Bibliography

The investigation on daytime conjugate hemispheric asymmetry along 100°E longitude using observations and model simulations: New insights

The hemispherical asymmetry of the low latitude region along 100°E ± 5°E is scrutinized for the year 2015 at magnetically conjugate points on seasonal and intra-seasonal time scales. Two conjugate Ionosonde station pairs are selected- one pair in the inner valley (from SEALION) and the other in the outer edges of the EIA region. The anomaly in the stations is estimated using the difference of low latitude NmF2 from the dip equatorial NmF2 in the same meridian. A monthly average scheme is used instead of a seasonal mean, as the month-to-month variations are found to provide intricate details. The anomaly at the conjugate stations is highly asymmetric even during the equinoctial months of March and October, whereas it is nearly symmetric during April. During June/July, the morning time hemispheric asymmetry (larger on the winter side) temporarily reduces in the midday period and then reverses sign (larger in summer) in the afternoon. The NmF2 observations suggest a close relation of hemispheric symmetry to the position of the subsolar point with respect to the dip equator and a shift/expansion of the trough region of the EIA towards the summer hemisphere. The inter-hemispheric comparison of the hmF2 suggests a strong modulating influence of meridional winds at both the inner and outer stations which depend strongly on the relative position of the subsolar point with respect to the field line geometry. Theoretical (SAMI3/SAMI2) and empirical model (IRI) simulations show a meridional movement of the EIA region with the subsolar point. The winter to summer hemisphere movement of the EIA trough and crest region is also reproduced in the GIM-TEC along 100°E for 2015. This shifting or tailoring of the trough and the crest region is attributed primarily to the meridional wind field, which varies with the shifting position of subsolar point relative to the field line geometry. The seasonal and intra-seasonal difference in the NmF2 hemispheric asymmetry is attributed to the misalignment of the two centers of power viz., the thermospheric/neutral processes and the electromagnetic forces, due to the geographic-geomagnetic offset in this longitude.

Kalita, B.; Bhuyan, P.; Nath, S.; Choudhury, M.; Chakrabarty, D.; Wang, K.; Hozumi, K.; Supnithi, P.; Komolmis, T.; . Y. Yatini, C; Le Huy, M.;

Published by: Advances in Space Research      Published on: may

YEAR: 2022     DOI: 10.1016/j.asr.2022.02.058

NmF2; asymmetry; Conjugate; EIA; model; Hemisphere; hmF2; Subsolar

The investigation on daytime conjugate hemispheric asymmetry along 100°E longitude using observations and model simulations: New insights

The hemispherical asymmetry of the low latitude region along 100°E ± 5°E is scrutinized for the year 2015 at magnetically conjugate points on seasonal and intra-seasonal time scales. Two conjugate Ionosonde station pairs are selected- one pair in the inner valley (from SEALION) and the other in the outer edges of the EIA region. The anomaly in the stations is estimated using the difference of low latitude NmF2 from the dip equatorial NmF2 in the same meridian. A monthly average scheme is used instead of a seasonal mean, as the month-to-month variations are found to provide intricate details. The anomaly at the conjugate stations is highly asymmetric even during the equinoctial months of March and October, whereas it is nearly symmetric during April. During June/July, the morning time hemispheric asymmetry (larger on the winter side) temporarily reduces in the midday period and then reverses sign (larger in summer) in the afternoon. The NmF2 observations suggest a close relation of hemispheric symmetry to the position of the subsolar point with respect to the dip equator and a shift/expansion of the trough region of the EIA towards the summer hemisphere. The inter-hemispheric comparison of the hmF2 suggests a strong modulating influence of meridional winds at both the inner and outer stations which depend strongly on the relative position of the subsolar point with respect to the field line geometry. Theoretical (SAMI3/SAMI2) and empirical model (IRI) simulations show a meridional movement of the EIA region with the subsolar point. The winter to summer hemisphere movement of the EIA trough and crest region is also reproduced in the GIM-TEC along 100°E for 2015. This shifting or tailoring of the trough and the crest region is attributed primarily to the meridional wind field, which varies with the shifting position of subsolar point relative to the field line geometry. The seasonal and intra-seasonal difference in the NmF2 hemispheric asymmetry is attributed to the misalignment of the two centers of power viz., the thermospheric/neutral processes and the electromagnetic forces, due to the geographic-geomagnetic offset in this longitude.

Kalita, B.; Bhuyan, P.; Nath, S.; Choudhury, M.; Chakrabarty, D.; Wang, K.; Hozumi, K.; Supnithi, P.; Komolmis, T.; . Y. Yatini, C; Le Huy, M.;

Published by: Advances in Space Research      Published on: may

YEAR: 2022     DOI: 10.1016/j.asr.2022.02.058

NmF2; asymmetry; Conjugate; EIA; model; Hemisphere; hmF2; Subsolar

The investigation on daytime conjugate hemispheric asymmetry along 100°E longitude using observations and model simulations: New insights

The hemispherical asymmetry of the low latitude region along 100°E ± 5°E is scrutinized for the year 2015 at magnetically conjugate points on seasonal and intra-seasonal time scales. Two conjugate Ionosonde station pairs are selected- one pair in the inner valley (from SEALION) and the other in the outer edges of the EIA region. The anomaly in the stations is estimated using the difference of low latitude NmF2 from the dip equatorial NmF2 in the same meridian. A monthly average scheme is used instead of a seasonal mean, as the month-to-month variations are found to provide intricate details. The anomaly at the conjugate stations is highly asymmetric even during the equinoctial months of March and October, whereas it is nearly symmetric during April. During June/July, the morning time hemispheric asymmetry (larger on the winter side) temporarily reduces in the midday period and then reverses sign (larger in summer) in the afternoon. The NmF2 observations suggest a close relation of hemispheric symmetry to the position of the subsolar point with respect to the dip equator and a shift/expansion of the trough region of the EIA towards the summer hemisphere. The inter-hemispheric comparison of the hmF2 suggests a strong modulating influence of meridional winds at both the inner and outer stations which depend strongly on the relative position of the subsolar point with respect to the field line geometry. Theoretical (SAMI3/SAMI2) and empirical model (IRI) simulations show a meridional movement of the EIA region with the subsolar point. The winter to summer hemisphere movement of the EIA trough and crest region is also reproduced in the GIM-TEC along 100°E for 2015. This shifting or tailoring of the trough and the crest region is attributed primarily to the meridional wind field, which varies with the shifting position of subsolar point relative to the field line geometry. The seasonal and intra-seasonal difference in the NmF2 hemispheric asymmetry is attributed to the misalignment of the two centers of power viz., the thermospheric/neutral processes and the electromagnetic forces, due to the geographic-geomagnetic offset in this longitude.

Kalita, B.; Bhuyan, P.; Nath, S.; Choudhury, M.; Chakrabarty, D.; Wang, K.; Hozumi, K.; Supnithi, P.; Komolmis, T.; . Y. Yatini, C; Le Huy, M.;

Published by: Advances in Space Research      Published on: may

YEAR: 2022     DOI: 10.1016/j.asr.2022.02.058

NmF2; asymmetry; Conjugate; EIA; model; Hemisphere; hmF2; Subsolar

Measurement of the vertical atmospheric density profile from the X-ray Earth occultation of the Crab Nebula with Insight-HXMT

\textlessp\textgreater\textlessstrong class="journal-contentHeaderColor"\textgreaterAbstract.\textless/strong\textgreater X-ray Earth occultation sounding (XEOS) is an emerging method for measuring the neutral density in the lower thermosphere. In this paper, the X-ray Earth occultation (XEO) of the Crab Nebula is investigated using the Hard X-ray Modulation Telescope (Insight-HXMT). The pointing observation data on the 30 September 2018 recorded by the low-energy X-ray telescope (LE) of Insight-HXMT are selected and analysed. The extinction light curves and spectra during the X-ray Earth occultation process are extracted. A forward model for the XEO light curve is established, and the theoretical observational signal for light curve is predicted. The atmospheric density model is built with a scale factor to the commonly used Mass Spectrometer Incoherent Scatter Radar Extended model (MSIS) density profile within a certain altitude range. A Bayesian data analysis method is developed for the XEO light curve modelling and the atmospheric density retrieval. The posterior probability distribution of the model parameters is derived through the Markov chain–Monte Carlo (MCMC) algorithm with the NRLMSISE-00 model and the NRLMSIS 2.0 model as basis functions, and the respective best-fit density profiles are retrieved. It is found that in the altitude range of 105–200 km, the retrieved density profile is 88.8 \% of the density of NRLMSISE-00 and 109.7 \% of the density of NRLMSIS 2.0 by fitting the light curve in the energy range of 1.0–2.5 keV based on the XEOS method. In the altitude range of 95–125 km, the retrieved density profile is 81.0 \% of the density of NRLMSISE-00 and 92.3 \% of the density of NRLMSIS 2.0 by fitting the light curve in the energy range of 2.5–6.0 keV based on the XEOS method. In the altitude range of 85–110 km, the retrieved density profile is 87.7 \% of the density of NRLMSISE-00 and 101.4 \% of the density of NRLMSIS 2.0 by fitting the light curve in the energy range of 6.0–10.0 keV based on the XEOS method. Goodness-of-fit testing is carried out for the validation of the results. The measurements of density profiles are compared to the NRLMSISE-00 and NRLMSIS 2.0 model simulations and the previous retrieval results with NASA s Rossi X-ray Timing Explorer (RXTE) satellite. For further confirmation, we also compare the measured density profile to the ones by a standard spectrum retrieval method with an iterative inversion technique. Finally, we find that the retrieved density profile from Insight-HXMT based on the NRLMSISE-00 and NRLMSIS 2.0 models is qualitatively consistent with the previous retrieved results from RXTE. The results of light curve fitting and standard energy spectrum fitting are in good agreement. This research provides a method for the evaluation of the density profiles from MSIS model predictions. This study demonstrates that the XEOS from the X-ray astronomical satellite Insight-HXMT can provide an approach for the study of the upper atmosphere. The Insight-HXMT satellite can join the family of the XEOS. The Insight-HXMT satellite with other X-ray astronomical satellites in orbit can form a space observation network for XEOS in the future.\textless/p\textgreater

