There are a great number of clinical and statistical studies confirming that the myocardial infar... more There are a great number of clinical and statistical studies confirming that the myocardial infarction number rises during geomagnetic disturbances, which have a maximum of occurrence near equinox. Contrary to that, the analysis of the daily numbers of Moscow ambulance calls (1979-1981), related to the myocardial infarction, showed the strong winter maximum and summer minimum. The similar result we obtained by using the 25 year data (1970-1995) on the death from infarction in Bulgaria. We analyzed the biotropic efficacy of 129 geomagnetic storms and found that its hazard depends on the season. About of 90% of the winter time magnetic storms were accompanied by the infarction enhancement, but only ~ 3% of the summer magnetic storms led to the increasing of the cardiac problems. It means that the human organism stability to the "negative" influence of magnetic storms is stronger in summer than in winter. We also found that the different magnetic storm phases demonstrate the ...
The location of the auroral oval boundaries has been mapped onto the Pc5 wave power spatial distr... more The location of the auroral oval boundaries has been mapped onto the Pc5 wave power spatial distribution. The poleward and equatorward boundaries of auroral oval are estimated using either the BAS database based on UV observations of the aurora by the IMAGE satellite or the OVATION model based on the DMSP particle data. The epicenter of the spectral power of broadband fluctuations in the Pc5 band during storm growth phase is mapped inside the auroral oval. During the storm recovery phase, the spectral power of narrowband Pc5 waves, both in the morning and dusk sector, is mapped inside the auroral oval or around its equatorward boundary. This observational result confirms the effects earlier reported: the spatial/temporal variations of the Pc5 wave power in the morning/pre-noon sector are closely related to the location of the auroral electrojet and magnetospheric field-aligned currents. At the same time, narrowband Pc5 waves demonstrate typical resonant features in the amplitude-pha...
The energetic (0.3-1.5 MeV) electron precipitation at polar latitudes of the northern hemisphere ... more The energetic (0.3-1.5 MeV) electron precipitation at polar latitudes of the northern hemisphere on December 13, 2003 are analyzed on the base of CORONAS-F satellite measurements. The comparison of the moment of electron precipitation registration and the ground-based observations of geomagnetic disturbances and optical auroras from the stations located near footprint of the satellite pass is carried out. It is found that the energetic electron precipitation in the night sector at comparatively high polar latitudes are accompanied by the simultaneous development of bay-like magnetic disturbances, by appearance of the riometer absorption bursts, Pi3 geomagnetic pulsations and visual auroras.
The several magnetic storms observations of high-latitude Pc5 range ULF pulsations have been anal... more The several magnetic storms observations of high-latitude Pc5 range ULF pulsations have been analyzed by using the ground data from 6 pairs of quasi-conjugated Arctic and Antarctic stations. The intense ULF waves at polar latitudes were observed during the initial and recovery phases of the magnetic storm. It was found the strong North - South asymmetry of even day-time ULF wave occurrence at the polar caps due to the difference in the ionosphere conductivity provided by difference in the geographic latitudes and longitudes of polar cap stations located at similar geomagnetic coordinates. The local time inter-hemisphere ULF asymmetry decreases with the latitude decreasing. The local time distinction between the stations located near the polar caps is as much as about 13 hours. The ground data demonstrated that during the storm initial phase under strong solar wind dynamic pressure values and the IMF Bz>0 and IMF By
Аннотация. Разработана численная модель, которая дает стационарное распределение компонент поля М... more Аннотация. Разработана численная модель, которая дает стационарное распределение компонент поля МГД-волны в неоднородном плазменном ящике, моделирующем реальную магнитосферу. Рассматривается проблема достаточного граничного условия на границе ионосфера–магнитосфера для связанной МГД-моды. Для обоснования модельных предположений в явном виде получено неравенство, показывающее, в каком случае можно пренебречь индуктивным xолловским эффектом при рассмотрении отраженной от ионосферных границ альфвеновской волны. Модель предсказывает наличие характерной особенности пространственного амплитуднофазового распределения поля УНЧ-колебаний, которая не была замечена в работах по теории резонанса силовых линий, – существование области с противоположными фазовыми задержками на стороне источника резонанса. Этот теоретический прогноз подтверждается амплитудно-фазовой широтной структурой Рс5-пульсаций, наблюдаемых STARE радаром и IMAGE магнитометрами. Постепенное увеличение азимутального волнового ч...
