Space Plasma Phenomena : Laboratory Modeling II. Waves and Particles in Plasma,Turbulence

Earth, Moon, and Planets -     

Desertification processes in the Ili River delta under anthropogenic pressure

Desertification of delta landscapes, mainly soil cover, is considered on the example of the Ili River, which basin is located in Kazakhstan and China. Long-term researches on the Ili River were begun in 1968 before creation of the large Kapchagay reservoir and proceed with the use of the space imagery NASA/MODIS/Terra. Degradation of delta landscapes is differentiated in space and in time depending on the features of the natural water regime and its transformation because of flow regulation. The main accent in research has been made on the newest processes of desertification, caused by intensification of irrigation. Characteristics of drying, desertification and salinization of soils in delta are estimated on the state of spring 2008.     

Fluctuations of energetic particle flux during solar cycle based on measurements in the solar wind,in the magnetosphere,and at Earth

We present the results of our studies of the cosmic-ray fluctuations in the frequency range 10⁻⁴−1.67 × 10⁻³ Hz based on energetic particle flux measurements on spacecraft in the solar wind, in the magnetosphere, and at Earth in the 11-year solar cycle. The cosmic-ray fluctuation spectrum is shown to have an 11-year modulation related to the solar cycle. A different behavior of the level of energetic particle fluctuations measured in different regions of space is observed for cosmic rays of different origins. We conclude that the new, previously unknown phenomenon of 11-year modulation of the cosmic-ray fluctuation spectrum has been established. A possible explanation of this phenomenon is given.     

Modulation of galactic cosmic rays in solar cycles 22–24: Analysis and physical interpretation

This work represents a physical interpretation of cosmic ray modulation in the 22nd–24th solar cycles, including an interpretation of an unusual behavior of their intensity in the last minimum of the solar activity (2008–2010). In terms of the Parker modulation model, which deals with regularly measured heliospheric characteristics, it is shown that the determining factor of the increased intensity of the galactic cosmic rays in the minimum of the 24th solar cycle is an anomalous reduction of the heliospheric magnetic field strength during this time interval under the additional influence of the solar wind velocity and the tilt angle of the heliospheric current sheet. We have used in the calculations the dependence of the diffusion tensor on the rigidity in the form K _ij ∝ R ^2?μ with μ = 1.2 in the sector zones of the heliospheric magnetic field and with μ = 0.8 outside the sector zones, which leads to an additional amplification of the diffusion mechanism of cosmic ray modulation. The proposed approach allows us to describe quite satisfactorily the integral intensity of protons with an energy above 0.1 GeV and the energy spectra in the minima of the 22nd–24th solar cycles at the same value of the free parameter. The determining factor of the anomalously high level of the galactic cosmic ray intensity in the minimum of the 24th solar cycle is the significant reduction of the heliospheric magnetic field strength during this time interval. The forecast of the intensity level in the minimum of the 25th solar cycle is provided.     

Diffusive propagation of fast particles in the presence of a moving shock wave

Based on an analytical model, we determined the temporal dynamics of the spectral shape and spatial distribution of the particles that were impulsively (in time) injected with a specified spectrum in the vicinity of a moving plane shock front. We obtained a condition to determine the influence of the shock front on the particle propagation, where the spatial diffusion coefficient of the particles plays a major role. Diffusive shock acceleration is shown to strongly affect low-energy particles (the intensity maximum coincides spatially with the shock front; hard and soft spectral regions are formed in the spectrum) and weakly affect high-energy particles (the time at which the intensity reaches its maximum is well ahead of the shock arrival time; the spectral shape does not change). In events accompanied by a significant increase in the turbulence level, the influence of the shock front on high-energy particles can change from weak to strong. This change shows up in the spatial distribution and spectral shape of the particles. The dynamics of the particle intensity, calculated with the diffusion coefficients that were determined in accordance with the quasi-linear theory for measured turbulence levels, qualitatively corresponds to the observed solar energetic-particle intensity.     

Dynamics of hydromorphic landscapes in the upper parts of Dnieper reservoirs

The rate and specifics of formation of unique hydromorphic landscapes in the upper parts of three Dnieper reservoirs are assessed based on the analysis of space photographs Landsat-5 and Landsat-7 over a many-year period, as well as topographic and electronic maps. Their area in the examined water bodies was found to exceed 25 thousand ha, and that in the entire chain of reservoirs, to exceed 35 thousand ha. The mean annual rate of increase in the area of hydromorphic landscapes varies from 66 in the Kanevskoe Reservoir to 351 ha/year in the Kievskoe Reservoir; the processes vegetation growth were found to significantly accelerate in the recent years.     

Heliospheric modulation of cosmic rays in solar cycles 19–23

The previously developed basic theory of the heliospheric modulation of high-energy cosmic rays is generalized to lower energies. Comparison of the theory with the results of long-term observations of cosmic rays in the stratosphere carried out by the group from the Lebedev Institute of Physics inMoscow andMurmansk shows satisfactory agreement. The cosmic rays are shown to behave quite differently when even and odd solar cycles alternate. Possible causes of the anomalously high cosmic-ray intensity recorded during the last solar activity minimum are discussed.     

The energy spectrum of Forbush decreases during the growth phase of solar cycle 24

The Forbush decrease energy spectrum, observed during the growth phase of cycle 24 in 2010–2012, was studied based on the measurements performed with the Kuzmin cosmic ray spectrograph. The data of the 24-NM-64 neutron monitor and muon telescopes, installed at water equivalent levels of 0, 7, 20, and 40 m, was used. The performed analysis indicated that a softer energy spectrum was observed during the growth phase of cycle 24 than during the previous cycle (cycle 23). The conclusion was been drawn that a more turbulent magnetic field with the predominant diffusion mechanism in the formation of the Forbush decreases in the cosmic ray intensity exists in the current cycle (cycle 24).     

Solar energetic particle events at the rise phase of the 23rd solar activity cycle registered aboard the spacecraft &;#x201C;INTERBALL-2&;#x201D;

The experiment with 10K-80 aboard the INTER-BALL-2 (which detects protons with energies > 7, 27–41, 41–58, 58–88, 88–180 and 180–300 MeV) registered six events of the solar energetic particle (SEP) increase. These events are during the initial rise phase of the 23rd solar activity cycle. Solar flares with the SEP generation are accompanied by coronal mass ejection (CME). Here we analyze the dynamics of the differential energy spectrum at different phases of the SEP increase.     

Rapid Cosmic Ray Fluctuations: Evidence for Cyclic Behaviour

We study rapid cosmic-ray fluctuations using 5-min resolution data from eight neutron monitors with different cutoff rigidities as well as from the ACE satellite. We define a proxy index of rapid cosmic-ray fluctuations as the mean power of the cosmic-ray power spectrum in the frequency range 10⁻⁴ −1.67 × 10⁻³ Hz (10 min to about 3 h). A dominant 11-year periodicity in the index is found in all neutron monitors. We also report on intermittent, short-term periodicities in the power of rapid cosmic-ray fluctuations. A strong mid-term periodicity of about 1.6 – 1.8 years, possibly related to a recently found similar periodicity in IMF, appears in CR fluctuation power since the 1980s. Another strong periodicity is found at 1 year, which is likely related to the relative position of the Earth in the heliosphere. These results also provide new challenge to test the cosmic-ray modulation theory.