Yu, Daochun; Li, Haitao; Li, Baoquan; Ge, Mingyu; Tuo, Youli; Li, Xiaobo; Xue, Wangchen; Liu, Yaning; Wang, Aoying; Zhu, Yajun; Luo, Bingxian;

Published by: Atmospheric Measurement Techniques      Published on: may

YEAR: 2022     DOI: 10.5194/amt-15-3141-2022

Far-ultraviolet airglow remote sensing measurements on Feng Yun 3-D meteorological satellite

\textlessp\textgreater\textlessstrong class="journal-contentHeaderColor"\textgreaterAbstract.\textless/strong\textgreater The Ionospheric Photometer (IPM) is carried on the Feng Yun 3-D (FY3D) meteorological satellite, which allows for the measurement of far-ultraviolet (FUV) airglow radiation in the thermosphere. IPM is a compact and high-sensitivity nadir-viewing FUV remote sensing instrument. It monitors 135.6 nm emission in the nightside thermosphere and 135.6 nm and N\textlessspan class="inline-formula"\textgreater$_\textrm2$\textless/span\textgreater Lyman–Birge–Hopfield (LBH) emissions in the dayside thermosphere that can be used to invert the peak electron density of the F\textlessspan class="inline-formula"\textgreater$_\textrm2$\textless/span\textgreater layer (NmF\textlessspan class="inline-formula"\textgreater$_\textrm2$)\textless/span\textgreater at night and the \textlessspan class="inline-formula"\textgreater\textlessmath xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"\textgreater\textlessmrow class="chem"\textgreater\textlessmi mathvariant="normal"\textgreaterO\textless/mi\textgreater\textlessmo\textgreater/\textless/mo\textgreater\textlessmi mathvariant="normal"\textgreaterN\textless/mi\textgreater\textless/mrow\textgreater\textless/math\textgreater\textlessspan\textgreater\textlesssvg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="73a3f14187048fa14eee70dd1027ad23"\textgreater\textlesssvg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-15-1577-2022-ie00001.svg" width="25pt" height="14pt" src="amt-15-1577-2022-ie00001.png"/\textgreater\textless/svg:svg\textgreater\textless/span\textgreater\textless/span\textgreater\textlessspan class="inline-formula"\textgreater$_\textrm2$\textless/span\textgreater ratio in the daytime, respectively. Preliminary observations show that the IPM could monitor the global structure of the equatorial ionization anomaly (EIA) structure around 02:00 LT using atomic oxygen (OI) 135.6 nm nightglow. It could also identify the reduction of \textlessspan class="inline-formula"\textgreater\textlessmath xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"\textgreater\textlessmrow class="chem"\textgreater\textlessmi mathvariant="normal"\textgreaterO\textless/mi\textgreater\textlessmo\textgreater/\textless/mo\textgreater\textlessmi mathvariant="normal"\textgreaterN\textless/mi\textgreater\textless/mrow\textgreater\textless/math\textgreater\textlessspan\textgreater\textlesssvg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="7662cd64e23809d534f2b5721e55261b"\textgreater\textlesssvg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-15-1577-2022-ie00002.svg" width="25pt" height="14pt" src="amt-15-1577-2022-ie00002.png"/\textgreater\textless/svg:svg\textgreater\textless/span\textgreater\textless/span\textgreater\textlessspan class="inline-formula"\textgreater$_\textrm2$\textless/span\textgreater in the high-latitude region during the geomagnetic storm of 26 August 2018. The IPM-derived NmF\textlessspan class="inline-formula"\textgreater$_\textrm2$\textless/span\textgreater agrees well with that observed by four ionosonde stations along 120\textlessspan class="inline-formula"\textgreater$^\textrm∘$\textless/span\textgreater E with a standard deviation of 26.67 \%. Initial results demonstrate that the performance of IPM meets the design requirements and therefore can be used to study the thermosphere and ionosphere in the future.\textless/p\textgreater

Wang, Yungang; Fu, Liping; Jiang, Fang; Hu, Xiuqing; Liu, Chengbao; Zhang, Xiaoxin; Li, JiaWei; Ren, Zhipeng; He, Fei; Sun, Lingfeng; Sun, Ling; Yang, Zhongdong; Zhang, Peng; Wang, Jingsong; Mao, Tian;

Published by: Atmospheric Measurement Techniques      Published on: mar

YEAR: 2022     DOI: 10.5194/amt-15-1577-2022

Local Persistent Ionospheric Positive Responses to the Geomagnetic Storm in August 2018 Using BDS-GEO Satellites over Low-Latitude Regions in Eastern Hemisphere

We present the ionospheric disturbance responses over low-latitude regions by using total electron content from Geostationary Earth Orbit (GEO) satellites of the BeiDou Navigation Satellite System (BDS), ionosonde data and Swarm satellite data, during the geomagnetic storm in August 2018. The results show that a prominent total electron content (TEC) enhancement over low-latitude regions is observed during the main phase of the storm. There is a persistent TEC increase lasting for about 1–2 days and a moderately positive disturbance response during the recovery phase on 27–28 August, which distinguishes from the general performance of ionospheric TEC in the previous storms. We also find that this phenomenon is a unique local-area disturbance of the ionosphere during the recovery phase of the storm. The enhanced foF2 and hmF2 of the ionospheric F2 layer is observed by SANYA and LEARMONTH ionosonde stations during the recovery phase. The electron density from Swarm satellites shows a strong equatorial ionization anomaly (EIA) crest over the low-latitude area during the main phase of storm, which is simultaneous with the uplift of the ionospheric F2 layer from the SANYA ionosonde. Meanwhile, the thermosphere O/N2 ratio shows a local increase on 27–28 August over low-latitude regions. From the above results, this study suggests that the uplift of F layer height and the enhanced O/N2 ratio are possibly main factors causing the local-area positive disturbance responses during the recovery phase of the storm in August 2018.

Tang, Jun; Gao, Xin; Yang, Dengpan; Zhong, Zhengyu; Huo, Xingliang; Wu, Xuequn;

Published by: Remote Sensing      Published on: jan

YEAR: 2022     DOI: 10.3390/rs14092272

BDS-GEO; differential code biases; geomagnetic storm; Ionospheric disturbance; TEC

Analytic and numerical methods for the Abel transform of exponential functions for planetary and cometary atmospheres

Line-of-sight integration of emissions from planetary and cometary atmospheres is the Abel transform of the emission rate, under the spherical symmetry assumption. Indefinite integrals constructed from the Abel transform integral are useful for implementing remote sensing data analysis methods, such as the numerical inverse Abel transform. We propose analytical expressions obtained by a suitable, non-alternating, series development to compute those indefinite integrals. We establish expressions allowing absolute accuracy control of the convergence of these series and illustrate how this accuracy depends on the number of terms involved in the series computation. We compare the analytical method with numerical computation techniques, which are found to be sufficiently accurate as well. Inverse Abel transform fitting is then tested in order to establish that the expected emission rate profiles can be retrieved from the observation of both planetary and cometary atmospheres. We show that the method is robust, i.e. that it can be applied even when the properties of the observed atmosphere depart from the assumed ones, especially when Tikhonov regularization is included. A first application is conducted over observation of comet 46P/Wirtanen, showing some variability, possibly attributable to an evolution of the contamination by dust and icy grains.

Hubert, B.; Munhoven, G.; Moulane, Y.; Hutsemekers, D.; Manfroid, J.; Opitom, C.; Jehin, E.;

Published by: Icarus      Published on: jan

YEAR: 2022     DOI: 10.1016/j.icarus.2021.114654

Abel transform; Aeronomy; Coma; Cometary atmospheres; Comets; Data reduction techniques; Planetary atmospheres.

Analytic and numerical methods for the Abel transform of exponential functions for planetary and cometary atmospheres

Line-of-sight integration of emissions from planetary and cometary atmospheres is the Abel transform of the emission rate, under the spherical symmetry assumption. Indefinite integrals constructed from the Abel transform integral are useful for implementing remote sensing data analysis methods, such as the numerical inverse Abel transform. We propose analytical expressions obtained by a suitable, non-alternating, series development to compute those indefinite integrals. We establish expressions allowing absolute accuracy control of the convergence of these series and illustrate how this accuracy depends on the number of terms involved in the series computation. We compare the analytical method with numerical computation techniques, which are found to be sufficiently accurate as well. Inverse Abel transform fitting is then tested in order to establish that the expected emission rate profiles can be retrieved from the observation of both planetary and cometary atmospheres. We show that the method is robust, i.e. that it can be applied even when the properties of the observed atmosphere depart from the assumed ones, especially when Tikhonov regularization is included. A first application is conducted over observation of comet 46P/Wirtanen, showing some variability, possibly attributable to an evolution of the contamination by dust and icy grains.

