In addition to being driven by tidal winds,the sporadic E(Es)layers are modulated by gravity waves(GWs),although the effects are not yet comprehensively understood.In this article,we discuss the effects of mesoscale G...In addition to being driven by tidal winds,the sporadic E(Es)layers are modulated by gravity waves(GWs),although the effects are not yet comprehensively understood.In this article,we discuss the effects of mesoscale GWs on the Es layers determined by using a newly developed model,MISE-1D(one-dimensional Model of Ionospheric Sporadic E),with low numerical dissipation and high resolution.Driven by the wind fields resolved by the high-resolution version of the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension(WACCM-X),the MISE-1D simulation revealed that GWs significantly influence the evolution of the Es layer above 100 km but have a very limited effect at lower altitudes.The effects of GWs are diverse and complex,generally including the generation of fluctuating wavelike structures on the Es layer with frequencies similar to those of the GWs.The mesoscale GWs can also cause increases in the density of Es layers,or they can disperse or diffuse the Es layers and increase their thickness.In addition,the presence of GWs is a key factor in sustaining the Es layers in some cases.展开更多
In this study, we present an innovative Mars Ionosphere-Thermosphere Model(MITM), which is a time-dependent, threedimensional(3-D) model that comprehensively represents the self-consistently coupled thermosphere and i...In this study, we present an innovative Mars Ionosphere-Thermosphere Model(MITM), which is a time-dependent, threedimensional(3-D) model that comprehensively represents the self-consistently coupled thermosphere and ionosphere of Mars within the altitude range of 70-300 km. The model incorporates an extensive range of parameters, including neutral number densities of CO_(2), CO,O, O_(2), N_(2), NO, N(^(2)D), N(^(4)S), Ar, and He;ion number densities of CO_(2)^(+), CO^(+), O^(+), O_(2)^(+), N_(2)^(+), NO^(+), N^(+) ions, and electrons;neutral temperature;and neutral wind fields. The MITM code employs a high-resolution grid system in a spherical geographical coordinate system, with a horizontal resolution of 5° latitude by 7.5° longitude. This altitude-resolved grid system enables accurate depiction of spatial variations in the Martian thermosphere and ionosphere. To showcase the capabilities of the MITM, we present two simulation cases: one during the equinox and another during the solstice. Both simulations reproduce key features of the Martian thermosphere and ionosphere including the characteristics of horizontal circulation, diurnal variations in chemical composition, and distribution of electron density. The MITM offers a robust framework for understanding the intricate interactions and processes that shape the Mars thermosphere and ionosphere,which are crucial for enhancing our understanding of Martian upper atmosphere and ionosphere.展开更多
In the past decades,the Incoherent Scatter Radar(ISR)has been demonstrated to be one of the most powerful instruments for ionosphere monitoring.The Institute of Geology and Geophysics at the Chinese Academy of Science...In the past decades,the Incoherent Scatter Radar(ISR)has been demonstrated to be one of the most powerful instruments for ionosphere monitoring.The Institute of Geology and Geophysics at the Chinese Academy of Sciences was founded to build a state-ofthe-art phased-array ISR at Sanya(18.3°N,109.6°E),a low-latitude station on Hainan Island,named the Sanya ISR(SYISR).As a first step,a prototype radar system consisting of eight subarrays(SYISR-8)was built to reduce the technical risk of producing the entire large array.In this work,we have summarized the preliminary experimental results based on the SYISR-8.The amplitude and phase among 256 channels were first calibrated through an embedded internal monitoring network.The mean oscillation of the amplitude and phase after calibration were about 1 dB and 5°,respectively,which met the basic requirements.The beam directivity was confirmed by crossing screen of the International Space Station.The SYISR-8 was further used to detect the tropospheric wind profile and meteors.The derived winds were evaluated by comparison with independent radiosonde and balloon-based GPS measurements.The SYISR-8 was able to observe several typical meteor echoes,such as the meteor head echo,range-spread trail echo,and specular trail echo.These results confirmed the validity and reliability of the SYISR-8 system,thereby reducing the technical risk of producing the entire large array of the SYISR to some extent.展开更多
We investigated the variations of equatorial plasma bubbles(EPBs)in the East-Asian sector during a strong geomagnetic storm in October 2016,based on observations from the Beidou geostationary(GEO)satellites,Swarm sate...We investigated the variations of equatorial plasma bubbles(EPBs)in the East-Asian sector during a strong geomagnetic storm in October 2016,based on observations from the Beidou geostationary(GEO)satellites,Swarm satellite and ground-based ionosonde.Significant nighttime depletions of F region in situ electron density from Swarm and obvious nighttime EPBs in the Beidou GEO observations were observed on 13 October 2016 during the main phase.Moreover,one interesting feature is that the rare and unique sunrise EPBs were triggered on 14 October 2016 in the main phase rather than during the recovery phase as reported by previous studies.In addition,the nighttime EPBs were suppressed during the whole recovery phase,and absent from 14 to 19 October 2016.Meanwhile,the minimum virtual height of F trace(h’F)at Sanya(18.3°N,109.6°E,MLAT 11.1°N)displayed obvious changes during these intervals.The h’F was enhanced in the main phase and declined during the recovery phase,compared with the values at pre-and post-storm.These results indicate that the enhanced nighttime EPBs and sunrise EPBs during the main phase and the absence nighttime EPBs for many days during the recovery phase could be associated with storm-time electric field changes.展开更多
Previous studies have shown that the ionospheric responses to a solar flare are significantly dependent on the solar zenith angle(SZA):the ionospheric responses are negatively related to the SZAs.The largest enhanceme...Previous studies have shown that the ionospheric responses to a solar flare are significantly dependent on the solar zenith angle(SZA):the ionospheric responses are negatively related to the SZAs.The largest enhancement in electron density always occurs around the subsolar point.However,from 2001 to 2014,the global distribution of total electron content(TEC)responses showed no obvious relationship between the increases in TEC and the SZA during some solar flares.During these solar flares,the greatest enhancements in TEC did not appear around the subsolar point,but rather far away from the subsolar point.The distribution of TEC enhancements showed larger TEC enhancements along the same latitude.The distribution of anomalous ionospheric responses to the solar flares was not structured the same as traveling ionospheric disturbances.This anomaly distribution was also unrelated to the distribution of background neutral density.It could not be explained by changes in the photochemical process induced by the solar flares.Thus,the transport process could be one of the main reasons for the anomaly distribution of ionospheric responses to the solar flares.This anomaly distribution also suggests that not only the photochemical process but also the transport process could significantly affect the variation in ionospheric electron density during some solar flares.展开更多
