Bibliography

Ionospheric effects of magnetospheric and thermospheric disturbances on March 17--19, 2015

Using vertical and oblique radio-sounding data, we analyze the ionospheric and thermospheric disturbances during the magnetic storm that occurred in northeastern Russia on March 17\textendash19, 2015. We consider the heliospheric sources that induced the magnetic storm. During the main and early recovery phases, the midlatitude stations are characterized by extremely low values of electron density at the F2 layer maximum. Using oblique sounding data, we recorded signals that propagated outside the great circle arc. In evening and night hours, no radio signals were found to pass along the Norilsk\textendashIrkutsk and Magadan\textendashIrkutsk paths. The observed ionospheric effects are shown to be caused by a sharp shift of the boundaries of the main ionospheric trough to the invariant latitude 46\textdegree N during the main phase of the magnetic storm. The negative ionospheric disturbance during the recovery phase of the storm, which was associated with significant variations in the composition of the neutral atmosphere, led to a change in the mode composition of received radio signals and a decline in observed maximal frequencies in daytime hours of March 18, 2015 by more than 2 times.

Polekh, N.; Zolotukhina, N.; Romanova, E.; Ponomarchuk, S.; Kurkin, V.; Podlesnyi, A.;

Published by: Geomagnetism and Aeronomy Published on: 09/2016

YEAR: 2016 DOI: 10.1134/S0016793216040174

The observation and simulation of ionospheric response to CIR/high-speed streams-induced geomagnetic activity on 4 April 2005

The ionospheric response to corotating interaction region (CIR)-induced geomagnetic activity on 4 April 2005 has been studied using in situ electron density measurements, ground GPS-total electron content (TEC) observations, and numerical simulations of the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). The case study resulted that the ionospheric positive response occurred from high to low latitudes. The positive effect at low latitudes could continue for 4 days, whereas at middle to high latitudes the disturbance mainly lasted only for 1 day. The modeled Ne and TEC from TIE-GCM had a good agreement with those from observations. The simulation results showed that penetration electric fields were responsible for the daytime positive response during the initial and main phases of the geomagnetic storm, while neutral winds were responsible for the presunset positive effects. The long-lasting positive storm effect during the storm recovery time at low latitudes was related to the thermospheric composition (O/N 2 ) changes during the storm event.

Chen, Yanhong; Wang, Wenbin; Qiu, Na; Liu, Siqing; Gong, Jiancun; Huang, Wengeng;

Published by: Radio Science Published on: 08/2016

YEAR: 2016 DOI: 10.1002/rds.v51.810.1002/2015RS005937

Solar wind driving of ionosphere-thermosphere responses in three storms near St. Patrick's Day in 2012, 2013, and 2015

We identify interplanetary plasma regions associated with three intense interplanetary coronal mass ejections (ICMEs)-driven geomagnetic storm intervals which occurred around the same time of the year: day of year 74\textendash79 (March) of 2012, 2013, and 2015. We show that differences in solar wind drivers lead to different dynamical ionosphere-thermosphere (IT) responses and to different preconditioning of the IT system. We introduce a new hourly based global metric for average low-latitude and northern middle-latitude vertical total electron content responses in the morning, afternoon, and evening local time ranges, derived from measurements from globally distributed Global Navigation Satellite System ground stations. Our novel technique of estimating nitric oxide (NO) cooling radiation in 11\textdegree latitudinal zones is based on Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED)/Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) measurements. The thermospheric cooling throughout the storm phases is studied with this high latitudinal resolution for the first time. Additionally, TIMED/Global Ultraviolet Imager (GUVI) observations of the dynamical response of the thermospheric composition (O/N₂ ratio) are utilized to study negative ionospheric storm effects. Based on these data sets, we describe and quantify distinct IT responses to driving by ICME sheaths, magnetic clouds, coronal loop remnants, plasma discontinuities, and high-speed streams following ICMEs. Our analysis of coupling functions indicates strong connection between coupling with the solar wind and IT system response in ICME-type storms and also some differences. Knowledge of interplanetary features is crucial for understanding IT storm dynamics.

Verkhoglyadova, O.; Tsurutani, B.; Mannucci, A.; Mlynczak, M.; Hunt, L.; Paxton, L.; Komjathy, A.;

Published by: Journal of Geophysical Research: Space Physics Published on: 07/2016

YEAR: 2016 DOI: 10.1002/jgra.v121.910.1002/2016JA022883

Equatorial ionospheric plasma drifts and O ⁺ concentration enhancements associated with disturbance dynamo during the 2015 St. Patrick\textquoterights Day magnetic storm

Disturbance dynamo is an important dynamic process during magnetic storms. However, very few direct observations of dynamo-induced plasma drifts and ion composition changes in the equatorial ionosphere are available. In this study, we use measurements of the Defense Meteorological Satellite Program (DMSP) satellites to identify the characteristics of the disturbance dynamo process in the topside equatorial ionosphere near dawn during the magnetic storm with a minimum Dst of -223 nT on 17 March 2015. Data from four DMSP satellites with equatorial crossings at 0245, 0430, 0630, and 0730 LT are available for this case. The dynamo process was first observed in the postmidnight sector 3\textendash4.7 h after the beginning of the storm main phase and lasted for 31 h, covering the second storm intensification and the initial 20 h of the recovery phase. The dynamo vertical ion drift was upward (up to 150\textendash200 m s^-1) in the postmidnight sector and downward (up to ~80 m s^-1) in the early morning sector. The dynamo zonal ion drift was westward at these locations and reached ~100 m s^-1. The dynamo process caused large enhancements of the O⁺ concentration (the ratio of the oxygen ion density to the total ion density) at the altitude of 840 km near dawn. The O⁺ concentration increased from below 60\% during the prestorm period to 80\textendash90\% during the storm time. More specifically, the O⁺ density was increased, and the H⁺ density was decreased. The variations of the O⁺ concentration were well correlated with the vertical ion drift.

Huang, Chao-Song; Wilson, Gordon; Hairston, Marc; Zhang, Yongliang; Wang, Wenbin; Liu, Jing;

Published by: Journal of Geophysical Research: Space Physics Published on: 06/2016

YEAR: 2016 DOI: 10.1002/2016JA023072

Ionospheric F2 layer responses to total solar eclipses at low and mid-latitude

In this article, we presented ionospheric F2 responses to total solar eclipses on the basis of the data obtained from five (5) equatorial/low-latitude and twenty-seven (27) mid-latitude ionosonde stations, which are within the obscuration percentage of 50\textendash100\% of the path of the total solar eclipses progression. Statistically, the diurnal changes in the F2 layer peak height hmF2 and electron density NmF2, as well as the latitudinal and hemispheric dependence and the contribution of both magnetic and solar activities during the eclipse window were investigated. The estimation of the solar ionizing radiation that remains unmasked during the eclipse window was as well carried out. Plasma diffusion processes dominate the F2 region plasma, and determine the height at which the F2 peak formed at mid-latitude. The electron density decreased during the eclipse window, closely following the variation in the local solar radiation at the mid-latitude. However, at equatorial/low-latitude, the plasma distribution during total solar eclipse depends on combine effect of solar radiation and the background nighttime ionospheric irregularities mechanism. The uncertainty level of the estimated solar ionizing radiation was \<\textpm0.3 at mid-latitude and greater\textpm0.3 at equatorial/low-latitude. Their correlation ranges from (0.42\textendash0.99). The ionospheric\ F2 layer eclipse effect is latitudinal and hemispheric dependent. The effect is largest at mid-latitude and relatively small at equatorial/low-latitudes. It is more pronounced at the equator, and decreases toward the equatorial ionospheric anomaly (EIA) region. The better correlation of 0.5840 and 0.6435 between geographic latitude and\ E(t) and electron density justifies the latitudinal relationship. The increase in percentage deviation of electron density increases with latitude and delay time (∆T) in the northern hemisphere of the mid-latitude. Conversely, in the southern hemisphere the percentage deviation decreases with an increase in ∆T\ and the latitude. The influence of the combined effect of solar activity and magnetic disturbances cannot the overlooked during total solar eclipse. At the eclipse shadow, the deviation increases with decreasing magnetic disturbances and solar activity. During magnetic quiet conditions the variation in maximum NmF2/hmF2 on the eclipse day are more decrease/increase than the control day and overturned during the magnetic disturbed condition.