Hubert, B.; Munhoven, G.; Moulane, Y.; Hutsemekers, D.; Manfroid, J.; Opitom, C.; Jehin, E.;

Published by: Icarus      Published on: jan

YEAR: 2022     DOI: 10.1016/j.icarus.2021.114654

Abel transform; Aeronomy; Coma; Cometary atmospheres; Comets; Data reduction techniques; Planetary atmospheres.

Responses of Mesosphere and Lower Thermosphere Temperature to the Geomagnetic Storm on 7–8 September 2017

The variations of neutral temperature in the mesosphere and lower thermosphere (MLT) region, during the 7–8 September 2017 intense geomagnetic storm, are studied using observations by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite. They are also studied using simulations by the Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIMEGCM). The neutral temperature data cover the altitudes from 80 km to 110 km between 83° N and 52° S latitude, obtained from both SABER observations and model simulations. The SABER observations reveal that temperature increases (the maximum increase is larger than 35 K at \textasciitilde108 km) and decreases (the maximum decrease is larger than 20 K at \textasciitilde105 km) during the geomagnetic storm. The storm effects penetrate down to \textasciitilde80 km. In observations, temperature variations corresponding to the storm show hemispheric asymmetry. That is, the variations of temperature are more prominent in the northern hemisphere than in the southern hemisphere. Conversely, the TIMEGCM outputs agree with the observations in general but overestimate the temperature increases and underestimate the temperature decreases at high and middle latitudes. Meanwhile, the simulations show stronger temperature decreases and weaker temperature increases than observations at low latitudes. After analyzing the temperature variations, we suggest that vertical winds may play an important role in inducing these significant variations of temperature in the MLT region.

Sun, Meng; Li, Zheng; Li, Jingyuan; Lu, Jianyong; Gu, Chunli; Zhu, Mengbin; Tian, Yufeng;

Published by: Universe      Published on: feb

YEAR: 2022     DOI: 10.3390/universe8020096

geomagnetic storm; temperature; the mesosphere and lower thermosphere (MLT); TIMEGCM

FUV observations of variations in thermospheric composition and topside ionospheric density during the November 2004 magnetic superstorm

We revisited the November 2004 superstorm by analyzing TIMED/GUVI data. The 135.6 nm limb radiances at 520-km are mainly due to the O+ and electron radiative recombination and represent the daytime ionosphere density at the altitude. The 135.6 nm radiances clearly showed a signature of ionospheric equatorial arcs and their variations during the November 2004 magnetic superstorm. When an intense eastward Interplanetary Electric Field (IEF) occurred, the dayside equatorial arcs were enhanced and their latitude separation increased. The enhanced equatorial arcs were hemispherically symmetric or asymmetric in the region with non-depleted O/N2 or hemispherically asymmetric O/N2 depletion, respectively. When O/N2 depletion reached the magnetic equator, there was no observable enhancement in the equatorial arcs regardless the IEF conditions, indicating O/N2 condition significantly modulated the variations in storm-time equatorial arcs. GUVI observations also showed that a westward IEF and/or disturbance dynamo electric field could also suppress the dayside equatorial arcs.

Zhang, Yongliang; Paxton, LarryJ.; Huang, Chaosong; Wang, Wenbin;

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

YEAR: 2022     DOI: 10.1016/j.jastp.2022.105832

geomagnetic storm; penetration electric field; Thermosperic composition; topside ionosphere

Multiresolution Data Assimilation for Auroral Energy Flux and Mean Energy Using DMSP SSUSI, THEMIS ASI, and An Empirical Model

We apply a multiresolution Gaussian process model (Lattice Kriging) to combine satellite observations, ground‐based observations, and an empirical auroral model, to produce the

Wu, Haonan; Tan, Xiyan; Zhang, Qiong; Huang, Whitney; Lu, Xian; Nishimura, Yukitoshi; Zhang, Yongliang;

Published by: Space Weather      Published on:

YEAR: 2022     DOI: 10.1029/2022SW003146

Sounding Rocket Observation of Nitric Oxide in the Polar Night

An altitude profile of Nitric Oxide (NO) in the 80–110 km altitude range was measured in the polar night from a sounding rocket on 27 January 2020. The observations were made using the technique of stellar occultation with a UV spectrograph observing the γ (1,0) band of NO near 215 nm. The tangent point for the altitude profile was at 74° latitude, a location that had been in darkness for 80 days. The retrieved slant column density profile is interpreted using an assumed four-parameter analytic profile shape. Retrievals of the fitting parameters yield a profile with a peak NO concentration of 2.2 ± 0.7 × 108 cm−3 at 93.5 ± 4.1 km. The observations were made during a time of minimum solar and geomagnetic activity. The NO maximum retrieved from the rocket profile is significantly larger in abundance and lower in altitude than other observations on the same day at nearby latitudes just outside the polar night. These rocket-borne results are consistent with NO that is created over the course over the polar winter and is confined to high latitudes in the polar night by the mesospheric polar vortex. During the course of that confinement the abundance increases due to the lack of photodissociation, allowing the NO to descend. We show that the observed descent can be explained by eddy diffusion-driven transport, though vertical advection cannot be ruled out.

Bailey, Scott; McClintock, William; Carstens, Justin; Thurairajah, Brentha; Das, Saswati; Randall, Cora; Harvey, Lynn; Siskind, David; Stevens, Michael; Venkataramani, Karthik;

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

YEAR: 2022     DOI: 10.1029/2021JA030257

Lower thermosphere; mesosphere; nitric oxide; polar night; sounding rocket; stellar occultation

Temporal Evolution of Low-Latitude Plasma Blobs Identified From Multiple Measurements: ICON, GOLD, and Madrigal TEC

Low-latitude plasma blobs have been studied since their first being reported in 1986. However, investigations on temporal evolution of a blob or on continental scale (\textgreater2,000 km) ionospheric contexts around it are relatively rare. Overcoming these limitations can help elucidate the blob generation mechanisms. On 21 January 2021, the Ionospheric Connection Explorer satellite encountered a typical low-latitude blob near the northeastern coast of South America. The event was collocated with a local enhancement in 135.6 nm nightglow at the poleward edge of an equatorial plasma bubble (EPB), as observed by the Global-scale Observations of the Limb and Disk (GOLD) imager. Total electron content maps from the Global Navigation Satellite System confirm the GOLD observations. Unlike typical medium-scale traveling ionospheric disturbances (MSTIDs), the blob had neither well-organized wavefronts nor moved in the southwest direction. Neither was the blob a monotonically decaying equatorial ionization anomaly crest past sunset. Rather, the blob varied following latitudinal expansion/contraction of EPBs at similar magnetic longitudes. The observational results support that mechanisms other than MSTIDs, such as EPBs, can also contribute to blob generation.

Park, Jaeheung; Huang, Chao-Song; Eastes, Richard; Coster, Anthea;

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

YEAR: 2022     DOI: 10.1029/2021JA029992

GOLD; ICON; low-latitude plasma blob; Madrigal TEC

Impact of Soft Electron Precipitation on the Thermospheric Neutral Mass Density During Geomagnetic Storms: GITM Simulations

In this study, the impact of improving soft (0.1–1 keV) electron precipitation on the F-region neutral mass density has been evaluated using the Global Ionosphere Thermosphere Model (GITM). Two types of electron energy spectra having the same total energy flux and average energy but different spectral shapes have been used to specify the electron precipitation in GITM. One is the Maxwellian spectrum and the other is from an empirical model, Auroral Spectrum and High-Latitude Electric field variabilitY (ASHLEY), which provides stronger (up to 2–3 orders of magnitude) soft electron precipitations than the Maxwellian spectrum. Data-model comparisons indicate that the storm-time orbital averaged neutral density can be increased by 10\%–40\% and is more consistent with the observation if the non-Maxwellian ASHLEY spectrum is used. This study reveals the importance of accurate soft electron precipitation specifications in the whole auroral zone to improving the F-region neutral mass density estimations.

Zhu, Qingyu; Deng, Yue; Sheng, Cheng; Anderson, Philip; Bukowski, Aaron;

Published by: Geophysical Research Letters      Published on:

YEAR: 2022     DOI: 10.1029/2021GL097260

ASHLEY; GITM; neutral mass density; soft electron precipitation

Revisiting the November 2004 Superstorm: Lessons from the TIMED/GUVI Limb Observation

We revisited the November 2004 superstorm by analyzing data from TIMED/GUVI, a FUV spectrograph imager. The GUVI 135.6 nm limb radiances at 520-km tangent altitude are mainly due to the O+ and electron radiative recombination and represent the daytime ionosphere density at the altitude. The 135.6 nm radiances clearly showed a signature of ionospheric equatorial arcs and their variations during the November 2004 magnetic superstorm. When an intense eastward Interplanetary Electric Field (IEF) occurred, the dayside equatorial arcs were enhanced and their latitude separation increased. The enhanced equatorial arcs were hemispherically symmetric or asymmetric in the region with non-depleted O/N2 or hemispherically asymmetric O/N2 depletion, respectively. When the O/N2 depletion reached the magnetic equator, there was no observable enhancement in the equatorial arcs regardless of the IEF conditions, indicating O/N2 conditions significantly modulated the variations in storm-time equatorial arcs.