A manifestation of the two-hundred-year solar cycle (de Vries cyclicity) in cli- matic changes is... more A manifestation of the two-hundred-year solar cycle (de Vries cyclicity) in cli- matic changes is considered. The consideration is based on analysis of radial growth of long- lived (800-1200 years) trees Juniperus turkestanica from Tien Shan mountains (Central Asia). Quasi-two-hundred-year oscillations in radial tree growth which correlate well (cor- relation coe cient is 0.82) with similar solar activity variations ( 14 C) and the 200-year component of temperature variations in the Northern Hemisphere in the last millenium and also with quasi-two-hundred-year variations in climatic processes in Europe, North and South America, and Asia have been revealed. The results obtained point to the influence of the deVries solar activity periodicity on global climatic processes.
Magnetopause surface eigenmodes were suggested as a potential source of dayside high-latitude bro... more Magnetopause surface eigenmodes were suggested as a potential source of dayside high-latitude broadband pulsations in the Pc5-6 band (~1-2 mHz) and as a mechanism of the "magic" frequency occurrence. However, the search for a ground signature of these modes has not provided encouraging results. The comparison of Svalbard SuperDARN radar data with the latitudinal structure of Pc5-6 pulsations recorded by magnetometers covering near-cusp latitudes showed that often the latitudinal maximum of the pulsation power maximizes ~2o-3o deeper in the magnetosphere than the dayside open-closed field line boundary (OCB). Here the OCB-ULF correspondence is further examined by comparison of the latitudinal profile of the near-noon pulsation power with the equatorward edge of the auroral red emission from the scanning photometer data. In most analyzed events the "epicenter" of the Pc5-6 power is at ~2o lower latitude than the optical OCB proxy. Therefore, the dayside Pc5-6 pulsa...
New types of the series of quasi-periodic (QP) VLF (very low frequency) emissions in frequency ra... more New types of the series of quasi-periodic (QP) VLF (very low frequency) emissions in frequency range of 1-5 kHz, not associated with geomagnetic pulsations, has been discovered at auroral latitudes (L=5.3) during the Finnish VLF campaign (held in December 2011). Several unusually spectacular events with duration of several hours have been observed in the night-time under conditions of quiet geomagnetic activity (Kp=0-1), while the usual QPs occurrence is the daytime. Contrary to the typical daytime QP emissions, the spectral structure of the reported QP events represented an extended complicated sequence of the combination of repeated discrete mostly rising diffuse VLF signals with the repetition periods ranged from ~several tens of seconds up to ~10 min. Four of such non-typical events are reported in this paper. The fine structure of the separated QP elements may represent a mixture of the different frequency bands signals, which seem to have independent origins. The VLF signals c...
We have developed a numerical model that yields a steady-state distribution of field components o... more We have developed a numerical model that yields a steady-state distribution of field components of MHD wave in an inhomogeneous plasma box simulating the realistic magnetosphere. The problem of adequate boundary condition at the ionosphere–magnetosphere interface for coupled MHD mode is considered. To justify the model’s assumptions, we have derived the explicit inequality showing when the ionospheric inductive Hall effect can be neglected upon the consideration of Alfven wave reflection from the ionospheric boundaries. The model predicts a feature of the ULF spatial amplitude/phase distribution that has not been noticed by the field line resonance theory: the existence of a region with opposite phase delays on the source side of the resonance. This theoretical prediction is supported by the amplitudephase latitudinal structures of Pc5 waves observed by STARE radar and IMAGE magnetometers. A gradual decrease in azimuthal wave number m at smaller L-shells was observed at longitudinal...
