Bibliography

This paper reports the existence of plasma caves, minima in the electron density located at 5\textendash10\textdegree to the magnetic equator, in the bottomside ionosphere based on electron densities simulations from the International Reference Ionosphere (IRI-2007) and clear evidences given by plasma density and drift measurements of the Dynamic Explorer 2 (DE 2) satellite during 1981\textendash1983. The IRI simulations suggest plasma caves as daytime features (08:00\textendash19:00 LT; length of 18,158 km in the longitudinal direction), that range from theE region up to about 300 km altitude with 10\textdegree (or 1100 km) width in the latitudinal direction. In situ measurements of the ion and electron densities probed by the DE 2 confirm the existence of the plasma caves at low altitudes of the EIA ionosphere. The unexpected downward and upward (or weakly and strongly upward) ion drifts at the magnetic equator and the two off equators seem to play an important role responsible for the plasma cave formation.

Lee, I.; Liu, J; Lin, C.; Oyama, K.-I.; Chen, C; Chen, C.;

Published by: Journal of Geophysical Research Published on: 11/2012

YEAR: 2012 DOI: 10.1029/2012JA017868

Dynamic Explorer 2; Equatorial ionization anomaly; plasma cave

Assimilation of FORMOSAT-3/COSMIC electron density profiles into a coupled thermosphere/ionosphere model using ensemble Kalman filtering

This paper presents our effort to assimilate FORMOSAT-3/COSMIC (F3/C) GPS Occultation Experiment (GOX) observations into the National Center for Atmospheric Research (NCAR) Thermosphere Ionosphere Electrodynamics General Circulation Model (TIE-GCM) by means of ensemble Kalman filtering (EnKF). The F3/C electron density profiles (EDPs) uniformly distributed around the globe which provide an excellent opportunity to monitor the ionospheric electron density structure. The NCAR TIE-GCM simulates the Earth\textquoterights thermosphere and ionosphere by using self-consistent solutions for the coupled nonlinear equations of hydrodynamics, neutral and ion chemistry, and electrodynamics. The F3/C EDP are combined with the TIE-GCM simulations by EnKF algorithms implemented in the NCAR Data Assimilation Research Testbed (DART) open-source community facility to compute the expected value of electron density, which is \textquoteleftthe best\textquoteright estimate of the current ionospheric state. Assimilation analyses obtained with real F3/C electron density profiles are compared with independent ground-based observations as well as the F3/C profiles themselves. The comparison shows the improvement of the primary ionospheric parameters, such as NmF2 and hmF2. Nevertheless, some unrealistic signatures appearing in the results and high rejection rates of observations due to the applied outlier threshold and quality control are found in the assimilation experiments. This paper further discusses the limitations of the model and the impact of ensemble member creation approaches on the assimilation results, and proposes possible methods to avoid these problems for future work.

Lee, I.; Matsuo, T.; Richmond, A.; Liu, J; Wang, W.; Lin, C.; Anderson, J.; Chen, M.;

Published by: Journal of Geophysical Research Published on: 10/2012

YEAR: 2012 DOI: 10.1029/2012JA017700

data assimilation; ensemble Kalman filter; FORMOSAT-3/COSMIC; Ionosphere

Influence of interplanetary solar wind sector polarity on the ionosphere

Knowledge of solar sector polarity effects on the ionosphere may provide some clues in understanding of the ionospheric day-to-day variability and \textquotedbllefthysteresis\textquotedblright effect on foF2. Ionospheric response to changes in solar sector polarity has not been fully documented previously, partly due to the limitation of observations. In this study, a solar-terrestrial connection ranging from solar sector boundary (SB) crossings, geomagnetic disturbances and ionospheric perturbations has been demonstrated. The increases in interplanetary solar wind speed within three days are seen after SB crossings, while the decreases in solar wind dynamic pressure and magnetic field intensity immediately after SB crossings are confirmed by the superposed epoch analysis results. Furthermore, the interplanetary magnetic field (IMF) Bz component turns from northward to southward in March equinox and June solstice as the Earth passes from a solar sector of outward to inward directed magnetic fields, whereas the reverse situation occurs for the transition from toward to away sectors. The IMF Bz component for the same solar sector polarity has opposite signs between March equinox and September equinox, and also between June solstice and December solstice. In order to know how the ionosphere reacts to the interplanetary solar wind variations linkage of SB crossings, the F2 region critical frequency (foF2) covering about four solar cycles and total electron content (TEC) during 1998\textendash2011 are utilized to extract the related information, revealing that they are not modified significantly and vary within the range of \textpm15\% on average. The responses of the ionospheric TEC to SB crossings exhibit complex temporal and spatial variations and have strong dependencies on season, latitude, and solar cycle. This effect is more appreciable in equinoctial months than in solstitial months, which is mainly caused by larger southwardBzcomponents in equinox. In September equinox, latitudinal profile of relative variations of foF2 at noon is featured by depressions at high latitudes and enhancements in low-equatorial latitudes during IMF away sectors. The negative phase of foF2 is delayed at solar minimum relative to it during other parts of solar cycle, which might be associated with the difference in longevity of major interplanetary solar wind drivers perturbing the Earth\textquoterights environment in different phases of solar cycle.