Zhang, Yongliang; Wang, Wenbin; Paxton, Larry; Schaefer, Robert; Huang, Chaosong;

Published by: 44th COSPAR Scientific Assembly. Held 16-24 July      Published on:

YEAR: 2022     DOI:

Geomagnetic and Solar Dependencies of Midlatitude E-Region Irregularity Occurrence Rate: A Climatology Based on Wuhan VHF Radar Observations

By using Wuhan VHF radar, we show the morphological features of E-region field-aligned irregularity (FAI) occurrence at Wuhan during 2015–2020. Statistical results present that E-region FAI occurrence reaches a maximum after sunset in summer season. According to Doppler spectrum features, type-2 irregularity is predominantly observed at Wuhan. In addition, we observed a remarkable correlation between E-region FAI occurrence and geomagnetic activity, which includes periods of positive correlation and negative correlation depending on different geomagnetic conditions. The strong negative correlation also exists between E-region FAI occurrence and solar activity. In our observed results, we find that E-region FAI occurrence shows a strong linkage with local sporadic E (ES) layer. A quantitative analysis of linear theory of plasma instability in the E-region at midlatitudes is also presented in our study. The calculated results of linear growth rate indicate the importance of plasma density gradient of local ES layer and field-line-integrated Pedersen conductivity on the generation of E-region FAI. The geomagnetic and solar variations of E-region FAI occurrence are also discussed in this study, which show a dependence on the geomagnetic and solar variations of both meteor rate and medium-scale traveling ionospheric disturbance occurrence.

Liu, Yi; Zhou, Chen; Xu, Tong; Deng, Zhongxin; Du, Zhitao; Lan, Ting; Tang, Qiong; Zhu, Yunzhou; Wang, Zhuangkai; Zhao, Zhengyu;

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

YEAR: 2022     DOI: 10.1029/2021JA029597

Aspects related to variability of radiative cooling by NO in lower thermosphere, TEC and O/N2 correlation, and diffusion of NO into mesosphere during the Halloween storms

Nitric Oxide is a very important trace species which plays a significant role acting as a natural thermostat in Earth’s thermosphere during strong geomagnetic activity. In this paper, we present various aspects related to the variation in the NO Infrared radiative flux (IRF) exiting the thermosphere by utilizing the TIMED/SABER (Thermosphere Ionosphere Mesosphere Energetics and Dynamics/ Sounding of the Atmosphere using Broadband Emission Radiometry) observational data during the Halloween storm which occurred in late October 2003. The Halloween storm comprised of three intense-geomagnetic storms. The variability of NO infrared flux during these storm events and its connection to the strength of the geomagnetic storms were found to be different in contrast to similar super storms.

Ranjan, Alok; Krishna, MV; Kumar, Akash; Sarkhel, Sumanta; Bharti, Gaurav; Bender, Stefan; Sinnhuber, Miriam;

Published by: Advances in Space Research      Published on:

YEAR: 2022     DOI: 10.1016/j.asr.2022.07.035

Behaviors of Ionospheric Topside Ion Density, Ion Temperature, and Electron Temperature During the 20 November 2003 Superstorm

We identified a few new storm‐time ionospheric phenomena by analyzing disturbances in topside ion density, electron temperature, and ion temperature at ∼840 km altitude measured

Huang, Chao-Song; Zhang, Yongliang; Wang, Wenbin; Lin, Dong; Wu, Qian;

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

YEAR: 2022     DOI: 10.1029/2022JA030468

Critical Dynamics in Stratospheric Potential Energy Variations Prior to Significant (M> 6.7) Earthquakes

Lithosphere–atmosphere–ionosphere coupling (LAIC) is studied through various physical or chemical quantities, obtained from different sources, which are observables of the involved

Politis, Dimitrios; Potirakis, Stelios; Kundu, Subrata; Chowdhury, Swati; Sasmal, Sudipta; Hayakawa, Masashi;

Published by: Symmetry      Published on:

YEAR: 2022     DOI: 10.3390/sym14091939

Seismogenic Anomalies in Atmospheric Gravity Waves as Observed from SABER/TIMED Satellite during Large Earthquakes

Atmospheric disturbances caused by seismic activity are a complex phenomenon. The Lithosphere–Atmosphere–Ionosphere Coupling (LAIC) (LAIC) mechanism gives a detailed idea

Kundu, Subrata; Chowdhury, Swati; Ghosh, Soujan; Sasmal, Sudipta; Politis, Dimitrios; Potirakis, Stelios; Yang, Shih-Sian; Chakrabarti, Sandip; Hayakawa, Masashi;

Published by: Journal of Sensors      Published on:

YEAR: 2022     DOI: 10.1155/2022/3201104

Model of the E-Layer Critical Frequency for the Auroral Region

A new foE model for the auroral region is constructed; the model is based on an analysis of the models of auroral electron precipitations, the boundaries of the discrete and diffusive aurora, the main ionospheric trough, and measurements of the E-layer critical frequency foE. The model is an analytical model. It consists of solar (foEsol) and auroral (foEavr) components. The solar component of the model does not depend of geomagnetic activity. It depends on solar activity via the F index, which is determined by the solar radio emission flux at a wavelength of 10.7 cm over the previous day and three solar rotations. The auroral component of the model does not depend of solar activity. It depends on geomagnetic activity via the effective Kp* index, which takes into account the prehistory of changes in this activity. The model indirectly takes into account the dependence of the relative contribution of  foEsol and  foEavr to the total  foE value on the difference in the heights of the maxima of these model components via the addition of a coefficient. The model qualitatively takes into account the effect of the winter anomaly in foEavr via the addition of a function. It is found that the errors of the new foE model in the auroral region at the nighttime hours are much lower than those in the international IRI model (with the STORM-E option) for both moderate and high geomagnetic activity. For example, the comparison with data from ionospheric stations shows that the IRI model underestimates foE in these conditions by approximately a factor of 2 on average. The average shift in foE relative to the experimental data in the new model does not exceed 20\%.

Deminov, M.; Shubin, V.; Badin, V.;

Published by: Geomagnetism and Aeronomy      Published on: sep

YEAR: 2021     DOI: 10.1134/S0016793221050054

Assessment of the predictive capabilities of NIGTEC model over Nigeria during geomagnetic storms

The Nigerian Total Electron Content (NIGTEC) is a regional neural network-based model developed by the Nigerian Centre for Atmospheric Research to predict the Total Electron Content (TEC) at any location over Nigeria. The addition of the disturbance storm time (Dst) index as one of NIGTEC s input layer neurons raises a question of its accuracy during geomagnetic storms. In this paper, the capability of NIGTEC in predicting the variability of TEC during geomagnetic storms has been assessed. TEC data predicted by NIGTEC is compared with those derived from Global Navigation Satellite System (GNSS) over Lagos (6.5oN, 3.4oE) and Toro (10.1oN, 9.12oE) during the intense storms in March 2012 and 2013. The model s predictive capability is evaluated in terms of Root Mean Square Error (RMSE). NIGTEC reproduced a fairly good storm time morphology in VTEC driven by the prompt penetration electric field and the increase in thermospheric O/N2. Nevertheless, it failed to predict the increase in TEC after the intense sudden impulse of 60 nT on 8 March 2012. And it could not capture the changes in VTEC driven by the storm time equatorward neutral wind especially during 18:00–24:00 UT. Consequently, the RMSEs were higher during this time window, and the highest RMSE value was obtained during the most intense storm in March 2012.

Amaechi, Paul; Humphrey, Ibifubara; Adewoyin, David;

Published by: Geodesy and Geodynamics      Published on: nov

YEAR: 2021     DOI: 10.1016/j.geog.2021.09.003

geomagnetic storm; global navigation satellite system; Nigerian Total Electron Content (NIGTEC); total electron content

The nighttime ionospheric response and occurrence of equatorial plasma irregularities during geomagnetic storms: a case study

Recent studies revealed that the long-lasting daytime ionospheric enhancements of Total Electron Content (TEC) were sometimes observed in the Asian sector during the recovery phase of geomagnetic storms (e.g., Lei (J Geophys Res Space Phys 123: 3217–3232, 2018), Li (J Geophys Res Space Phys 125: e2020JA028238, 2020). However, they focused only on the dayside ionosphere, and no dedicated studies have been performed to investigate the nighttime ionospheric behavior during such kinds of storm recovery phases. In this study, we focused on two geomagnetic storms that happened on 7–8 September 2017 and 25–26 August 2018, which showed the prominent daytime TEC enhancements in the Asian sector during their recovery phases, to explore the nighttime large-scale ionospheric responses as well as the small-scale Equatorial Plasma Irregularities (EPIs). It is found that during the September 2017 storm recovery phase, the nighttime ionosphere in the American sector is largely depressed, which is similar to the daytime ionospheric response in the same longitude sector; while in the Asian sector, only a small TEC increase is observed at nighttime, which is much weaker than the prominent daytime TEC enhancement in this longitude sector. During the recovery phase of the August 2018 storm, a slight TEC increase is observed on the night side at all longitudes, which is also weaker than the prominent daytime TEC enhancement. For the small-scale EPIs, they are enhanced and extended to higher latitudes during the main phase of both storms. However, during the recovery phases of the first storm, the EPIs are largely enhanced and suppressed in the Asian and American sectors, respectively, while no prominent nighttime EPIs are observed during the second storm recovery phase. The clear north–south asymmetry of equatorial ionization anomaly crests during the second storm should be responsible for the suppression of EPIs during this storm. In addition, our results also suggest that the dusk side ionospheric response could be affected by the daytime ionospheric plasma density/TEC variations during the recovery phase of geomagnetic storms, which further modulates the vertical plasma drift and plasma gradient. As a result, the growth rate of post-sunset EPIs will be enhanced or inhibited.

