Asymmetric behaviour and geomagnetic dependencies of zonal winds in the middle latitude upper thermosphere

Sivla, W.T.; Mtumela, Zolile; Ogunjobi, O.

doi:10.1016/j.asr.2020.07.020

Cited by 2 publications

(2 citation statements)

References 26 publications

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“…For example, high‐latitude electrodynamic forcing is associated with complex temporal and spatial changes, characterized by large‐scale anti‐sunward convection flows (e.g., Burch et al., 1985; Cousins & Shepherd, 2010; Nishitani et al., 2003; Reiff & Burch, 1985), enhanced ionospheric currents near the auroral region (e.g., Østgaard & Laundal, 2012), and equatorward expansions of the auroral oval (e.g., Cowley & Lockwood, 1992; Fuller‐Rowell et al., 1994). Furthermore, asymmetric electrodynamics leads to IHA in Joule heating (e.g., Codrescu et al., 1995; Foster et al., 1983), which contributes to the changes in the thermospheric neutral wind (e.g., Deng & Ridley, 2006; Sivla et al., 2020), neutral mass density (e.g., Aa et al., 2012; Hong et al., 2023; Sutton et al., 2009; Zhu et al., 2023) and large‐scale structures in total electron content (TEC) (e.g., Dashora et al., 2019; Zhu, Lu, & Deng, 2022; Zhu, Lu, Mate, et al., 2022).…”

Section: Introductionmentioning

confidence: 99%

Relative Contributions of Field‐Aligned Currents and Particle Precipitation to Inter‐Hemispheric Asymmetry at High Latitudes During the 2015 St. Patrick's Day Storm

Hong,

Deng,

Maute

et al. 2024

JGR Space Physics

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High latitude upper atmospheric inter‐hemispheric asymmetry (IHA) tends to be enhanced during geomagnetic storms, which may be due to the complex spatiotemporal changes and magnitude modifications in field aligned currents (FACs) and particle precipitation (PP). However, the relative contribution of FACs and PP to IHA in high‐latitude forcing and energy is not well understood. The IHA during the 2015 St. Patrick’s Day storm has been investigated using the global ionosphere thermosphere model (GITM), driven by FACs from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) and PP from the Assimilative Mapping of Ionospheric Electrodynamics (AMIE). A comprehensive study of the (a) relative contributions of FACs and PP to electric potential and Joule heating and (b) sensitivity of electric potential and Joule heating to the changes in magnitude and distribution of FACs and PP is presented. The results indicate that FACs lead to larger potential and Joule heating changes compared with PP. The spatial variations of potential and Joule heating are also affected by variation in FACs. As for asymmetric magnitude and distribution, it is found that electric potential and Joule heating are more sensitive to changes in the distribution of FACs and PP than the magnitude of FACs and PP. A new spatial asymmetry index (SAI) is introduced, which reveals spatial asymmetric details that are often overlooked by previous studies. This sensitivity study reveals the relative contributions in high‐latitude forcing and emphasizes the importance of obtaining accurate FACs and PP in both hemispheres.

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Section: Introductionmentioning

confidence: 99%

Relative Contributions of Field‐Aligned Currents and Particle Precipitation to Inter‐Hemispheric Asymmetry at High Latitudes During the 2015 St. Patrick's Day Storm

Hong,

Deng,

Maute

et al. 2024

JGR Space Physics

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“…During geomagnetic active times, the high-latitude electron density structures including the tongue of ionization (TOIs) and polar patches (Cherniak et al, 2016;Jin & Xiong, 2020;Spicher et al, 2017), and the mid-latitudes electron density structures including the storm-time enhanced density (SED) plume and ionospheric trough, exhibit large differences between the northern hemisphere (NH) and the southern hemisphere (SH) (e.g., Prikryl et al, 2015). As for the thermosphere, observations also indicate that there are significant inter-hemispheric asymmetries in the neutral mass density (e.g., A et al, 2012;Liu et al, 2005;Sutton et al, 2009), neutral wind (e.g., Sivla et al, 2020), neutral temperature (e.g., Roble & Dickinson, 1973) and neutral composition (e.g., Mayr et al, 1978). Overall, these observed inter-hemispheric asymmetries and the associated causes and mechanisms need to be fully understood.…”

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confidence: 99%

Impacts of Different Causes on the Inter‐Hemispheric Asymmetry of Ionosphere‐Thermosphere System at Mid‐ and High‐Latitudes: GITM Simulations

Deng

Zhu

et al. 2021

Space Weather

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In this study, the Global Ionosphere Thermosphere Model is utilized to investigate the inter‐hemispheric asymmetry in the ionosphere‐thermosphere (I‐T) system at mid‐ and high‐latitudes (|geographic latitude| > 45°) associated with inter‐hemispheric differences in (a) the solar irradiance, (b) geomagnetic field, and (c) magnetospheric forcing under moderate geomagnetic conditions. Specifically, we have quantified the relative significance of the above three causes to the inter‐hemispheric asymmetries in the spatially weighted averaged E‐region electron density, F‐region neutral mass density, and horizontal neutral wind along with the hemispheric‐integrated Joule heating. Further, an asymmetry index defined as the percentage differences of these four quantities between the northern and southern hemispheres (|geographic latitude| > 45°) was calculated. It is found that: (a) The difference of the solar extreme ulutraviolet (EUV) irradiance plays a dominant role in causing inter‐hemispheric asymmetries in the four examined I‐T quantities. Typically, the asymmetry index for the E‐region electron density and integrated Joule heating at solstices with F10.7 = 150 sfu can reach 92.97% and 38.25%, respectively. (b) The asymmetric geomagnetic field can result in a strong daily variation of inter‐hemispheric asymmetries in the F‐region neutral wind and hemispheric‐integrated Joule heating over geographic coordinates. Their amplitude of asymmetry indices can be as large as 20.81% and 42.52%, which can be comparable to the solar EUV irradiance effect. (c) The contributions of the asymmetric magnetospheric forcing, including particle precipitation and ion convection pattern, can cause the asymmetry of integrated Joule heating as significant as 28.43% and 34.72%, respectively, which can be even stronger than other causes when the geomagnetic activity is intense.

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Asymmetric behaviour and geomagnetic dependencies of zonal winds in the middle latitude upper thermosphere

Cited by 2 publications

References 26 publications

Relative Contributions of Field‐Aligned Currents and Particle Precipitation to Inter‐Hemispheric Asymmetry at High Latitudes During the 2015 St. Patrick's Day Storm

Relative Contributions of Field‐Aligned Currents and Particle Precipitation to Inter‐Hemispheric Asymmetry at High Latitudes During the 2015 St. Patrick's Day Storm

Impacts of Different Causes on the Inter‐Hemispheric Asymmetry of Ionosphere‐Thermosphere System at Mid‐ and High‐Latitudes: GITM Simulations

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