Liu, Jing; Liu, Libo; Zhao, Biqiang; Wan, Weixing;

Published by: Journal of Geophysical Research Published on: 08/2012

YEAR: 2012 DOI: 10.1029/2012JA017859

interplanetary magnetic field; Ionospheric disturbance; solar sector polarity

Influence of interplanetary solar wind sector polarity on the ionosphere

Knowledge of solar sector polarity effects on the ionosphere may provide some clues in understanding of the ionospheric day-to-day variability and \textquotedbllefthysteresis\textquotedblright effect on foF2. Ionospheric response to changes in solar sector polarity has not been fully documented previously, partly due to the limitation of observations. In this study, a solar-terrestrial connection ranging from solar sector boundary (SB) crossings, geomagnetic disturbances and ionospheric perturbations has been demonstrated. The increases in interplanetary solar wind speed within three days are seen after SB crossings, while the decreases in solar wind dynamic pressure and magnetic field intensity immediately after SB crossings are confirmed by the superposed epoch analysis results. Furthermore, the interplanetary magnetic field (IMF) Bz component turns from northward to southward in March equinox and June solstice as the Earth passes from a solar sector of outward to inward directed magnetic fields, whereas the reverse situation occurs for the transition from toward to away sectors. The IMF Bz component for the same solar sector polarity has opposite signs between March equinox and September equinox, and also between June solstice and December solstice. In order to know how the ionosphere reacts to the interplanetary solar wind variations linkage of SB crossings, the F2 region critical frequency (foF2) covering about four solar cycles and total electron content (TEC) during 1998\textendash2011 are utilized to extract the related information, revealing that they are not modified significantly and vary within the range of \textpm15\% on average. The responses of the ionospheric TEC to SB crossings exhibit complex temporal and spatial variations and have strong dependencies on season, latitude, and solar cycle. This effect is more appreciable in equinoctial months than in solstitial months, which is mainly caused by larger southwardBzcomponents in equinox. In September equinox, latitudinal profile of relative variations of foF2 at noon is featured by depressions at high latitudes and enhancements in low-equatorial latitudes during IMF away sectors. The negative phase of foF2 is delayed at solar minimum relative to it during other parts of solar cycle, which might be associated with the difference in longevity of major interplanetary solar wind drivers perturbing the Earth\textquoterights environment in different phases of solar cycle.

Liu, Jing; Liu, Libo; Zhao, Biqiang; Wan, Weixing;

Published by: Journal of Geophysical Research Published on: 08/2012

YEAR: 2012 DOI: 10.1029/2012JA017859

interplanetary magnetic field; Ionospheric disturbance; solar sector polarity

Long-term variations of the nighttime electron density enhancement during the ionospheric midlatitude summer

This study, for the first time, presented the long-term variations of Midlatitude Summer Nighttime Anomaly (MSNA) in the two hemispheres by using 66 ground-based ionosonde observations from 1957 to 2010. MSNA is characterized by the feature of higher nighttime electron density than daytime density in the midlatitude region during local summer months. Observations from 66 ionosonde stations were used to calculate the MSNA index which is defined by the difference between nighttime and noontime NmF2 values. The MSNA occurrence is determined by positive value of the MSNA index. The global distribution map of the MSNA index shows that there are three regions of intense MSNA. Three ionosonde stations in each of active MSNA regions were chosen to study the long-term variation of MSNA covering longer than one solar cycle. One station in the southern hemisphere is AIJ6N (Argentine IS; 65.2\textdegreeS, 64.3\textdegreeW geographic) and two stations in the northern hemisphere are LN047 (Lannion; 48.8\textdegreeN, -3.4\textdegreeE geographic) and MG560 (Magadan; 60.0\textdegreeN, 151.0\textdegreeE geographic). Results show that there is a clear solar activity negative dependence of the MSNA index, high MSNA in the low solar activity condition and low MSNA in the high solar activity condition. The seasonal and solar activity variations of the MSNA index are explained by the combined effects of the vertical plasma drift induced by the neutral wind and photoionization during the nighttime.

Chen, C.; Saito, A.; Lin, C.; Liu, J;

Published by: Journal of Geophysical Research Published on: 07/2012

YEAR: 2012 DOI: 10.1029/2011JA017138

ionization-uplift effect; midlatitude summer nighttime anomaly; MSNA index

Integral cross sections for the electron-impact excitation of the b 1 $\Pi$ u, c 3 1 $\Pi$ u, o 3 1 $\Pi$ u, b′ 1 $\Sigma$ u+, c 4′ 1 $\Sigma$ u+, G 3 $\Pi$ u, and F 3 $\Pi$ u states of N 2

Malone, Charles; Johnson, Paul; Liu, Xianming; Ajdari, Bahar; Kanik, Isik; Khakoo, Murtadha;

Published by: Physical Review A Published on: 06/2012

YEAR: 2012 DOI: 10.1103/PhysRevA.85.062704

Observations of global ionospheric responses to the 2009 stratospheric sudden warming event by FORMOSAT-3/COSMIC