Adekoya, B.J.; Chukwuma, V.U.;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 02/2016

YEAR: 2016 DOI: 10.1016/j.jastp.2016.01.006

Equatorial/low-latitude; Hemisphere; mid-latitude; NmF2 and hmF2; Solar ionizing radiation

Ionosphere-thermosphere (IT) response to solar wind forcing during magnetic storms

During magnetic storms, there is a strong response in the ionosphere and thermosphere which occurs at polar latitudes. Energy input in the form of Poynting flux and energetic particle precipitation, and energy output in the form of heated ions and neutrals have been detected at different altitudes and all local times. We have analyzed a number of storms, using satellite data from the Defense Meteorological Satellite Program (DMSP), the Gravity Recovery and Climate Experiment (GRACE), Gravity field and steady-state Ocean Circulation Explorer (GOCE), and Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission. Poynting flux measured by instruments on four DMSP spacecraft during storms which occurred in 2011\textendash2012 was observed in both hemispheres to peak at both auroral and polar latitudes. By contrast, the measured ion temperatures at DMSP and maxima in neutral density at GOCE and GRACE altitudes maximize in the polar region most frequently with little evidence of Joule heating at auroral latitudes at these spacecraft orbital locations.

Huang, Cheryl; Huang, Yanshi; Su, Yi-Jiun; Sutton, Eric; Hairston, Marc; Coley, William;

Published by: Journal of Space Weather and Space Climate Published on: 01/2016

YEAR: 2016 DOI: 10.1051/swsc/2015041

Energy distribution; Ionosphere; polar cap; solar wind; thermosphere

Ionosphere-thermosphere (IT) response to solar wind forcing during magnetic storms

During magnetic storms, there is a strong response in the ionosphere and thermosphere which occurs at polar latitudes. Energy input in the form of Poynting flux and energetic particle precipitation, and energy output in the form of heated ions and neutrals have been detected at different altitudes and all local times. We have analyzed a number of storms, using satellite data from the Defense Meteorological Satellite Program (DMSP), the Gravity Recovery and Climate Experiment (GRACE), Gravity field and steady-state Ocean Circulation Explorer (GOCE), and Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission. Poynting flux measured by instruments on four DMSP spacecraft during storms which occurred in 2011\textendash2012 was observed in both hemispheres to peak at both auroral and polar latitudes. By contrast, the measured ion temperatures at DMSP and maxima in neutral density at GOCE and GRACE altitudes maximize in the polar region most frequently with little evidence of Joule heating at auroral latitudes at these spacecraft orbital locations.

Huang, Cheryl; Huang, Yanshi; Su, Yi-Jiun; Sutton, Eric; Hairston, Marc; Coley, William;

Published by: Journal of Space Weather and Space Climate Published on: 01/2016

YEAR: 2016 DOI: 10.1051/swsc/2015041

Energy distribution; Ionosphere; polar cap; solar wind; thermosphere

SPIE ProceedingsThe reconnaissance and early-warning optical system design for dual field of space-based "solar blind ultraviolet"

With the development of modern technology, especially the development of information technology at high speed, the ultraviolet early warning system plays an increasingly important role. In the modern warfare, how to detect the threats earlier, prevent and reduce the attack of precision-guided missile has become a new challenge. Because the ultraviolet warning technology has high environmental adaptability, the low false alarm rate, small volume and other advantages, in the military field applications it has been developed rapidly. According to current application demands for solar blind ultraviolet detection and warning, this paper proposes a reconnaissance and early-warning optical system, which covers solar blind ultraviolet (250nm-280nm) and dual field. This structure takes advantage of a narrow field of view and long focal length optical system to achieve the target object detection, uses wide-field and short focal length optical system to achieve early warning of the target object. It makes use of an ultraviolet beam-splitter to achieve the separation of two optical systems. According to the detector and the corresponding application needs of two visual field of the optical system, the calculation and optical system design were completed. After the design, the MTF of the two optical system is more than 0.8@39lp/mm. A single pixel energy concentration is greater than 80\%.

Wang, Wen-cong; Jin, Dong-dong; Shao, Fei; Hu, Hui-jun; Shi, Yu-feng; Song, Juan; Zhang, Yu-tu; Yong, Liu;

Published by: Published on:

YEAR: 2016 DOI: 10.1117/12.2236440

Conjugate hemisphere ionospheric response to the St. Patrick s Day storms of 2013 and 2015 in the 100° E longitude sector

The GUVI data used here are provided through support from the NASA MO&DA program. The GUVI instrument was designed and built by The Aerospace Corporation and The John

Kalita, Bitap; Hazarika, Rumajyoti; Kakoti, Geetashree; Bhuyan, PK; Chakrabarty, D; Seemala, Gopi; Wang, K; Sharma, S; Yokoyama, T; Supnithi, P; , others;

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

YEAR: 2016 DOI: 10.1002/2016JA023119

Ionospheric effects of magnetospheric and thermospheric disturbances on March 17—19, 2015

Using vertical and oblique radio-sounding data, we analyze the ionospheric and thermospheric disturbances during the magnetic storm that occurred in northeastern Russia on March

Polekh, NM; Zolotukhina, NA; Romanova, EB; Ponomarchuk, SN; Kurkin, VI; Podlesnyi, AV;

Published by: Geomagnetism and Aeronomy Published on:

YEAR: 2016 DOI:

The reconnaissance and early-warning optical system design for dual field of space-based" solar blind ultraviolet"

With the development of modern technology, especially the development of information technology at high speed, the ultraviolet early warning system plays an increasingly important

Wang, Wen-cong; Jin, Dong-dong; Shao, Fei; Hu, Hui-jun; Shi, Yu-feng; Song, Juan; Zhang, Yu-tu; Yong, Liu;

Published by: Published on:

YEAR: 2016 DOI: 10.1117/12.2236440

Heliosphere-ionosphere-thermosphere coupling and energy budget in geomagnetic storms

1. Solar irradiance: F10. 7 2. High-latitude electric and magnetic field potential patterns and field-aligned currents (FAC): empirical Weimer05 model (Weimer, 2005), can use AMIE input

Verkhoglyadova, OP; Mannucci, AJ; Meng, X; Komjathy, A; Mlynczak, MG; Hunt, LA; Tsurutani, BT;

Published by: Published on:

YEAR: 2016 DOI:

Conjugate hemisphere ionospheric response to the St. Patrick s Day storms of 2013 and 2015 in the 100° E longitude sector