Wan, Xin; Xiong, Chao; Gao, Shunzu; Huang, Fuqing; Liu, Yiwen; Aa, Ercha; Yin, Fan; Cai, Hongtao;

Published by: Satellite Navigation      Published on: nov

YEAR: 2021     DOI: 10.1186/s43020-021-00055-x

Equatorial plasma irregularity; Geomagneitc storm; Ionospheric response; longitudinal variations; Storm recovery phase

Latitudinal Dependence of Ionospheric Responses to Some Geomagnetic Storms during Low Solar Activity

The Latitudinal dependence in the response of the Ionospheric F2-layer electron density (NmF2) and peak height (hmF2) to three geomagnetic storms of May and August 2010 has been examined. The data-sets used for the study were obtained from Ilorin, Nigeria (1.87° S/76.67° E), San Vito, Italy (34.68° N/90.38° E), Hermanus, South Africa (42.34° S/82.15° E), and Pruhonice, Czech Republic (45.66° N/90.38° E) geomagnetic coordinates. The quiet time result shows that the rise in NmF2 began earlier at San Vito, followed by Pruhonice. The rate of ionization was observed to be highest in Ilorin, while, the rate of decay in NmF2 is faster at Hermanus. For disturbed NmF2 condition, remarkable similarities in the NmF2 responses during geomagnetic storms were recorded from Hermanus in the mid-latitude and Ilorin, an equatorial station. NmF2 enhancements (\textgreater6 hours) that is consistent with the increase in hmF2 were observed at all the mid-latitude stations during the main phase of the 02 May, 2010 storm, without any noticeable change over ILN. Similarly, 12 hours of positive phase was observed at ILN and HMN, with 30 hours of NmF2 depletions at PRN and SVT during the recovery phase. ILN is in the equatorial Trough, so most of the NmF2 produced at this region is lifted to the higher latitudes by the fountain effect during the main phase. The suppression of the zonal electric field at ILN is responsible for the NmF2 enhancement during the recovery phase, while the mid-latitude responses have been attributed to the effect of the thermospheric winds and neutral composition changes.

Joshua, B.; Adeniyi, J.; Olawepo, A.; Rabiu, Babatunde; Daniel, Okoh; Adebiyi, S.; Adebesin, B.; Ikubanni, S.; Abdurahim, B.;

Published by: Geomagnetism and Aeronomy      Published on: may

YEAR: 2021     DOI: 10.1134/S0016793221030063

Electric field; Electron density; Geomagnetic storms; magnetosphere; peak height

The distribution characteristics of GPS cycle slip over the China mainland and adjacent region during the declining solar activity (2015--2018) period of solar cycle 24

The Global Positioning System (GPS) cycle slip has a marked impact on the application of communication and navigation systems and therefore is one of the main concerns of the user and designer of terminal systems. In this study, we analyzed the temporal and spatial characteristics of cycle slip events using the GPS data detected from 260 observations in the China sector during the period of the year 2015–2018. The results show that the temporal variations of cycle slips are dependent on the local time, seasons, and solar activity. It occurs from 20:00 LT to midnight and more frequently in the equinox months, especially in solar maximum years. The spatial distribution occurs mainly at southern sector below 25°N, which should be associated with the solar condition and ionospheric irregularities in the equatorial region, and the case analyses reveal that the variation of cycle slips has a similar tendency with the ionospheric scintillation monitored at low-latitude station Guangzhou explaining this relationship. Our results reflect the performance of the GPS signals monitored in the China area during the declining period of solar activity to some degree.

Geng, Wei; Huang, Wengeng; Liu, Guoqi; Liu, Siqing; Luo, Binxian; Chen, Yanhong;

Published by: Radio Science      Published on: may

YEAR: 2021     DOI: 10.1029/2020RS007196

Monitoring; Delays; Global positioning system; Indexes; Receivers; Satellite broadcasting; Signal to noise ratio

Features of topside ionospheric background over China and its adjacent areas obtained by the ZH-1 satellite

\textlessp\textgreaterTopside ionospheric background distribution and its seasonal variations over China and its adjacent areas, e.g. 0°-54°N and 70°-140°E, are studied using the in situ electron density (Ne) measurements obtained by the LAP payload on board the ZH-1 (CSES) satellite. Results are as followings:(1) Regularities consistent with results from previous studies are shown on the latitudinal extension, longitudinal distribution, and seasonal variations of the EIA (Equatorial Ionization Anomaly) phenomenon in the study area. (2) In the mid-latitude regions, there is a relative low-value zone for the daytime Ne, which shows relative high-value data during nighttime. Nighttime Ne enhancement is shown in all the mid-latitudes for all the seasons when comparing the nighttime and daytime Ne together. The equatorward extension of this phenomenon is in contrast to the poleward extension of the EIA phenomenon; when this phenomenon extends, the EIA shrinks, and vice versa. (3) For the daytime Ne, semiannual anomaly demonstrates a regular pattern, in which the two peaks start in spring and autumn equinoxes at the Equator, then evolve toward the summer solstice with increasing latitude, and finally combine into one summer time peak in mid-latitudes; seasonal anomaly only appears within latitude 4° of the Equator. While for the nighttime Ne, semiannual anomaly appears between latitude 22° and 50°, and seasonal anomaly appears below latitude 22°. (4) The monthly average background of the ionosphere generally shows that the nighttime Ne varies more dramatically than the daytime Ne. For the daytime Ne, observations in both equinoxes and summer solstice vary more violently than that in winter solstice, and observations in EIA regions vary more violently than that in mid-latitude regions. And for the nighttime Ne, observation variations are roughly similar in all seasons and latitudes. (5) Features of the ionospheric background, which fluctuates with time and space in the study area, are relatively complicated, therefore it is necessary to pay attention to the ionosphere background and its fluctuations when conducting studies on ionosphere related scientific problems. Based on the above results and comparisons with other simultaneous observations, we believe that the relative variations of the in situ Ne measurements from the ZH-1 satellite are in consistent with that from other datasets. Besides the well-known ionosphere features, some features which were not found in previous studies are found from the ionosphere background in the study area. The in situ Ne measurements from the ZH-1 satellite are a good data source for systematic studies on ionosphere-related scientific problems due to the similar local times and locations of the observations.\textless/p\textgreater

XiuYing, Wang; DeHe, Yang; ZiHan, Zhou; Jing, C.; Na, Zhou; XuHui, Shen;

Published by: Chinese Journal of Geophysics      Published on: feb

YEAR: 2021     DOI: 10.6038/cjg2021O0152

Teleseismic measurements of upper mantle shear wave anisotropy in the Isthmus of Tehuantepec, Mexico

Shear wave splitting measurements in the Isthmus of Tehuantepec (IT), southern Mexico, inferred from teleseismic core phases are presented. Measurements were made along a south-to-north profile across the IT. The results show a predominantly trench-normal pattern of fast polarization orientations with averaged delay times up to 2.2 s. Fast orientations near the trench suggest a corner flow in the mantle wedge and an entrained flow in the subslab region. Away the trench, fast orientations are parallel to the Absolute Plate Motion, suggesting that the anisotropy in that region is driven by a simple asthenospheric flow. A comparison with splitting measurements made in the Mexican subduction zone shows a 17° clockwise rotation of the fast orientations of between east and west Mexico. This is consistent with the observed change in orientation of 19° clockwise in the Middle American Trench (MAT). This suggests that the rotation of the fast orientations is controlled by the change of orientation in the MAT.

León Soto, Gerardo; Valenzuela, Raúl; Arceo, R; Huesca-Pérez, Eduardo; Rosas, Ricardo;

Published by: Geophysical Journal International      Published on: dec

YEAR: 2021     DOI: 10.1093/gji/ggab301

A Statistical Analysis of Plasma Bubbles Observed by Swarm Constellation during Different Types of Geomagnetic Storms

Based on the observations of Ionospheric Bubble Index (IBI) data from the Swarm mission, the characteristics of plasma bubbles are investigated during different types of geomagnetic storms recorded from 2014 to 2020. The geometrical constellation of the Swarm mission enabled us to investigate the altitudinal profile of the IBIs during different activity levels in a statistical mean. Results show that the majority of IBIs associated with moderate storms are observed at low altitudes and the probability of observing IBIs at high altitudes (Swarm-B) increases with the increase in storm level. This is confirmed by observing the F2 layer peak height (hmF2) during super storm events at larger altitudes using COSMIC data. The maximum number of IBIs is recorded within the South Atlantic Anomaly (SAA) region with a long duration time and tends to increase only during dusk time. Both the large duration time and number of IBIs over the South Atlantic Anomaly (SAA) suggest that the gradient in the electron density and the depression in the magnetic field are the main factors controlling IBI events. Also, the IBIs at high altitudes are larger at sunset and at low altitudes pre-midnight. In addition, the occurrence of IBIs is always larger in the northern hemisphere than in the southern hemisphere irrespective of the type of storm, as well as during the summer months. Moreover, there is no correlation between the duration time of IBIs and both the altitudinal observation of the IBIs and the storm type. Seasonal occurrence of IBIs is larger during equinoxes and vice versa during solstices irrespective of both the type of storm and the altitude of the satellite. The large number of IBIs during equinoxes agrees with the previous studies, which expect that the large electron density is a developer of steeper ∇n. Large occurrences of super storm IBIs observed within the pre-midnight during summer and at sunset during equinoxes are a novel observation that needs further investigation. Also, the majority of IBIs are observed a few hours after geomagnetic substorms, which reflects the role of the Disturbance Dynamo Electric Field (DDEF) as a main driver of IBIs.

