Jan Lastovicka - Academia.edu (original) (raw)

Papers by Jan Lastovicka

Research paper thumbnail of Differences in Midlatitude Ionospheric Response to Magnetic Disturbances at Northern and Southern Hemispheres and Anomalous Response During the Last Extreme Solar Minimum

Geophysical monograph, Nov 18, 2016

Research paper thumbnail of Differences in regular and storm time ionospheric variability at magnetically conjugated locations of the Northern and Southern Hemisphere&#160

<p>The paper is focused on differences/similarities in regular dail... more <p>The paper is focused on differences/similarities in regular daily ionospheric variability and in the ionospheric response to CME- and CIR/CHSS-related magnetic disturbances above magnetically conjugated ionospheric stations located at Northern and Southern Hemisphere. We analysed variability of critical frequency foF2 and the F2 layer peak height hmF2 obtained for European-African sector for initial, main and recovery phases of magnetic storms of different intensity, which occurred within the last two solar cycles. We also used exclusively GPS-based detection methods, specifically information on TEC, TEC deviations in space and time from a background reference (dTEC), and the Rate of TEC change in time (ROT), all inferred from GPS receiver networks in Europe and Africa to compare behavior of Large Scale Traveling Ionospheric Disturbances (LSTIDs) at both hemispheres. We conclude that hemispheric conjugacy of LSTID is highly probable during both CME- and CIR/CHSS-related storms while interhemispheric circulation rather unlikely but still occurring during some periods.</p>

Research paper thumbnail of Long-Term Changes in Ionospheric Climate in Terms of foF2

Atmosphere, Jan 10, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of Long-term variations and residual trends in the E, F and sporadic E (Es) layer over Juliusruh, Europe

In the present study, using sixty-three and fifty-six years of continuous observations, we invest... more In the present study, using sixty-three and fifty-six years of continuous observations, we investigate the long-term oscillations and residual trends, respectively, in the E-and F-region ionosonde measured parameters over Juliusruh, Europe. Using the Lomb-Scargle periodogram (LSP) long-term variations are estimated before the trend estimation. We found that the amplitude of the annual oscillation is higher than the 11-year solar cycle variation in the critical frequencies of the daytime E (foE) and Es (foEs) layers. A weak semi-annual oscillation is also identified in the foE. In the F-region, except for daytime hmF2, and nighttime foF2, the amplitude of the 11-year solar cycle variation is higher than the annual oscillation. The LSP estimated periods and their corresponding amplitudes are used to construct a model E-and F-region ionospheric parameters that are in good agreement with the observation. The linear trend estimation is derived by applying a least-squares fit analysis to the residuals, subtracting the model from the observation. Except for the daytime foF2, all the other parameters like nighttime foF2, day and nighttime h'F, and hmF2 show a negative trend. Present results suggest that the greenhouse effect is a prime driver for the observed long-term trend in the F-region. Interestingly, weak negative trends in the foE and foEs are found which contradicts an earlier investigation. The present study suggests that the changes in the upper stratospheric ozone and mesosphere wind shear variability could be the main driver for the observed weak negative trends in the foE, and foEs, respectively.

Research paper thumbnail of 27-DAY Variation in the Lower Ionosphere

Research paper thumbnail of Stability of the relationship between ionospheric parameters and solar activity proxies

Research paper thumbnail of Infrasound in the ionosphere and disturbances triggered by earthquakes

EGU General Assembly Conference Abstracts, Apr 1, 2013

Research paper thumbnail of Effects of the interplanetary magnetic field in the midlatitude ionosphere

Ionosfernye Issledovaniia, 1982

Research paper thumbnail of Climatic Change in the Ionosphere and Upper Atmosphere and its Impact

Research paper thumbnail of On differences of magnetic storm effects on ionosphere above neighbouring locations

Research paper thumbnail of Ionospheric co-seismic signatures at far and near distances from the earthquake epicenters

Research paper thumbnail of On some difference in the behaviour of the upper and lower part of the lower ionosphere in relation to meteorological parameters

Annales Geophysicae

ABSTRACT

Research paper thumbnail of Long-period fluctuations in ionospheric absorption and their relation with planetary activity in the stratosphere

Studia Geophysica et Geodaetica, 1989

S u m m a r y : By investigating the quasi-regular variations in ionospheric absorption along thr... more S u m m a r y : By investigating the quasi-regular variations in ionospheric absorption along three distant radio paths with approximately one and the same equivalent frequency during the winters 1983/84 and 1984/85 ,an attempt is made to study the stratospheric-mesospheric relations at typical geographic mid latitudes. It is shown that the quasi-regular oscillations o f ionospheric absorption, investigated in this paper, reach maximum development in each time series at one and the same time. This means, that i f they are provoked by an external source when it starts acting, a spectrum o f frequencies is generated rather than a definite fixed frequency. By studying the variation o f the instantaneous amplitudes o f the quasi-regular oscillations in ionospheric absorption with time, their connection with the amplification o f the quasi-stationary planetary waves in the stratodphere with a zonal wave number 2 during the winter periods under investigation is shown.