Kalita, Bitap; Hazarika, Rumajyoti; Kakoti, Geetashree; Bhuyan, PK; Chakrabarty, D; Seemala, Gopi; Wang, K; Sharma, S; Yokoyama, T; Supnithi, P; , others;

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

YEAR: 2016 DOI:

TIME after TIMED-A perspective on Thermosphere-Ionosphere Mesosphere science and future observational needs after the TIMED mission epoch

Mlynczak, Martin; , Russell; Hunt, Linda; Christensen, Andrew; Paxton, Larry; Woods, Thomas; Niciejewski, Richard; Yee, Jeng-Hwa;

Published by: Published on:

YEAR: 2016 DOI:

Ionospheric responses to geomagnetic storms during 2015-2016 at longitude 120° E in China

Chen, Yanhong; Tianjiao, Yuan; Hua, Shen; Liu, Siqing; Wengeng, Huang; Gong, Jiancun;

Published by: Published on:

YEAR: 2016 DOI:

Equatorial ionospheric plasma drifts and O+ concentration enhancements associated with disturbance dynamo during the 2015 St. Patrick's Day magnetic storm

Huang, Chao-Song; Wilson, Gordon; Hairston, Marc; Zhang, Yongliang; Wang, Wenbin; Liu, Jing;

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

YEAR: 2016 DOI:

Multi-Instrument Observations of Geomagnetic Storms in the Arctic Ionosphere

Durgonics, Tibor; Komjathy, Attila; Verkhoglyadova, Olga; Shume, Esayas; Benzon, Hans-Henrik; Mannucci, Anthony; Butala, Mark; H\oeg, Per; Langley, Richard;

Published by: Published on:

YEAR: 2016 DOI:

Ionospheric response to the 17-18 March 2015 geomagnetic storm as seen from multiple TEC and NmF2 measurements along 100° E

Bhuyan, Pradip; Yokoyama, Tatsuhiro; Kalita, Bitap; Seemala, GK; Hazarika, Rumajyoti; Komolmis, Tharadol; Yatini, Clara; Chakrabarty, Dibyendu; Supnithi, Pornchai;

Published by: 41st COSPAR Scientific Assembly Published on:

YEAR: 2016 DOI:

Profiles of ionospheric storm-enhanced density during the 17 March 2015 great storm

Liu, Jing; Wang, Wenbin; Burns, Alan; Yue, Xinan; Zhang, Shunrong; Zhang, Yongliang; Huang, Chaosong;

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

YEAR: 2016 DOI:

NmF2 and hmF2 measurements at 95\textdegree E and 127\textdegree E around the EIA northern crest during 2010\textendash2014

The characteristics of the F2 layer parameters NmF2 and hmF2 over Dibrugarh (27.5\textdegree N, 95\textdegree E, 17\textdegree N geomagnetic, 43\textdegree dip) measured by a Canadian Advanced Digital Ionosonde (CADI) for the period of August 2010 to July 2014 are reported for the first time from this low mid-latitude station lying within the daytime peak of the longitudinal wave number 4 structure of equatorial anomaly (EIA) around the northern edge of anomaly crest. Equinoctial asymmetry is clearly observed at all solar activity levels whereas the midday winter anomaly is observed only during high solar activity years and disappears during the temporary dip in solar activity in 2013 but forenoon winter anomaly can be observed even at moderate solar activity. The NmF2/hmF2 variations over Dibrugarh are compared with that of Okinawa (26.5\textdegree N, 127\textdegree E, 17\textdegree N geomagnetic), and the eastward propagation speed of the wave number 4 longitudinal structure from 95\textdegree E to 127\textdegree E is estimated. The speed is found to be close to the theoretical speed of the wave number 4 (WN4) structure. The correlation of daily NmF2 over Dibrugarh and Okinawa with solar activity exhibits diurnal and seasonal variations. The highest correlation in daytime is observed during the forenoon hours in equinox. The correlation of daily NmF2 (linear or non-linear) with solar activity exhibits diurnal variation. A tendency for amplification with solar activity is observed in the forenoon and late evening period of March equinox and the postsunset period of December solstice. NmF2 saturation effect is observed only in the midday period of equinox. Non-linear variation of neutral composition at higher altitudes and variation of recombination rates with solar activity via temperature dependence may be related to the non-linear trend. The noon time maximum NmF2 over Dibrugarh exhibits better correlation with equatorial electrojet (EEJ) than with solar activity and, therefore, new low-latitude NmF2 index is proposed taking both solar activity and EEJ strength into account.

Kalita, Bitap; Bhuyan, Pradip; Yoshikawa, Akimasa;

Published by: Earth, Planets and Space Published on: Jan-12-2015

YEAR: 2015 DOI: 10.1186/s40623-015-0355-3

Space-borne imager of mesospheric gravity waves

Mesospheric gravity waves play important roles in atmospheric circulation and variability. It is meaningful to obtain the features of the mesospheric gravity waves on a global scale, such as the distribution and the sources. However, limited by the field of view, the ground-based instrument can only access some local information. We developed a space-borne imager to observe the global gravity waves by collecting the O2 airglow with TDI (Time Delayed and Integration) method. The function of the imager was testified in our laboratory with a led screen, where the gravity waves were simulated and shown. On a satellite orbit with the altitude of 700 km and inclination of 73 degree, the imager can obtain the gravity waves with horizontal wavelength more than 10 km, even taking the effect induced by the earth rotation into account. \textcopyright (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Tu, Cui; Hu, Xiong; Xu, Qingchen; Song, Liang; Li, Hui;

Published by: Published on: 10/2015

YEAR: 2015 DOI: 10.1117/12.2197894

airglow imaging; gravity wave; mesosphere; space borne; TDI

A case study of ionospheric storm effects in the Chinese sector during the October 2013 geomagnetic storm

In this study, we investigate the ionospheric storm effects in the Chinese sector during 2 October 2013 geomagnetic storm. The TEC map over China sector (1\textdegree\ \texttimes\ 1\textdegree) and eight ionosondes data along the longitude of 110\textdegreeE are used to show significant positive ionospheric phases (enhancements in TEC and ionospheric peak electron density NmF2) in the high-middle latitude region and the negative effects at the low latitude and equatorial region during the storm. A wave structure with periods about 1\textendash2\ h and horizontal speed about 680\ m/s, propagating from the high latitudes to the low latitudes is observed in electron densities within the height region from 200 to 400\ km, which is caused by the combined effects of neutral wind and the large-scale traveling disturbances (LSTIDs). In the low latitude regions, compared with those in the quiet day, the ionospheric peak heights of the F2 layer (hmF2) in the storm day obviously increase accompanying a notably decrease in TEC and NmF2, which might be as a result of the eastward prompt penetration electric field (PPEF) evidenced by the two magnetometers and the subsequent westward disturbance dynamo electric fields (DDEF). The storm-time TEC enhancement mainly occurs in the topside ionosphere, as revealed from the topside TEC, bottomside TEC and GPS TEC.