Meteoroids entering the Earth's atmosphere can create meteor trail irregularity seriously disturbing the background ionosphere. Although numerous observations of meteor trail irregularities were performed with VHF...Meteoroids entering the Earth's atmosphere can create meteor trail irregularity seriously disturbing the background ionosphere. Although numerous observations of meteor trail irregularities were performed with VHF/UHF coherent scatter radars in the past, no simultaneous radar and optical instruments were employed to investigate the characteristics of meteor trail irregularity and its corresponding meteoroid. By installing multiple video cameras near the Sanya VHF radar site, an observational campaign was conducted during the period from November 2016 to February 2017. A total of 242 optical meteors with simultaneous non-specular echoes backscattered from the plasma irregularities generated in the corresponding meteor trails were identified. A good agreement between the angular positions of non-specular echoes derived from the Sanya radar interferometer and those of optical meteors was found,validating that the radar system phase offsets have been properly calibrated. The results also verify the interferometry capability of Sanya radar for meteor trail irregularity observation. The non-specular echoes with simultaneous optical meteors were detected at magnetic aspect angles greater than ~78°. Based on the meteor visual magnitude estimated from the optical data, it was found that the radar nonspecular echoes corresponding to brighter meteors survived for longer duration. This could provide observational evidence for the significance of meteoroid mass on the duration of meteor trail irregularity. On the other hand, the simultaneous radar and video common-volume observations showed that there were some cases with optical meteors but without radar non-specular echoes. One possibility could be that some of the optical meteors appeared at extremely low altitudes where meteor trail irregularities rarely occur.展开更多
Unlike Earth,Mars lacks a global dipolar magnetic field but is dominated by patches of a remnant crustal magnetic field.In 2021,the Chinese Mars Rover will land on the surface of Mars and measure the surface magnetic ...Unlike Earth,Mars lacks a global dipolar magnetic field but is dominated by patches of a remnant crustal magnetic field.In 2021,the Chinese Mars Rover will land on the surface of Mars and measure the surface magnetic field along a moving path within the possible landing region of 20°W-50°W,20°N-30°N.One scientific target of the Rover is to monitor the variation in surface remnant magnetic fields and reveal the source of the ionospheric current.An accurate local crustal field model is thus considered necessary as a field reference.Here we establish a local crust field model for the candidate landing site based on the joint magnetic field data set from Mars Global Explorer(MGS)and Mars Atmosphere and Volatile Evolution(MAVEN)data combined.The model is composed of 1,296 dipoles,which are set on three layers but at different buried depths.The application of the dipole model to the joint data set allowed us to calculate the optimal parameters of their dipoles.The calculated results demonstrate that our model has less fitting error than two other state-of-the art global crustal field models,which would indicate a more reasonable assessment of the surface crustal field from our model.展开更多
Responses of atmospheric carbon dioxide(CO_(2))density to geomagnetic secular variation are investigated using the Whole Atmosphere Community Climate Model-eXtended(WACCM-X).Our ensemble simulations show that CO_(2) v...Responses of atmospheric carbon dioxide(CO_(2))density to geomagnetic secular variation are investigated using the Whole Atmosphere Community Climate Model-eXtended(WACCM-X).Our ensemble simulations show that CO_(2) volume mixing ratios(VMRs)increase at high latitudes and decrease at mid and low latitudes by several ppmv in response to a 50%weakening of the geomagnetic field.Statistically significant changes in CO_(2) are mainly found above~90 km altitude and primarily redetermine the energy budget at~100-110 km.Our analysis of transformed Eulerian mean(TEM)circulation found that CO_(2) change is caused by enhanced upwelling at high latitudes and downwelling at mid and low latitudes as a result of increased Joule heating.We further analyzed the atmospheric CO_(2) response to realistic geomagnetic weakening between 1978 and 2013,and found increasing(decreasing)CO_(2) VMRs at high latitudes(mid and low latitudes)accordingly.For the first time,our simulation results demonstrate that the impact of geomagnetic variation on atmospheric CO_(2) distribution is noticeable on a time scale of decades.展开更多
The occurrence of midnight Equatorial Plasma Bubbles(EPBs)during the June solstice period of the ascending phase of solar cycle 24,from 2010 to 2014,was studied using data from the 47 MHz Equatorial Atmosphere Radar(E...The occurrence of midnight Equatorial Plasma Bubbles(EPBs)during the June solstice period of the ascending phase of solar cycle 24,from 2010 to 2014,was studied using data from the 47 MHz Equatorial Atmosphere Radar(EAR)at Kototabang,Indonesia.The analysis shows that the occurrence of midnight hour EPBs was at its maximum during the low solar activity year 2010 and monotonically decreased thereafter with increasing solar activity.Details of the dependence of midnight hour EPB occurrence on solar activity were investigated using SAMI2 model simulation with a realistic input of E×B drift velocity data obtained from the CINDI-IVM onboard the C/NOFS satellite.Results obtained from term-by-term analysis of the flux tube integrated linear growth rate of RT instability indicate that the formation of a high flux tube electron content height gradient(steep vertical gradient)region at higher altitudes,due to the elevated F layer,is the key factor enhancing the growth rate of RT instability during low solar activity June solstices.Other factors are discussed in light of the relatively weak westward zonal electric field in the presence of the equatorward neutral wind and north-to-south transequatorial wind around the midnight hours of low solar activity June solstices.Also discussed are the initial seeding of RT instability by MSTIDs and how the threshold height required for EPB development varies with solar activity.展开更多