Hussien, Fayrouz; Ghamry, Essam; Fathy, Adel;

Published by: Universe      Published on: apr

YEAR: 2021     DOI: 10.3390/universe7040090

geomagnetic storm; ionospheric irregularity; plasma bubble; Swarm mission

Periodic Variations in Solar Wind and Responses of the Magnetosphere and Thermosphere in March 2017

TIMED/GUVI observed thermospheric column ∑O/N2 depletion in both hemispheres between March 1 and 21, 2017 which was caused by large periodic variations in interplanetary magnetic field (IMF) and a high solar wind speed, likely in a solar wind. The dominant periods seen in the solar wind and magnetosphere coupling function (CF) were around 1.9, 3.0, 4.7, 7.6, 14.0 and 22.0 h on March 1 and 2. The major AE variations were around 3.0, 4.7, 7.6, 10.7, 14.0 and 22.0 h. Auroral hemispheric power (HP) also showed periodic variations similar to that of AE, except for the absence of the 3.0 h variation due to a low sampling rate in HP data. SymH data didn t show the periodic variations seen in AE but a weak 12-h periodic variation which was seen in the solar wind dynamic pressure. A weak AE and HP variation at 10.7-h period was not observed in CF or any individual solar wind parameters or IMF components. These results suggest that (a) the oscillating IMF pumped energy and mass periodically into the magnetosphere and the polar ionosphere, creating a long lasting (20-days) storm and O/N2 depletion, (b) the high latitude AE and HP responded to the solar wind and IMF variations directly, (c) SymH did not show any direct periodic responses, likely due to the fact that the ring current response resulted from the cumulative effect of solar wind and IMF drivers, (d) the 10.7-h variations in AE and HP were likely due to magnetospheric internal processes.

Zhang, Yongliang; Paxton, Larry; Wang, Wenbin; Huang, Chaosong;

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

YEAR: 2021     DOI: 10.1029/2021JA029387

AE index; geomagnetic storm; hemispheric power; periodic variation; solar wind and magnetosphere coupling; thermospheric composition

Wide-field aurora imager onboard Fengyun satellite: Data products and validation

New observations of auroras based on the wide-field aurora imager (WAI) onboard Fengyun-3D (FY-3D) satellite are exhibited in this paper. Validity of the WAI data is analyzed by comparing auroral boundaries derived from WAI observations with results obtained from data collected by the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) aboard the Defense Meteorological Satellite Program (DMSP F18). Dynamic variations of the aurora with the solar wind, interplanetary magnetic field (IMF) parameters, and the SYM-H index are also investigated. The comparison of auroral boundaries indicates that the WAI data are morphologically valid and suitable to the study of auroral dynamics. Effective responses to solar wind parameters indicate that the WAI data can be useful to monitor and predict the Earth s space weather. Since the configuration of aurora is a good indicator of the solar wind-magnetosphere-ionosphere (SW-M-I) coupling system, and can reflect the disturbance of the space environment, the WAI will provide important data to help us to study the physical processes in space.

Ding, GuangXing; Li, JiaWei; Zhang, Xiaoxin; He, Fei; He, LingPing; Song, KeFei; Sun, Liang; Dai, Shuang; Liu, ShiJie; Chen, Bo; Yu, Chao; Hu, Xiuqing; Gu, SongYan; Yang, Zhongdong; Zhang, Peng;

Published by: Earth and Planetary Physics      Published on:

YEAR: 2021     DOI: 10.26464/epp2021003

auroral dynamics; FY-3D; SSUSI; SW-M-I; WAI

Transpolar Arcs During a Prolonged Radial Interplanetary Magnetic Field Interval

Transpolar arcs (TPAs) are believed to predominantly occur under northward interplanetary magnetic field (IMF) conditions with their hemispheric asymmetry controlled by the Sun-Earth (radial) component of the IMF. In this study, we present observations of TPAs that appear in both the northern and southern hemispheres even during a prolonged interval of radially oriented IMF. The Defense Meteorological Satellite Program (DMSP) F16 and the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellites observed TPAs on the dawnside polar cap in both hemispheres (one TPA structure in the southern hemisphere and two in the northern hemisphere) during an interval of nearly earthward-oriented IMF on October 29, 2005. The southern hemisphere TPA and one of the northern hemisphere TPAs are associated with electron and ion precipitation and mostly sunward plasma flow (with shears) relative to their surroundings. Meanwhile, the other TPA in the northern hemisphere is associated with an electron-only precipitation and antisunward flow relative to its surroundings. Our observations indicate the following: (a) the TPA formation is not limited to northward IMF conditions; (b) the TPAs can be located on both closed field lines rooted in the polar cap of both hemispheres and open field lines connected to the northward field lines draped over one hemisphere of the magnetopause. We believe that the TPAs presented here are the result of both indirect and direct processes of solar wind energy transfer to the high-latitude ionosphere.

Park, Jong-Sun; Shi, Quan; Nowada, Motoharu; Shue, Jih-Hong; Kim, Khan-Hyuk; Lee, Dong-Hun; Zong, Qiu-Gang; Degeling, Alexander; Tian, An; Pitkänen, Timo; Zhang, Yongliang; Rae, Jonathan; Hairston, Marc;

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

YEAR: 2021     DOI: 10.1029/2021JA029197

radial IMF; solar wind-magnetosphere-ionosphere coupling; transpolar arc

The Ionosphere at Middle and Low Latitudes Under Geomagnetic Quiet Time of December 2019

The ionospheric electron density shows remarkable day-to-day variability due to solar radiance, geomagnetic activity and lower atmosphere forcing. In this report, we investigated the ionospheric variations at middle and low latitudes during a period under geomagnetic quiet time (Kpmax = 1.7) from November 30 to December 8, 2019. During the quiescent period, the ionosphere is not undisturbed as expected in the Asian-Australian and the American sectors. Total electron content (TEC) has multiple prominent enhancements at middle and low latitudes in the two sectors, and TEC depletions also occur repeatedly in the Asian-Australian sector. The low-latitude electric fields vary significantly, which is likely to be modulated by the notably changing tides in the mesosphere and lower thermosphere region. It is worth noting that the variations of TEC and the electric fields are not consistent in the two sectors, particularly on December 4–6. Further investigation reveals that the increase in TEC depends on altitude. The TEC enhancements are mainly contributed by the altitude below 500 km in both two sectors, which indirectly reflects that the driving sources may come from the lower atmosphere. Especially, a mid-latitude band structure continuously appears at all local times in the North American sector on December 6–8, which is also mainly contributed by the altitude below 500 km.

Kuai, Jiawei; Li, Qiaoling; Zhong, Jiahao; Zhou, Xu; Liu, Libo; Yoshikawa, Akimasa; Hu, Lianhuan; Xie, Haiyong; Huang, Chaoyan; Yu, Xumin; Wan, Xin; Cui, Jun;

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

YEAR: 2021     DOI: 10.1029/2020JA028964

low-latitude electric fields; the ionosphere variations in solar minimum; the ionospheric day-to-day variations; the ionospheric disturbance; the ionospheric variations; topside ionosphere

The Ionosphere at Middle and Low Latitudes Under Geomagnetic Quiet Time of December 2019

The ionospheric electron density shows remarkable day-to-day variability due to solar radiance, geomagnetic activity and lower atmosphere forcing. In this report, we investigated the ionospheric variations at middle and low latitudes during a period under geomagnetic quiet time (Kpmax = 1.7) from November 30 to December 8, 2019. During the quiescent period, the ionosphere is not undisturbed as expected in the Asian-Australian and the American sectors. Total electron content (TEC) has multiple prominent enhancements at middle and low latitudes in the two sectors, and TEC depletions also occur repeatedly in the Asian-Australian sector. The low-latitude electric fields vary significantly, which is likely to be modulated by the notably changing tides in the mesosphere and lower thermosphere region. It is worth noting that the variations of TEC and the electric fields are not consistent in the two sectors, particularly on December 4–6. Further investigation reveals that the increase in TEC depends on altitude. The TEC enhancements are mainly contributed by the altitude below 500 km in both two sectors, which indirectly reflects that the driving sources may come from the lower atmosphere. Especially, a mid-latitude band structure continuously appears at all local times in the North American sector on December 6–8, which is also mainly contributed by the altitude below 500 km.

Kuai, Jiawei; Li, Qiaoling; Zhong, Jiahao; Zhou, Xu; Liu, Libo; Yoshikawa, Akimasa; Hu, Lianhuan; Xie, Haiyong; Huang, Chaoyan; Yu, Xumin; Wan, Xin; Cui, Jun;

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

YEAR: 2021     DOI: 10.1029/2020JA028964

low-latitude electric fields; the ionosphere variations in solar minimum; the ionospheric day-to-day variations; the ionospheric disturbance; the ionospheric variations; topside ionosphere

First Look at a Geomagnetic Storm With Santa Maria Digisonde Data: F Region Responses and Comparisons Over the American Sector

Santa Maria Digisonde data are used for the first time to investigate the F region behavior during a geomagnetic storm. The August 25, 2018 storm is considered complex due to the incidence of two Interplanetary Coronal Mass Ejections and a High-Speed Solar Wind Stream (HSS). The F 2 layer critical frequency (f o F 2) and its peak height (h m F 2) collected over Santa Maria, near the center of the South American Magnetic Anomaly (SAMA), are compared with data collected from Digisondes installed in the Northern (NH) and Southern (SH) Hemispheres in the American sector. The deviation of f o F 2 (Df o F 2) and h m F 2 (Dh m F 2) are used to quantify the ionospheric storm effects. Different F region responses were observed during the main phase (August 25–26), which is attributed to the traveling ionospheric disturbances and disturbed eastward electric field during nighttime. The F region responses became highly asymmetric between the NH and SH at the early recovery phase (RP, August 26) due to a combination of physical mechanisms. The observed asymmetries are interpreted as caused by modifications in the thermospheric composition and a rapid electrodynamic mechanism. The persistent enhanced thermospheric [O]/[N2] ratio observed from August 27 to 29 combined with the increased solar wind speed induced by the HSS and IMF B z fluctuations seem to be effective in causing the positive ionospheric storm effects and the shift of the Equatorial Ionization Anomaly crest to higher than typical latitudes. Consequently, the most dramatic positive ionospheric storm during the RP occurred over Santa Maria (∼120\%).