Space and time variations of equivalent currents during morning-sector Pc5 pulsations (<i>T... more Space and time variations of equivalent currents during morning-sector Pc5 pulsations (<i>T</i> ∼ 2–8 min) on 2 days (18 January and 19 February 2008) are studied in the context of substorm activity with THEMIS and MIRACLE ground-based instruments and THEMIS P3, P5, and P2 probes. These instruments covered the 22:00–07:00 magnetic local time during the analyzed events. In these cases abrupt changes in the Pc5 amplitudes, intensifications and/or weakenings, were recorded some minutes after auroral breakups in the midnight sector. We analyze three examples of Pc5 changes with the goal to resolve whether substorm activity can have an effect on Pc5 amplitude or not. In two cases (on 19 February) the most likely explanation for Pc5 amplitude changes comes from the solar wind (changes in the sign of interplanetary magnetic field <i>B</i><sub><i>z</i></sub>). In the third case (on 18 January) equivalent current patterns in the morning secto...
Many independent observations have shown that resonant field line Pc5 pulsations (typical periods... more Many independent observations have shown that resonant field line Pc5 pulsations (typical periods of about several minutes) are preferably excited inside the auroral oval. Consideration of the most evident interpretation schemes shows that there is no simple explanation of this effect. Here we consider theoretically the generation of toroidal Pc5 Alfvén waves by fluctuating magnetospheric field-aligned currents. It is shown that the Alfvén wave latitudinal structure has the same features as in the case of the classical field line resonance driven by external sources: a peak localized in latitude and a 180° phase shift across the resonant magnetic shell. This model suggests an additional mechanism of ultra-low-frequency (ULF) wave excitation which can operate at auroral latitudes.
There are a great number of clinical and statistical studies confirming that the myocardial infar... more There are a great number of clinical and statistical studies confirming that the myocardial infarction number rises during geomagnetic disturbances, which have a maximum of occurrence near equinox. Contrary to that, the analysis of the daily numbers of Moscow ambulance calls (1979-1981), related to the myocardial infarction, showed the strong winter maximum and summer minimum. The similar result we obtained by using the 25 year data (1970-1995) on the death from infarction in Bulgaria. We analyzed the biotropic efficacy of 129 geomagnetic storms and found that its hazard depends on the season. About of 90% of the winter time magnetic storms were accompanied by the infarction enhancement, but only ~ 3% of the summer magnetic storms led to the increasing of the cardiac problems. It means that the human organism stability to the "negative" influence of magnetic storms is stronger in summer than in winter. We also found that the different magnetic storm phases demonstrate the ...
The location of the auroral oval boundaries has been mapped onto the Pc5 wave power spatial distr... more The location of the auroral oval boundaries has been mapped onto the Pc5 wave power spatial distribution. The poleward and equatorward boundaries of auroral oval are estimated using either the BAS database based on UV observations of the aurora by the IMAGE satellite or the OVATION model based on the DMSP particle data. The epicenter of the spectral power of broadband fluctuations in the Pc5 band during storm growth phase is mapped inside the auroral oval. During the storm recovery phase, the spectral power of narrowband Pc5 waves, both in the morning and dusk sector, is mapped inside the auroral oval or around its equatorward boundary. This observational result confirms the effects earlier reported: the spatial/temporal variations of the Pc5 wave power in the morning/pre-noon sector are closely related to the location of the auroral electrojet and magnetospheric field-aligned currents. At the same time, narrowband Pc5 waves demonstrate typical resonant features in the amplitude-pha...