The global ionospheric response to a stratospheric sudden warming (SSW) is studied using three-dimensional electron density maps derived from radio occultation observations of FORMOSAT-3/COSMIC during the 2009 SSW periods. Results show that the ionospheric electron density at EIA crests exhibit a morning/early afternoon increase followed by an afternoon decrease and an evening increase, indicative of a semidiurnal component during the SSW period, which is consistent with recent studies. The latitude-altitude electron density slice maps show that the SSW related modifications of the equatorial plasma fountain interact with the existing summer-to-winter neutral winds and resulting in a north\textendashsouth asymmetry. The global ionospheric response shows a clear longitudinal dependence in the equatorial plasma fountain enhancement during morning/early afternoon, inferred from the duration of the equatorial ionization anomaly (EIA) enhancement. Following the enhancement, prominent global EIA reductions resulting from the equatorial plasma fountain weakening in the afternoon sector are seen. The ionospheric response to the 2009 SSW event is also compared with the usual seasonal variation during January\textendashFebruary 2007. Instead of showing the electron density increase in the northern hemisphere and decrease in the southern hemisphere as the usual seasonal variation does, the SSW period ionosphere shows prominent global electron density reductions in the afternoon period during the 2009 SSW event.

Lin, C.; Lin, J.; Chang, L.; Liu, J; Chen, C.; Chen, W.; Huang, H.; Liu, C.;

Published by: Journal of Geophysical Research Published on: 06/2012

YEAR: 2012 DOI: 10.1029/2011JA017230

FORMOSAT-3/COSMIC; ionospheric responses to stratospheric sudden warming

Observations of global ionospheric responses to the 2009 stratospheric sudden warming event by FORMOSAT-3/COSMIC

The global ionospheric response to a stratospheric sudden warming (SSW) is studied using three-dimensional electron density maps derived from radio occultation observations of FORMOSAT-3/COSMIC during the 2009 SSW periods. Results show that the ionospheric electron density at EIA crests exhibit a morning/early afternoon increase followed by an afternoon decrease and an evening increase, indicative of a semidiurnal component during the SSW period, which is consistent with recent studies. The latitude-altitude electron density slice maps show that the SSW related modifications of the equatorial plasma fountain interact with the existing summer-to-winter neutral winds and resulting in a north\textendashsouth asymmetry. The global ionospheric response shows a clear longitudinal dependence in the equatorial plasma fountain enhancement during morning/early afternoon, inferred from the duration of the equatorial ionization anomaly (EIA) enhancement. Following the enhancement, prominent global EIA reductions resulting from the equatorial plasma fountain weakening in the afternoon sector are seen. The ionospheric response to the 2009 SSW event is also compared with the usual seasonal variation during January\textendashFebruary 2007. Instead of showing the electron density increase in the northern hemisphere and decrease in the southern hemisphere as the usual seasonal variation does, the SSW period ionosphere shows prominent global electron density reductions in the afternoon period during the 2009 SSW event.

Lin, C.; Lin, J.; Chang, L.; Liu, J; Chen, C.; Chen, W.; Huang, H.; Liu, C.;

Published by: Journal of Geophysical Research Published on: 06/2012

YEAR: 2012 DOI: 10.1029/2011JA017230

FORMOSAT-3/COSMIC; ionospheric responses to stratospheric sudden warming

Recent Progresses on Ionospheric Climatology Investigations

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.

Liu, L.; Le, H.; Zhao, B.;

Published by: Chin. J. Space Sci. Published on:

YEAR: 2012 DOI:

Climatological variation; Ionosphere; Ionospheric modeling; Seasonal variations; solar cycle

Strong evidence for couplings between the ionospheric wave-4 structure and atmospheric tides

He, Maosheng; Liu, Libo; Wan, Weixing; Wei, Yong;

Published by: Geophysical Research Letters Published on: Jan-07-2011

YEAR: 2011 DOI: 10.1029/2011GL047855

Ionospheric electron content and NmF2 from nighttime OI 135.6 nm intensity

Rajesh, P.; Liu, J; Hsu, M.; Lin, C.; Oyama, K.; Paxton, L.;

Published by: Journal of Geophysical Research Published on: Jan-01-2011

YEAR: 2011 DOI: 10.1029/2010JA015686

The O I 135.6 nm airglow observations of the midlatitude summer nighttime anomaly by TIMED/GUVI

Hsu, M.; Lin, C.; Hsu, R.; Liu, J; Paxton, L.; Su, H.; Tsai, H.; Rajesh, P.; Chen, C.;

Published by: Journal of Geophysical Research Published on: Jan-01-2011

YEAR: 2011 DOI: 10.1029/2010JA016150

The OI 135.6 nm airglow observations of the midlatitude summer nighttime anomaly by TIMED/GUVI

Hsu, ML; Lin, CH; Hsu, RR; Liu, JY; Paxton, LJ; Su, HT; Tsai, HF; Rajesh, PK; Chen, CH;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2011 DOI:

Fast meridional transport in the lower thermosphere by planetary-scale waves

Yue, Jia; Liu, Han-Li;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: Jan-12-2010

YEAR: 2010 DOI: 10.1016/j.jastp.2010.10.001

Longitudinal modulation of the O/N2 column density retrieved from TIMED/GUVI measurement

He, Maosheng; Liu, Libo; Wan, Weixing; Lei, Jiuhou; Zhao, Biqiang;

Published by: Geophysical Research Letters Published on: Jan-10-2010

YEAR: 2010 DOI: 10.1029/2010GL045105

Artificial plasma cave in the low-latitude ionosphere results from the radio occultation inversion of the FORMOSAT-3/COSMIC

Liu, J; Lin, C; Lin, C.; Tsai, H.; Solomon, S.; Sun, Y; Lee, I.; Schreiner, W.; Kuo, Y.;

Published by: Journal of Geophysical Research Published on: Jan-01-2010

YEAR: 2010 DOI: 10.1029/2009JA015079

Correlation between the ionospheric WN4 signature and the upper atmospheric DE3 tide

Wan, W.; Xiong, J.; Ren, Z.; Liu, L.; Zhang, M.-L.; Ding, F.; Ning, B.; Zhao, B.; Yue, X.;

Published by: Journal of Geophysical Research Published on: Jan-01-2010

YEAR: 2010 DOI: 10.1029/2010JA015527

Dayside ionospheric response to recurrent geomagnetic activity during the extreme solar minimum of 2008

Ram, Tulasi; Lei, J.; Su, S.-Y.; Liu, C.; Lin, C.; Chen, W.;

Published by: Geophysical Research Letters Published on: Jan-01-2010

YEAR: 2010 DOI: 10.1029/2009GL041038

Ionosphere around equinoxes during low solar activity

Liu, Libo; He, Maosheng; Yue, Xin\textquoterightan; Ning, Baiqi; Wan, Weixing;

Published by: Journal of Geophysical Research Published on: Jan-01-2010

YEAR: 2010 DOI: 10.1029/2010JA015318

Simulated wave number 4 structure in equatorial F -region vertical plasma drifts

Ren, Zhipeng; Wan, Weixing; Xiong, Jiangang; Liu, Libo;

Published by: Journal of Geophysical Research Published on: Jan-01-2010

YEAR: 2010 DOI: 10.1029/2009JA014746

Longitudinal variation of the O/N2 column density retrieved from TIMED/GUVI measurement

Liu, Libo; He, Maosheng;

Published by: 38th COSPAR Scientific Assembly Published on:

YEAR: 2010 DOI:

The ground calibration of far ultraviolet scanning imaging spectrometer (FUSIS)

The far ultraviolet scanning imaging spectrometer (FUSIS) is used to measure the composition and distribution of the main molecules and atoms in the Earth s upper atmosphere. It is an important instrument in investigation of the physical and chemical processes in the Earth s upper atmosphere. FUSIS works between 120nm to 180nm, its spectral resolution is better than 1.0nm and its spatial resolution is 8 pixels. This paper describes a kind of ground calibration method and facility of FUSIS. The FUV light is invisible, so all works must be done in high vacuum.

Wu, Yan; Tang, Yi; Liu, Jianpeng; Zhang, Zhige; Ni, Guoqiang;

Published by: Published on:

YEAR: 2010 DOI: 10.1117/12.870475

Simulated wave number 4 structure in equatorial F-region vertical plasma drifts

Ren, Zhipeng; Wan, Weixing; Xiong, Jiangang; Liu, Libo;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2010 DOI:

Variability study of the crest-to-trough TEC ratio of the equatorial ionization anomaly around 120\textdegreeE longitude

Zhang, Man-Lian; Wan, Weixing; Liu, Libo; Ning, Baiqi;

Published by: Advances in Space Research Published on: Jan-06-2009

YEAR: 2009 DOI: 10.1016/j.asr.2008.09.031

Ionospheric response to the geomagnetic storm on 13\textendash17 April 2006 in the West Pacific region

This paper presents an investigation of geomagnetic storm effects in the equatorial and middle-low latitude F-region in the West Pacific sector during the intense geomagnetic storm on 13\textendash17 April, 2006. The event, preceded by a minor storm, started at 2130 UT on April 13 while interplanetary magnetic field (IMF)\ B_zcomponent was ready to turn southward. From 14\textendash17 the ionosphere was characterized by a large scale enhancement in critical frequency, foF2 (4\~6\ MHz) and total electron content (TEC) (\~30TECU, 1TECU=1\texttimes10¹⁶el/m²) followed by a long-duration negative phase observed through the simultaneous ionospheric sounding measurements from 14 stations and GPS network along the meridian 120\textdegreeE. A periodic wave structure, known as traveling ionospheric disturbances (TIDs) was observed in the morning sector during the initial phase of the storm which should be associated with the impulsive magnetospheric energy injection to the auroral. In the afternoon and nighttime, the positive phase should be caused by the combination of equatorward winds and disturbed electric fields verified through the equatorial F-layer peak height variation and modeled upward drift of Fejer and Scherliess [1997. Empirical models of storm time equatorial electric fields. Journal of Geophysical Research 102, 24,047\textendash24,056]. It is shown that the large positive storm effect was more pronounced in the Southern Hemisphere during the morning-noon sector on April 15 and negative phase reached to lower magnetic latitudes in the Northern Hemisphere which may be related to the asymmetry of the thermospheric condition during the storm.