Mao, Tian; Sun, Lingfeng; Hu, Lianhuan; Wang, Yungang; Wang, Zhijun;

Published by: Advances in Space Research Published on: 06/2015

YEAR: 2015 DOI: 10.1016/j.asr.2015.05.045

Ionospheric storm; Neutral wind; LSTIDs; PPEF; DDEF

Characteristics of ionospheric north-south asymmetry and their relationship with irregularity

Using the empirical ionospheric model, the flux-tube integrated electron density and the ratio between the F-region Pedersen conductivity and the total E- and F-region Pedersen conductivity are calculated to investigate the characteristics of the ionospheric asymmetry after sunset during a solar cycle. Furthermore, two indices representing the asymmetric strength of the parameters respectively are defined to study its relationship with the occurrences of the irregularities during different seasons and with different solar activities. The results indicate that the electron density and the Pedersen conductivity ratio show north-south remarkable hemispheric asymmetry at different solar energy levels. The asymmetric strengths represent the dependence on seasons and solar activities, and their variation depending on seasons and solar activities show a negative correlation with the occurrences of the equatorial irregularities and also have a negative relation with the linear growth rate of the generalized Rayleigh-Taylor instability.

Luo, Weihua; Zhu, Zhengping; Lan, Jiaping; Li, Xuejing;

Published by: Wuhan University Journal of Natural Sciences Published on: 06/2015

YEAR: 2015 DOI: 10.1007/s11859-015-1088-7

asymmetry; Electron density; Ionosphere; irregularity; Pedersen conductivity

NmF2 and hmF2 measurements at 95 E and 127 E around the EIA northern crest during 2010—2014

Non-linear variation of neutral composition at higher altitudes and variation of recombination rates with solar activity via temperature dependence may be related to the non-linear trend. The noon time maximum NmF2 over Dibrugarh exhibits better correlation with equatorial electrojet (EEJ) than with solar activity and, therefore, new low-latitude NmF2 index is proposed taking both solar activity and EEJ strength into account.

Kalita, Bitap; Bhuyan, Pradip; Yoshikawa, Akimasa;

Published by: Earth, Planets and Space Published on:

YEAR: 2015 DOI: 10.1186/s40623-015-0355-3

Where does the Thermospheric Ionospheric GEospheric Research (TIGER) Program go?

At the 10th Thermospheric Ionospheric GEospheric Research (TIGER/COSPAR) symposium held in Moscow in 2014 the achievements from the start of TIGER in 1998 were summarized. During that period, great progress was made in measuring, understanding, and modeling the highly variable UV-Soft X-ray (XUV) solar spectral irradiance (SSI), and its effects on the upper atmosphere. However, after more than 50years of work the radiometric accuracy of SSI observation is still an issue and requires further improvement. Based on the extreme ultraviolet (EUV) data from the SOLAR/SolACES, and SDO/EVE instruments, we present a combined data set for the spectral range from 16.5 to 105.5nm covering a period of 3.5years from 2011 through mid of 2014. This data set is used in ionospheric modeling of the global Total Electron Content (TEC), and in validating EUV SSI modeling. For further investigations the period of 3.5years is being extended to about 12years by including data from SOHO/SEM and TIMED/SEE instruments. Similarly, UV data are used in modeling activities. After summarizing the results, concepts are proposed for future real-time SSI measurements with in-flight calibration as experienced with the ISS SOLAR payload, for the development of a space weather camera for observing and investigating space weather phenomena in real-time, and for providing data sets for SSI and climate modeling. Other planned topics are the investigation of the relationship between solar EUV/UV and visible/near-infrared emissions, the impact of X-rays on the upper atmosphere, the development of solar EUV/UV indices for different applications, and establishing a shared TIGER data system for EUV/UV SSI data distribution and real-time streaming, also taking into account the achievements of the FP7 SOLID (First European SOLar Irradiance Data Exploitation) project. For further progress it is imperative that coordinating activities in this special field of solar–terrestrial relations and solar physics is emphasized.

Schmidtke, G.; Avakyan, S.V.; Berdermann, J.; Bothmer, V.; Cessateur, G.; Ciraolo, L.; Didkovsky, L.; de Wit, Dudok; Eparvier, F.G.; Gottwald, A.; Haberreiter, M.; Hammer, R.; Jacobi, Ch.; Jakowski, N.; Kretzschmar, M.; Lilensten, J.; Pfeifer, M.; Radicella, S.M.; Schäfer, R.; Schmidt, W.; Solomon, S.C.; Thuillier, G.; Tobiska, W.K.; Wieman, S.; Woods, T.N.;

Published by: Advances in Space Research Published on:

YEAR: 2015 DOI: https://doi.org/10.1016/j.asr.2015.07.043

UV/EUV solar spectral irradiance; Instrumentation; Calibration; Modeling

Solar wind driving of ionosphere-thermosphere responses during three storms on St. Patrick's Day.

Verkhoglyadova, Olga; Tsurutani, Bruce; Mannucci, Anthony; Komjathy, Attila; Mlynczak, Martin; Hunt, Linda; Paxton, Larry;

Published by: Published on:

YEAR: 2015 DOI:

A study of GPS ionospheric scintillations observed at Shenzhen

Ionospheric scintillation variations are studied using GPS measurements at the low latitude station of Shenzhen (22.59\textdegreeN,\ 113.97\textdegreeE), situated under the northern crest of the equatorial anomaly region, from the Chinese Meridian Project. The results are presented for data collected during the current phase of rising solar activity (low to high solar activity) from December 2010 to April 2014. The results show that GPS scintillation events were largely a nighttime phenomenon during the whole observation period. Scintillation events mainly occurred along the inner edge of the northern crest of the equatorial anomaly in China. The occurrence of scintillations in different sectors of the sky was also investigated, and the results revealed that it is more likely for the scintillations to be observed in the west sector of the sky above Shenzhen. During the present period of study, a total number of 512 total electron content (TEC) depletions and 460 lock loss events were observed. In addition, both of these events are likely to increase during periods of high solar activity, especially because the strong scintillations are often simultaneously accompanied by TEC depletions and lock losses by GPS receivers.

Huang, Linfeng; Wang, Jinsong; Jiang, Yong; Chen, Zhou; Zhao, Kai;

Published by: Advances in Space Research Published on: 12/2014

YEAR: 2014 DOI: 10.1016/j.asr.2014.08.023

GPS; Ionospheric scintillation; Scintillation event

Spatial distribution of TEC across India in 2005: Seasonal asymmetries and IRI prediction

Total electron content measured simultaneously at 10 locations over India during the low solar activity year 2005 is used to examine the temporal and spatial asymmetries and also to assess the predictability of the International Reference Ionosphere in respect of the observed asymmetrical distribution. The stations are distributed in latitude along 77\textdegreeE and in longitude along 23\textdegreeN forming a meridional and a zonal chain respectively. A longitudinal gradient positive towards east was observed in the daytime hours of equinox and summer. Equinoctial asymmetry was prevalent across India during this year. Within the crest and equator, winter anomaly has been observed. It is found that IRI 2012 (with Ne Quick option, URSI coefficients) is unable to fully capture the temporal variation and spatial gradients of the ionization density in the Indian sector during 2005. The amount of offset between the model and measurement varies with local time and location.

Hazarika, Rumajyoti; Bhuyan, Pradip;

Published by: Advances in Space Research Published on: 11/2014

YEAR: 2014 DOI: 10.1016/j.asr.2014.07.011

Equatorial ionization anomaly; Ionosphere; IRI; solar activity; TEC

Global distribution of atomic oxygen in the mesopause region as derived from SCIAMACHY O( ¹ S) green line measurements

A new data set of atomic oxygen abundance in the upper mesosphere and lower thermosphere is presented. The data are derived from the nighttime atomic oxygen green line limb emission measurements of the SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) instrument on the European Environmental Satellite. The temporal coverage is October 2002 until April 2012, and the latitudinal extent is 50\textdegreeS to 80\textdegreeN at 10 P.M. local time. This data set is compared to other satellite data sets, in particular to recently published data of SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) and the Mass Spectrometer and Incoherent Scatter model. SCIAMACHY atomic oxygen peak abundances are typically 3\textendash6\texttimes10¹¹ mol/cm³ at the atomic oxygen maximum region, depending on latitude and season. These values are similar to previous values based on chemiluminescence measurements of the atomic oxygen three-body recombination reaction but at least 30\% lower than atomic oxygen abundances obtained from SABER.