The Venusian dayside ionosphere, similar to other planetary ionospheres, is produced primarily by ionization of its neutral upper atmosphere due to solar extreme ultraviolet (EUV) radiation. It has become clear that t...The Venusian dayside ionosphere, similar to other planetary ionospheres, is produced primarily by ionization of its neutral upper atmosphere due to solar extreme ultraviolet (EUV) radiation. It has become clear that the expansion of the ionosphere may be strongly controlled by the EUV level, as exhibited in data collected by the Pioneer Venus Orbiter (PVO) during one solar cycle (1978 1992). However, the EUV-dependence of the Venusian dayside ionopause altitude, which defines the outer boundary of the ionosphere, remains obscure because the PVO crossed the dayside ionopause only during the solar maximum;its periapsis lifted too high during the solar minimum. Recently, during the period 2006 2014, which included the longest and quietest solar minimum of the past several decades, Venus Express (VEX) provided measurements of the photoelectron boundary (PEB) over the northern high-latitude region. Since the photoelectron boundary is closely related to the ionopause, we have an opportunity to analyze the EUV effect on the dayside ionopause by combining PVO and VEX observations. We have evaluated and then reduced the orbit bias effect in data from both PVO and VEX, and then used the results to derive a relationship between solar EUV level and the dayside ionopause altitude. We find that the dayside ionopause altitude increases as the solar EUV level increases, which is consistent with theoretical expectations.展开更多
In the ionospheric research,various progresses have been made during the last two years.This paper reviews the recent works of Chinese scientists.For convenience,the contents include:ionospheric storms and space weath...In the ionospheric research,various progresses have been made during the last two years.This paper reviews the recent works of Chinese scientists.For convenience,the contents include:ionospheric storms and space weather;ionospheric irregularities and scintillation;ionospheric variability;ionospheric disturbances;ionospheric response to solar eclipses;ionospheric coupling with atmosphere and lithosphere;ionospheric climatology;ionospheric modeling;and ionospheric prediction and application.展开更多
With the method of Hough mode decomposition(HMD),the tidal sources of the three main tidal components,namely,the migrating components DW1(diurnal westward propagating wavenumber 1)and SW2(semidiurnal westward propagat...With the method of Hough mode decomposition(HMD),the tidal sources of the three main tidal components,namely,the migrating components DW1(diurnal westward propagating wavenumber 1)and SW2(semidiurnal westward propagating wavenumber 2)and the non-migrating component DE3(diurnal eastward propagating wavenumber 3),at the tropospheric altitudes(1–12 km)and in the latitude range of±60°,were obtained from National Centers for Environmental Prediction(NCEP)Climate Forecast System Reanalysis(CFSR)data during the interval from 1988 to 2011.We analyzed these sources in detail at 6 km and obtained the main properties of their yearly variations.The DW1 source was found to present a weak seasonal variation in the lower latitudes(about±10°–15°).That is,the amplitudes of the DW1 sources were larger in the summer months than in the winter months,and DW1 presented semi-annual variation near the equator(±10°)such that the DW1 source was larger at the equinoxes than at the solstices.In addition,the SW2 source was symmetric and was stronger in the southern hemisphere than in the northern hemisphere.The SW2 source presented remarkable annual and semi-annual variation such that the amplitudes were largest during the March equinox months and larger during the June solstice months.In contrast,DE3 appeared mainly around the equatorial latitudes within about±30°.The DE3 source presented remarkable semiannual variation that was larger around the solstices than the equinoxes in the southern hemisphere,and it was opposite in the northern hemisphere.By HMD,we found that the tropospheric tides were primarily dominated by some leading propagating Hough modes,specifically,the(1,1),(2,3),and(3,3)modes;the influences of the other Hough modes were negligible.The consequences of an El Niño–Southern Oscillation modulation of tidal amplitudes for the energy and momentum budgets of the troposphere may now be expected to attract attention.In summary,the above yearly variations of the main tidal sources and the Hough coefficients demonstrate that an HMD analysis can be used to investigate the tropospheric tides.展开更多
Through respectively adding June tide and December tide at the low boundary of the GCITEM-IGGCAS model (Global CoupledIonosphere–Thermosphere–Electrodynamics Model, Institute of Geology and Geophysics, Chinese Acade...Through respectively adding June tide and December tide at the low boundary of the GCITEM-IGGCAS model (Global CoupledIonosphere–Thermosphere–Electrodynamics Model, Institute of Geology and Geophysics, Chinese Academy of Sciences), we simulate theinfluence of atmospheric tide on the annual anomalies of the zonal mean state of the ionospheric electron density, and report that thetidal influence varies with latitude, altitude, and solar activity level. Compared with the density driven by the December tide, the June tidemainly increases lower ionospheric electron densities (below roughly the height of 200 km), and decreases electron densities in thehigher ionosphere (above the height of 200 km). In the low-latitude ionosphere, tides affect the equatorial ionization anomaly structure(EIA) in the relative difference of electron density, which suggests that tides affect the equatorial vertical E×B plasma drifts. Although thetide-driven annual anomalies do not vary significantly with the solar flux level in the lower ionosphere, in the higher ionosphere theannual anomalies generally decrease with solar activity.展开更多
Geomagnetic storm events have a strong influence on the ionosphere–thermosphere(I-T)coupling system.Analyzing the regional response process of the I-T system and its differences across the northern and southern hemis...Geomagnetic storm events have a strong influence on the ionosphere–thermosphere(I-T)coupling system.Analyzing the regional response process of the I-T system and its differences across the northern and southern hemispheres is an important but challenging task.In this study,we used a combination of multiple observations and a model simulation to examine the north–south hemispheric difference in the I-T coupling system in the American and Asian sectors during the geomagnetic superstorm that occurred in May 2024.Observations of the total electron content(TEC)showed that the Asian sector had negative storms in the northern hemisphere and positive storms in the southern hemisphere,a process that exacerbated the hemispheric differences in the TEC.However,both hemispheres of the American sector showed negative storms.The thermospheric composition changes also differed between the two sectors,and their variation could partially explain the hemispheric differences caused by positive and negative storms.Moreover,the influence of the thermospheric density change was less than that of the thermospheric composition.Finally,the dynamic effect of the thermospheric wind and the plasma transport processes strongly modulated the north–south differences in the TEC at nighttime in the American and Asian sectors,respectively,during this superstorm.展开更多
