TEC differences for the mid-latitude ionosphere in both sides of the longitudes with zero declination

Xu, Jisheng; Li, X. J.; Liu, Y. W.; Jing, Ming-Zhen

doi:10.1016/j.asr.2013.01.010

Cited by 25 publications

(37 citation statements)

References 22 publications

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“…3o). Similar results were found by Zhang et al (2011Zhang et al ( ,2013, Xu et al (2013), and Chen et al (2015).…”

Section: Pca On Vtec Gnsssupporting

confidence: 79%

“…8i, j). Xu et al (2013) analyzed the longitudinal anomaly in South America at different local times from 2001 to 2010 and found negative values for the east-west difference, with larger values during December and lower ones during June; our results are similar.…”

Section: Pca On Vtec Gnsssupporting

confidence: 77%

“…At night and at mid-latitudes, the ionosphere is characterized by: annual and semiannual temporal variations (Rishbeth 1998), the mid-latitude summer night anomaly (MSNA) Lin et al 2010), and the eastwest difference (Xu et al 2013;Zhao et al 2013). The MSNA has its origin in the Weddell Sea Anomaly, which is characterized by higher electron densities during the night than during the day near the Antarctic Peninsula.…”

Section: Introductionmentioning

confidence: 99%

“…Lastly, some authors report an ionospheric east-west difference in both sides of the longitudes with zero magnetic declination (Zhang et al 2011;Xu et al 2013;Zhao et al 2013), hereafter named longitudinal anomaly. They suggested that this longitudinal anomaly is caused by the difference in magnetic declination that gives rise to upward and downward ion drifts across the zero declination for a given thermospheric zonal wind direction.…”

Section: Introductionmentioning

confidence: 99%

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PCA and vTEC climatology at midnight over mid-latitude regions

Natali

Meza

2017

Earth Planets Space

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The effect of the thermospheric vertical neutral wind on vertical total electron content (vTEC) variations including longitudinal anomaly, remaining winter anomaly, mid-latitude summer night anomaly, and semiannual anomaly is studied at mid-latitude regions around zero magnetic declination at midnight during high solar activity. By using the principal component analysis (PCA) numerical technique, this work studies the spatial and temporal variations of the ionosphere at midnight over mid-latitude regions during [2000][2001][2002]. PCA is applied to a time series of global vTEC maps produced by the International Global Navigation Satellite System (GNSS) Service. Four regions were studied in particular, each located at mid-latitude and approximately centered at zero magnetic declination, with two in the northern hemisphere and two in southern hemisphere, and all are located near and far from geomagnetic poles in each case. This technique provides an effective method to analyze the main ionospheric variabilities at mid-latitudes. PCA is also applied to the vTEC computed using the International Reference Ionosphere (IRI) 2012 model, to analyze the capability of this model to represent ionospheric variabilities at mid-latitude. Also, the Horizontal Wind Model 2007 (HWM07) is used to improve our climatology interpretation, by analyzing the relationship between vTEC and thermospheric wind, both quantitatively and qualitatively. At midnight, the behavior of mean vTEC values strongly responds to vertical wind variation, experiencing a decrease of about 10-15% with the action of the positive vertical component of the field-aligned neutral wind lasting for 2 h in all regions except for Oceania. Notable results include: a significant increase toward higher latitudes during summer in the South America and Asia regions, associated with the mid-latitude summer night anomaly, and an increase toward higher latitudes in winter in the North America and Oceania regions, highlighting the remnant effect of the winter anomaly. Finally, the longitudinal variations of eastwest differences, named longitudinal anomaly, show maximum values in March for North America, in December for South America and Oceania, and are not shown for Asia. Our results show that at mid-latitudes regions, the IRI model represents midnight ionospheric mean values with a similar spatial distribution, but the values are always lower than those obtained by GNSS. The differences between IRI and GNSS results include: the longitudinal anomaly is characterized by a stronger semiannual variation in both North America and South America, with a maximum in the equinoxes, while for the Asian region, the behavior is almost constant throughout the years, and finally, there is an absence of the winter anomaly remnant.

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“…3o). Similar results were found by Zhang et al (2011Zhang et al ( ,2013, Xu et al (2013), and Chen et al (2015).…”

Section: Pca On Vtec Gnsssupporting

confidence: 79%

Section: Pca On Vtec Gnsssupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

PCA and vTEC climatology at midnight over mid-latitude regions

Natali

Meza

2017

Earth Planets Space

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“…Previous regional and global observations have disclosed prominent wave-2 and wave-1 longitudinal structures of the Ne in the F layer in the Northern and Southern Hemispheres Zhao et al 2013;Xu et al 2013;Wang et al 2016). Wang et al (2016) found a wave-1 longitudinal structure of Ne existing in the E layer in both hemispheres.…”

Section: Introductionmentioning

confidence: 99%

Longitudinal structure in electron density at mid-latitudes: upward-propagating tidal effects

Wang

Zhang

2017

Earth Planets Space

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This work studies the upward-propagating migrating and non-migrating tidal effects from the lower atmosphere on the longitudinal variation of electron density ( Ne) in both the E and F regions at mid-latitudes during the 2002 March equinox. A total of 12 runs are conducted using the Thermosphere Ionosphere Electrodynamic General Circulation model for theoretical investigation. The Ne at altitudes above 200 km is affected by upward-propagating tides, with maximum values attained around 300 km. Migrating tides result in reduced longitudinal differences in the Ne over North America and in the Southern Hemisphere, while non-migrating tides induce a wave-4 pattern in both hemispheres. The non-migrating effect is weaker than the migrating effect after penetrating into the F region. The neutral composition (i.e., ratio of atom oxygen to molecular nitrogen) is dominant in regulating the Ne in both the migrating (accounting for approximately 64%) and non-migrating (about 60%) tidal penetration processes. TheNe caused by the tidal meridional wind (accounting for approximately 70%) is stronger than the tidal zonal wind (about 30%) under both the migrating and non-migrating tidal conditions, except in the Southern Hemisphere under migrating tidal input. This work contributes to our understanding of the mechanisms for the longitudinal modulation of the Ne at mid-latitudes.

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Ionospheric symmetry caused by geomagnetic declination over North America

Zhang

Chen

Coster

et al. 2013

Geophysical Research Letters

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[1] We describe variations in total electron content (TEC) in the North American sector exhibiting pronounced longitudinal progression and symmetry with respect to zero magnetic declination. Patterns were uncovered by applying an empirical orthogonal function (EOF) decomposition procedure to a 12 year ground-based American longitude sector GPS TEC data set. The first EOF mode describes overall average TEC, while the strong influence of geomagnetic declination on the midlatitude ionosphere is found in the second EOF mode (or the second most significant component). We find a high degree of correlation between spatial variations in the second EOF mode and vertical drifts driven by thermospheric zonal winds, along with well-organized temporal variation. Results strongly suggest a causative mechanism involving varying declination with longitude along with varying zonal wind climatology with local time, season, and solar cycle. This study highlights the efficiency and key role played by the geomagnetic field effect in influencing mesoscale ionospheric structures over a broad midlatitude range.

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TEC differences for the mid-latitude ionosphere in both sides of the longitudes with zero declination

Cited by 25 publications

References 22 publications

PCA and vTEC climatology at midnight over mid-latitude regions

PCA and vTEC climatology at midnight over mid-latitude regions

Longitudinal structure in electron density at mid-latitudes: upward-propagating tidal effects

Ionospheric symmetry caused by geomagnetic declination over North America

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