Zhao, Biqiang; Wan, Weixing; Liu, Libo; Igarashi, K.; Yumoto, K.; Ning, Baiqi;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: Jan-01-2009

YEAR: 2009 DOI: 10.1016/j.jastp.2008.09.029

Magnetic storm; total electron content; Mid-low latitude

Overview and summary of the Spread F Experiment (SpreadFEx)

We provide here an overview of, and a summary of results arising from, an extensive experimental campaign (the Spread F Experiment, or SpreadFEx) performed from September to November 2005, with primary measurements in Brazil. The motivation was to define the potential role of neutral atmosphere dynamics, specifically gravity wave motions propagating upward from the lower atmosphere, in seeding Rayleigh-Taylor instability (RTI) and plasma bubbles extending to higher altitudes. Campaign measurements focused on the Brazilian sector and included ground-based optical, radar, digisonde, and GPS measurements at a number of fixed and temporary sites. Related data on convection and plasma bubble structures were also collected by GOES 12, and the GUVI instrument aboard the TIMED satellite.\

Initial results of our SpreadFEx analyses are described separately by Fritts et al. (2009). Further analyses of these data provide additional evidence of 1) gravity wave (GW) activity near the mesopause apparently linked to deep convection predominantly to the west of our measurement sites, 2) small-scale GWs largely confined to lower altitudes, 3) larger-scale GWs apparently penetrating to much higher altitudes, 4) substantial GW amplitudes implied by digisonde electron densities, and 5) apparent influences of these perturbations in the lower F-region on the formation of equatorial spread F, RTI, and plasma bubbles extending to much higher altitudes. Other efforts with SpreadFEx data have also yielded 6) the occurrence, locations, and scales of deep convection, 7) the spatial and temporal evolutions of plasma bubbles, 8) 2-D (height-resolved) structures in electron density fluctuations and equatorial spread F at lower altitudes and plasma bubbles above, and 9) the occurrence of substantial tidal perturbations to the large-scale wind and temperature fields extending to bottomside F-layer and higher altitudes. Collectively, our various SpreadFEx analyses suggest direct links between deep tropical convection and large GW perturbations at large spatial scales at the bottomside F-layer and their likely contributions to the excitation of RTI and plasma bubbles extending to much higher altitudes.

Fritts, D.; Abdu, M.; Batista, B.; Batista, I.; Batista, P.; Buriti, R.; Clemesha, B.; Dautermann, T.; de Paula, E.; Fechine, B.; Fejer, B.; Gobbi, D.; Haase, J.; Kamalabadi, F.; Kherani, E.; Laughman, B.; Lima, P.; Liu, H.-L.; Medeiros, A.; Pautet, P.-D.; Riggin, D.; Rodrigues, F.; Sabbas, F.; Sobral, J.; Stamus, P.; Takahashi, H.; Taylor, M.; Vadas, S.; Vargas, F.; Wrasse, C.;

Published by: Annales Geophysicae Published on: Jan-01-2009

YEAR: 2009 DOI: 10.5194/angeo-27-2141-2009

Observations of the Ionosphere Using the Tiny Ionospheric Photometer.

Coker, Clayton; Dymond, Kenneth; Budzien, Scott; Chua, Damien; Liu, Jann-Yenq; Anderson, David; Basu, Sunanda; Pedersen, Todd;

Published by: Terrestrial, Atmospheric \& Oceanic Sciences Published on:

YEAR: 2009 DOI:

Variability study of the crest-to-trough TEC ratio of the equatorial ionization anomaly around 120 E longitude

Zhang, Man-Lian; Wan, Weixing; Liu, Libo; Ning, Baiqi;

Published by: Advances in Space Research Published on:

YEAR: 2009 DOI:

The Spread F Experiment (SpreadFEx): Program overview and first results

Fritts, D.; Abdu, M.; Batista, B.; Batista, I.; Batista, P.; Buriti, R.; Clemesha, B.; Dautermann, T.; de Paula, E.; Fechine, B.; Fejer, B.; Gobbi, D.; Haase, J.; Kamalabadi, F.; Kherani, E.; Laughman, B.; Lima, J.; Liu, H.-L.; Medeiros, A.; Pautet, P.-D.; Riggin, D.; Rodrigues, F.; Sabbas, Sao; Sobral, J.; Stamus, P.; Takahasi, H.; Taylor, M.; Vadas, S.; Vargas, F.; Wrasse, C.;

Published by: Earth Planets Space Published on:

YEAR: 2009 DOI:

The Ionospheric Mid-Latitude Summer Nighttime Anomaly

This paper presents monthly variations of the mid-latitude summer nighttime anomaly (MSNA) of the ionosphere for the first time by using global observations of the FORMOSAT-3/COSMIC (F3/C), NASA TIMED-GUVI, ground-based radars and GPS receiver network. The MSNA is characterized by greater nighttime (19:00 LT - 24:00 LT, or period of larger solar zenith angles) ionospheric electron density than that during daytime (08:00 - 18:00 LT, or period of smaller solar zenith angles) at middle latitudes during solstices. The anomaly shown in the southern hemisphere during December solstice was previously known as the Weddell Sea Anomaly (WSA) occurring around the Antarctica and the nearby Pacific Ocean, while a WSA-like electron density structure also occurs in the northern hemisphere around June solstice. This study demonstrates that the anomalies occurred in both the northern and southern hemispheres share similar character of greater nighttime density. Moreover, the latitude-altitude cross-section plots of the electron density structure show very similar time-varying electron density evolutions of the MSNA. In both hemispheres, the anomalies with similar electron density characteristics and variations caused by the similar mechanism prompts us to name this phenomenon the mid-latitude summer nighttime anomaly.

Lin, C; Chen, C; Hsu, M; Liu, CH; Liu, JG; Burns, AG; Wang, W;

Published by: Published on:

YEAR: 2009 DOI:

The Ionospheric Mid-Latitude Summer Nighttime Anomaly

This paper presents monthly variations of the mid-latitude summer nighttime anomaly (MSNA) of the ionosphere for the first time by using global observations of the FORMOSAT-3/COSMIC (F3/C), NASA TIMED-GUVI, ground-based radars and GPS receiver network. The MSNA is characterized by greater nighttime (19:00 LT - 24:00 LT, or period of larger solar zenith angles) ionospheric electron density than that during daytime (08:00 - 18:00 LT, or period of smaller solar zenith angles) at middle latitudes during solstices. The anomaly shown in the southern hemisphere during December solstice was previously known as the Weddell Sea Anomaly (WSA) occurring around the Antarctica and the nearby Pacific Ocean, while a WSA-like electron density structure also occurs in the northern hemisphere around June solstice. This study demonstrates that the anomalies occurred in both the northern and southern hemispheres share similar character of greater nighttime density. Moreover, the latitude-altitude cross-section plots of the electron density structure show very similar time-varying electron density evolutions of the MSNA. In both hemispheres, the anomalies with similar electron density characteristics and variations caused by the similar mechanism prompts us to name this phenomenon the mid-latitude summer nighttime anomaly.

Lin, C; Chen, C; Hsu, M; Liu, CH; Liu, JG; Burns, AG; Wang, W;

Published by: Published on:

YEAR: 2009 DOI:

Ionospheric response to the geomagnetic storm on 13–17 April 2006 in the West Pacific region

This paper presents an investigation of geomagnetic storm effects in the equatorial and middle-low latitude F-region in the West Pacific sector during the intense geomagnetic storm on 13–17 April, 2006. The event, preceded by a minor storm, started at 2130 UT on April 13 while interplanetary magnetic field (IMF) Bz component was ready to turn southward. From 14–17 the ionosphere was characterized by a large scale enhancement in critical frequency, foF2 (4∼6MHz) and total electron content (TEC) (∼30TECU, 1TECU=1×1016el/m2) followed by a long-duration negative phase observed through the simultaneous ionospheric sounding measurements from 14 stations and GPS network along the meridian 120°E. A periodic wave structure, known as traveling ionospheric disturbances (TIDs) was observed in the morning sector during the initial phase of the storm which should be associated with the impulsive magnetospheric energy injection to the auroral. In the afternoon and nighttime, the positive phase should be caused by the combination of equatorward winds and disturbed electric fields verified through the equatorial F-layer peak height variation and modeled upward drift of Fejer and Scherliess [1997. Empirical models of storm time equatorial electric fields. Journal of Geophysical Research 102, 24,047–24,056]. It is shown that the large positive storm effect was more pronounced in the Southern Hemisphere during the morning-noon sector on April 15 and negative phase reached to lower magnetic latitudes in the Northern Hemisphere which may be related to the asymmetry of the thermospheric condition during the storm.

Zhao, Biqiang; Wan, Weixing; Liu, Libo; Igarashi, K.; Yumoto, K.; Ning, Baiqi;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on:

YEAR: 2009 DOI: https://doi.org/10.1016/j.jastp.2008.09.029

Magnetic storm; total electron content; Mid-low latitude

Ionospheric Electron Density Concurrently Derived by TIP and GOX of FORMOSAT-3/COSMIC.

The tiny ion o spheric pho tom e ter (TIP) and GPS occultation ex per i ment (GOX) onboard FORMOSAT-3/COS MIC (F3/C) are em ployed to mea sure the OI 135.6 nm in ten si ties in

Hsu, Mei-Lan; Rajesh, Panthalingal; Liu, Jann-Yenq; Tsai, Lung-Chih; Tsai, Ho-Fang; Lin, Chien-Hung; Dymond, Kenneth; Coker, Clayton; Chua, Damien; Budzien, Scott; , others;

Published by: Terrestrial, Atmospheric \& Oceanic Sciences Published on:

YEAR: 2009 DOI: 10.3319/TAO.2008.04.24.02(F3C)

FORMOSAT-3/COSMIC observations of seasonal and longitudinal variations of equatorial ionization anomaly and its interhemispheric asymmetry during the solar minimum period

Ram, Tulasi; Su, S-Y; Liu, CH;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2009 DOI:

Global Ionospheric Structure Imaged by FORMOSAT-3/COSMIC: Early Results.