Kaufmann, M.; Zhu, Y.; Ern, M.; Riese, M.;

Published by: Geophysical Research Letters Published on: 09/2014

YEAR: 2014 DOI: 10.1002/grl.v41.1710.1002/2014GL060574

atomic oxygen; energy balance; mesopause; remote sensing data; SCIAMACHY

\textquoterightSpace bubbles\textquoteright may have led to deadly battle in Afghanistan

One of the deadliest battles of the U.S. war in Afghanistan may have been caused by plasma bubbles. That\textquoterights the conclusion of this unusual study, which finds that the turbulent pockets of ionized gas may have deflected U.S. military satellite radio signals enough to cause temporary communications blackouts in the region. Be sure to check out the amazing artwork.

Shultz, David;

Published by: Published on: 09/2014

YEAR: 2014 DOI:

Space bubble

GPS derived TEC and foF2 variability at an equatorial station and the performance of IRI-model

The ionosphere induces a time delay in transionospheric radio signals such as the Global Positioning System (GPS) signal. The Total Electron Content (TEC) is a key parameter in the mitigation of ionospheric effects on transionospheric signals. The delay in GPS signal induced by the ionosphere is proportional to TEC along the path from the GPS satellite to a receiver. The diurnal monthly and seasonal variations of ionospheric electron content were studied during the year 2010, a year of extreme solar minimum (F10.7\ =\ 81 solar flux unit), with data from the GPS receiver and the Digisonde Portable Sounder (DPS) collocated at Ilorin (Geog. Lat. 8.50\textdegreeN, Long. 4.50\textdegreeE, dip -7.9\textdegree). The diurnal monthly variation shows steady increases in TEC and F2-layer critical frequency (foF2) from pre-dawn minimum to afternoon maximum and then decreases after sunset. TEC show significant seasonal variation during the daytime between 0900 and 1900\ UT (LT\ =\ UT\ +\ 1\ h) with a maximum during the March equinox (about 35 TECU) and minimum during the June solstice (about 24 TECU). The GPS-TEC and foF2 values reveal a weak seasonal anomaly and equinoctial asymmetry during the daytime. The variations observed find their explanations in the amount of solar radiation and neutral gas composition. The measured TEC and foF2 values were compared with last two versions of the International Reference Ionosphere (IRI-2007 and IRI-2012) model predictions using the NeQuick and CCIR (International Radio Consultative Committee) options respectively in the model. In general, the two models give foF2 close to the experimental values, whereas significant discrepancies are found in the predictions of TEC from the models especially during the daytime. The error in height dependent thickness parameter, daytime underestimation of equatorial drift and contributions of electrons from altitudes above 2000\ km have been suggested as the possible causes.

Adebiyi, S.J.; Odeyemi, O.O.; Adimula, I.A.; Oladipo, O.A.; Ikubanni, S.O.; Adebesin, B.O.; Joshua, B.W.;

Published by: Advances in Space Research Published on: 08/2014

YEAR: 2014 DOI: 10.1016/j.asr.2014.03.026

Equator; IRI-model; NmF2; Prediction; TEC

Height-integrated Pedersen conductivity in both E and F regions from COSMIC observations

Altitudinal distribution of Joule heating is very important to the thermosphere and ionosphere, which is roughly proportional to the Pedersen conductance at high latitudes. Based on the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites observations from 2008 to 2011, the height-integrated Pedersen conductivities in both E (100\textendash150\ km) and F (150\textendash600\ km) regions and their ratio _γ_PγP (_∑_PE/_∑_PF∑PE/∑PF) have been calculated. The result shows that the maximum ratio in the northern summer hemisphere is ~5.5, which is smaller than that from the Thermosphere\textendashIonosphere\textendashElectrodynamics General Circulation Model (TIE-GCM v1.94) simulation (~9). This indicates that the energy inputs into the F region may be underestimated in the model. The seasonal variations of the ratio have been investigated for both hemispheres, and an interhemispheric asymmetry has been identified. The variational trend of the ratio is similar in both hemispheres, which reaches minimum at local summer and maximum at local winter. However, the difference of the ratio from local summer to local winter in the southern hemisphere is larger than that in the northern hemisphere.

Sheng, Cheng; Deng, Yue; Yue, Xinan; Huang, Yanshi;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 08/2014

YEAR: 2014 DOI: 10.1016/j.jastp.2013.12.013

COSMIC; Interhemispheric asymmetry; Joule heating; Pedersen conductivity

Ionospheric response to magnetic activity at low and mid-latitude stations

The F2-layer response to the moderate storm of 5\textendash7 April 2010 was investigated using data from two equatorial stations (Ilorin: lat. 8.5\textdegreeN, 4.5\textdegreeE; Kwajalein: lat. 9\textdegreeN, long. 167.2\textdegreeE) and mid-latitude (San Vito: lat. 40.6\textdegreeN, long. 17.8\textdegreeE; Pruhonice: lat. 50\textdegreeN, long. 14.6\textdegreeE). Before storm commencement, enhancement, and depletion of NmF2 values were observed in the equatorial and mid-latitude stations, respectively, indicating the latitudinal dependence of the pre-storm event. All the stations with the exception of Kwajalein show positive phase in NmF2 response at the storm onset stage. Positive phase in NmF2 continues over Ilorin and appears on the daytime ionosphere of Kwajalein on 6 April, whereas negative phase suppressed the positive feature in Pruhonice and San Vito until the recovery condition. The differences in the response of F2-layer to the storm for the two equatorial stations were attributed to their longitudinal differences. On the average, both theAE and D _stindices revealed poor correlation relationship. More studies are required to ascertain this finding.

Adebiyi, Shola; Adimula, Isaac; Oladipo, Olusola; Joshua, Benjamin; Adebesin, Babatunde; Ikubanni, Stephen;

Published by: Acta Geophysica Published on: 08/2014

YEAR: 2014 DOI: 10.2478/s11600-014-0205-x

Electric field; equatorial station; Ionosphere; mid-latitude; moderate storm; positive phase

Ionospheric TEC, thermospheric cooling and $\Sigma$ [O/N2] compositional changes during the 6--17 March 2012 magnetic storm interval (CAWSES II)

A series of four geomagnetic storms (the minimum SYM-H~-148\ nT) occurred during the March 6\textendash17, 2012 in the ascending phase of the solar cycle 24. This interval was selected by CAWSES II for its campaign. The GPS total electron content (TEC) database and JPL\textquoterights Global Ionospheric Maps (GIM) were used to study vertical TEC (VTEC) for different local times and latitude ranges. The largest response to geomagnetic activity is shown in increases of the low-latitude dayside VTEC. Several GPS sites feature post-afternoon VTEC \textquotedblleftbite-outs\textquotedblright. During Sudden Impulse (SI⁺) event on March 8th a peak daytime VTEC restores to about quiet-time values. It is shown that the TIMED/SABER zonal flux of nitric oxide (NO) infrared cooling radiation correlates well with auroral heating. A factor of ~5 cooling increase is noted in some storms. The cooling radiation intensifies in the auroral zone and spreads towards the equator. Effects of the storm appear at lower latitudes ~18.6\ h later. The column density ratio Σ[O/N₂] is analyzed based on TIMED/GUVI measurements. Both increases (at low latitudes) and decreases (from auroral to middle latitudes) in the ratio occurs during the geomagnetic storms. We suggest that the column density ratio could be enhanced at low to middle latitudes on the dayside partially due to the superfountain effect (atomic oxygen uplift due to ion-neutral drag). It is suggested that decreases in the Σ[O/N₂] ratio at high to middle-latitudes may be caused by high thermospheric temperatures. During SI⁺s, there is an increase in Σ[O/N₂] ratio at auroral latitudes.

Verkhoglyadova, O.P.; Tsurutani, B.T.; Mannucci, A.J.; Mlynczak, M.G.; Hunt, L.A.; Paxton, L.J.;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 08/2014

YEAR: 2014 DOI: 10.1016/j.jastp.2013.11.009

Geomagnetic storms; Ionosphere; thermosphere

Meteor radar wind over Chung-Li (24.9 N, 121 E), Taiwan, for the period 10--25 November 2012 which includes Leonid meteor shower: Comparison with empirical model and satellite measurements

The neutral winds in the mesosphere and lower thermosphere (MLT) region are measured by a newly installed meteor trail detection system (or meteor radar) at Chung-Li, Taiwan, for the period 10\textendash25 November 2012, which includes the Leonid meteor shower period. In this study, we use the 3 m field-aligned plasma irregularities in the sporadic E (E_s) region in combination with the International Geomagnetic Reference Field model to calibrate the system phase biases such that the true positions of the meteor trails can be correctly determined with interferometry technique. The horizontal wind velocities estimated from the radial velocities of the meteor trails and their locations by using a least squares method show that the diurnal tide dominates the variation of the MLT neutral wind with time over Chung-Li, which is in good agreement with the horizontal wind model (HWM07) prediction. However, harmonic analysis reveals that the amplitudes of the mean wind, diurnal, and semidiurnal tides of the radar-measured winds in height range 82\textendash100 km are systematically larger than those of the model-predicted winds by up to a factor of 3. A comparison shows that the overall pattern of the height-local time distribution of the composite radar-measured meteor wind is, in general, consistent with that of the TIMED Doppler Interferometer-observed wind, which is dominated by a diurnal oscillation with downward phase progression at a rate of about 1.3 km/h. The occurrences of the E_s layers retrieved from fluctuations of the amplitude and excess phase of the GPS signal received by the FORMOSAT-3/COSMIC satellites during the GPS radio occultation (RO) process are compared with the shear zones of the radar-measured meteor wind and HWM07 wind. The result shows that almost all of the RO-retrieved E_s layers occur within the wind shear zones that favor the E_s layer formation based on the wind shear theory, suggesting that the primary physical process responsible for the E_s layer events retrieved from the scintillations of the GPS RO signal is very likely the plasma convergence effect of the neutral wind shear.

Su, C.; Chen, H.; Chu, Y.; Chung, M.; Kuong, R.; Lin, T.; Tzeng, K.; Wang, C; Wu, K.; Yang, K.;

Published by: Radio Science Published on: 08/2014

YEAR: 2014 DOI: 10.1002/2013RS005273

HWM07; radar meteor wind; tide

Meteor radar wind over Chung-Li (24.9 N, 121 E), Taiwan, for the period 10--25 November 2012 which includes Leonid meteor shower: Comparison with empirical model and satellite measurements

The neutral winds in the mesosphere and lower thermosphere (MLT) region are measured by a newly installed meteor trail detection system (or meteor radar) at Chung-Li, Taiwan, for the period 10\textendash25 November 2012, which includes the Leonid meteor shower period. In this study, we use the 3 m field-aligned plasma irregularities in the sporadic E (E_s) region in combination with the International Geomagnetic Reference Field model to calibrate the system phase biases such that the true positions of the meteor trails can be correctly determined with interferometry technique. The horizontal wind velocities estimated from the radial velocities of the meteor trails and their locations by using a least squares method show that the diurnal tide dominates the variation of the MLT neutral wind with time over Chung-Li, which is in good agreement with the horizontal wind model (HWM07) prediction. However, harmonic analysis reveals that the amplitudes of the mean wind, diurnal, and semidiurnal tides of the radar-measured winds in height range 82\textendash100 km are systematically larger than those of the model-predicted winds by up to a factor of 3. A comparison shows that the overall pattern of the height-local time distribution of the composite radar-measured meteor wind is, in general, consistent with that of the TIMED Doppler Interferometer-observed wind, which is dominated by a diurnal oscillation with downward phase progression at a rate of about 1.3 km/h. The occurrences of the E_s layers retrieved from fluctuations of the amplitude and excess phase of the GPS signal received by the FORMOSAT-3/COSMIC satellites during the GPS radio occultation (RO) process are compared with the shear zones of the radar-measured meteor wind and HWM07 wind. The result shows that almost all of the RO-retrieved E_s layers occur within the wind shear zones that favor the E_s layer formation based on the wind shear theory, suggesting that the primary physical process responsible for the E_s layer events retrieved from the scintillations of the GPS RO signal is very likely the plasma convergence effect of the neutral wind shear.

Su, C.; Chen, H.; Chu, Y.; Chung, M.; Kuong, R.; Lin, T.; Tzeng, K.; Wang, C; Wu, K.; Yang, K.;

Published by: Radio Science Published on: 08/2014

YEAR: 2014 DOI: 10.1002/2013RS005273

HWM07; radar meteor wind; tide

Effects of prolonged southward interplanetary magnetic field on low-latitude ionospheric electron density

The present work describes the low-latitude ionospheric variability during an unusually prolonged (~33 h) geomagnetically disturbed condition that prevailed during 15\textendash16 July 2012. The low-latitude electron density in summer hemisphere, investigated using ground- and satellite-based observations, responded to this by generating strong negative ionospheric storm on 16 July. The maximum electron density on 16 July over Indian low latitudes was reduced by more than 50\% compared to that on a geomagnetically quiet day (14 July 2012). In contrast to the extreme reduction in total electron content (TEC) in the Northern Hemisphere, TEC from a winter hemispheric station revealed substantial (~23 total electron content unit, 1 TECU = 10¹⁶ el m^-2) enhancements on the same day. This contrasting hemispherical response in TEC is suggested to be due to the combined effects of strong interhemispheric and solar-driven day-night winds. Further, very weak equatorial electrojet (EEJ) strength on 16 July indicated that the westward electric field perturbations in the low-latitude ionosphere were possibly due to the disturbance dynamo effect associated with meridional circulation from polar to equatorial latitudes. Interestingly, despite reduction in the integrated EEJ strength on 15 July, the low-latitude electron density showed substantial enhancement, highlighting the significant effect of the positive ionospheric storm on the low-latitude ionosphere. The roles of electrodynamical/neutral-dynamical and compositional disturbances are discussed in view of these observations to understand low-latitude ionospheric response when geomagnetic disturbance persists for longer duration.

