Disturbances of the upper atmosphere and ionosphere caused by acoustic-gravity wave sources in the lower atmosphere

The results of observations of acoustic-gravity waves in the troposphere and the ionosphere at middle latitudes during periods of passage of the solar terminator are presented. Tropospheric observations were performed using a lidar. The frequency characteristics of variations of the tropospheric parameters are determined based on observations of the intensity of the scattered lidar signal. The characteristics of variations of the total electron content (TEC) in the atmosphere are determined from data collected by GPS navigation satellites. An analysis of the observational data showed that the spectrum of variations of the atmospheric and ionospheric parameters is indicative of acoustic-gravity waves (AGW) propagating from the lower atmosphere. Modeling studies of the vertical propagation of AGW from the Earth’s surface showed that such waves quickly (within ~15 min) reach altitudes of the upper atmosphere (~300 km). The refraction and dissipation of waves in the upper atmosphere produces perturbations of the background state of the atmosphere and gives rise to the waveguide propagation of infrasonic wave components. The observed manifestations of TEC disturbances caused by AGW propagating from the lower atmosphere can be explained by the diurnal variation of the altitude of the ionosphere and the waveguide propagation of infrasonic waves.     

Use of total electron content maps for analysis of spatial-temporal structures of the ionosphere

The main aspects of a methodology for determining the total electron content (TEC) of the ionosphere from GPS observations and the principles of using two-frequency measurements of satellite signal delays in navigation systems are presented. The method developed and used at the Western Department of Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radio Waves Propagation, RAS enables to determine the absolute values of the TEC and monitor the diurnal behavior of this quantity for individual monitoring stations. The methodology for obtaining information on the spatial distribution of TEC maps of the ionosphere on the basis of an algorithm for multi-station processing of GPS observations. Using a set of algorithms and programs, regional TEC maps with a spatial resolution of 1° and a time resolution of 15 min-1 h are regularly drawn. This precision allows using TEC maps for studying the structure and dynamics of the ionosphere during different geophysical events. The results of studies of the response of the ionosphere to the solar eclipse on November 3, 2005 and the geomagnetic storms on January 22, 2012.     

Variations in the Geomagnetic Cutoff Rigidity during the Magnetic Storm in March 2015

Variations in the planetary system of the geomagnetic cutoff rigidity during the moderate geomagnetic storm in March 2015 are calculated on the basis of data from cosmic-ray measurements at the world network of stations. The distance to the subsolar point and the radius of the ring current are calculated on the basis of the axisymmetric restricted Earth’smagnetosphere model that takes into account currents at the magnetopause and the ring current. The contribution of the ring current to variations in the geomagnetic cutoff rigidity and to the disturbance storm time (Dst) index is also determined within this model.     

Modeling of variations of the peak F2 layer electron density and total electron content during the recovery period after the magnetic storm of April 15–20, 2002

The results of numerical modeling by using the global upper atmosphere model of the Earth (UAM) for reproducing the peak F2 layer electron density (N _m F2) and total electron content (TEC) during recovery period after the magnetic storm of the April 15–20, 2002 are discussed. According to the simulations, the time it takes to reach a stationary regime of N _m F2 and TEC diurnal variations is 24 hours, much shorter then the plasmasphere refilling time. The results are compared with the predictions of the IRI-2007 empirical model and GPS data on the TEC and found in good quantitative agreement for the latitudinal variations of N _m F2 and TEC for daytime conditions in the southern hemisphere. The worst agreement occurs in the region of the main ionospheric trough.     

Effect of strongly perturbed magnetosphere on the cosmic-ray cutoff rigidity

Comprehensive determination of the cosmic-ray cutoff rigidity in strongly perturbed periods has been performed for a number of stations located at different latitudes. To calculate the geomagnetic cutoffs by tracing the trajectories of cosmic-ray particles in the magnetic field of the magnetosphere, the model of strongly perturbed magnetosphere was used [1–3]. The diurnal anisotropy of the geomagnetic cutoff rigidity in the minimum of D _st variation in the geomagnetic field has been estimated.     