Research paper thumbnail of Impact of (almost forgotten?) infrasound from below on the upper atmosphere and ionosphere

Acoustic waves have a remarkable ability to transfer energy from the ground quasi-vertically up t... more Acoustic waves have a remarkable ability to transfer energy from the ground quasi-vertically up to the uppermost layers of the atmosphere On the ground there are many permanent sources of infrasound and also pulse and or sporadic sources The infrasonic waves carry the major part of their energy upwards to the upper atmosphere The propagation of sinusoidal signals of different among others meteorological origin is simulated with a new model that takes into account the inhomogeneity of the atmosphere non-linear effects absorption divergence of wave front due to the long-range acoustic wave propagation etc The calculations show that nonlinear processes destroy sinusoidal signal during its upward propagation it transforms into two initial and final impulses The location of the transformation region where most of wave energy is deposited into the atmosphere depends on frequency its height increases with decreasing frequency Thus the acoustic waves can in principle selectively heat the up...

Research paper thumbnail of Quasi-periodic fluctuations in ionospheric absorption in relation to planetary activity in the stratosphere

Journal of Atmospheric and Terrestrial Physics, 1991

Quasi-periodic fluctuations (2-15 days) in ionospheric absorption along three radio paths in Cent... more Quasi-periodic fluctuations (2-15 days) in ionospheric absorption along three radio paths in Central and Southern Europe are investigated for three winter periods 1985/86, 1986/87 and 1987/88. The periods of dominant fluctuations in absorption and the time variations of their amplitudes are similar for all radio paths and every winter period. The shorter-period fluctuations are found to be associated with enhancements of planetary wave two activity in the stratosphere (30 hPa, 60"N), while longer period fluctuations appear to be associated with intensification of planetary wave one activity in the stratosphere.

Research paper thumbnail of Nitric oxide and lower ionosphere quantities during solar particle events of October 1989 after rocket and ground-based measurements

Journal of Atmospheric and Terrestrial Physics, 1992

The most dramatic demonstrations of solar activity are solar proton flares. One such very strong ... more The most dramatic demonstrations of solar activity are solar proton flares. One such very strong flare, accompanied by a solar proton event (SPE) and a large ground level enhancement of cosmic rays on Earth, was observed in October 1989. During this SPE, ion density and nitric oxide concentration pro&s were measured by rockets launched from the Soviet research vessel 'Akademik Shirshou' in the southern part of the Indian Ocean. The rocket experiment yielded the first in-s&u measurement of NO concentration increased by SPE. The NO con~ntrations estimated from ion-pair production rates due to measured fluxes of high energy particles agree fairly well with the observed NO concentrations in the stratopause region. The results of rocket measurements are compared with measurements of the radio wave absorption in the lower ionosphere performed at similar Iatitudes in central Europe. Model calculations of absorption show that while the night-time enhancement of absorption can be explained by increased electron density related to the measured increase of ion density as a consequence of enhanced penetration of high energy particles, the daytime increase of absorption needs to be explained mainly in terms of the observed increase of nitric oxide concentration.

Research paper thumbnail of The ionosphere: morphology, development and coupling

Journal of Atmospheric and Terrestrial Physics, 1987

The morphology of the MAP/WINE winter is examined, principally from ground-based and satellite ob... more The morphology of the MAP/WINE winter is examined, principally from ground-based and satellite observations. Winter anomaly is evident, occurring in bursts with a west to east shift in time. Aurora1 activity, particularly with reference to the times of major rocket salvoes, is generally low, with Andoya to the south of the aurora1 boundary in most cases. Minor stratospheric warmings, of which 4 occurred, are found to correlate with minima in radio wave absorption. Salvo Rl was launched during one of the minor warmings. Using data from a broad sector of Europe, coupling between the lower thermosphere and mesosphere is seen over large areas. Westerly winds are associated with high absorption (winter anomaly) and reversal to easterly winds with stratospheric warmings and low absorption. It is found possible to select cases, from amongst the MT series of rocket launchings, corresponding to quiet conditions, stratospheric warming, winter anomaly and particle precipitation in the general absence of other effects. Examining Dand lower E-region ionisation profiles for these caes it is found that, compared with a quiet night, the stratwarm night shows the lower E-region to have reduced ionisation. The ionisation ledge is of similar shape in all cases, but occurs over different height ranges. The observed effects all point to transport being a major factor and the need to measure vertical transport over the range of geophysical conditions examined is highlighted.