The data observed by a spectral airglow temperature imager （SATI） at Beijing National Observatory of Space Environment from July 23, 2008 to July 3l, 2009 are used to study night mesopause temperature in Beijing. Fr...The data observed by a spectral airglow temperature imager （SATI） at Beijing National Observatory of Space Environment from July 23, 2008 to July 3l, 2009 are used to study night mesopause temperature in Beijing. From variations of temperature at 87 and 94 km obtained from OH （6-2） and 02 （0-1） airglow spectra, temperature at night is shown lowest in the summer and highest in the winter. In summer, average temperature at 87 km is 173.9 K, lower than average temperature 180.1 K at 94 km. But in winter, average temperature at 87 Ion is 201.2 K, higher than average temperature 194.8 K at 94 kin. The altitude of mesopause in Beijing is below 87 km in summer and above 94 km in winter. There are about 120-150 days when the mesopause locates below 87 km, which is in agreement with the results of SABER/TIMED. Variations of temperatures at 87 and 94 km are analyzed by harmonic method. Our results show that amplitudes of annual oscillation of temperature at 87 and 94 km are 17.5 and 7.8 K respectively. Amplitudes of semi-annual oscillation at 87 and 94 km are 1.6 and 5.3 K, which are smaller than those of annual oscillation. Although there are differences among different observations because of different locations and different instruments, our results are in general agreement with observation at similar latitude as Beijing.展开更多
Since the release of the 2018 National Report of China on ionospheric research(Liu LB and Wan WX,2018)to the Committee on Space Research(COSPAR),scientists from China's Mainland have made many new fruitful investi...Since the release of the 2018 National Report of China on ionospheric research(Liu LB and Wan WX,2018)to the Committee on Space Research(COSPAR),scientists from China's Mainland have made many new fruitful investigations of various ionospheric-related issues.In this update report,we briefly introduce more than 130 recent reports(2018–2019).The current report covers the following topics:ionospheric space weather,ionospheric structures and climatology,ionospheric dynamics and couplings,ionospheric irregularity and scintillation,modeling and data assimilation,and radio wave propagation in the ionosphere and sounding techniques.展开更多
The ionosphere varies over multiple time scales,which are classified into two categories: the climatology and weather variations.In this national report,we give a brief summary of recent progresses in ionospheric clim...The ionosphere varies over multiple time scales,which are classified into two categories: the climatology and weather variations.In this national report,we give a brief summary of recent progresses in ionospheric climatology with focus on(1) the seasonal variations,(2) solar cycle effects, and(3) empirical modeling of the ionosphere.The seasonal variations of the ionosphere have been explored in many works to give a more detailed picture with regional and global features at various altitudes by analyzing the observation data from various sources and models.Moreover,a series of studies reported the response of the ionosphere to solar cycle variations,which revealed some novel and detailed features of solar activity dependence of ionospheric parameters at different altitudes. These investigations have improved our understanding on the states of the ionosphere and underlying fundamental processes,provided clues to future studies on ionospheric weather,and guided ionospheric modeling,forecasting and related applications.展开更多
The wavenumber spectral components WN4 at the mesosphere and low thermosphere(MLT)altitudes(70–10 km)and in the latitude range between±45°are obtained from temperature data(T)observed by the Sounding of the...The wavenumber spectral components WN4 at the mesosphere and low thermosphere(MLT)altitudes(70–10 km)and in the latitude range between±45°are obtained from temperature data(T)observed by the Sounding of the Atmosphere using Broadband Emission Radiometry(SABER)instruments on board the National Aeronautics and Space Administration(NASA)’s Thermosphere–Ionosphere–Mesosphere Energetics and Dynamics(TIMED)spacecraft during the 11-year solar period from 2002 to 2012.We analyze in detail these spectral components WNk and obtain the main properties of their vertical profiles and global structures.We report that all of the wavenumber spectral components WNk occur mainly around 100 km altitude,and that the most prominent component is the wavenumber spectral component WN4 structure.Comparing these long duration temperature data with results of previous investigations,we have found that the yearly variation of spectral component WN4 is similar to that of the eastward propagating non-migrating diurnal tide with zonal wavenumber 3(DE3)at the low latitudes,and to that of the semi-diurnal tide with zonal wavenumber 2(SE2)at the mid-latitudes:the amplitudes of the A4 are larger during boreal summer and autumn at the low-latitudes;at the mid-latitudes the amplitudes have a weak peak in March.In addition,the amplitudes of component WN4 undergo a remarkable short period variation:significant day-to-day variation of the spectral amplitudes A4 occurs primarily in July and September at the low-latitudes.In summary,we conclude that the non-migrating tides DE3 and SE2 are likely to be the origins,at the low-latitudes and the mid-latitudes in the MLT region,respectively,of the observed wavenumber spectral component WN4.展开更多
After the release of the previous report to the Committee on Space Research(COSPAR) on progress achieved by Chinese scientists in ionospheric researches(Liu LB and Wan WX, 2016), in the recent two years(2016–2017) ma...After the release of the previous report to the Committee on Space Research(COSPAR) on progress achieved by Chinese scientists in ionospheric researches(Liu LB and Wan WX, 2016), in the recent two years(2016–2017) many interesting new investigations into various ionospheric related issues have been completed. In this report, about 100 publications are summarized. The topics highlighted are as follows: Ionospheric space weather, ionospheric dynamics, ionospheric climatology and modelling, ionospheric irregularity and scintillation, Global Navigation Satellite System(GNSS) related ionospheric issues and other techniques, and radio wave propagation in the ionosphere. An outstanding feature is that more and more observations from the Meridional Project supported the ionospheric investigations.展开更多
In this national biannual report, we will outline some recent progresses in ionospheric studies conducted by Chinese scientists since 2012. The mentioned aspects include: the solar activity control of the ionosphere; ...In this national biannual report, we will outline some recent progresses in ionospheric studies conducted by Chinese scientists since 2012. The mentioned aspects include: the solar activity control of the ionosphere; couplings between the ionosphere, lower atmosphere and plasmasphere;ionospheric climatology and disturbances; ionospheric irregularities and scintillation; models, data assimilation and simulations; unusual phenomena of the ionosphere; possible seismic signatures presented in ionospheric observations, and some methodology progresses. These progresses will enhance our ability to observe the ionosphere, provide more reasonable understanding about the states of the ionosphere and underlying fundamental processes, and stimulate ionospheric modeling, forecasting and related applications.展开更多
基金supported by the Project of Stable Support for Youth Teams in Basic Research Field,Chinese Academy of Sciences(CASGrant No.YSBR-018)+2 种基金the B-type Strategic Priority Program of CAS(Grant No.XDB41000000)the National Natural Science Foundation of China(Grant No.42204165)the National Key Research and Development Program(Grant No.2022YFF0504400).
