scholarly journals Simulations of resonant Alfvén waves generated by artificial HF heating of the auroral ionosphere

2004 ◽  
Vol 22 (8) ◽  
pp. 2943-2949 ◽  
Author(s):  
D. Pokhotelov ◽  
W. Lotko ◽  
A. V. Streltsov
Keyword(s):  
Plasma Temperature ◽  
Dispersion Analysis ◽  
Marginal Stability ◽  
Auroral Ionosphere ◽  
Linear Dispersion ◽  
High Latitude Ionosphere ◽  
Artificial Heating ◽  
E Region ◽  
Hf Heating ◽  
Favorable Conditions

Abstract. Numerical two-dimensional two-fluid MHD simulations of dynamic magnetosphere-ionosphere (MI) coupling have been performed to model the effects imposed on the auroral ionosphere by a powerful HF radio wave transmitter. The simulations demonstrate that modifications of the ionospheric plasma temperature and recombination due to artificial heating may trigger the ionospheric feedback instability when the coupled MI system is close to the state of marginal stability. The linear dispersion analysis of MI coupling has been performed to find the favorable conditions for marginal stability of the system. The development of the ionospheric feedback instability leads to the generation of shear waves which resonate in the magnetosphere between the heated ionospheric E-region and the strong gradient in the speed at altitudes of 1-2 RE. The application of the numerical results for the explanation of observations performed by low-orbiting satellites above the high-latitude ionosphere heated with a high power ground-based HF transmitter is discussed.

scholarly journals VARIABILITY AND GENETIC CONTROL OF WINTER WHEAT RESISTANCE TO WINTER

2019 ◽  
pp. 35-41
Author(s):  
M. E. Mukhordova
Keyword(s):  
Winter Wheat ◽  
Dispersion Analysis ◽  
Genetic Determination ◽  
Genetic Features ◽  
Recessive Genes ◽  
Siberian Research Institute ◽  
Soft Winter Wheat ◽  
Favorable Conditions ◽  
Additive Genes

Winterhardiness is regarded as a parameter controlled by the activities performed by a large number of genes. In diallel crossbreeding, a researcher has complete combinations of genes that parental varieties possess. The paper analyses additivity and dominance of the crossbreeding population. It allows to assess the contribution made by the main types of gene interactions to parameter expression by decomposing the genotypic variant into a general and specific combination ability. The research aims at exploring the variability of winterhardiness of soft winter wheat and determining the system of genetic determination of this indicator. The experiment was conducted in the experimental field of Siberian Research Institute of Agriculture in Omsk in 2013-2014. The varieties and hybrids of F1 had triple sowing. The area of plant nutrition was 10 x 20 (cm2). The coulisse fallow was forecrop. The authors explored six samples of soft winter wheat and 30 F1 diallel hybrids. They observed reliable differences among genotypes according to “winterhardiness” parameter (P ≤ 0.05). Variability of this parameter is specified by meteorological conditions (95.07%) and determined by means of two-factor dispersion analysis. The authors used Heiman’s figures in order to evaluate and explore the genetic features of winter wheat winterhardiness (relationship between Wr and Vr - covariance and variant) and genetic parameters. The OCS effect was high (P<0.05), therefore, additive genes played an important role in the features heritability. The effect of SCS was high and reliable as well. Positive correlation values (r (2013) = 0.81 and (r (2014) = 0.19) among the average parental values (P) and (Wr + Vr) indicate that their dominance is indirect and recessive genes may increase winterhardiness. The average dominance parameter was higher than 1. This proves the great contribution of nonadditive genes to possessing winterhardiness. Selection of unique genotypes with strong winterhardiness is supposed to occur in older generations of hybrids (F4 - F6). The Zhemchuzhina Povolzhya variety can become a donor in stressful conditions of overwintering (OCS effect is 13.33), in favorable conditions – Fantasia variety (OCS=12.69).

scholarly journals The structure of mid- and high-latitude ionosphere during September 1999 storm event obtained from GPS observations

2002 ◽  
Vol 20 (5) ◽  
pp. 655-660 ◽  
Author(s):  
I. I. Shagimuratov ◽  
L. Baran ◽  
P. Wielgosz ◽  
G. A. Yakimova
Keyword(s):  
Magnetic Storm ◽  
High Latitude ◽  
Sampling Rate ◽  
Negative Phase ◽  
Storm Event ◽  
Ionospheric Disturbances ◽  
Auroral Ionosphere ◽  
Data Set ◽  
High Latitude Ionosphere ◽  
Gps Observations