Research paper thumbnail of Photochemical response of neutral and ionized middle atmosphere composition to the strong solar proton event of October 1989

Advances in Space Research, 2001

One of the strongest solar proton events (SPE) occurred in October 1989. Its forcing of the middl... more One of the strongest solar proton events (SPE) occurred in October 1989. Its forcing of the middle atmosphere chemistry including ionized components in the D-region is examined. The ionization rate, and ozone, NO and OH density temporal and spatial (vertical) deviations induced by the SPE, calculated by a 1-D time-dependent photochemical model separately for daytime and nighttime (not shown here), are used in a 1-D model of the lower ionosphere to calculate the response of ionized components to combined forcing by ionization rate and neutral chemical composition disturbances. The radio wave absorption caused by electron density disturbances after the SPE is calculated and compared with observations. The computed ozone values are compared with observations, as well.

Research paper thumbnail of The possible coupling of the stratosphere and lower ionosphere at middle latitudes

Advances in Space Research, 1996

A study is presented about the possible coupling of the stratosphere and the lower ionosphere sup... more A study is presented about the possible coupling of the stratosphere and the lower ionosphere supported by analysis of total ozone content and ionospheric radio waves absorption data obtained by A3 method (oblique incidence) for some radiopaths and the ozone data obtained by groundbased Dobson spectrophotometers and by Total Ozone Mapping Spectrometer (TOMS/NASA) near the radiowaves reflection points. The data were obtained for Southern Spain, Czechia and Bulgaria. Some statistically significant correlations between variations of total ozone content considered as a measure of the stratospheric changes and radio waves absorption as an indicator of the lower ionosphere behaviour are interpreted as a consequence of the trace gases transport which are of importance for the neutral and ion chemistry of the ionospheric D-region and ozone chemistry.

Research paper thumbnail of Lower ionosphere at middle latitudes: its morphology and response to meteorological and solar-terrestrial activity during the DYANA campaign 1990

Journal of Atmospheric and Terrestrial Physics, 1994

Research paper thumbnail of Differences in Midlatitude Ionospheric Response to Magnetic Disturbances at Northern and Southern Hemispheres and Anomalous Response During the Last Extreme Solar Minimum

Geophysical monograph, Nov 18, 2016

Research paper thumbnail of Differences in regular and storm time ionospheric variability at magnetically conjugated locations of the Northern and Southern Hemisphere&#160

<p>The paper is focused on differences/similarities in regular dail... more <p>The paper is focused on differences/similarities in regular daily ionospheric variability and in the ionospheric response to CME- and CIR/CHSS-related magnetic disturbances above magnetically conjugated ionospheric stations located at Northern and Southern Hemisphere. We analysed variability of critical frequency foF2 and the F2 layer peak height hmF2 obtained for European-African sector for initial, main and recovery phases of magnetic storms of different intensity, which occurred within the last two solar cycles. We also used exclusively GPS-based detection methods, specifically information on TEC, TEC deviations in space and time from a background reference (dTEC), and the Rate of TEC change in time (ROT), all inferred from GPS receiver networks in Europe and Africa to compare behavior of Large Scale Traveling Ionospheric Disturbances (LSTIDs) at both hemispheres. We conclude that hemispheric conjugacy of LSTID is highly probable during both CME- and CIR/CHSS-related storms while interhemispheric circulation rather unlikely but still occurring during some periods.</p>

Research paper thumbnail of Long-Term Changes in Ionospheric Climate in Terms of foF2

Atmosphere, Jan 10, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of Long-term variations and residual trends in the E, F and sporadic E (Es) layer over Juliusruh, Europe

In the present study, using sixty-three and fifty-six years of continuous observations, we invest... more In the present study, using sixty-three and fifty-six years of continuous observations, we investigate the long-term oscillations and residual trends, respectively, in the E-and F-region ionosonde measured parameters over Juliusruh, Europe. Using the Lomb-Scargle periodogram (LSP) long-term variations are estimated before the trend estimation. We found that the amplitude of the annual oscillation is higher than the 11-year solar cycle variation in the critical frequencies of the daytime E (foE) and Es (foEs) layers. A weak semi-annual oscillation is also identified in the foE. In the F-region, except for daytime hmF2, and nighttime foF2, the amplitude of the 11-year solar cycle variation is higher than the annual oscillation. The LSP estimated periods and their corresponding amplitudes are used to construct a model E-and F-region ionospheric parameters that are in good agreement with the observation. The linear trend estimation is derived by applying a least-squares fit analysis to the residuals, subtracting the model from the observation. Except for the daytime foF2, all the other parameters like nighttime foF2, day and nighttime h'F, and hmF2 show a negative trend. Present results suggest that the greenhouse effect is a prime driver for the observed long-term trend in the F-region. Interestingly, weak negative trends in the foE and foEs are found which contradicts an earlier investigation. The present study suggests that the changes in the upper stratospheric ozone and mesosphere wind shear variability could be the main driver for the observed weak negative trends in the foE, and foEs, respectively.

Research paper thumbnail of 27-DAY Variation in the Lower Ionosphere

Research paper thumbnail of Stability of the relationship between ionospheric parameters and solar activity proxies

Research paper thumbnail of Infrasound in the ionosphere and disturbances triggered by earthquakes

EGU General Assembly Conference Abstracts, Apr 1, 2013

Research paper thumbnail of Effects of the interplanetary magnetic field in the midlatitude ionosphere

Ionosfernye Issledovaniia, 1982

Research paper thumbnail of Climatic Change in the Ionosphere and Upper Atmosphere and its Impact

Research paper thumbnail of On differences of magnetic storm effects on ionosphere above neighbouring locations

Research paper thumbnail of Ionospheric co-seismic signatures at far and near distances from the earthquake epicenters

Research paper thumbnail of On some difference in the behaviour of the upper and lower part of the lower ionosphere in relation to meteorological parameters

Annales Geophysicae

ABSTRACT

Research paper thumbnail of Long-period fluctuations in ionospheric absorption and their relation with planetary activity in the stratosphere

Studia Geophysica et Geodaetica, 1989

S u m m a r y : By investigating the quasi-regular variations in ionospheric absorption along thr... more S u m m a r y : By investigating the quasi-regular variations in ionospheric absorption along three distant radio paths with approximately one and the same equivalent frequency during the winters 1983/84 and 1984/85 ,an attempt is made to study the stratospheric-mesospheric relations at typical geographic mid latitudes. It is shown that the quasi-regular oscillations o f ionospheric absorption, investigated in this paper, reach maximum development in each time series at one and the same time. This means, that i f they are provoked by an external source when it starts acting, a spectrum o f frequencies is generated rather than a definite fixed frequency. By studying the variation o f the instantaneous amplitudes o f the quasi-regular oscillations in ionospheric absorption with time, their connection with the amplification o f the quasi-stationary planetary waves in the stratodphere with a zonal wave number 2 during the winter periods under investigation is shown.

Research paper thumbnail of Impact of (almost forgotten?) infrasound from below on the upper atmosphere and ionosphere

Acoustic waves have a remarkable ability to transfer energy from the ground quasi-vertically up t... more Acoustic waves have a remarkable ability to transfer energy from the ground quasi-vertically up to the uppermost layers of the atmosphere On the ground there are many permanent sources of infrasound and also pulse and or sporadic sources The infrasonic waves carry the major part of their energy upwards to the upper atmosphere The propagation of sinusoidal signals of different among others meteorological origin is simulated with a new model that takes into account the inhomogeneity of the atmosphere non-linear effects absorption divergence of wave front due to the long-range acoustic wave propagation etc The calculations show that nonlinear processes destroy sinusoidal signal during its upward propagation it transforms into two initial and final impulses The location of the transformation region where most of wave energy is deposited into the atmosphere depends on frequency its height increases with decreasing frequency Thus the acoustic waves can in principle selectively heat the up...

Research paper thumbnail of Quasi-periodic fluctuations in ionospheric absorption in relation to planetary activity in the stratosphere

Journal of Atmospheric and Terrestrial Physics, 1991

Quasi-periodic fluctuations (2-15 days) in ionospheric absorption along three radio paths in Cent... more Quasi-periodic fluctuations (2-15 days) in ionospheric absorption along three radio paths in Central and Southern Europe are investigated for three winter periods 1985/86, 1986/87 and 1987/88. The periods of dominant fluctuations in absorption and the time variations of their amplitudes are similar for all radio paths and every winter period. The shorter-period fluctuations are found to be associated with enhancements of planetary wave two activity in the stratosphere (30 hPa, 60"N), while longer period fluctuations appear to be associated with intensification of planetary wave one activity in the stratosphere.

Research paper thumbnail of Nitric oxide and lower ionosphere quantities during solar particle events of October 1989 after rocket and ground-based measurements

Journal of Atmospheric and Terrestrial Physics, 1992

The most dramatic demonstrations of solar activity are solar proton flares. One such very strong ... more The most dramatic demonstrations of solar activity are solar proton flares. One such very strong flare, accompanied by a solar proton event (SPE) and a large ground level enhancement of cosmic rays on Earth, was observed in October 1989. During this SPE, ion density and nitric oxide concentration pro&s were measured by rockets launched from the Soviet research vessel 'Akademik Shirshou' in the southern part of the Indian Ocean. The rocket experiment yielded the first in-s&u measurement of NO concentration increased by SPE. The NO con~ntrations estimated from ion-pair production rates due to measured fluxes of high energy particles agree fairly well with the observed NO concentrations in the stratopause region. The results of rocket measurements are compared with measurements of the radio wave absorption in the lower ionosphere performed at similar Iatitudes in central Europe. Model calculations of absorption show that while the night-time enhancement of absorption can be explained by increased electron density related to the measured increase of ion density as a consequence of enhanced penetration of high energy particles, the daytime increase of absorption needs to be explained mainly in terms of the observed increase of nitric oxide concentration.

Research paper thumbnail of The ionosphere: morphology, development and coupling

Journal of Atmospheric and Terrestrial Physics, 1987

The morphology of the MAP/WINE winter is examined, principally from ground-based and satellite ob... more The morphology of the MAP/WINE winter is examined, principally from ground-based and satellite observations. Winter anomaly is evident, occurring in bursts with a west to east shift in time. Aurora1 activity, particularly with reference to the times of major rocket salvoes, is generally low, with Andoya to the south of the aurora1 boundary in most cases. Minor stratospheric warmings, of which 4 occurred, are found to correlate with minima in radio wave absorption. Salvo Rl was launched during one of the minor warmings. Using data from a broad sector of Europe, coupling between the lower thermosphere and mesosphere is seen over large areas. Westerly winds are associated with high absorption (winter anomaly) and reversal to easterly winds with stratospheric warmings and low absorption. It is found possible to select cases, from amongst the MT series of rocket launchings, corresponding to quiet conditions, stratospheric warming, winter anomaly and particle precipitation in the general absence of other effects. Examining Dand lower E-region ionisation profiles for these caes it is found that, compared with a quiet night, the stratwarm night shows the lower E-region to have reduced ionisation. The ionisation ledge is of similar shape in all cases, but occurs over different height ranges. The observed effects all point to transport being a major factor and the need to measure vertical transport over the range of geophysical conditions examined is highlighted.

Research paper thumbnail of Photochemical response of neutral and ionized middle atmosphere composition to the strong solar proton event of October 1989

Advances in Space Research, 2001

One of the strongest solar proton events (SPE) occurred in October 1989. Its forcing of the middl... more One of the strongest solar proton events (SPE) occurred in October 1989. Its forcing of the middle atmosphere chemistry including ionized components in the D-region is examined. The ionization rate, and ozone, NO and OH density temporal and spatial (vertical) deviations induced by the SPE, calculated by a 1-D time-dependent photochemical model separately for daytime and nighttime (not shown here), are used in a 1-D model of the lower ionosphere to calculate the response of ionized components to combined forcing by ionization rate and neutral chemical composition disturbances. The radio wave absorption caused by electron density disturbances after the SPE is calculated and compared with observations. The computed ozone values are compared with observations, as well.

Research paper thumbnail of The possible coupling of the stratosphere and lower ionosphere at middle latitudes

Advances in Space Research, 1996

A study is presented about the possible coupling of the stratosphere and the lower ionosphere sup... more A study is presented about the possible coupling of the stratosphere and the lower ionosphere supported by analysis of total ozone content and ionospheric radio waves absorption data obtained by A3 method (oblique incidence) for some radiopaths and the ozone data obtained by groundbased Dobson spectrophotometers and by Total Ozone Mapping Spectrometer (TOMS/NASA) near the radiowaves reflection points. The data were obtained for Southern Spain, Czechia and Bulgaria. Some statistically significant correlations between variations of total ozone content considered as a measure of the stratospheric changes and radio waves absorption as an indicator of the lower ionosphere behaviour are interpreted as a consequence of the trace gases transport which are of importance for the neutral and ion chemistry of the ionospheric D-region and ozone chemistry.

Research paper thumbnail of Lower ionosphere at middle latitudes: its morphology and response to meteorological and solar-terrestrial activity during the DYANA campaign 1990

Journal of Atmospheric and Terrestrial Physics, 1994