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Found 2 entries in the Bibliography.
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2015 |
Characteristics of ionospheric north-south asymmetry and their relationship with irregularity Using the empirical ionospheric model, the flux-tube integrated electron density and the ratio between the F-region Pedersen conductivity and the total E- and F-region Pedersen conductivity are calculated to investigate the characteristics of the ionospheric asymmetry after sunset during a solar cycle. Furthermore, two indices representing the asymmetric strength of the parameters respectively are defined to study its relationship with the occurrences of the irregularities during different seasons and with different solar activities. The results indicate that the electron density and the Pedersen conductivity ratio show north-south remarkable hemispheric asymmetry at different solar energy levels. The asymmetric strengths represent the dependence on seasons and solar activities, and their variation depending on seasons and solar activities show a negative correlation with the occurrences of the equatorial irregularities and also have a negative relation with the linear growth rate of the generalized Rayleigh-Taylor instability. Luo, Weihua; Zhu, Zhengping; Lan, Jiaping; Li, Xuejing; Published by: Wuhan University Journal of Natural Sciences Published on: 06/2015 YEAR: 2015   DOI: 10.1007/s11859-015-1088-7 asymmetry; Electron density; Ionosphere; irregularity; Pedersen conductivity |
2013 |
Ground-based GPS observation of SED-associated irregularities over CONUS \ It has been known that steep total electron content (TEC) gradients observed at the boundary between the storm-enhanced plasma density (SED) and the low TEC region at subauroral and midlatitude regions are associated with ionospheric irregularities that impact communication and navigation systems. However, the relationship between the SED-associated irregularities and TEC gradients is still not well understood, partly because of the difficulties of resolving small-scale TEC gradients from sparsely distributed TEC observations. In this study, we examine the relationship between the SED-associated irregularities and TEC gradients during the intense geomagnetic storms of 31 March 2001 and 30 October 2003. To explore this relationship, TEC maps over the continental United States (CONUS) were constructed from ground-based GPS TEC observations, using Kalman filter update formulae with a recently developed nonstationary wavelet-based covariance model that enables resolution of TEC structures on both large and finer scales. Our results show that intense TEC gradients and ion drifts are thought to be required conditions for the formation of irregularities on the northeast side of the SED. Additionally, our methodology identified the narrow east-west stretch of TEC enhancement within the midlatitude low TEC region on 30 October 2003, and this TEC enhancement is most likely to be caused by auroral precipitation. Sun, Yang-Yi; Matsuo, Tomoko; Araujo-Pradere, Eduardo; Liu, Jann-Yenq; Published by: Journal of Geophysical Research: Space Physics Published on: 05/2013 YEAR: 2013   DOI: 10.1029/2012JA018103 data assimilation; irregularity; nonstationary covariance; SED; TEC gradient |
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