Assessment of International GNSS Service Global Ionosphere Map products over China region based on measurements from the Crustal Movement Observation Network of China

The global ionosphere maps(GIM)provided by the International GNSS Service(IGS)are extensively utilized for ionospheric morphology monitoring,scientific research,and practical application.Assessing the credibility of GIM products in data-sparse regions is of paramount importance.In this study,measurements from the Crustal Movement Observation Network of China(CMONOC)are leveraged to evaluate the suitability of IGS-GIM products over China region in 2013-2014.The indices of mean error(ME),root mean square error(RMSE),and normalized RMSE(NRMSE)are then utilized to quantify the accuracy of IGS-GIM products.Results revealed distinct local time and latitudinal dependencies in IGS-GIM errors,with substantially high errors at nighttime(NRMSE:39%)and above 40°latitude(NRMSE:49%).Seasonal differences also emerged,with larger equinoctial deviations(NRMSE:33.5%)compared with summer(20%).A preliminary analysis implied that the irregular assimilation of sparse IGS observations,compounded by China’s distinct geomagnetic topology,may manifest as error variations.These results suggest that modeling based solely on IGS-GIM observations engenders inadequate representations across China and that a thorough examination would proffer the necessary foundation for advancing regional total electron content(TEC)constructions.

Observations of equatorial plasma bubbles during the geomagnetic storm of October 2016

We investigated the variations of equatorial plasma bubbles(EPBs)in the East-Asian sector during a strong geomagnetic storm in October 2016,based on observations from the Beidou geostationary(GEO)satellites,Swarm satellite and ground-based ionosonde.Significant nighttime depletions of F region in situ electron density from Swarm and obvious nighttime EPBs in the Beidou GEO observations were observed on 13 October 2016 during the main phase.Moreover,one interesting feature is that the rare and unique sunrise EPBs were triggered on 14 October 2016 in the main phase rather than during the recovery phase as reported by previous studies.In addition,the nighttime EPBs were suppressed during the whole recovery phase,and absent from 14 to 19 October 2016.Meanwhile,the minimum virtual height of F trace(h’F)at Sanya(18.3°N,109.6°E,MLAT 11.1°N)displayed obvious changes during these intervals.The h’F was enhanced in the main phase and declined during the recovery phase,compared with the values at pre-and post-storm.These results indicate that the enhanced nighttime EPBs and sunrise EPBs during the main phase and the absence nighttime EPBs for many days during the recovery phase could be associated with storm-time electric field changes.

Prediction of the thermospheric and ionospheric responses to the 21 June 2020 annular solar eclipse

On 21 June 2020,an annular solar eclipse will traverse the low latitudes from Africa to Southeast Asia.The highest latitude of the maximum eclipse obscuration is approximately 30°.This low-latitude solar eclipse provides a unique and unprecedented opportunity to explore the impact of the eclipse on the low-latitude ionosphere–thermosphere(I–T)system,especially in the equatorial ionization anomaly region.In this study,we describe a quantitative prediction of the impact of this upcoming solar eclipse on the I–T system by using Thermosphere–Ionosphere–Electrodynamics General Circulation Model simulations.A prominent total electron content(TEC)enhancement of around 2 TEC units occurs in the equatorial ionization anomaly region even when this region is still in the shadow of the eclipse.This TEC enhancement lasts for nearly 4.5 hours,long after the solar eclipse has ended.Further model control simulations indicate that the TEC increase is mainly caused by the eclipse-induced transequatorial plasma transport associated with northward neutral wind perturbations,which result from eclipse-induced pressure gradient changes.The results illustrate that the effect of the solar eclipse on the I–T system is not transient and linear but should be considered a dynamically and energetically coupled system.

Design and Application of a MCU-based Smart Contactor System

This paper aims to design a MCU-based smart contactor system, which will realize functions of real time surveillance of contactors’ work status and data exchange with host computer, thus instantly reflect different status of the system. In case of abnormal status such as over-current or under-voltage, the contactor will be able to automatically cut off power supply to protect electrical load and the circuit. Through ARINC485 bus, system computer will collect and record contactor parameters, including contact voltage, contact current, supply frequency, contact temperature and contact status to provide critical data to the examination and repair of contactors.

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.