The energetic (0.3-1.5 MeV) electron precipitation at polar latitudes of the northern hemisphere ... more The energetic (0.3-1.5 MeV) electron precipitation at polar latitudes of the northern hemisphere on December 13, 2003 are analyzed on the base of CORONAS-F satellite measurements. The comparison of the moment of electron precipitation registration and the ground-based observations of geomagnetic disturbances and optical auroras from the stations located near footprint of the satellite pass is carried out. It is found that the energetic electron precipitation in the night sector at comparatively high polar latitudes are accompanied by the simultaneous development of bay-like magnetic disturbances, by appearance of the riometer absorption bursts, Pi3 geomagnetic pulsations and visual auroras.
The several magnetic storms observations of high-latitude Pc5 range ULF pulsations have been anal... more The several magnetic storms observations of high-latitude Pc5 range ULF pulsations have been analyzed by using the ground data from 6 pairs of quasi-conjugated Arctic and Antarctic stations. The intense ULF waves at polar latitudes were observed during the initial and recovery phases of the magnetic storm. It was found the strong North - South asymmetry of even day-time ULF wave occurrence at the polar caps due to the difference in the ionosphere conductivity provided by difference in the geographic latitudes and longitudes of polar cap stations located at similar geomagnetic coordinates. The local time inter-hemisphere ULF asymmetry decreases with the latitude decreasing. The local time distinction between the stations located near the polar caps is as much as about 13 hours. The ground data demonstrated that during the storm initial phase under strong solar wind dynamic pressure values and the IMF Bz>0 and IMF By
Аннотация. Разработана численная модель, которая дает стационарное распределение компонент поля М... more Аннотация. Разработана численная модель, которая дает стационарное распределение компонент поля МГД-волны в неоднородном плазменном ящике, моделирующем реальную магнитосферу. Рассматривается проблема достаточного граничного условия на границе ионосфера–магнитосфера для связанной МГД-моды. Для обоснования модельных предположений в явном виде получено неравенство, показывающее, в каком случае можно пренебречь индуктивным xолловским эффектом при рассмотрении отраженной от ионосферных границ альфвеновской волны. Модель предсказывает наличие характерной особенности пространственного амплитуднофазового распределения поля УНЧ-колебаний, которая не была замечена в работах по теории резонанса силовых линий, – существование области с противоположными фазовыми задержками на стороне источника резонанса. Этот теоретический прогноз подтверждается амплитудно-фазовой широтной структурой Рс5-пульсаций, наблюдаемых STARE радаром и IMAGE магнитометрами. Постепенное увеличение азимутального волнового ч...
A manifestation of the two-hundred-year solar cycle (de Vries cyclicity) in cli- matic changes is... more A manifestation of the two-hundred-year solar cycle (de Vries cyclicity) in cli- matic changes is considered. The consideration is based on analysis of radial growth of long- lived (800-1200 years) trees Juniperus turkestanica from Tien Shan mountains (Central Asia). Quasi-two-hundred-year oscillations in radial tree growth which correlate well (cor- relation coe cient is 0.82) with similar solar activity variations ( 14 C) and the 200-year component of temperature variations in the Northern Hemisphere in the last millenium and also with quasi-two-hundred-year variations in climatic processes in Europe, North and South America, and Asia have been revealed. The results obtained point to the influence of the deVries solar activity periodicity on global climatic processes.
Magnetopause surface eigenmodes were suggested as a potential source of dayside high-latitude bro... more Magnetopause surface eigenmodes were suggested as a potential source of dayside high-latitude broadband pulsations in the Pc5-6 band (~1-2 mHz) and as a mechanism of the "magic" frequency occurrence. However, the search for a ground signature of these modes has not provided encouraging results. The comparison of Svalbard SuperDARN radar data with the latitudinal structure of Pc5-6 pulsations recorded by magnetometers covering near-cusp latitudes showed that often the latitudinal maximum of the pulsation power maximizes ~2o-3o deeper in the magnetosphere than the dayside open-closed field line boundary (OCB). Here the OCB-ULF correspondence is further examined by comparison of the latitudinal profile of the near-noon pulsation power with the equatorward edge of the auroral red emission from the scanning photometer data. In most analyzed events the "epicenter" of the Pc5-6 power is at ~2o lower latitude than the optical OCB proxy. Therefore, the dayside Pc5-6 pulsa...