A new era of study ing the ion o spheric space weather ef fects has come af ter launch of the in no va tive sat el lite con stel la tion, named as Formosa Sat el lite 3 or Con stel la tion Ob

Lin, Chien-Hung; Liu, Jann-Yenq; Hsiao, Chun-Chieh; Liu, Chao-Han; Cheng, Chio-Zong; Chang, Po-Ya; Tsai, Ho-Fang; Fang, Tzu-Wei; Chen, Chia-Hung; Hsu, Mei-Lan;

Published by: Terrestrial, Atmospheric \& Oceanic Sciences Published on:

YEAR: 2009 DOI:

Global Ionospheric Structure Imaged by FORMOSAT-3/COSMIC: Early Results.

A new era of study ing the ion o spheric space weather ef fects has come af ter launch of the in no va tive sat el lite con stel la tion, named as Formosa Sat el lite 3 or Con stel la tion Ob

Lin, Chien-Hung; Liu, Jann-Yenq; Hsiao, Chun-Chieh; Liu, Chao-Han; Cheng, Chio-Zong; Chang, Po-Ya; Tsai, Ho-Fang; Fang, Tzu-Wei; Chen, Chia-Hung; Hsu, Mei-Lan;

Published by: Terrestrial, Atmospheric \& Oceanic Sciences Published on:

YEAR: 2009 DOI:

GCITEM-IGGCAS: A new global coupled ionosphere–thermosphere-electrodynamics model

The Global Coupled Ionosphere–Thermosphere-Electrodynamics Model developed at Institute of Geology and Geophysics, Chinese Academy of Sciences (GCITEM-IGGCAS), is introduced in this paper. This new model self-consistently calculates the time-dependent three-dimensional (3-D) structures of the main thermospheric and ionospheric parameters in the height range from 90 to 600km, including neutral number density of major species O2, N2, and O and minor species N(2D), N(4S), NO, He and Ar; ion number densities of O+ ,O2+, N2+, NO+, N+ and electron; neutral, electron and ion temperature; and neutral wind vectors. The mid- and low-latitude electric fields can also be self-consistently calculated. GCITEM-IGGCAS is a full 3-D code with 5° latitude by 7.5° longitude cells in a spherical geographical coordinate system, which bases on an altitude grid. We show two simulations in this paper: a March Equinox one and a June Solstice one, and compare their simulation results to MSIS00 and IRI2000 empirical model. GCITEM-IGGCAS can reproduce the main features of the thermosphere and ionosphere in both cases.

Ren, Zhipeng; Wan, Weixing; Liu, Libo;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on:

YEAR: 2009 DOI: https://doi.org/10.1016/j.jastp.2009.09.015

thermosphere; Ionosphere; Modeling; Global circulation models

Ionospheric response to the geomagnetic storm on 13—17 April 2006 in the West Pacific region

Zhao, Biqiang; Wan, Weixing; Liu, Libo; Igarashi, K; Yumoto, K; Ning, Baiqi;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on:

YEAR: 2009 DOI:

Seasonal variation of the longitudinal structure of the equatorial ionosphere: Does it reflect tidal influences from below?

Liu, Huixin; Watanabe, Shigeto;

Published by: Journal of Geophysical Research Published on: Jan-01-2008

YEAR: 2008 DOI: 10.1029/2008JA013027

Gravity wave and tidal influences on equatorial spread F based on observations during the Spread F Experiment (SpreadFEx)

The Spread F Experiment, or SpreadFEx, was performed from September to November 2005 to define the potential role of neutral atmosphere dynamics, primarily gravity waves propagating upward from the lower atmosphere, in seeding equatorial spread F (ESF) and plasma bubbles extending to higher altitudes. A description of the SpreadFEx campaign motivations, goals, instrumentation, and structure, and an overview of the results presented in this special issue, are provided by Fritts et al. (2008a). The various analyses of neutral atmosphere and ionosphere dynamics and structure described in this special issue provide enticing evidence of gravity waves arising from deep convection in plasma bubble seeding at the bottomside F layer. Our purpose here is to employ these results to estimate gravity wave characteristics at the bottomside F layer, and to assess their possible contributions to optimal seeding conditions for ESF and plasma instability growth rates. We also assess expected tidal influences on the environment in which plasma bubble seeding occurs, given their apparent large wind and temperature amplitudes at these altitudes. We conclude 1) that gravity waves can achieve large amplitudes at the bottomside F layer, 2) that tidal winds likely control the orientations of the gravity waves that attain the highest altitudes and have the greatest effects, 3) that the favored gravity wave orientations enhance most or all of the parameters influencing plasma instability growth rates, and 4) that gravity wave and tidal structures acting together have an even greater potential impact on plasma instability growth rates and plasma bubble seeding.

