The responses of Equatorial Ionosphere Anomaly(EIA) to the storm occurred on 17 March 2015 were studied using Global Ionosphere Map(GIM). The variations of Total Electron Content(TEC), latitudinal TEC gradients ...The responses of Equatorial Ionosphere Anomaly(EIA) to the storm occurred on 17 March 2015 were studied using Global Ionosphere Map(GIM). The variations of Total Electron Content(TEC), latitudinal TEC gradients and the rate of latitudinal TEC gradients in EIA regions were investigated in 75?E, 110?E and-60?E longitudinal sectors. The results from the GIM data showed that the distributions of the latitudinal gradient of TEC became monotonous in three longitudes on 18 March(the first day of the recovery phase), but the variations were different. On 18 March, the magnitudes of latitudinal gradients decreased in spatial and temporal in 75?E and 110?E, which means the EIA was suppressed during the recovery phase of the storm, especially in 110?E. The magnitudes of latitudinal TEC gradients showed an obvious increase in spatial and temporal in-60?E. The SAMI2 reproduced the suppression of EIA with a disturbance dynamo electric field, which indicated that the physical process controlled the behaviors of the plasma during the recovery phase of the storm.展开更多
Total Electron Content(TEC)and electron density enhancement were observed on the day before 17 March 2015 great storm in the China Region.Observations from ground-and space-based instruments are used to investigate th...Total Electron Content(TEC)and electron density enhancement were observed on the day before 17 March 2015 great storm in the China Region.Observations from ground-and space-based instruments are used to investigate the temporal and spatial evolution of the pre-storm enhancement.TEC enhancement was observed from 24°N to 30°N after 10:00 UT at 105°E,110°E and 115°E longitudes on March 16.The maximum magnitude of TEC enhancement was more than 10 TECU and the maximal relative TEC enhancement exceeded 30%.Compared with geomagnetic quiet days,the electron density of Equatorial Ionization Anomaly(EIA)northern peak from Swarm A/C satellites on March 16 was larger and at higher latitudes.NmF2 enhanced during 11:30—21:00 UT at Shaoyang Station and increased by 200%at~16:00 UT.However,TEC and electron density enhancement were not accompanied by a significant change of hmF2.Most research has excluded some potential mechanisms as the main driving factors for storm-time density enhancements by establishing observational constraints.In this paper,we observed pre-storm enhancement in electron density at different altitudes and Equatorial Electrojet(EEJ)strength results derived from ground magnetometers observations suggest an enhanced eastward electric field from the E region probably played a significant role in this event.展开更多
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 ...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.展开更多
基金Supported by the National Natural Science Foundation of China(41474134,41474135)
文摘The responses of Equatorial Ionosphere Anomaly(EIA) to the storm occurred on 17 March 2015 were studied using Global Ionosphere Map(GIM). The variations of Total Electron Content(TEC), latitudinal TEC gradients and the rate of latitudinal TEC gradients in EIA regions were investigated in 75?E, 110?E and-60?E longitudinal sectors. The results from the GIM data showed that the distributions of the latitudinal gradient of TEC became monotonous in three longitudes on 18 March(the first day of the recovery phase), but the variations were different. On 18 March, the magnitudes of latitudinal gradients decreased in spatial and temporal in 75?E and 110?E, which means the EIA was suppressed during the recovery phase of the storm, especially in 110?E. The magnitudes of latitudinal TEC gradients showed an obvious increase in spatial and temporal in-60?E. The SAMI2 reproduced the suppression of EIA with a disturbance dynamo electric field, which indicated that the physical process controlled the behaviors of the plasma during the recovery phase of the storm.
基金Fundamental Research Funds for the Central Universities(No.B230201012)National Natural Science Foundation of China(No.42104009)China Postdoctoral Science Foundation(No.2022M720988)。
文摘Total Electron Content(TEC)and electron density enhancement were observed on the day before 17 March 2015 great storm in the China Region.Observations from ground-and space-based instruments are used to investigate the temporal and spatial evolution of the pre-storm enhancement.TEC enhancement was observed from 24°N to 30°N after 10:00 UT at 105°E,110°E and 115°E longitudes on March 16.The maximum magnitude of TEC enhancement was more than 10 TECU and the maximal relative TEC enhancement exceeded 30%.Compared with geomagnetic quiet days,the electron density of Equatorial Ionization Anomaly(EIA)northern peak from Swarm A/C satellites on March 16 was larger and at higher latitudes.NmF2 enhanced during 11:30—21:00 UT at Shaoyang Station and increased by 200%at~16:00 UT.However,TEC and electron density enhancement were not accompanied by a significant change of hmF2.Most research has excluded some potential mechanisms as the main driving factors for storm-time density enhancements by establishing observational constraints.In this paper,we observed pre-storm enhancement in electron density at different altitudes and Equatorial Electrojet(EEJ)strength results derived from ground magnetometers observations suggest an enhanced eastward electric field from the E region probably played a significant role in this event.
基金supported by the B-type Strategic Priority Program of the Chinese Academy of Sciences (XDB41000000)the National Natural Science Foundation of China (41831070, 41974181)+5 种基金the Open Research Project of Large Research Infrastructures of the Chinese Academy of Sciences, “Study of the interaction between low- and mid-latitude atmosphere and ionosphere based on the Chinese Meridian Project.”supported by the National Natural Science Foundation of China (41904138)the National Postdoctoral Program for Innovative Talents (BX20180286)the China Postdoctoral Science Foundation (2018M642525)the Fundamental Research Funds for the Central UniversitiesThe National Center for Atmospheric Research is sponsored by the National Science Foundation。
文摘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.