Bagiya, Mala; Hazarika, Rumajyoti; Laskar, Fazlul; Sunda, Surendra; Gurubaran, S.; Chakrabarty, D.; Bhuyan, P.; Sridharan, R.; Veenadhari, B.; Pallamraju, D.;

Published by: Journal of Geophysical Research: Space Physics Published on: 07/2014

YEAR: 2014 DOI: 10.1002/2014JA020156

low-latitude ionosphere; neutral winds; prolonged southward IMF Bz; thermospheric neutral composition

Climatology of global gravity wave activity and dissipation revealed by SABER/TIMED temperature observations

Gravity wave activity and dissipation in the height range from the low stratosphere to the low thermosphere (25\textendash115 km) covering latitudes between 50\textdegreeS and 50\textdegreeN are statistically studied by using 9-year (January 22, 2002\textendashDecember 31, 2010) SABER/TIMED temperature data. We propose a method to extract realistic gravity wave fluctuations from the temperature profiles and treat square temperature fluctuations as GW activity. Overall, the gravity wave activity generally increases with height. Near the equator (0\textdegree\textendash10\textdegree), the gravity wave activity shows a quasi-biennial variation in the stratosphere (below 40 km) while from 20\textdegree to 30\textdegree, it exhibits an annual variation below 40 km; in low latitudes (0\textdegree\textendash30\textdegree) between the upper stratosphere and the low thermosphere (40\textendash115 km), the gravity wave activity shows a semi-annual variation. In middle latitudes (40\textdegree\textendash50\textdegree), the gravity wave activity has a clear annual variation below 85 km. In addition, we observe a four-monthly variation with peaks occurring usually in April, August, December in the northern hemisphere and in February, June, October in the southern hemisphere, respectively, above 85 km in middle latitudes, which has been seldom reported in gravity wave activity. In order to study the dissipation of gravity wave propagation, we calculate the gravity wave dissipation ratio, which is defined as the ratio of the gravity wave growth scale height to the atmosphere density scale height. The height variation of the dissipation ratio indicates that strong gravity wave dissipation mainly concentrates in the three height regions: the stratosphere (30\textendash60 km), the mesopause (around 85 km) and the low thermosphere (above 100 km). Besides, gravity wave energy enhancement can be also observed in the background atmosphere.

Shuai, Jing; Zhang, ShaoDong; Huang, ChunMing; YI, Fan; Huang, KaiMing; Gan, Quan; Gong, Yun;

Published by: Science China Technological Sciences Published on: 05/2014

YEAR: 2014 DOI: 10.1007/s11431-014-5527-z

climatology; dissipation; gravity wave; middle and high atmosphere; SABER; TIMED

Climatology of global gravity wave activity and dissipation revealed by SABER/TIMED temperature observations

Gravity wave activity and dissipation in the height range from the low stratosphere to the low thermosphere (25\textendash115 km) covering latitudes between 50\textdegreeS and 50\textdegreeN are statistically studied by using 9-year (January 22, 2002\textendashDecember 31, 2010) SABER/TIMED temperature data. We propose a method to extract realistic gravity wave fluctuations from the temperature profiles and treat square temperature fluctuations as GW activity. Overall, the gravity wave activity generally increases with height. Near the equator (0\textdegree\textendash10\textdegree), the gravity wave activity shows a quasi-biennial variation in the stratosphere (below 40 km) while from 20\textdegree to 30\textdegree, it exhibits an annual variation below 40 km; in low latitudes (0\textdegree\textendash30\textdegree) between the upper stratosphere and the low thermosphere (40\textendash115 km), the gravity wave activity shows a semi-annual variation. In middle latitudes (40\textdegree\textendash50\textdegree), the gravity wave activity has a clear annual variation below 85 km. In addition, we observe a four-monthly variation with peaks occurring usually in April, August, December in the northern hemisphere and in February, June, October in the southern hemisphere, respectively, above 85 km in middle latitudes, which has been seldom reported in gravity wave activity. In order to study the dissipation of gravity wave propagation, we calculate the gravity wave dissipation ratio, which is defined as the ratio of the gravity wave growth scale height to the atmosphere density scale height. The height variation of the dissipation ratio indicates that strong gravity wave dissipation mainly concentrates in the three height regions: the stratosphere (30\textendash60 km), the mesopause (around 85 km) and the low thermosphere (above 100 km). Besides, gravity wave energy enhancement can be also observed in the background atmosphere.

Shuai, Jing; Zhang, ShaoDong; Huang, ChunMing; YI, Fan; Huang, KaiMing; Gan, Quan; Gong, Yun;

Published by: Science China Technological Sciences Published on: 05/2014

YEAR: 2014 DOI: 10.1007/s11431-014-5527-z

climatology; dissipation; gravity wave; middle and high atmosphere; SABER; TIMED

Climatology of global gravity wave activity and dissipation revealed by SABER/TIMED temperature observations

Gravity wave activity and dissipation in the height range from the low stratosphere to the low thermosphere (25\textendash115 km) covering latitudes between 50\textdegreeS and 50\textdegreeN are statistically studied by using 9-year (January 22, 2002\textendashDecember 31, 2010) SABER/TIMED temperature data. We propose a method to extract realistic gravity wave fluctuations from the temperature profiles and treat square temperature fluctuations as GW activity. Overall, the gravity wave activity generally increases with height. Near the equator (0\textdegree\textendash10\textdegree), the gravity wave activity shows a quasi-biennial variation in the stratosphere (below 40 km) while from 20\textdegree to 30\textdegree, it exhibits an annual variation below 40 km; in low latitudes (0\textdegree\textendash30\textdegree) between the upper stratosphere and the low thermosphere (40\textendash115 km), the gravity wave activity shows a semi-annual variation. In middle latitudes (40\textdegree\textendash50\textdegree), the gravity wave activity has a clear annual variation below 85 km. In addition, we observe a four-monthly variation with peaks occurring usually in April, August, December in the northern hemisphere and in February, June, October in the southern hemisphere, respectively, above 85 km in middle latitudes, which has been seldom reported in gravity wave activity. In order to study the dissipation of gravity wave propagation, we calculate the gravity wave dissipation ratio, which is defined as the ratio of the gravity wave growth scale height to the atmosphere density scale height. The height variation of the dissipation ratio indicates that strong gravity wave dissipation mainly concentrates in the three height regions: the stratosphere (30\textendash60 km), the mesopause (around 85 km) and the low thermosphere (above 100 km). Besides, gravity wave energy enhancement can be also observed in the background atmosphere.

Shuai, Jing; Zhang, ShaoDong; Huang, ChunMing; YI, Fan; Huang, KaiMing; Gan, Quan; Gong, Yun;

Published by: Science China Technological Sciences Published on: 05/2014

YEAR: 2014 DOI: 10.1007/s11431-014-5527-z

climatology; dissipation; gravity wave; middle and high atmosphere; SABER; TIMED

Strong ionospheric field-aligned currents for radial interplanetary magnetic fields

The present work has investigated the configuration of field-aligned currents (FACs) during a long period of radial interplanetary magnetic field (IMF) on 19 May 2002 by using high-resolution and precise vector magnetic field measurements of CHAMP satellite. During the interest period IMF B_y and B_z are weakly positive and B_x keeps pointing to the Earth for almost 10 h. The geomagnetic indices Dst is about -40 nT and AE about 100 nT on average. The cross polar cap potential calculated from Assimilative Mapping of Ionospheric Electrodynamics and derived from DMSP observations have average values of 10\textendash20 kV. Obvious hemispheric differences are shown in the configurations of FACs on the dayside and nightside. At the south pole FACs diminish in intensity to magnitudes of about 0.1 μA/m², the plasma convection maintains two-cell flow pattern, and the thermospheric density is quite low. However, there are obvious activities in the northern cusp region. One pair of FACs with a downward leg toward the pole and upward leg on the equatorward side emerge in the northern cusp region, exhibiting opposite polarity to FACs typical for duskward IMF orientation. An obvious sunward plasma flow channel persists during the whole period. These ionospheric features might be manifestations of an efficient magnetic reconnection process occurring in the northern magnetospheric flanks at high latitude. The enhanced ionospheric current systems might deposit large amount of Joule heating into the thermosphere. The air densities in the cusp region get enhanced and subsequently propagate equatorward on the dayside. Although geomagnetic indices during the radial IMF indicate low-level activity, the present study demonstrates that there are prevailing energy inputs from the magnetosphere to both the ionosphere and thermosphere in the northern polar cusp region.

