Heliogeophysical Conditions Research Articles

The kriging method of TEC instantaneous mapping

The spatial variations of total electron content (TEC) over the European area for single epochs are examined using a so-called instantaneous mapping procedure applied to simultaneous data collected from a limited number of measuring stations. The method of map generation is explained involving an application of the kriging technique and construction of the associated semi-variogram. Examples of maps thereby produced are presented for magnetically quiet and disturbed days and their spatial structures are discussed in terms of the prevailing helio-geophysical conditions.

Ions with a Mass Number of Two in Mass-Spectrometric Experiments aboard Rockets and Satellites

Deuterium ions D+and doubly-charged helium ions He++have the same mass-to- charge ratio (M/Z= 2) and are not distinguished by the mass-spectrometer. On the basis of analysis of published data, Interkosmos-24satellite data, and theoretical estimations, it is shown that in the ionosphere and plasmasphere the ion with a mass number of two is He++and not D+, at least at altitudes of higher than 600–800 km. Arguments in favor of the validity of this assumption at lower altitudes are presented. Regularities of the dependence of the N(He++)/N(He+) ratio on altitude, time of day, season, and solar activity are derived. It is found that in the daytime the N(He++)/N(He+) ratio decreases with increasing solar activity. The seasonal dependence is most pronounced at nighttime in the altitude interval 1000–2000 km, where this ratio decreases in passing from winter to summer. Peculiarities of the latitude distribution of the absolute and relative values of the He++concentration are found in the Interkosmos-24satellite data. On the basis of the same data, a strong longitude effect in the N(He++) concentration occurring under certain heliogeophysical conditions is discovered, an effect amplitude attaining one order of magnitude on adjacent orbits. An interpretation of this effect is given.

Role of the ionospheric plasma in the formation of a shortwave radiation field in the environment

Using a model formulation, we study how the ionospheric plasma affects the formation of a short-wave electromagnetic field in near space by an operating broadcasting network. The principles underlying the construction of the model and the methods of solution are elucidated. An analysis is made of the variation of the global distribution of anthropogenic electromagnetic background for specific heliogeophysical conditions. Zones of maximum electromagnetic energy density are distinguished in the ionospheric plasma.

On the potential applicability of the simplified ionospheric regional model to different midlatitude areas

The simplified ionospheric regional model (SIRM) was originally developed for modeling the most relevant ionospheric characteristics over Europe for radiocommunication purposes. The model, based mainly on the Fourier expansion of a reference past data set, is here adapted and applied to different sets of dishomogeneous periods of observed data coming from a sparse network of ionospheric stations in midlatitude areas, that is, northeastern North America, southeastern South America, northeast Asia, and southeast Australia. Notwithstanding the simple SIRM formulation and the reduced number of numerical coefficients involved, a good agreement has been found between modeled and observed monthly median values of ƒ0F2 and M(3000)F2 under different heliogeophysical conditions.

Climatic trends of the mid-latitude upper atmosphere and ionosphere

Long-term variations of electron concentration in the mid-latitude ionosphere, independent of heliogeophysical conditions and the meteorological characteristics of the atmosphere, have been determined. It is suggested that a long-term decrease of atomic and molecular oxygen concentrations in the mid-latitude thermosphere is the most possible reason for the trends found in ionospheric parameters.

An empirical model description of ionospheric critical frequencies and parabolic heights

A large amount of ionospheric data stored in WDC-B has been used at developing, in computerized form, global empirical models for a few ionospheric parameters. Applying this code, representative values of these parameters can readily be obtained for a large variety of helio-geophysical conditions.

A model description of the ionospheric peak height

For a wide range of helio-geophysical conditions, a set of typical peak heights was derived from the global, semi-empirical ionospheric model that our group has worked out. Based on this data, a descriptive computer code has been established giving hmF2 as function of the modified magnetic dip, local time, day of year and solar activity. It is shown that this code gives a more reliable peak height than the currently used procedure based on the ionogram parameter M(3000)F2.

On the influence of heliogeophysical factors on the health of patients with cardiovascular diseases

Throughout life, the organism constantly has to adapt to continuously changing environmental conditions. Sensitivity of patients with cardiovascular diseases to heliogeophysical and adverse weather conditions ranges from 42 to 100% and is manifested by heliometeotropic reactions of varying severity. Studies have shown that sick people are affected by sudden intensification of solar activity, geomagnetic storms and changes of meteorological elements, and the organism may react to variations of external factors 1-2 days before the change of heliogeophysical conditions, on the day of direct exposure to the factors and 2-3 days after their change. The greatest biotropic effect of meteorological factors is manifested when the intensity of the Earth's magnetic field changes against the background of a sharp increase in solar activity. Under the influence of geomagnetic field strength fluctuations, a person suffering from a chronic disease may easily go into a state of stress. It determines the necessity to develop methods of forecasting unfavorable geomagnetic and meteorological situations, which can provoke aggravation of pathological processes.

An analysis of the empirical models and the measurement results of the polar atmospheric composition at 120–150 km height

δ = (O/N 2) exp/(O/N 2) mod ratios are analysed for the polar thermosphere depending on the season and the heliogeophysical activity where (O/N 2) exp values are measured at high latitudes with radiofrequency mass spectrometers at MP-12 rocket launchings and (O/N 2) mod values are calculated for the corresponding conditions of every experiment from 4 models (DTM, MSIS-77, MSIS-83 and Köhnlein model (KL)). The analysis reveals certain regularities in variations for different models. In summer δ DTM does not depend on the heliogeophysical activity and is within a factor of 2–3 for the polar cap and the daytime cusp at 150 km; during the polar night δ DTM depends on the geomagnetic disturbance and varies with the solar activity cycle. The δ MSIS-77 and δ KL values have little dependence on the heliogeophysical conditions and have approximately the same seasonal variations. During the polar night δ MSIS-83 corresponds to 1 ± 0.25 at high and low solar activity. The increase in δ dispersion for every model considered is noted at low solar activity in the morning and evening sectors of the auroral oval.