Abstract. TEC data, obtained from over 60 GPS stations, were used to study the ionospheric effects of the 12–16 September 1999 magnetic storm over Europe. The spatial and temporal changes of the ionosphere were analysed as a time series of TEC maps, which present 15 min averages of TEC. The data set consisting of GPS observations, collected by a dense network of European stations, with sampling rate of 30 s, enable the creation of TEC maps with high spatial and temporal resolution. The storm included the positive as well as the negative phase. The positive phase took place during the first storm day of 12 September 1999. The short-lived daytime TEC enhancement was observed at all latitudes. The maximal enhancement reached a factor of 1.3–1.5. On the second and third days, the negative phase of the storm developed. The TEC decrease was registered regardless of time of the day. The TEC depression exceeded 70% relative to quiet days. On the following days (15 and 16 September), a significant daytime enhancement of TEC was observed once again. The complex occurrence of the ionospheric storm was probably related to the features of development of the magnetic storm. We found out that during the storm the large and medium-scale irregularities developed in the high-latitude ionosphere. The multi-stations technique, employed to create TEC maps, was particularly successful while studying the mid-latitude ionospheric trough. We found out that the essential changes of TEC during the storm, which were registered at the auroral and sub-auroral ionosphere, were connected with the effect of the trough and its dynamics, which depends on geomagnetic activity.Key words. Ionosphere (ionospheric disturbances; auroral ionosphere; mid-latitude ionosphere)

scholarly journals Sausage mode instability of thin current sheets as a cause of magnetospheric substorms

1999 ◽  
Vol 17 (5) ◽  
pp. 604-612 ◽  
Author(s):  
J. Büchner ◽  
J.-P. Kuska
Keyword(s):  
Current Sheet ◽  
Three Dimensional ◽  
Dispersion Analysis ◽  
Magnetospheric Substorms ◽  
Linear Dispersion ◽  
Current Sheets ◽  
Kinetic Effects ◽  
The Stability ◽  
Substorm Onsets ◽  
Pic Code

Abstract. Observations have shown that, prior to substorm explosions, thin current sheets are formed in the plasma sheet of the Earth's magnetotail. This provokes the question, to what extent current-sheet thinning and substorm onsets are physically, maybe even causally, related. To answer this question, one has to understand the plasma stability of thin current sheets. Kinetic effects must be taken into account since particle scales are reached in the course of tail current-sheet thinning. We present the results of theoretical investigations of the stability of thin current sheets and about the most unstable mode of their decay. Our conclusions are based upon a non-local linear dispersion analysis of a cross-magnetic field instability of Harris-type current sheets. We found that a sausage-mode bulk current instability starts after a sheet has thinned down to the ion inertial length. We also present the results of three-dimensional electromagnetic PIC-code simulations carried out for mass ratios up to Mi / me=64. They verify the linearly predicted properties of the sausage mode decay of thin current sheets in the parameter range of interest.Key words. Magnetospheric physics (plasma waves and instabilities; storms and substorms) · Space plasma physics (magnetic reconnection)

scholarly journals AIM-E auroral ionosphere model adjustment for the regular E layer

2021 ◽  
Vol 7 (1) ◽  
pp. 41-46
Author(s):  
Vera Nikolaeva ◽  
Evgeniy Gordeev ◽  
Denis Rogov ◽  
Aleksandr Nikolaev
Keyword(s):  
Electron Density ◽  
Input Parameter ◽  
Magnetic Activity ◽  
Auroral Zone ◽  
Auroral Ionosphere ◽  
Solar Radio Flux ◽  
Ionosphere Model ◽  
E Region ◽  
Ap Index ◽  
Euv Spectrum

The E-Region Auroral Ionosphere Model (AIM-E) was developed to determine the chemical composition and electron density in the auroral zone at E-layer heights (90–150 km). Solar and magnetic activity input parameters for AIM-E are the three-hour Ap index and the daily solar radio flux at a wavelength of 10.7 cm (index F10.7). In this paper, we compare AIM-E calculations of the electron density for the daytime with EUV radiation spectrum specified in two different ways: 1) the EUV spectrum theoretically calculated using the F10.7 index as an input parameter; 2) using TIMED satellite direct measurements of the EUV spectrum. We have corrected the EUVAC EUV radiation model to specify a photoionization source in AIM-E. Calculations of regular E-region critical frequencies show good agreement with the vertical sounding data from Russian high-latitude stations. Results we obtained make it possible to do a quick on-line assessment of the regular E layer, using the daily index F10.7 as an input parameter.