文摘In addition to being driven by tidal winds,the sporadic E(Es)layers are modulated by gravity waves(GWs),although the effects are not yet comprehensively understood.In this article,we discuss the effects of mesoscale GWs on the Es layers determined by using a newly developed model,MISE-1D(one-dimensional Model of Ionospheric Sporadic E),with low numerical dissipation and high resolution.Driven by the wind fields resolved by the high-resolution version of the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension(WACCM-X),the MISE-1D simulation revealed that GWs significantly influence the evolution of the Es layer above 100 km but have a very limited effect at lower altitudes.The effects of GWs are diverse and complex,generally including the generation of fluctuating wavelike structures on the Es layer with frequencies similar to those of the GWs.The mesoscale GWs can also cause increases in the density of Es layers,or they can disperse or diffuse the Es layers and increase their thickness.In addition,the presence of GWs is a key factor in sustaining the Es layers in some cases.
基金This work is supported by the B-type Strategic Priority Program of the Chinese Academy of Sciences (Grant No. XDB4100000)the pre-research Project on Civil Aerospace Technologies No. D020105 funded by CNSAthe Strategic Priority Research Program of Chinese Academy of Sciences (Grant XDA17010404, XDA17010201)。
文摘In this study, we present an innovative Mars Ionosphere-Thermosphere Model(MITM), which is a time-dependent, threedimensional(3-D) model that comprehensively represents the self-consistently coupled thermosphere and ionosphere of Mars within the altitude range of 70-300 km. The model incorporates an extensive range of parameters, including neutral number densities of CO_(2), CO,O, O_(2), N_(2), NO, N(^(2)D), N(^(4)S), Ar, and He;ion number densities of CO_(2)^(+), CO^(+), O^(+), O_(2)^(+), N_(2)^(+), NO^(+), N^(+) ions, and electrons;neutral temperature;and neutral wind fields. The MITM code employs a high-resolution grid system in a spherical geographical coordinate system, with a horizontal resolution of 5° latitude by 7.5° longitude. This altitude-resolved grid system enables accurate depiction of spatial variations in the Martian thermosphere and ionosphere. To showcase the capabilities of the MITM, we present two simulation cases: one during the equinox and another during the solstice. Both simulations reproduce key features of the Martian thermosphere and ionosphere including the characteristics of horizontal circulation, diurnal variations in chemical composition, and distribution of electron density. The MITM offers a robust framework for understanding the intricate interactions and processes that shape the Mars thermosphere and ionosphere,which are crucial for enhancing our understanding of Martian upper atmosphere and ionosphere.
基金This work was supported by the National Natural Science Foundation of China(grant no.41427901)the Strategic Priority Research Program of the Chinese Academy of Sciences(grant no.XDA17010206).We acknowledge the significant contributions of the engineering team from the Nanjing Research Institute of Electronics Technology beyond the author list.The experimental data can be obtained upon request through the corresponding authors.
文摘In the past decades,the Incoherent Scatter Radar(ISR)has been demonstrated to be one of the most powerful instruments for ionosphere monitoring.The Institute of Geology and Geophysics at the Chinese Academy of Sciences was founded to build a state-ofthe-art phased-array ISR at Sanya(18.3°N,109.6°E),a low-latitude station on Hainan Island,named the Sanya ISR(SYISR).As a first step,a prototype radar system consisting of eight subarrays(SYISR-8)was built to reduce the technical risk of producing the entire large array.In this work,we have summarized the preliminary experimental results based on the SYISR-8.The amplitude and phase among 256 channels were first calibrated through an embedded internal monitoring network.The mean oscillation of the amplitude and phase after calibration were about 1 dB and 5°,respectively,which met the basic requirements.The beam directivity was confirmed by crossing screen of the International Space Station.The SYISR-8 was further used to detect the tropospheric wind profile and meteors.The derived winds were evaluated by comparison with independent radiosonde and balloon-based GPS measurements.The SYISR-8 was able to observe several typical meteor echoes,such as the meteor head echo,range-spread trail echo,and specular trail echo.These results confirmed the validity and reliability of the SYISR-8 system,thereby reducing the technical risk of producing the entire large array of the SYISR to some extent.
基金supported by the National Natural Science Foundation of China(41831070,41974181)supported by the National Natural Science Foundation of China(42004136)+7 种基金supported by the National Natural Science Foundation of China(41804150)the Project of Stable Support for Youth Team in Basic Research Field,CAS(YSBR-018)the B-type Strategic Priority Program of the Chinese Academy of Sciences(XDB41000000)the Open Research Project of Large Research Infrastructures of CAS-“Study on the interaction between low/mid-latitude atmosphere and ionosphere based on the Chinese Meridian Project”the China Postdoctoral Science Foundation(2020T130628 and 2019M662170)the Fundamental Research Funds for the Central Universities(WK2080000130)the Joint Open Fund of Mengcheng National Geophysical Observatory(No.MENGO202010)the Guangdong Basic and Applied Basic Research Foundation(2021A1515011216)。
文摘We investigated the variations of equatorial plasma bubbles(EPBs)in the East-Asian sector during a strong geomagnetic storm in October 2016,based on observations from the Beidou geostationary(GEO)satellites,Swarm satellite and ground-based ionosonde.Significant nighttime depletions of F region in situ electron density from Swarm and obvious nighttime EPBs in the Beidou GEO observations were observed on 13 October 2016 during the main phase.Moreover,one interesting feature is that the rare and unique sunrise EPBs were triggered on 14 October 2016 in the main phase rather than during the recovery phase as reported by previous studies.In addition,the nighttime EPBs were suppressed during the whole recovery phase,and absent from 14 to 19 October 2016.Meanwhile,the minimum virtual height of F trace(h’F)at Sanya(18.3°N,109.6°E,MLAT 11.1°N)displayed obvious changes during these intervals.The h’F was enhanced in the main phase and declined during the recovery phase,compared with the values at pre-and post-storm.These results indicate that the enhanced nighttime EPBs and sunrise EPBs during the main phase and the absence nighttime EPBs for many days during the recovery phase could be associated with storm-time electric field changes.