Wang, Hui; Lühr, Hermann; Shue, Jih-Hong; Frey, Harald.; Kervalishvili, Guram; Huang, Tao; Cao, Xue; Pi, Gilbert; Ridley, Aaron;

Published by: Journal of Geophysical Research: Space Physics Published on: 05/2014

YEAR: 2014 DOI: 10.1002/2014JA019951

air upwelling; field-aligned currents; radial interplanetary magnetic field

Strong ionospheric field-aligned currents for radial interplanetary magnetic fields

The present work has investigated the configuration of field-aligned currents (FACs) during a long period of radial interplanetary magnetic field (IMF) on 19 May 2002 by using high-resolution and precise vector magnetic field measurements of CHAMP satellite. During the interest period IMF B_y and B_z are weakly positive and B_x keeps pointing to the Earth for almost 10 h. The geomagnetic indices Dst is about -40 nT and AE about 100 nT on average. The cross polar cap potential calculated from Assimilative Mapping of Ionospheric Electrodynamics and derived from DMSP observations have average values of 10\textendash20 kV. Obvious hemispheric differences are shown in the configurations of FACs on the dayside and nightside. At the south pole FACs diminish in intensity to magnitudes of about 0.1 μA/m², the plasma convection maintains two-cell flow pattern, and the thermospheric density is quite low. However, there are obvious activities in the northern cusp region. One pair of FACs with a downward leg toward the pole and upward leg on the equatorward side emerge in the northern cusp region, exhibiting opposite polarity to FACs typical for duskward IMF orientation. An obvious sunward plasma flow channel persists during the whole period. These ionospheric features might be manifestations of an efficient magnetic reconnection process occurring in the northern magnetospheric flanks at high latitude. The enhanced ionospheric current systems might deposit large amount of Joule heating into the thermosphere. The air densities in the cusp region get enhanced and subsequently propagate equatorward on the dayside. Although geomagnetic indices during the radial IMF indicate low-level activity, the present study demonstrates that there are prevailing energy inputs from the magnetosphere to both the ionosphere and thermosphere in the northern polar cusp region.

Wang, Hui; Lühr, Hermann; Shue, Jih-Hong; Frey, Harald.; Kervalishvili, Guram; Huang, Tao; Cao, Xue; Pi, Gilbert; Ridley, Aaron;

Published by: Journal of Geophysical Research: Space Physics Published on: 05/2014

YEAR: 2014 DOI: 10.1002/2014JA019951

air upwelling; field-aligned currents; radial interplanetary magnetic field

Ionization due to electron and proton precipitation during the August 2011 storm

The parameterizations of monoenergetic particle impact ionization in Fang et al. (2010) (Fang2010) and Fang et al. (2013) (Fang2013) are applied to the complex energy spectra measured by DMSP F16 satellite to calculate the ionization rates from electron and ion precipitations for a Northern Hemisphere pass from 0030 UT to 0106 UT on 6 August 2011. Clear enhancement of electron flux is found in the polar cap. The mean electron energy in the polar cap is mostly above 100 eV, while the mean energy in the auroral zone is typically above 1 keV. At the same time, F16 captures a strong Poynting flux enhancement in the polar cap, which is comparable to those in the auroral zone. The particle impact ionization rates using Fang2010 and Fang2013 parameterizations show clear enhancement at F region altitudes mainly due to the low-energy precipitating electrons, peaking probably in the cusp but also showing enhanced levels throughout most of the polar cap region. The general circulation models (GCMs), National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model, and Global Ionosphere-Thermosphere Model, using their default empirical formulations of particle impact ionization, do not capture the observed features shown in the total particle ionization rate applying the Fang2010 and Fang2013 parameterizations to DMSP measurements. The difference between GCM simulations and Fang2010 and Fang2013 applied to DMSP data is due to the difference of both the inputs to the models and the parameterization of the ionization rates.

Huang, Yanshi; Huang, Cheryl; Su, Yi-Jiun; Deng, Yue; Fang, Xiaohua;

Published by: Journal of Geophysical Research: Space Physics Published on: 04/2014

YEAR: 2014 DOI: 10.1002/2013JA019671

Fang 2010 parameterization; Fang 2013 parameterization; particle impact ionization; polar cap

Ionization due to electron and proton precipitation during the August 2011 storm

The parameterizations of monoenergetic particle impact ionization in Fang et al. (2010) (Fang2010) and Fang et al. (2013) (Fang2013) are applied to the complex energy spectra measured by DMSP F16 satellite to calculate the ionization rates from electron and ion precipitations for a Northern Hemisphere pass from 0030 UT to 0106 UT on 6 August 2011. Clear enhancement of electron flux is found in the polar cap. The mean electron energy in the polar cap is mostly above 100 eV, while the mean energy in the auroral zone is typically above 1 keV. At the same time, F16 captures a strong Poynting flux enhancement in the polar cap, which is comparable to those in the auroral zone. The particle impact ionization rates using Fang2010 and Fang2013 parameterizations show clear enhancement at F region altitudes mainly due to the low-energy precipitating electrons, peaking probably in the cusp but also showing enhanced levels throughout most of the polar cap region. The general circulation models (GCMs), National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model, and Global Ionosphere-Thermosphere Model, using their default empirical formulations of particle impact ionization, do not capture the observed features shown in the total particle ionization rate applying the Fang2010 and Fang2013 parameterizations to DMSP measurements. The difference between GCM simulations and Fang2010 and Fang2013 applied to DMSP data is due to the difference of both the inputs to the models and the parameterization of the ionization rates.

Huang, Yanshi; Huang, Cheryl; Su, Yi-Jiun; Deng, Yue; Fang, Xiaohua;

Published by: Journal of Geophysical Research: Space Physics Published on: 04/2014

YEAR: 2014 DOI: 10.1002/2013JA019671

Fang 2010 parameterization; Fang 2013 parameterization; particle impact ionization; polar cap

The variations of geomagnetic energy and solar irradiance and their impacts on Earth s upper atmosphere

The primary energy sources of Earth s upper atmosphere are the solar irradiance and geomagnetic energy including Joule heating and particle precipitation. Various data and models

Huang, Yanshi;

Published by: Published on:

YEAR: 2014 DOI:

Mars Reconnaissance Orbiter observation of Comet C/2013 A1 (Siding Spring)

Tamppari, Leslie; Zurek, Richard; Cantor, Bruce; Delamere, WA; Egan, Anthony; Humm, David; Kass, David; McEwen, Alfred; McGovern, Andy; Phillips, Roger; , others;