New types of the series of quasi-periodic (QP) VLF (very low frequency) emissions in frequency ra... more New types of the series of quasi-periodic (QP) VLF (very low frequency) emissions in frequency range of 1-5 kHz, not associated with geomagnetic pulsations, has been discovered at auroral latitudes (L=5.3) during the Finnish VLF campaign (held in December 2011). Several unusually spectacular events with duration of several hours have been observed in the night-time under conditions of quiet geomagnetic activity (Kp=0-1), while the usual QPs occurrence is the daytime. Contrary to the typical daytime QP emissions, the spectral structure of the reported QP events represented an extended complicated sequence of the combination of repeated discrete mostly rising diffuse VLF signals with the repetition periods ranged from ~several tens of seconds up to ~10 min. Four of such non-typical events are reported in this paper. The fine structure of the separated QP elements may represent a mixture of the different frequency bands signals, which seem to have independent origins. The VLF signals c...
We have developed a numerical model that yields a steady-state distribution of field components o... more We have developed a numerical model that yields a steady-state distribution of field components of MHD wave in an inhomogeneous plasma box simulating the realistic magnetosphere. The problem of adequate boundary condition at the ionosphere–magnetosphere interface for coupled MHD mode is considered. To justify the model’s assumptions, we have derived the explicit inequality showing when the ionospheric inductive Hall effect can be neglected upon the consideration of Alfven wave reflection from the ionospheric boundaries. The model predicts a feature of the ULF spatial amplitude/phase distribution that has not been noticed by the field line resonance theory: the existence of a region with opposite phase delays on the source side of the resonance. This theoretical prediction is supported by the amplitudephase latitudinal structures of Pc5 waves observed by STARE radar and IMAGE magnetometers. A gradual decrease in azimuthal wave number m at smaller L-shells was observed at longitudinal...
Space and time variations of equivalent currents during morning-sector Pc5 pulsations (<i>T... more Space and time variations of equivalent currents during morning-sector Pc5 pulsations (<i>T</i> ∼ 2–8 min) on 2 days (18 January and 19 February 2008) are studied in the context of substorm activity with THEMIS and MIRACLE ground-based instruments and THEMIS P3, P5, and P2 probes. These instruments covered the 22:00–07:00 magnetic local time during the analyzed events. In these cases abrupt changes in the Pc5 amplitudes, intensifications and/or weakenings, were recorded some minutes after auroral breakups in the midnight sector. We analyze three examples of Pc5 changes with the goal to resolve whether substorm activity can have an effect on Pc5 amplitude or not. In two cases (on 19 February) the most likely explanation for Pc5 amplitude changes comes from the solar wind (changes in the sign of interplanetary magnetic field <i>B</i><sub><i>z</i></sub>). In the third case (on 18 January) equivalent current patterns in the morning secto...
Many independent observations have shown that resonant field line Pc5 pulsations (typical periods... more Many independent observations have shown that resonant field line Pc5 pulsations (typical periods of about several minutes) are preferably excited inside the auroral oval. Consideration of the most evident interpretation schemes shows that there is no simple explanation of this effect. Here we consider theoretically the generation of toroidal Pc5 Alfvén waves by fluctuating magnetospheric field-aligned currents. It is shown that the Alfvén wave latitudinal structure has the same features as in the case of the classical field line resonance driven by external sources: a peak localized in latitude and a 180° phase shift across the resonant magnetic shell. This model suggests an additional mechanism of ultra-low-frequency (ULF) wave excitation which can operate at auroral latitudes.
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Papers by O. Kozyreva