Fractal Dimension Analysis of Earth Magnetic Field during 26 August 2018 Geomagnetic Storm

We analyse the fractal nature of geomagnetic field northward and eastward horizontal components with 1 min resolution measured by the four stations Belsk, Hel, Sodankylä and Hornsund during the period of 22 August–1 September, when the 26 August 2018 geomagnetic storm appeared. To reveal and to quantitatively describe the fractal scaling of the considered data, three selected methods, structure function scaling, Higuchi, and detrended fluctuation analysis are applied. The obtained results show temporal variation of the fractal dimension of geomagnetic field components, revealing differences between their irregularity (complexity). The values of fractal dimension seem to be sensitive to the physical conditions connected with the interplanetary shock, the coronal mass ejection, the corotating interaction region, and the high-speed stream passage during the storm development. Especially, just after interplanetary shock occurrence, a decrease in the fractal dimension for all stations is observed, not straightforwardly visible in the geomagnetic field components data.     

Observations of Acoustic Gravity Waves during the Solar Eclipse of March 20, 2015 in Kaliningrad

Results of observations of atmospheric and ionospheric parameters during the solar eclipse of March 20, 2015 have been described. The observations have been conducted by lidar sensing in the lower atmosphere and analysis of the total electron content (TEC) in the ionosphere in Kaliningrad. Observations at the troposphere altitudes have been conducted using an atmospheric lidar. Ionospheric parameter TEC has been determined according to observations of navigation satellite signals. The spectral analysis of the monitored parameters during the solar eclipse has shown that, in the lower atmosphere and the ionosphere in a period range of 2–20 min, internal gravity waves (IGWs) and infrasonic waves are excited. During the main phase of the eclipse, the major contribution to variations in the parameters of the medium comes from infrasonic vibrations. Changes in the variations in the atmospheric and ionospheric parameters with IGW periods are observed only in the initial and final phases of the eclipse.     

Geomagnetic Control of the Spectrum of Traveling Ionospheric Disturbances Based on Data from a Global GPS Network

An attempt is made to verify the hypothesis on the role of geomagnetic disturbances as a factor determining the intensity of traveling ionospheric disturbances (TIDs). To improve the statistical validity of the data, we used the method of global spatial averaging of disturbance spectra of the total electron content (TEC), which is based on the new GLOBDET technology. To characterize the TID intensity quantitatively, we propose using a new global index of the degree of disturbance, which is equal to the mean value of the r.m.s. TEC variations within the chosen range of TID periods (20-60 min in the present case). The analysis was made for a set of 100 to 300 GPS stations, and for 10 days with different levels of geomagnetic activity (the Dst index varied from -13 to -321 nT and the Kp index, from 3 to 9). It was found that as the magnetic disturbance increases, the total intensity of TIDs also increases monotonically; however, the latter correlates not with the absolute value of Dst but with the value of the time derivative of Dst (the maximum correlation coefficient reaches -0.94). The delay about 2 h in the TID response is consistent with the viewpoint that TIDs are generated in auroral regions and propagate toward the equator with a velocity of about 300-400 m/s.     

Ionospheric effect of the magnetospheric substorms at middle latitudes

Summary A study is made of theF2-layer effect of magnetospheric substorms over the Mediterranean area using data from several ionospheric stations for selected events in the current sunspot cycle 21. The night-time enhancements in the critical frequency of theF2-layer (f ₀ F2) and the total electron content (TEC) have been found with both premidnight and postmidnightf ₀ F2 peaks and a subsequent decrease in the minimum virtual height of theF region (h′F). It is found that the enhancements occur through the nights under steady geomagnetic conditions and that the time at which it is seen at Rome and Grocka ionospheric stations is progressively earlier as geomagnetic activity increases. It has been further shown that this type of thef ₀ F2 night-time increases is not always accompanied by an increase in TEC, although the reverse holds true during the nights of increased substorm activity. The fact that the considerable variability inf ₀ F2, TEC andh′F at the onset of the substorm expansion are preceded by the ionospheric dynamics associated with these observations can be very useful in the identification of precursor indicative of short-term variations of ionospheric propagation conditions.     

Diurnal and seasonal variations in h’F and foF2 over low (Indian) and mid (Japanese) latitude stations — a comparative study

Using the simultaneous data of ionosonde from a low latitude station, Waltair, India (17.7°N,83.3°E) in the Indian sector and a mid latitude station, Kokubunji, Japan (35.7°N,139.5°E) in the Japanese sector during the high sunspot year of 2001, a comparative study of the variations in the diurnal, seasonal and day to day characteristics of the ionospheric F-region parameters, such as the virtual height of the F-layer (h’F) and the critical frequency of the F₂ layer (foF2), are studied. The effect of geomagnetic activity variations of the F-region parameters over the low and mid latitude stations is also presented.     

