The asymmetrical features in electron density during extreme solar minimum

Zhang, Xuemin; Shen, Xuhui; Liu, Jing; Lu, Yao; Yuan, Guiping; Huang, Jianping

doi:10.1016/j.asr.2014.08.028

Cited by 4 publications

(6 citation statements)

References 32 publications

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“…These results agree with those by Zhang et al. (2014) (based on DEMETER data at ∼700 km) but are in contrast to Bailey et al. (2000) in the SH (from Hinotori data at ∼600 km) who reported the hemispheric‐dependent asymmetry (larger September N e in the SH) at low latitudes (±25°).…”

Section: Discussion and Summarysupporting

confidence: 91%

“…The larger March equinox N e was evident for all longitudes in both hemispheres. These results agree with those by Zhang et al (2014) (based on DEMETER data at ∼700 km) but are in contrast to Bailey et al (2000) in the SH (from Hinotori data at ∼600 km) who reported the hemispheric-dependent asymmetry (larger September N e in the SH) at low latitudes (±25°). The differences could be attributed to differences in ionospheric behavior during different solar cycles, or to methods of selecting and binning the data.…”

Section: Discussion and Summarysupporting

confidence: 90%

“…Understanding the causative mechanisms behind IEA is still an open question in the study of ionospheric seasonal variations (L. Liu et al, 2012;Ren et al, 2014;Zhang et al, 2014). Suggested theories attempting to explain the IEA at low and middle latitudes are based on equinoctial differences in thermospheric neutral winds (Balan et al, 2000;Kawamura et al, 2002), thermospheric global circulation (Bailey et al, 2000), neutral composition (Richards, 2001), and plasma drifts (Ren et al, 2011(Ren et al, , 2014, but with no apparent consensus as to the primary mechanism emerging to date.…”

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confidence: 99%

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Equinoctial Asymmetry in the Upper Ionosphere: Comparison of Satellite Observations and Models

et al. 2023

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The terrestrial ionosphere displays significant equinoctial asymmetry despite the upper atmosphere receiving similar levels of solar ionization energy at a given location and local time in March and September during similar solar activity conditions. This intriguing feature is not well understood or modeled, particularly in the upper ionosphere, and causes of the asymmetry are not fully established and quantified. Yet, their study is important to provide better insights into the atmosphere‐ionosphere coupling processes. Analysis of Langmuir probe data from ESA's Swarm B satellite at ∼525 km altitude reveals that the daytime electron density is larger for all latitudes during the March equinox than during the September equinox, while the electron temperature shows an inverted asymmetry except at low latitudes. Simultaneously obtained neutral density data from Swarm GPS accelerations indicate that the thermosphere is denser during the March equinox. The asymmetry seen by Swarm electron density observations is also present in electron densities obtained using GPS radio occultation measurements from the COSMIC satellites. Simulations were performed using physics‐based ionosphere models (SAMI3, WACCM‐X, and TIE‐GCM) to determine their ability to produce the observed asymmetry, understand the generation mechanism(s), and establish the relative role of physical drivers. Results produced by TIE‐GCM are closest to the observations when seasonally varying eddy diffusivity is considered in the model. The asymmetry produced by other models is noticeably weaker. Modeling of the asymmetry by SAMI3 driven with the TIE‐GCM neutral atmosphere shows that both neutral density and winds play a critical role, but the density has a greater effect.

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Section: Discussion and Summarysupporting

confidence: 91%

Section: Discussion and Summarysupporting

confidence: 90%

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confidence: 99%

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Equinoctial Asymmetry in the Upper Ionosphere: Comparison of Satellite Observations and Models

et al. 2023

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“…There is only an equatorial peak structure in Ne at 660 km during solar minimum, not the double-crest structure predicted in the IRI model. Zhang et al [36] found an abnormal enhancement in the solstitial asymmetry between both the hemispheres during 2008-2009.…”

Section: Ionospheric Climatology and Structuresmentioning

confidence: 98%

New understanding achieved from 2 years of Chinese ionospheric investigations

Liu

Wan

2016

Science Bulletin

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“…To detect the weak ionospheric perturbations induced by earthquakes or other disasters on ground, CSES is designed to operate during low solar activity years with less disturbances from outer space. In the 23rd solar cycle, 2008 was under the extremely low solar activity with the lowest electron density during the DEMETER satellite operation time in 2004-2010 [40], when Ne exhibited different temporal and spatial features with that in high solar activity years [41,42]. Ten years after, 2018 began into another quiet solar year, when CSES may show similar electromagnetic features in the topside ionosphere.…”

Section: Background Informationmentioning

confidence: 99%

The Ionospheric Responses from Satellite Observations within Middle Latitudes to the Strong Magnetic Storm on 25–26 August 2018

Zhang

Dong

2022

Atmosphere

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The multi observations from the China Seismo-Electromagnetic Satellite (CSES) were presented and analyzed during the biggest magnetic storm on 25–26 August in the quiet solar activity year of 2018, together with the Swarm satellite and GNSS TEC (Global Navigation Satellite System, Total Electron Content). The whole tempo-spatial evolutional process was demonstrated in electromagnetic fields and in-situ plasma parameters within the whole magnetic storm time period of three phases, the main phase with quick decrease in SYM-H, the quick recovery phase, and the slow recovery phase. Strong correlations were revealed in time and space between electric fields and electron density. During the main phase, the penetrated electric field was the major factor to induce the injection of electric fields to low latitudes even to the equator and contribute to constructing the double peaks of Ne at altitudes above 500 km of CSES in daytime. In the quick recovery phase, Ne depletion was found in low middle and low latitudes in the daytime, associated with a quick decrease in solar wind dynamic pressure, but in the nightside Ne maintained or increased. Due to the high solar wind speed following the quick recovery phase, it controlled the enhancements in an electric field below 1125 Hz at medium and low latitudes in daytime and produced similar structures in a 225 Hz electric field with the mid-latitude trough of Ne in local nighttime and maintained their equator-ward movements in this time period. Ne/TEC showed typical local time-dependence in this magnetic storm, which illustrated that although the electron density in the ionosphere was mainly caused by this solar activity event, local background environments must also not be ignored for their final evolutional modes.

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The asymmetrical features in electron density during extreme solar minimum

Cited by 4 publications

References 32 publications

Equinoctial Asymmetry in the Upper Ionosphere: Comparison of Satellite Observations and Models

Equinoctial Asymmetry in the Upper Ionosphere: Comparison of Satellite Observations and Models

New understanding achieved from 2 years of Chinese ionospheric investigations

The Ionospheric Responses from Satellite Observations within Middle Latitudes to the Strong Magnetic Storm on 25–26 August 2018

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