STUDY OF THE IMPACT OF THE DEVELOPMENT OF SOCIAL INFRASTRUCTURE ON THE MIGRATION ATTRACTIVENESS OF THE TERRITORY USING THE METHODS OF ECONOMIC AND MATHEMATICAL MODELING

2021 ◽  
Vol 0 (4) ◽  
pp. 110-116
Author(s):  
V.V. ORESHNIKOV ◽  
Keyword(s):  
Dispersion Analysis ◽  
Social Infrastructure ◽  
Strategic Development ◽  
Republic Of Bashkortostan ◽  
Social And Economic Development ◽  
The Republic ◽  
High Level ◽  
Favorable Conditions ◽  
Far Eastern ◽  
The Impact

The article is devoted to the study of migration processes in Russia. The population migration forms the settlement system, has a significant impact on the social and economic development of the regions, it is a reflection of the high level of their differentiation on various features, leads to a change in balance both between macroregions and between the types of settlements. The problem of migration outflow in recent years has become characteristic not only for the Northern and Far Eastern regions of the country, but also for other subjects, including the Republic of Bashkortostan. In such conditions, the need to solve it is facing the authorities at all levels of management. At the same time, these issues are not directly reflected in national projects. Moreover, many indicators used in the strategic development documents of the federal level today, in fact, cannot be applicable to the purposes of predicting migration processes due to the lack of a sufficient retrospective base. Taking into account the impossibility of direct impact on the migratory behavior of the population, priority is given to creating favorable conditions. With such a formulation of the task, not financial and economic indicators of development, and the living conditions of people and, first of all, access to social infrastructure facilities are published. In this aspect, its development becomes a competitive control tool for human capital. However, as the study showed, the effectiveness of the implementation of similar activities is significantly varied in a particular region. For a quantitative assessment of the influence of the factors under consideration, the migration processes were asked to form the appropriate economic and mathematical model. The article briefly considers the prerequisites and features of its formation. According to the results of the study, the regression equation was obtained and dispersion analysis was carried out. The results of the assessment of the model according to the Russian regions confirm its adequacy. The study allows you to more fully assess the impact of the development of social infrastructure on the demographic situation in Russia.

scholarly journals SuperDARN E-region backscatter boundary in the dusk-midnight sector – tracer of equatorward boundary of the auroral oval

2002 ◽  
Vol 20 (12) ◽  
pp. 1899-1904 ◽  
Author(s):  
P. T. Jayachandran ◽  
E. F. Donovan ◽  
J. W. MacDougall ◽  
D. R. Moorcroft ◽  
J.-P. St. Maurice ◽  
...  
Keyword(s):  
Energy Flux ◽  
Proton Energy ◽  
Auroral Oval ◽  
Ionospheric Irregularities ◽  
Auroral Ionosphere ◽  
Particle Precipitation ◽  
Equatorward Boundary ◽  
E Region ◽  
Proton Aurora

Abstract. We compare the locations of the equatorward boundaries of SuperDARN E-region backscatter and Hb  emissions, focusing on the dusk-midnight sector of the auroral oval where the proton aurora is statistically located equatorward of the discrete electron aurora. We show that, whenever both boundaries can be simultaneously identified, they are coincident. Our result complements earlier studies, which demonstrated the correspondence between the DMSP b2i boundary and both the equatorward boundary of the proton auroral oval (Donovan et al., 2002), and the equatorward boundary of SuperDARN E-region echoes (Jayachandran et al., 2002). Further, our result shows that, provided there is sufficient precipitating proton energy flux, the SuperDARN radars can be used to monitor the equatorward edge of the proton auroral oval.Key words. Ionosphere (auroral ionosphere; particle precipitation; ionospheric irregularities)

scholarly journals Relation of anomalous F region radar echoes in the high-latitude ionosphere to auroral precipitation

2017 ◽  
Vol 35 (3) ◽  
pp. 475-479
Author(s):  
Hanna Dahlgren ◽  
Nicola M. Schlatter ◽  
Nickolay Ivchenko ◽  
Lorenz Roth ◽  
Alexander Karlsson
Keyword(s):  
High Latitude ◽  
Spatial Scales ◽  
Doppler Frequency ◽  
High Energy ◽  
Occurrence Rate ◽  
Characteristic Energy ◽  
Observation Volume ◽  
Radar Echoes ◽  
High Latitude Ionosphere ◽  
E Region

Abstract. Non-thermal echoes in incoherent scatter radar observations are occasionally seen in the high-latitude ionosphere. Such anomalous echoes are a manifestation of plasma instabilities on spatial scales matching the radar wavelength. Here we investigate the occurrence of a class of spatially localized anomalous echoes with an enhanced zero Doppler frequency feature and their relation to auroral particle precipitation. The ionization profile of the E region is used to parametrize the precipitation, with nmE and hmE being the E region peak electron density and the altitude of the peak, respectively. We find the occurrence rate of the echoes to generally increase with nmE and decrease with hmE, thereby indicating a correlation between the echoes and high-energy flux precipitation of particles with a high characteristic energy. The highest occurrence rate of > 20 % is found for hmE  =  109 km and nmE  =  1011. 9 m−3, averaged over the radar observation volume.

scholarly journals On the usefulness of <i>E</i> region electron temperatures and lower <i>F</i> region ion temperatures for the extraction of thermospheric parameters: a case study

1999 ◽  
Vol 17 (9) ◽  
pp. 1182-1198 ◽  
Author(s):  
J.-P. St.-Maurice ◽  
C. Cussenot ◽  
W. Kofman
Keyword(s):  
Electric Field ◽  
Electron Temperature ◽  
Plasma Temperature ◽  
Ion Temperature ◽  
Heating Rates ◽  
Neutral Winds ◽  
F Region ◽  
E Region ◽  
Effective Electric Field ◽  
Temperature Observations

Abstract. Using EISCAT data, we have studied the behavior of the E region electron temperature and of the lower F region ion temperature during a period that was particularly active geomagnetically. We have found that the E region electron temperatures responded quite predictably to the effective electric field. For this reason, the E region electron temperature correlated well with the lower F region ion temperature. However, there were several instances during the period under study when the magnitude of the E region electron temperature response was much larger than expected from the ion temperature observations at higher altitudes. We discovered that these instances were related to very strong neutral winds in the 110-175 km altitude region. In one instance that was scrutinized in detail using E region ion drift measurement in conjunction with the temperature observations, we uncovered that, as suspected, the wind was moving in a direction closely matching that of the ions, strongly suggesting that ion drag was at work. In this particular instance the wind reached a magnitude of the order of 350 m/s at 115 km and of at least 750 m/s at 160 km altitude. Curiously enough, there was no indication of strong upper F region neutral winds at the time; this might have been because the event was uncovered around noon, at a time when, in the F region, the E×B drift was strongly westward but the pressure gradients strongly northward in the F region. Our study indicates that both the lower F region ion temperatures and the E region electron temperatures can be used to extract useful geophysical parameters such as the neutral density (through a determination of ion-neutral collision frequencies) and Joule heating rates (through the direct connection that we have confirmed exists between temperatures and the effective electric field).Key words. Ionosphere (auroral ionosphere; ionosphere atmosphere interactions; plasma temperature and density)

scholarly journals The effects of mesoscale regions of precipitation on the ionospheric dynamics, electrodynamics and electron density in the presence of strong ambient electric fields

2010 ◽  
Vol 28 (6) ◽  
pp. 1345-1360 ◽  
Author(s):  
J. D. de Boer ◽  
J.-M. A. Noël ◽  
J.-P. St.-Maurice
Keyword(s):  
Electron Density ◽  
Electric Fields ◽  
Current Density Distribution ◽  
Electron Density Profile ◽  
Particle Precipitation ◽  
Advection Term ◽  
Nonlinear Advection ◽  
High Latitude Ionosphere ◽  
E Region ◽  
Current Densities

Abstract. We have developed a new high resolution two-dimensional model of the high latitude ionosphere in which nonlinear advection terms are closely coupled with the electrodynamics. The model provides a self-consistent description of the ionospheric feedback on the electrodynamical perturbations produced by auroral arc-related particle precipitation in regions with strong ambient electric fields. We find in particular that a heretofore neglected ion Pedersen advection term can introduce considerable changes in the electron density profile, the current density distribution, the conductivities and the electron temperatures. We find that the convective effects can carry the ionisation more than 150 km outside the precipitation region in a few minutes, with attendant large changes in the current distribution and E-region densities that become enhanced outside the region of particle precipitation. The production of a tongue of ionisation that slowly decays outside the auroral boundaries contrasts with the sharp geometric cut-off and associated stronger current densities found in previous studies.

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