model to study its qualitative effects on cosmic-ray modulation. We find that this field causes large solar-cycle polarity dependent increases in cosmic-ray intensities at either high or low latitudes and we discuss the reasons for this.     

Stratospheric polar vortex as a possible reason for temporal variations of solar activity and galactic cosmic ray effects on the lower atmosphere circulation

Possible reasons for the temporal instability of long-term effects of solar activity (SA) and galactic cosmic ray (GCR) variations on the lower atmosphere circulation were studied. It was shown that the detected earlier ∼60-year oscillations of the amplitude and sign of SA/GCR effects on the troposphere pressure at high and middle latitudes (Veretenenko and Ogurtsov, Adv.Space Res., 2012) are closely related to the state of a cyclonic vortex forming in the polar stratosphere. The intensity of the vortex was found to reveal a roughly 60-year periodicity affecting the evolution of the large-scale atmospheric circulation and the character of SA/GCR effects. An intensification of both Arctic anticyclones and mid-latitudinal cyclones associated with an increase of GCR fluxes at minima of the 11-year solar cycles is observed in the epochs of a strong polar vortex. In the epochs of a weak polar vortex SA/GCR effects on the development of baric systems at middle and high latitudes were found to change the sign. The results obtained provide evidence that the mechanism of solar activity and cosmic ray influences on the lower atmosphere circulation involves changes in the evolution of the stratospheric polar vortex.     

The role of drift and convection–diffusion mechanisms in small energy global cosmic ray modulation: Application to the hysteresis phenomenon of proton and alpha particle satellite data

The hysteresis effect for small energies of galactic cosmic rays is due to two effects. The first is the same as for neutron monitor energies – the delay of the interplanetary processes responsible for cosmic ray modulation with respect to the initiating solar processes, according to the effective velocity of solar wind and shock waves propagation. Then, the observed cosmic ray intensity is connected to the solar activity variations during many months before the time of cosmic ray measurement. The second is caused by the time delay of small energy cosmic ray diffusion from the boundary of modulation region to the Earth’s orbit. The model describing the connection between solar activity variation and cosmic ray convection–diffusion global modulation for neutron monitor energies is here developed by taking into account also the time-lag of the small energy particle diffusion in the Heliosphere. We use theoretical results on drifts and analytically approximate the dependences of drifts from tilt angle, and take into account the dependence from the sign of primary particles, and from the sign of polar magnetic field (A > 0 or A < 0). The obtained results are applied on proton and alpha-particle satellite data. We analyze satellite 5-min data of proton fluxes with energies >1 MeV, >2 MeV, >5 MeV, >10 MeV, >30 MeV, >50 MeV, >60 MeV, >100 MeV, and in intervals 10–30 MeV, 30–60 MeV, and 60–100 MeV during January 1986–December 1999. We exclude periods with great cosmic ray increases caused by particle acceleration in solar flare events. Then, we determine monthly averaged fluxes, as well as 5-month and 11-month smoothed data. We analyze also satellite 5-min data on alpha-particle fluxes in the energy intervals 60-160 MeV, 160–260 MeV and 330–500 MeV during January 1986–May 2000. We correct observation data for drifts and then compare with what is expected according to the convection–diffusion mechanism. We assume different dimensions of the modulation region (by the time propagation X₀ of solar wind from the Sun to the boundary of modulation region), for X₀ values from 1 to 60 average months, by one-month steps. For each value of X₀ we determine the correlation coefficient between variations of expected and observed cosmic ray intensities (the estimation of cosmic ray intensities values is given in Section 3 by Eq. (9), and the determination of correlation and regression coefficients in Section 3 by Eq. (8)). The dimension of modulation region is determined by the value of X_0 max, for which the correlation coefficient reaches the maximum value. Then the effective radial diffusion coefficient and residual modulation in small energy region can be estimated.     

Formation of oligopeptides on the surface of small bodies in solar system by cosmic radiation.

The present experiment indicates that oligopeptides are easily produced in solid state from mixtures of simple amino acids by irradiating with high energy charged particles. We investigated such amino acids and their mixtures as tryptophan, tyrosine and glycine. The thin films was irradiated with protons (6.6 MeV). Such dipeptides as Trp-Trp, Gly-Tyr, Tyr-Gly, and Tyr-Tyr have been detected as products of irradiation. Cosmic rays might be an effective energy source for abiotic formation of bioorganic compounds on the surface of small bodies in the solar system on early stage of formation of planets as well as at present day.     

North-south asymmetries of the solar magnetic field in conjunction with the location of the heliospheric current sheet on both sides of the solar equator

Reported heliospheric current-sheet displacements from the equatorial plane have been found to be in agreement with north-south asymmetries of the solar magnetic field. Mean heliospheric sector width estimations in the period 1947–1977 have shown that the heliospheric current sheet demonstrates an asymmetric placement with respect to the solar equator. This asymmetry is very prominent in the epochs of the solar cycle minima while it almost disappears in the epochs of maxima. At the same time, the sums of the maxima values of the sunspot magnetic field intensity showed in the epochs of minimum a characteristic asymmetry which implies an essential conjunction among the heliospheric current sheet, the solar cycle and the solar magnetic field. The main conclusion which could be derived of these observations is that the heliospheric current sheet has its origin on the solar surface while its location with respect to the solar equator appears to be affected by the variability of the lower layers of the solar interior.     

Statistical properties of the IMF clock angle in the solar wind with northward and southward interplanetary magnetic field based on ACE observation from 1998 to 2009: Dependence on the temporal scale of the solar wind

Utilizing ACE satellite observations from 1998 to 2009, we performed the elaborate study on the properties of the clock angle θ_CA (arctan(By/Bz) (?90° to 90°) of the interplanetary magnetic field (IMF) in the solar wind at 1?AU. The solar wind with northward IMF (NW-IMF) and southward IMF (SW-IMF) are analyzed, independently. Statistical analysis shows that the solar wind with SW-IMF and NW-IMF has similar properties in general, including their durations, the IMF Bz and By components, and the IMF θ_CA. Then, the solar wind with NW-IMF (SW-IMF) is classified into five different temporal scales according to the duration of the NW-IMF (SW-IMF), i.e., very-short wind of 10–30?min, short-scale wind of 0.5–1?h, moderate-scale wind of 1–3?h, long-scale wind of 3–5?h, and super-long wind >5?h. Our analysis reveals that the IMF θ_CA has a distinct decrease with increase of the temporal scale of the solar wind. Next, the solar wind is classified into two groups, i.e., the high-speed solar wind (>450?km/s) and the low-speed solar wind (<450?km/s). Our analysis indicates that the IMF θ_CA depends highly on the solar wind speed. Statistically, high-speed solar wind tends to have larger IMF θ_CA than low-speed solar wind. The evolutions of the solar wind and IMF with the solar activity are further studied, revealing no clear solar variation of the IMF θ_CA. Finally, we analyze the monthly variation of the IMF θ_CA. Superposed epoch result strongly suggests the seasonal variation of the IMF θ_CA.