基金supported by the National Key Research and Development Program (2018YFC1503504)the National Natural Science Foundation of China (41822403, 41621063, 41774165)the Youth Innovation Promotion Association CAS
文摘Previous studies have shown that the ionospheric responses to a solar flare are significantly dependent on the solar zenith angle(SZA):the ionospheric responses are negatively related to the SZAs.The largest enhancement in electron density always occurs around the subsolar point.However,from 2001 to 2014,the global distribution of total electron content(TEC)responses showed no obvious relationship between the increases in TEC and the SZA during some solar flares.During these solar flares,the greatest enhancements in TEC did not appear around the subsolar point,but rather far away from the subsolar point.The distribution of TEC enhancements showed larger TEC enhancements along the same latitude.The distribution of anomalous ionospheric responses to the solar flares was not structured the same as traveling ionospheric disturbances.This anomaly distribution was also unrelated to the distribution of background neutral density.It could not be explained by changes in the photochemical process induced by the solar flares.Thus,the transport process could be one of the main reasons for the anomaly distribution of ionospheric responses to the solar flares.This anomaly distribution also suggests that not only the photochemical process but also the transport process could significantly affect the variation in ionospheric electron density during some solar flares.
基金carried out as a part of the project funded by the National Natural Science Foundation of China (41422404 and 41727803)
文摘Meteoroids entering the Earth's atmosphere can create meteor trail irregularity seriously disturbing the background ionosphere. Although numerous observations of meteor trail irregularities were performed with VHF/UHF coherent scatter radars in the past, no simultaneous radar and optical instruments were employed to investigate the characteristics of meteor trail irregularity and its corresponding meteoroid. By installing multiple video cameras near the Sanya VHF radar site, an observational campaign was conducted during the period from November 2016 to February 2017. A total of 242 optical meteors with simultaneous non-specular echoes backscattered from the plasma irregularities generated in the corresponding meteor trails were identified. A good agreement between the angular positions of non-specular echoes derived from the Sanya radar interferometer and those of optical meteors was found,validating that the radar system phase offsets have been properly calibrated. The results also verify the interferometry capability of Sanya radar for meteor trail irregularity observation. The non-specular echoes with simultaneous optical meteors were detected at magnetic aspect angles greater than ~78°. Based on the meteor visual magnitude estimated from the optical data, it was found that the radar nonspecular echoes corresponding to brighter meteors survived for longer duration. This could provide observational evidence for the significance of meteoroid mass on the duration of meteor trail irregularity. On the other hand, the simultaneous radar and video common-volume observations showed that there were some cases with optical meteors but without radar non-specular echoes. One possibility could be that some of the optical meteors appeared at extremely low altitudes where meteor trail irregularities rarely occur.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(grant no.XDA17010201)the National Natural Science Foundation of China(grants nos.41922031,41774188,41525016,and 41621063).
文摘Unlike Earth,Mars lacks a global dipolar magnetic field but is dominated by patches of a remnant crustal magnetic field.In 2021,the Chinese Mars Rover will land on the surface of Mars and measure the surface magnetic field along a moving path within the possible landing region of 20°W-50°W,20°N-30°N.One scientific target of the Rover is to monitor the variation in surface remnant magnetic fields and reveal the source of the ionospheric current.An accurate local crustal field model is thus considered necessary as a field reference.Here we establish a local crust field model for the candidate landing site based on the joint magnetic field data set from Mars Global Explorer(MGS)and Mars Atmosphere and Volatile Evolution(MAVEN)data combined.The model is composed of 1,296 dipoles,which are set on three layers but at different buried depths.The application of the dipole model to the joint data set allowed us to calculate the optimal parameters of their dipoles.The calculated results demonstrate that our model has less fitting error than two other state-of-the art global crustal field models,which would indicate a more reasonable assessment of the surface crustal field from our model.
基金This work was supported by the B-type Strategic Priority Program of the Chinese Academy of Sciences(Grant No.XDB41000000)the National Natural Science Foundation of China(41621004,41427901)+2 种基金the Open Research Project of Large Research Infrastructures—“Study on the interaction between low/mid-latitude atmosphere and ionosphere based on the Chinese Meridian Project”the Key Research Program of the IGGCAS with Grant No.IGGCAS-201904XZ thanks the UCAS Joint PhD Training Program.The National Center for Atmospheric Research is a major facility sponsored by the National Science Foundation under Cooperative Agreement No.1852977.
文摘Responses of atmospheric carbon dioxide(CO_(2))density to geomagnetic secular variation are investigated using the Whole Atmosphere Community Climate Model-eXtended(WACCM-X).Our ensemble simulations show that CO_(2) volume mixing ratios(VMRs)increase at high latitudes and decrease at mid and low latitudes by several ppmv in response to a 50%weakening of the geomagnetic field.Statistically significant changes in CO_(2) are mainly found above~90 km altitude and primarily redetermine the energy budget at~100-110 km.Our analysis of transformed Eulerian mean(TEM)circulation found that CO_(2) change is caused by enhanced upwelling at high latitudes and downwelling at mid and low latitudes as a result of increased Joule heating.We further analyzed the atmospheric CO_(2) response to realistic geomagnetic weakening between 1978 and 2013,and found increasing(decreasing)CO_(2) VMRs at high latitudes(mid and low latitudes)accordingly.For the first time,our simulation results demonstrate that the impact of geomagnetic variation on atmospheric CO_(2) distribution is noticeable on a time scale of decades.
基金partly supported by the National Natural Science Foundation of China(42020104002)by a Postdoctoral Fellowship at the Institute of Geology and Geophysics,Chinese Academy of Sciences(IGGCAS)partially supported by JSPS KAKENHI Grant Number 20H00197。
文摘The occurrence of midnight Equatorial Plasma Bubbles(EPBs)during the June solstice period of the ascending phase of solar cycle 24,from 2010 to 2014,was studied using data from the 47 MHz Equatorial Atmosphere Radar(EAR)at Kototabang,Indonesia.The analysis shows that the occurrence of midnight hour EPBs was at its maximum during the low solar activity year 2010 and monotonically decreased thereafter with increasing solar activity.Details of the dependence of midnight hour EPB occurrence on solar activity were investigated using SAMI2 model simulation with a realistic input of E×B drift velocity data obtained from the CINDI-IVM onboard the C/NOFS satellite.Results obtained from term-by-term analysis of the flux tube integrated linear growth rate of RT instability indicate that the formation of a high flux tube electron content height gradient(steep vertical gradient)region at higher altitudes,due to the elevated F layer,is the key factor enhancing the growth rate of RT instability during low solar activity June solstices.Other factors are discussed in light of the relatively weak westward zonal electric field in the presence of the equatorward neutral wind and north-to-south transequatorial wind around the midnight hours of low solar activity June solstices.Also discussed are the initial seeding of RT instability by MSTIDs and how the threshold height required for EPB development varies with solar activity.
基金supported by the National Natural Science Foundation of China (41525016, 41525015, 41661164034, 41621063)the National Important Basic Research Project (2011CB811405)supported by the Thousand Young Talents Program of China
文摘The Venusian dayside ionosphere, similar to other planetary ionospheres, is produced primarily by ionization of its neutral upper atmosphere due to solar extreme ultraviolet (EUV) radiation. It has become clear that the expansion of the ionosphere may be strongly controlled by the EUV level, as exhibited in data collected by the Pioneer Venus Orbiter (PVO) during one solar cycle (1978 1992). However, the EUV-dependence of the Venusian dayside ionopause altitude, which defines the outer boundary of the ionosphere, remains obscure because the PVO crossed the dayside ionopause only during the solar maximum;its periapsis lifted too high during the solar minimum. Recently, during the period 2006 2014, which included the longest and quietest solar minimum of the past several decades, Venus Express (VEX) provided measurements of the photoelectron boundary (PEB) over the northern high-latitude region. Since the photoelectron boundary is closely related to the ionopause, we have an opportunity to analyze the EUV effect on the dayside ionopause by combining PVO and VEX observations. We have evaluated and then reduced the orbit bias effect in data from both PVO and VEX, and then used the results to derive a relationship between solar EUV level and the dayside ionopause altitude. We find that the dayside ionopause altitude increases as the solar EUV level increases, which is consistent with theoretical expectations.
文摘In the ionospheric research,various progresses have been made during the last two years.This paper reviews the recent works of Chinese scientists.For convenience,the contents include:ionospheric storms and space weather;ionospheric irregularities and scintillation;ionospheric variability;ionospheric disturbances;ionospheric response to solar eclipses;ionospheric coupling with atmosphere and lithosphere;ionospheric climatology;ionospheric modeling;and ionospheric prediction and application.
基金The present work is supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(grant no.XDA17010201)the National Science Foundation of China(grant nos.41604138,41427901,41621063,41474133,41674158,41874179,and 41322030).
文摘With the method of Hough mode decomposition(HMD),the tidal sources of the three main tidal components,namely,the migrating components DW1(diurnal westward propagating wavenumber 1)and SW2(semidiurnal westward propagating wavenumber 2)and the non-migrating component DE3(diurnal eastward propagating wavenumber 3),at the tropospheric altitudes(1–12 km)and in the latitude range of±60°,were obtained from National Centers for Environmental Prediction(NCEP)Climate Forecast System Reanalysis(CFSR)data during the interval from 1988 to 2011.We analyzed these sources in detail at 6 km and obtained the main properties of their yearly variations.The DW1 source was found to present a weak seasonal variation in the lower latitudes(about±10°–15°).That is,the amplitudes of the DW1 sources were larger in the summer months than in the winter months,and DW1 presented semi-annual variation near the equator(±10°)such that the DW1 source was larger at the equinoxes than at the solstices.In addition,the SW2 source was symmetric and was stronger in the southern hemisphere than in the northern hemisphere.The SW2 source presented remarkable annual and semi-annual variation such that the amplitudes were largest during the March equinox months and larger during the June solstice months.In contrast,DE3 appeared mainly around the equatorial latitudes within about±30°.The DE3 source presented remarkable semiannual variation that was larger around the solstices than the equinoxes in the southern hemisphere,and it was opposite in the northern hemisphere.By HMD,we found that the tropospheric tides were primarily dominated by some leading propagating Hough modes,specifically,the(1,1),(2,3),and(3,3)modes;the influences of the other Hough modes were negligible.The consequences of an El Niño–Southern Oscillation modulation of tidal amplitudes for the energy and momentum budgets of the troposphere may now be expected to attract attention.In summary,the above yearly variations of the main tidal sources and the Hough coefficients demonstrate that an HMD analysis can be used to investigate the tropospheric tides.
基金This work is supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA17010201),the National Natural Science Foundation of China(41674158,41874179,41621063,41427901,41474133,41322030)the Youth Innovation Promotion Association CAS(2014057)and the Opening Funding of Chinese Academy of Sciences dedicated for the Chinese Meridian Project.
文摘Through respectively adding June tide and December tide at the low boundary of the GCITEM-IGGCAS model (Global CoupledIonosphere–Thermosphere–Electrodynamics Model, Institute of Geology and Geophysics, Chinese Academy of Sciences), we simulate theinfluence of atmospheric tide on the annual anomalies of the zonal mean state of the ionospheric electron density, and report that thetidal influence varies with latitude, altitude, and solar activity level. Compared with the density driven by the December tide, the June tidemainly increases lower ionospheric electron densities (below roughly the height of 200 km), and decreases electron densities in thehigher ionosphere (above the height of 200 km). In the low-latitude ionosphere, tides affect the equatorial ionization anomaly structure(EIA) in the relative difference of electron density, which suggests that tides affect the equatorial vertical E×B plasma drifts. Although thetide-driven annual anomalies do not vary significantly with the solar flux level in the lower ionosphere, in the higher ionosphere theannual anomalies generally decrease with solar activity.
基金supported by the National Natural Science Foundation of China (Grant Nos. 42030202, 42241115, and 42174204)the China Postdoctoral Science Foundation (Grant No. 2023M743467)+2 种基金the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant No. Y202021)the National Key R&D Program of China (Grant No. 2022YFF0504400)the Opening Funding of the Chinese Academy of Sciences dedicated to the Chinese Meridian Project
文摘Geomagnetic storm events have a strong influence on the ionosphere–thermosphere(I-T)coupling system.Analyzing the regional response process of the I-T system and its differences across the northern and southern hemispheres is an important but challenging task.In this study,we used a combination of multiple observations and a model simulation to examine the north–south hemispheric difference in the I-T coupling system in the American and Asian sectors during the geomagnetic superstorm that occurred in May 2024.Observations of the total electron content(TEC)showed that the Asian sector had negative storms in the northern hemisphere and positive storms in the southern hemisphere,a process that exacerbated the hemispheric differences in the TEC.However,both hemispheres of the American sector showed negative storms.The thermospheric composition changes also differed between the two sectors,and their variation could partially explain the hemispheric differences caused by positive and negative storms.Moreover,the influence of the thermospheric density change was less than that of the thermospheric composition.Finally,the dynamic effect of the thermospheric wind and the plasma transport processes strongly modulated the north–south differences in the TEC at nighttime in the American and Asian sectors,respectively,during this superstorm.
基金supported by the National Natural Science Foundation of China (Grant No. 40974086)the National Important Basic Research Project (Grant No. 2011CB811405)
文摘The data observed by a spectral airglow temperature imager （SATI） at Beijing National Observatory of Space Environment from July 23, 2008 to July 3l, 2009 are used to study night mesopause temperature in Beijing. From variations of temperature at 87 and 94 km obtained from OH （6-2） and 02 （0-1） airglow spectra, temperature at night is shown lowest in the summer and highest in the winter. In summer, average temperature at 87 km is 173.9 K, lower than average temperature 180.1 K at 94 km. But in winter, average temperature at 87 Ion is 201.2 K, higher than average temperature 194.8 K at 94 kin. The altitude of mesopause in Beijing is below 87 km in summer and above 94 km in winter. There are about 120-150 days when the mesopause locates below 87 km, which is in agreement with the results of SABER/TIMED. Variations of temperatures at 87 and 94 km are analyzed by harmonic method. Our results show that amplitudes of annual oscillation of temperature at 87 and 94 km are 17.5 and 7.8 K respectively. Amplitudes of semi-annual oscillation at 87 and 94 km are 1.6 and 5.3 K, which are smaller than those of annual oscillation. Although there are differences among different observations because of different locations and different instruments, our results are in general agreement with observation at similar latitude as Beijing.
基金financially supported by National Natural Science Foundation of China(41774161,41621063)by the Open Research Project of Large Research Infrastructures of CAS-“Study of the interaction between low/mid-latitude atmosphere and ionosphere based on the Chinese Meridian Project”。
文摘Since the release of the 2018 National Report of China on ionospheric research(Liu LB and Wan WX,2018)to the Committee on Space Research(COSPAR),scientists from China's Mainland have made many new fruitful investigations of various ionospheric-related issues.In this update report,we briefly introduce more than 130 recent reports(2018–2019).The current report covers the following topics:ionospheric space weather,ionospheric structures and climatology,ionospheric dynamics and couplings,ionospheric irregularity and scintillation,modeling and data assimilation,and radio wave propagation in the ionosphere and sounding techniques.
基金supported by the Chinese Academy of Sciences(KZZD-EW-01-3)National Key Basic Research Program of China(2012- CB825604)National Natural Science Foundation of China(41074112,41174137)
文摘The ionosphere varies over multiple time scales,which are classified into two categories: the climatology and weather variations.In this national report,we give a brief summary of recent progresses in ionospheric climatology with focus on(1) the seasonal variations,(2) solar cycle effects, and(3) empirical modeling of the ionosphere.The seasonal variations of the ionosphere have been explored in many works to give a more detailed picture with regional and global features at various altitudes by analyzing the observation data from various sources and models.Moreover,a series of studies reported the response of the ionosphere to solar cycle variations,which revealed some novel and detailed features of solar activity dependence of ionospheric parameters at different altitudes. These investigations have improved our understanding on the states of the ionosphere and underlying fundamental processes,provided clues to future studies on ionospheric weather,and guided ionospheric modeling,forecasting and related applications.
基金The present work is supported by National Science Foundation of China(41604138,41427901,41621063,41474133,41674158,41874179,41322030).
文摘The wavenumber spectral components WN4 at the mesosphere and low thermosphere(MLT)altitudes(70–10 km)and in the latitude range between±45°are obtained from temperature data(T)observed by the Sounding of the Atmosphere using Broadband Emission Radiometry(SABER)instruments on board the National Aeronautics and Space Administration(NASA)’s Thermosphere–Ionosphere–Mesosphere Energetics and Dynamics(TIMED)spacecraft during the 11-year solar period from 2002 to 2012.We analyze in detail these spectral components WNk and obtain the main properties of their vertical profiles and global structures.We report that all of the wavenumber spectral components WNk occur mainly around 100 km altitude,and that the most prominent component is the wavenumber spectral component WN4 structure.Comparing these long duration temperature data with results of previous investigations,we have found that the yearly variation of spectral component WN4 is similar to that of the eastward propagating non-migrating diurnal tide with zonal wavenumber 3(DE3)at the low latitudes,and to that of the semi-diurnal tide with zonal wavenumber 2(SE2)at the mid-latitudes:the amplitudes of the A4 are larger during boreal summer and autumn at the low-latitudes;at the mid-latitudes the amplitudes have a weak peak in March.In addition,the amplitudes of component WN4 undergo a remarkable short period variation:significant day-to-day variation of the spectral amplitudes A4 occurs primarily in July and September at the low-latitudes.In summary,we conclude that the non-migrating tides DE3 and SE2 are likely to be the origins,at the low-latitudes and the mid-latitudes in the MLT region,respectively,of the observed wavenumber spectral component WN4.
基金supported by National Natural Science Foundation of China (41621063,41774161)by the Opening Funding of Chinese Academy of Sciences dedicated for the Chinese Meridian Project
文摘After the release of the previous report to the Committee on Space Research(COSPAR) on progress achieved by Chinese scientists in ionospheric researches(Liu LB and Wan WX, 2016), in the recent two years(2016–2017) many interesting new investigations into various ionospheric related issues have been completed. In this report, about 100 publications are summarized. The topics highlighted are as follows: Ionospheric space weather, ionospheric dynamics, ionospheric climatology and modelling, ionospheric irregularity and scintillation, Global Navigation Satellite System(GNSS) related ionospheric issues and other techniques, and radio wave propagation in the ionosphere. An outstanding feature is that more and more observations from the Meridional Project supported the ionospheric investigations.
基金Supported by National Natural Science Foundation of China(41231065)the Project of Chinese Academy of Sciences(KZZD-EW-01-3)National Key Basic Research Program of China(2012CB825604)
文摘In this national biannual report, we will outline some recent progresses in ionospheric studies conducted by Chinese scientists since 2012. The mentioned aspects include: the solar activity control of the ionosphere; couplings between the ionosphere, lower atmosphere and plasmasphere;ionospheric climatology and disturbances; ionospheric irregularities and scintillation; models, data assimilation and simulations; unusual phenomena of the ionosphere; possible seismic signatures presented in ionospheric observations, and some methodology progresses. These progresses will enhance our ability to observe the ionosphere, provide more reasonable understanding about the states of the ionosphere and underlying fundamental processes, and stimulate ionospheric modeling, forecasting and related applications.