Moro, J.; Xu, J.; Denardini, C.; Resende, L.; Neto, P.; Da Silva, L.; Silva, R.; Chen, S.; Picanço, G.; Carmo, C.; Liu, Z.; Yan, C.; Wang, C.; Schuch, N.;

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

YEAR: 2021     DOI: 10.1029/2020JA028663

Digisonde; Equatorial ionization anomaly; F-region; Ionospheric storm; SAMA; space weather

Extreme Positive Ionosphere Storm Triggered by a Minor Magnetic Storm in Deep Solar Minimum Revealed by FORMOSAT-7/COSMIC-2 and GNSS Observations

This study examines an unexpected and extreme positive ionospheric response to a minor magnetic storm on August 5, 2019 by using global ionosphere specification (GIS) 3D electron density profiles obtained by assimilating radio occultation total electron content (TEC) measurements of the recently launched FORMOSAT-7/COSMIC-2 satellites, and ground-based global navigation satellite system (GNSS) TEC. The results reveal ∼300\% enhancement of equatorial ionization anomaly (EIA) crests, appearing over 200–300 km altitudes, and a much intense localized density enhancement over the European sector. These are the most intense ionospheric response that has ever been detected for a small magnetic storm with Dst ∼ −53 nT (SYM-H ∼ −64 nT). The enhancements are validated by using global ionosphere map (GIM) TEC and ground-based GNSS TEC. The GIS vertical electron density structures during the storm are examined to understand the physical processes giving rise to such an intense ionosphere response during deep solar minimum conditions when the background electron density is very low. Altitude variations and poleward shifts of the locations of the EIA crests indicate that prompt penetration electric fields (PPEF) play an important role in producing the observed positive storm responses, with the storm-induced equatorward circulation supporting the plasma accumulation against recombination losses. Additional physical mechanisms are required to fully explain the unexpected electron density enhancements for this minor storm event.

Rajesh, P.; Lin, C.; . Y. Lin, C; Chen, C.; . Y. Liu, J; Matsuo, T.; Chen, S.; Yeh, W.; . Y. Huang, C;

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

YEAR: 2021     DOI: 10.1029/2020JA028261

FORMOSAT-7/COSMIC-2; Global Ionospheric Specification; ionospheric data assimilation; ionospheric response to magnetic storm; magnetosphere-ionosphere coupling; minor magnetic storm

Conjugate Photoelectron Energy Spectra Derived From Coincident FUV and Radio Measurements

We present a method for estimating incident photoelectrons energy spectra as a function of altitude by combining global scale far-ultraviolet (FUV) and radio-occultation (RO) measurements. This characterization provides timely insights important for accurate interpretation of ionospheric parameters inferred from the recently launched Ionospheric Connection Explorer (ICON) observations. Quantification of photoelectron impact is enabled by the fact that conjugate photoelectrons (CPEs) directly affect FUV airglow emissions but not RO measurements. We demonstrate a technique for estimation of photoelectron fluxes and their spectra by combining coincident ICON and COSMIC2 measurements and show that a significant fraction of ICON-FUV measurements is affected by CPEs during the winter solstice. A comparison of estimated photoelectron fluxes with measured photoelectron spectra is used to gain further insights into the estimation method and reveals consistent values within 10–60 eV.

Urco, J.; Kamalabadi, F.; Kamaci, U.; Harding, B.; Frey, H.; Mende, S.; Huba, J.; England, S.; Immel, T.;

Published by: Geophysical Research Letters      Published on:

YEAR: 2021     DOI: 10.1029/2021GL095839

airglow; conjugate photolectrons; COSMIC2; energy spectra; ICON

Modeling of Ultraviolet Aurora Intensity Associated With Interplanetary and Geomagnetic Parameters Based on Neural Networks

The spatial distribution of aurora intensity is an important manifestation of solar wind-magnetosphere-ionosphere energy coupling process, and it oscillates with the change of space environment parameters and geomagnetic index. It is of great significance to establish an appropriate aurora intensity model for the prediction of space weather and the study of magnetosphere dynamics. Based on Ultraviolet Imager (UVI) data of Polar satellite, we constructed two auroral models by using two different neural networks, that is, the generalized regression neural network (GRNN), and the conditional generation adversarial network (CGAN). Input parameters of the models include interplanetary magnetic field, solar wind velocity and density, and the geomagnetic AE index. Output result is the spatial distribution of auroral intensity in altitude adjusted corrected geomagnetic (AACGM) coordinates. The structural similarity index (SSIM) of image quality is used as an evaluation standard of detail similarity between the prediction results of auroral intensity model and corresponding UVI images (complete similarity is 1, dissimilarity is 0, SSIM is generally considered to have good similarity if it is greater than 0.5). Based on the respective training datasets of GRNN and CGAN models, the evaluating results showed that the mean values (standard deviation) of SSIM were 0.5409 (0.0912) and 0.5876 (0.0712), respectively, so the prediction results from both models can restore the auroral intensity distribution of the original images of UVI. In addition, the value of SSIM can increase with the increase of the number of training data. Therefore, more training data will help improve the effectiveness of these models.

Hu, Ze-Jun; Han, Bing; Zhang, Yisheng; Lian, Huifang; Wang, Ping; Li, Guojun; Li, Bin; Chen, Xiang-Cai; Liu, Jian-Jun;

Published by: Space Weather      Published on:

YEAR: 2021     DOI: 10.1029/2021SW002751

conditional generation adversarial network; generalized regression neural network; interplanetary and geomagnetic parameters; neural networks; ultraviolet auroral intensity model

Non-storm time thermospheric O/N 2 depletion and NO enhancement

Zhang, Yongliang; Paxton, Larry; Wang, Wenbin; Huang, Chaosong;

Published by:       Published on:

YEAR: 2021     DOI:

Progresses and Challenges to specifying the IT system during weak storms

Deng, Yue; Heelis, Roderick; Paxton, Larry; Lyons, Larry; Nishimura, Toshi; Zhang, Shunrong; Bristow, Bill; Maute, Astrid; Sheng, Cheng; Zhu, Qingyu; , others;

Published by:       Published on:

YEAR: 2021     DOI:

Signatures of conjugate photoelectrons in the ionosphere and thermosphere

Kil, Hyosub; Paxton, Larry; Schaefer, Robert; Huba, Joseph;

Published by:       Published on:

YEAR: 2021     DOI:

Inversion of Ionospheric O/N-2 by Using FY-3D Ionospheric Photometer Data

Da-xin, Wang; Li-ping, Fu; Fang, Jiang; Nan, Jia; Tian-fang, Wang; Shuang-tuan, Dou;

Published by: SPECTROSCOPY AND SPECTRAL ANALYSIS      Published on:

YEAR: 2021     DOI:

Evaluating Auroral Forecasts Against Satellite Observations

The aurora is a readily visible phenomenon of interest to many members of the public. However, the aurora and associated phenomena can also significantly impact communications, ground-based infrastructure, and high-altitude radiation exposure. Forecasting the location of the auroral oval is therefore a key component of space weather forecast operations. A version of the OVATION-Prime 2013 auroral precipitation model (Newell et al., 2014, https://doi.org/10.1002/2014sw001056) was used by the UK Met Office Space Weather Operations Centre (MOSWOC). The operational implementation of the OVATION-Prime 2013 model at the UK Met Office delivered a 30-min forecast of the location of the auroral oval and the probability of observing the aurora. Using weather forecast evaluation techniques, we evaluate the ability of the OVATION-Prime 2013 model forecasts to predict the location and probability of the aurora occurring by comparing the forecasts with auroral boundaries determined from data from the IMAGE satellite between 2000 and 2002. Our analysis shows that the operational model performs well at predicting the location of the auroral oval, with a relative operating characteristic (ROC) score of 0.82. The model performance is reduced in the dayside local time sectors (ROC score = 0.59) and during periods of higher geomagnetic activity (ROC score of 0.55 for Kp = 8). As a probabilistic forecast, OVATION-Prime 2013 tends to underpredict the occurrence of aurora by a factor of 1.1–6, while probabilities of over 90\% are overpredicted.

Mooney, M.; Marsh, M.; Forsyth, C.; Sharpe, M.; Hughes, T.; Bingham, S.; Jackson, D.; Rae, I.; Chisham, G.;

Published by: Space Weather      Published on:

YEAR: 2021     DOI: 10.1029/2020SW002688

AURORA; auroral forecasting; forecast verification; OVATION-Prime 2013; ROC scores; space weather

Low-Latitude Zonal Ion Drifts and Their Relationship With Subauroral Polarization Streams and Auroral Return Flows During Intense Magnetic Storms

We analyze horizontal plasma drifts measured by the Defense Meteorological Satellite Program satellites during two intense magnetic storms. It is found, for the first time, that westward plasma flows associated with subauroral polarization streams (SAPS) in the dusk-evening sector penetrate continuously to equatorial latitudes. The westward ion drifts between subauroral and equatorial latitudes occur nearly simultaneously. The latitudinal profile of the westward ion drifts at low latitudes (approximately within ±30° magnetic latitude [MLat]) is relatively flat, and the westward ion drifts at the magnetic equator reach 200–300 m s−1. In the dawn-morning sector, eastward ion drifts at subauroral latitudes are also SAPS. The storm-time dawnside auroral boundary moves to ∼±55° MLat, and the dawnside SAPS penetrate to ∼±20° MLat at 0930 local time. A dawnside SAPS flow channel appears to exist, although it is not as well defined as the duskside SAPS flow channel. Thermospheric wind data measured by the Challenging Minisatellite Payload satellite are analyzed, and zonal disturbance winds are derived. Disturbance winds can reach equatorial latitudes rapidly near midnight but are limited to ±40° geographic latitude or higher near noon. The effects of disturbance winds on the zonal ion drifts at middle and low latitudes are discussed. It is suggested that both the westward ion drifts at middle and low latitudes in the dusk-evening sector and the eastward ion drifts at middle and lower latitudes in the dawn-morning sector are caused primarily by penetration of the SAPS and auroral electric fields.