上甸子区域大气本底站NO2柱浓度光谱反演及其变化特征

为了探究京津冀本底浓度地区NO₂这一重要空气污染物的变化特征,采用多轴差分吸收光谱技术（MAX-DOAS）在上甸子区域大气本底站开展了太阳散射光谱观测以及NO₂柱浓度反演研究。在NO₂的405～430nm特征谱段进行了定量光谱解析,并通过几何近似法计算了2009年7～9月NO₂对流层垂直柱浓度（VCD_trop）。观测期间NO₂ VCD_trop平均值和最大值分别为5.43×1015和7.15×1016 molec·cm-2。NO₂ VCD_trop日均值浓度水平较低,但总体上有上升趋势。NO₂ VCD_trop变化过程与风速风向关系密切：西南风时风速越小NO₂ VCD_trop越低,东北风对NO₂ VCD_trop有扩散稀释作用。NO₂ VCD_trop日变化形态总体上呈现为中午时段低、早晚较高的特征,并且傍晚峰值比早间峰值略高。上甸子站NO₂ VCD_trop浓度水平和日变化幅度相比北京城区同期观测结果明显偏小。NO₂ VCD_trop变化特征与河北香河和固城等污染相对较轻站点观测到的变化特征相一致。总之,MAX-DOAS能够有效监测区域本底大气的NO₂ VCD_trop,其变化特征与工业和交通排放、大气光化学过程、大气传输等复杂因素有关,还需积累更多数据和深入研究。     

Effect of NO concentration disturbances on the global distribution of ionospheric parameters during geomagnetic storms

The role of nitric oxide (NO) in the ionospheric effects during geomagnetic storm on May 1–3, 2010, is examined. The studies are performed using a global self-consistent model of the thermosphere, ionosphere and protonosphere (GSM TIP). Two versions of calculations are used: (1) based on an analytical approximation of the NO concentration and (2) self-consistent calculation of the global distribution of nitric oxide over the ionosphere. It is shown that, during a geomagnetic disturbance, the NO concentration at high latitudes shows an increase, which under the influence of the horizontal circulation of neutral gas leads to an increase in the concentration of NO at mid-latitudes ～1 day after the start of the perturbation. Simulated values of foF2 are compared to experimental data obtained at a number of Russian mid-latitude stations. It is noted that the self-consistent calculations of the NO concentration better describes the spatial-temporal behavior of ionospheric parameters during geomagnetic storms.     

Geometric phases for scalar wave superpositions

Geometric phases are defined for superpositions of scalar waves of various nature. The geometric phases possess similar properties to those of polarized light wave ones, but require a different parametric space. An appropriate parametric space is constructed on the basis of a modified Poincaré sphere. An example considering spherical scalar waves is presented.     

Frequency characteristics of the troposphere and ionosphere variations in periods of solar terminator passage

An analysis of the results of lidar observations in the lower atmosphere and observations of the total electron content in the ionosphere (TEC) in Kaliningrad (53°N, 22°E) during the period of solar terminator passage is presented. The observations at troposphere altitudes were performed with a two-wavelength atmospheric lidar (532 and 1064 nm). The ionospheric TEC was determined using signals from GLO-NASS navigation satellites. The observations in the lower atmosphere were performed in February and March 2012, starting ～1 h before sunrise and ending ～1–2 h after sunrise, whereas ionospheric observations were performed continuously throughout the day. Analysis of the spectrum of the observed parameters showed that, during solar terminator passage, the lower atmosphere and ionosphere parameters vary with periods of 4–6 min. Variations of the parameters in the atmosphere with these periods are associated with the propagation of acoustic-gravity waves (AGW). Analysis of the experimental results shows that AGW arise in the lower atmosphere and propagate vertically to ionospheric altitudes. It is assumed that AGW with these periods can be efficiently excited in the lower atmosphere and play an important role in the dynamic interactions between the lower and upper atmosphere.     

Modeling of total electron content disturbances caused by electric currents between the Earth and the ionosphere

The results of simulation of ionospheric total electron content (TEC) caused by the electric field induced by an electric current between the Earth and the ionosphere are reported. The calculations are performed using a model of the upper atmosphere of the Earth (UAM). The equation for the electric potential in the UAM is solved by specifying vertical electric currents in a limited area of the lower boundary of the ionosphere, presumably over the epicenter of a forthcoming earthquake. The dependence of the intensity of TEC disturbances on the electric current direction, latitudinal location of the sources, and their configurations is examined. The most intense TEC disturbance are predicted when the sources are located within 30°–45° geomagnetic latitude. Simulating the concurrent action of vertical currents and compensating “return” currents uniformly distributed around the globe outside the region of “direct” currents showed no significant changes in the TEC disturbances compared with the situation where merely “direct” currents are considered. The role of the vertical and horizontal components of the electromagnetic drift of ionospheric plasma in the variations of the electron density in different areas relative to the electric current source is discussed.     

Proton loss of inner radiation belt during geomagnetic storm of 2018 based on CSES satellite observation

The proton distribution in inner radiation belt is often affected by strong geomagnetic storm disturbance. Based on the data of the sun-synchronous CSES satellite, which carries with several high energy particle payloads and was launched in February 2018, we analyzed the extensive proton variations in the inner radiation belt in a wide energy range of 2 MeV-220 MeV during 2018 major geomagnetic storm. The result indicates that the loss mechanism of protons was energy dependence which is consistent with some previous studies. For protons at low energy 2 MeV-20 MeV, the fluxes were decreased during main phase of the storm and did not come back quickly during the recovery phase, which is likely to be caused by Coulomb collision due to neutral atmosphere density variation. At higher energy 30 MeV-100 MeV, it was confirmed that the magnetic field line curvature scattering plays a significant role in the proton loss phenomenon during this storm. At highest energies > 100 MeV, the fluxes of protons kept a stable level and did not exhibit a significant loss during this storm.     

Poincaré Invariant Three-Body Scattering

Relativistic Faddeev equations for three-body scattering are solved at arbitrary energies in terms of momentum vectors without employing a partial wave decomposition. Relativistic invariance is incorporated withing the framework of Poincaré invariant quantum mechanics. Based on a Malfliet–Tjon interaction, observables for elastic and breakup scattering are calculated and compared to non-relativistic ones.     

Geomagnetic bending and effective angles of approach of the cosmic rays for various stations

Data from 20 neutron monitor stations are used to estimate an effective geomagnetic bending for cosmic rays causing the diurnal variation of the neutron component at these stations. Correlation functions between each pair of stations were computed for that purpose and the temporal shifts giving the peak correlation were found.Devoted to Professor V. Petrílka on his sixty-fifth birthday.     

Propagation features of head-on collision dust acoustic solitary waves in four-component quantum plasmas

ABSTRACT

In framework of the extended Poincaré–Lighthill–Kuo, the properties of dust acoustic (DA) solitary wave’s interaction are investigated in four-component quantum dusty plasma. Two Korteweg–de Vries equations describing the colliding DA solitary waves are derived by eliminating the secularities. By knowing the explicit form of the solitary wave solutions, the leading phase changes, trajectories and phase shifts are obtained, accordingly. The effects of various physical parameters such as the quantum mechanical parameters, the charge ratio between positive and negative dust particles, the mass ratio between negative and positive dust particles and the ratio of electron to ion temperatures are studied extensively. Our findings showed that these parameters play a significant role on the characteristics and basic features of DA solitary waves such as phase shifts in trajectories due to collision. The obtained results may be beneficial to understand well the collision of DA solitary waves that may occur in laboratory plasmas, space plasma as well as in plasma applications.     

Voltage interval mappings for activity transitions in neuron models for elliptic bursters

We performed a thorough bifurcation analysis of a mathematical elliptic bursting model, using a computer-assisted reduction to equationless, one-dimensional Poincaré mappings for a voltage interval. Using the interval mappings, we were able to examine in detail the bifurcations that underlie the complex activity transitions between: tonic spiking and bursting, bursting and mixed-mode oscillations, and finally mixed-mode oscillations and quiescence in the FitzHugh–Nagumo–Rinzel model. We illustrate the wealth of information, qualitative and quantitative, that was derived from the Poincaré mappings, for the neuronal models and for similar (electro)chemical systems.