Fritts, D.; Vadas, S.; Riggin, D.; Abdu, M.; Batista, I.; Takahashi, H.; Medeiros, A.; Kamalabadi, F.; Liu, H.-L.; Fejer, B.; Taylor, M.;

Published by: Annales Geophysicae Published on: 10/2008

YEAR: 2008 DOI: 10.5194/angeo-26-3235-2008

The OI 135.6 nm Observations of the Weddell Sea Anomaly and the Nighttime Mid-Latitude Enhancement

Hsu, M; Liu, J; Lin, C; Tsai, H; Rajesh, P; Paxton, L; Hsu, R; Su, H;

Published by: Published on:

YEAR: 2008 DOI:

Features of annual and semiannual variations derived from the global ionospheric maps of total electron content

Zhao, B; Wan, W; Liu, L; Mao, T; Ren, Z; Wang, M; Christensen, AB;

Published by: Published on:

YEAR: 2008 DOI:

Correlative study of plasma bubbles, evening equatorial ionization anomaly, and equatorial prereversal E$\times$ B drifts at solar maximum

Previous ground observations have revealed a correlation that exists between equatorial plasma bubbles, evening equatorial ionization anomaly (EIA), and prereversal E × B drift velocity using latitudinal arrays of ionospheric sounders, such as in the Indian and American regions. Besides the ground measurements, the space-based observations also provide a convenient way to study the global-scale variations.

Li, Guozhu; Ning, Baiqi; Liu, Libo; Zhao, Biqiang; Yue, Xinan; Su, S-Y; Venkatraman, Sarita;

Published by: Radio Science Published on:

YEAR: 2008 DOI: 10.1029/2007RS003760

Longitudinal variations of electron temperature and total ion density in the sunset equatorial topside ionosphere

Based on the DMSP F13 Satellite observations from 1995 to 2005, the longitudinal distributions of the electron temperature (Te) and total ion density (Ni) in the sunset equatorial topside ionosphere are examined. The results suggest that the longitudinal variations of both Te and Ni exhibit obvious seasonal dependence as follows: (1) wavenumber-four longitudinal structure in equinox, (2) three peaks structure in June solstice, and (3) two peaks structure in December solstice. Moreover, the longitudinal variations of Te and Ni show significant anti-correlation, and we speculate that the longitudinal variation of Te may result from that of Ni which can control Te through the electron cooling rate. The wavenumber-four longitudinal structures of both Te and Ni in equinox may relate to the eastward propagating zonal wavenumber-3 diurnal tide (DE3), which has effect on the amplitude of the daytime zonal electric field. The longitudinal variation of Te and Ni in the two solstices may be caused both by longitudinal variation of geomagnetic declination and DE3.

Ren, Zhipeng; Wan, Weixing; Liu, Libo; Zhao, Biqiang; Wei, Yong; Yue, Xinan; Heelis, Roderick;

Published by: Geophysical Research Letters Published on:

YEAR: 2008 DOI: https://doi.org/10.1029/2007GL032998

topside ionosphere; longitudinal variation

Prestorm enhancements in NmF2 and total electron content at low latitudes

The enhancement of electron concentrations in the ionosphere before geomagnetic storms is one of the open questions. Using ionosonde observations and total electron content (TEC) from Global Positioning System (GPS) measurements along longitude 120°E, we analyzed three low latitude pre-storm enhancement events that occurred on 21 April (day 111) 2001, 29 May (day 149) 2003, and 22 September (day 265) 2001, respectively, in the Asia/Australia sector. All three events (and other two cases on 9 August 2000 and 10 May 2002) show quite similar features. The strong prestorm enhancements during these events are simultaneously presented in foF2 and TEC and enhancements have latitudinal dependence, tending to occur at low latitudes with maxima near the northern and southern equatorial ionization anomaly (EIA) crests and depletions in the equatorial region. This is quite different from what reported by Burešová and Laštovička (2007) for middle latitudes. They found no systemic latitudinal dependence in prestorm enhancements over Europe. It is argued that solar flares are not the main drivers for the enhancements, at least for low-latitude events. Main features of low-latitude prestorm enhancements do not coincide with the solar flare effects. We postulate that the vertical plasma drift or zonal electric field is a likely cause for the low-latitude prestorm enhancements. Its existence is supported by the facts of stronger EIA, the latitudinal coverage of the enhancements as well as the lift of the F layer peak height at an equatorward station during the prestorm enhancements. Moreover, the behaviors of hmF2 at low latitudes during the prestorm enhancements may possibly be explained in terms of the coupling nature of parallel and perpendicular dynamics at low latitudes (see, e.g., Behnke and Harper, 1973; Rishbeth et al., 1978).

Liu, Libo; Wan, Weixing; Zhang, Man-Lian; Zhao, Biqiang; Ning, Baiqi;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2008 DOI: https://doi.org/10.1029/2007JA012832

Ionosphere; prestorm enhancement; low latitude

Author name:
Keyword:
Year:
DOI:

Bibliography

Found 171 entries in the Bibliography.

Showing entries from 101 through 150