Huang, Chao-Song; Zhang, Yongliang; Wang, Wenbin; Lin, Dong; Wu, Qian;

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

YEAR: 2021     DOI: 10.1029/2021JA030001

Electric field; Ionosphere; ionospheric plasma drift; penetration electric field; Subauroral Polarization Streams; thermospheric wind

Plasma depletions lasting into daytime during the recovery phase of a geomagnetic storm in May 2017: Analysis and simulation of GPS total electron content observations

This paper reports that plasma density depletions appearing at middle latitudes near sunrise survived until afternoon on 29 May 2017 during the recovery phase of a geomagnetic storm. By analyzing GPS data collected in Japan, we investigate temporal variations in the horizontal two-dimensional distribution of total electron content (TEC) during the geomagnetic storm. The SYM-H index reached −142 nT around 08 UT on 28 May 2017. TEC depletions extending up to approximately 38°N along the meridional direction appeared over Japan around 05 LT (LT = UT + 9 hours) on 29 May 2017, when TEC rapidly increased at sunrise due to the solar extreme ultraviolet (EUV) radiation. The TEC depletions appeared sequentially over Japan for approximately 8 hours in sunlit conditions. At 06 LT on 29 May, when the plasma depletions first appeared over Japan, the background TEC was enhanced to approximately 17 TECU, and then decreased to approximately 80\% of the TEC typical of magnetically quiet conditions. We conclude that this temporal variation of background plasma density in the ionosphere was responsible for the persistence of these plasma depletions for so long in daytime. By using the Naval Research Laboratory: Sami2 is Another Model of the Ionosphere (SAMI2), we have evaluated how plasma production and ambipolar diffusion along the magnetic field may affect the rate of plasma depletion disappearance. Simulation shows that the plasma density increases at the time of plasma depletion appearance; subsequent decreases in the plasma density appear to be responsible for the long-lasting persistence of plasma depletions during daytime. The plasma density depletion in the top side ionosphere is not filled by the plasma generated by the solar EUV productions because plasma production occurs mainly at the bottom side of the ionosphere.

Otsuka, Yuichi; Shinbori, Atsuki; Sori, Takuya; Tsugawa, Takuya; Nishioka, Michi; Huba, Joseph;

Published by: Earth and Planetary Physics      Published on:

YEAR: 2021     DOI: 10.26464/epp2021046

Ionosphere; GPS; ionospheric irregularity; plasma bubble; SAMI2

Non-storm time thermospheric O/N2 depletion and NO enhancement

It is well known that significant thermospheric O/N2 depletion and nitric oxide (NO) enhancement is a storm-time phenomenon. However, TIMED/GUVI observed events with a

Zhang, Yongliang; Paxton, Larry; Wang, Wenbin; Huang, Chaosong;

Published by:       Published on:

YEAR: 2021     DOI:

Interaction Between an EMSTID and an EPB in the EIA Crest Region Over China

Few observations investigated the interaction between an electrical medium-scale traveling ionospheric disturbance (EMSTID) and an equatorial plasma bubble (EPB). This paper presents another interaction between a southwestward propagating EMSTID and an eastward drifting EPB in the equatorial ionization anomaly (EIA) crest region of China. When the EMSTID and the EPB touched each other, several depletions of the EMSTID (EPB) showed the eastward (westward) velocity disturbances of the EPB (EMSTID) depletions. Besides, phase elongations of the EPB depletions contrarotated as the EMSTID propagated southwestward. However, of important finding is that the interaction of the EMSTID and the EPB could have polarized one depletion of the postmidnight EPB that should have become a fossilized bubble. Inside that polarized EPB depletion were meter-scale irregularities that caused activated radar echoes and enhanced ranged spread F (RSF). The interaction occurred in descending ionosphere and the lower density regions got filled up with an enhanced density plasma. We propose that the EMSTID and the EPB could have electrically coupled with each other, causing an enhanced polarization electric field (PEF) that polarized that EPB depletion; the E × B gradient drift instability (Kelley, 1989) could have caused the meter-scale irregularities when that enhanced PEF was imposed on that reactivated EPB depletion surrounded by that enhanced density plasma. This study provides observational evidence that how an electrical couple of EMSTID and EPB events can activate a postmidnight EPB depletion that should become a fossilized structure.

Sun, Longchang; Xu, JiYao; Zhu, Yajun; Xiong, Chao; Yuan, Wei; Wu, Kun; Hao, Yongqiang; Chen, Gang; Yan, Chunxiao; Wang, Zhihua; Zhao, Xiukuan; Luo, Xiaomin;

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

YEAR: 2021     DOI: 10.1029/2020JA029005

airglow; EIA crest region; Interaction between MSTID and EPB; Nighttime plasma density enhancement; Polarization of postmidnight EPB; VHF radar echoes and range spread F

Modeling the Impact of Metallic Ion Layers on Equatorial Spread With SAMI3/ESF

The impact of region metal ion layers on the development of equatorial plasma bubbles is investigated using the SAMI3/ESF model. We find that metal ion layers reduce the growth rate of the generalized Rayleigh-Taylor instability (GRTI) and act to suppress the development of equatorial plasma bubbles. This is consistent with theoretical expectations and observations and is attributed to the increase in both the Pedersen and Hall conductances. Additionally, inhomogeneities in the region metal ion layer can map into the layer and alter the morphology of equatorial spread (ESF) bubble evolution. Lastly, we find that if EFS bubbles develop in the presence of a metal ion layer, then the electric fields generated by the instability can lift the metal ions into the region. This is consistent with observations of Fe in the region during equatorial spread .

Huba, J.; Krall, J.; Drob, D.;

Published by: Geophysical Research Letters      Published on: 02/2020

YEAR: 2020     DOI: 10.1029/2020GL087224

Equatorial ionosphere; Equatorial Spread F; metal ions; sporadic E

Impacts of Binning Methods on High-Latitude Electrodynamic Forcing: Static Versus Boundary-Oriented Binning Methods

An outstanding issue in the general circulation model simulations for Earth\textquoterights upper atmosphere is the inaccurate estimation of Joule heating, which could be associated with the inaccuracy of empirical models for high-latitude electrodynamic forcing. The binning methods used to develop those empirical models may contribute to the inaccuracy. Traditionally, data are binned through a static binning approach by using fixed geomagnetic coordinates, in which the dynamic nature of the forcing is not considered and therefore the forcing patterns may be significantly smeared. To avoid the smoothing issue, data can be binned according to some physically important boundaries in the high-latitude forcing, that is, through a boundary-oriented binning approach. In this study, we have investigated the sensitivity of high-latitude forcing patterns to the binning methods by applying both static and boundary-oriented binning approaches to the electron precipitation and electric potential data from the Defense Meteorological Satellite Program satellites. For this initial study, we have focused on the moderately strong and dominantly southward interplanetary magnetic field conditions. As compared with the static binning results, the boundary-oriented binning approach can provide a more confined and intense electron precipitation pattern. In addition, the magnitudes of the electric potential and electric field in the boundary-oriented binning results increase near the convection reversal boundary, leading to a ~11\% enhancement of the cross polar cap potential. The forcing patterns obtained from both binning approaches are used to drive the Global Ionosphere and Thermosphere Model to assess the impacts on Joule heating by using different binning patterns. It is found that the hemispheric-integrated Joule heating in the simulation driven by the boundary-oriented binning patterns is 18\% higher than that driven by the static binning patterns.

Zhu, Qingyu; Deng, Yue; Richmond, Arthur; Maute, Astrid; Chen, Yun-Ju; Hairston, Marc; Kilcommons, Liam; Knipp, Delores; Redmon, Robert; Mitchell, Elizabeth;

Published by: Journal of Geophysical Research: Space Physics      Published on: 01/2020

YEAR: 2020     DOI: 10.1029/2019JA027270

Electric field; high latitude; Joule heating; particle precipitation

Persistence of the long-duration daytime TEC enhancements at different longitudinal sectors during the August 2018 geomagnetic storm

Li, Qiaoling; Huang, Fuqing; Zhong, Jiahao; Zhang, Ruilong; Kuai, Jiawei; Lei, Jiuhou; Liu, Libo; Ren, Dexin; Ma, Han; Yoshikawa, Akimasa; , others;

Published by: Journal of geophysical research: space physics      Published on:

YEAR: 2020     DOI:

Dual-lobe reconnection and horse-collar auroras

Milan, Stephen; Carter, Jennifer; Bower, Gemma; Imber, Suzanne; Paxton, Larry; Anderson, Brian; Hairston, Marc; Hubert, Benoit;

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

YEAR: 2020     DOI: