Ionospheric symmetry caused by geomagnetic declination over North America

Zhang, Shun‐Rong; Chen, Zi-Wei; Coster, A. J.; Erickson, P. J.; Foster, J. C.

doi:10.1002/2013gl057933

Cited by 26 publications

(33 citation statements)

References 33 publications

(44 reference statements)

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“…The spatial variation pattern, as given by the EOF basis function E 1 (Figure ), is essentially the same as the mean one determined over the whole time period as shown in Figure 1 of Zhang et al . []. A general decreasing trend with increasing latitude, or higher TEC in the south than in the north, can be found.…”

Section: Results Of Eof Analysismentioning

confidence: 80%

“…This is related to the magnetic field configuration for North America as suggested in Zhang et al . [].…”

Section: Results Of Eof Analysismentioning

confidence: 99%

“…The second‐order EOF components show great symmetric longitudinal variation of the ionosphere which has been discussed in detail in Zhang et al . []. For the completeness of the current paper, we briefly summarize Zhang et al .…”

Section: Results Of Eof Analysismentioning

confidence: 99%

“…For the completeness of the current paper, we briefly summarize Zhang et al . [] results using Figure that shows the second‐order EOF basis function E 2 . This mode is featured with a prominent longitudinal variation, where the west side TEC basic function is positive and the east side is negative.…”

Section: Results Of Eof Analysismentioning

confidence: 99%

“…[], Zhang et al . [] and Stoneback et al . [], indicate that the EOF analysis is a powerful method for use in ionospheric data analysis and empirical modeling.…”

Section: Description Of Tec Data and Eof Analysis Methodsmentioning

confidence: 99%

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EOF analysis and modeling of GPS TEC climatology over North America

et al. 2015

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An empirical ionospheric model of the total electron content (TEC) over North America (20°-60°N, 40°-140°W) is constructed using the GPS TEC data collected by Massachusetts Institute of Technology (MIT) Haystack Observatory during the years 2001-2012. This model is based on an analysis of quiet time monthly averages using the empirical orthogonal function (EOF) decomposition technique, allowing for separation of spatial and temporal variations. The importance of different types of spatial-temporal variations to the overall TEC variability can be well represented by the characteristics of EOF basis functions and associated principal components coefficients, with various modes. The mode one EOF decomposition constitutes 97.5% of the total variance and therefore represents the essential feature of North America spatial and diurnal variation of the TEC. The mode two EOF, as reported in an earlier study, reveals a large and significant symmetric longitudinal variation of the ionosphere, organized with respect to magnetic declination. The mode three EOF decomposition shows midlatitude latitudinal structure that varies with season in a manner very similar to the so-called winter anomaly. Because of the quick convergence of EOF decomposition modes, the first four EOF modes are utilized for constructing a TEC empirical model. For each of the EOF modes, the temporal variations are expressed analytically in terms of local time, season, and solar activity, and the spatial variations by cubic-spline functions. An analysis of accuracy and quality indicates that this regional empirical TEC model can reflect the majority of the quiet time monthly means, and represent characteristic temporal-spatial variations in the North America.

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Section: Results Of Eof Analysismentioning

confidence: 80%

“…This is related to the magnetic field configuration for North America as suggested in Zhang et al . [].…”

Section: Results Of Eof Analysismentioning

confidence: 99%

Section: Results Of Eof Analysismentioning

confidence: 99%

Section: Results Of Eof Analysismentioning

confidence: 99%

“…[], Zhang et al . [] and Stoneback et al . [], indicate that the EOF analysis is a powerful method for use in ionospheric data analysis and empirical modeling.…”

Section: Description Of Tec Data and Eof Analysis Methodsmentioning

confidence: 99%

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EOF analysis and modeling of GPS TEC climatology over North America

et al. 2015

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Modeling Chinese ionospheric layer parameters based on EOF analysis

Wan

Xiong

et al. 2015

Space Weather

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Using 24-ionosonde observations in and around China during the 20th solar cycle, an assimilative model is constructed to map the ionospheric layer parameters (f o F 2 , h m F 2 , M(3000)F 2 , and f o E) over China based on empirical orthogonal function (EOF) analysis. First, we decompose the background maps from the International Reference Ionosphere model 2007 (IRI-07) into different EOF modes. The obtained EOF modes consist of two factors: the EOF patterns and the corresponding EOF amplitudes. These two factors individually reflect the spatial distributions (e.g., the latitudinal dependence such as the equatorial ionization anomaly structure and the longitude structure with east-west difference) and temporal variations on different time scales (e.g., solar cycle, annual, semiannual, and diurnal variations) of the layer parameters. Then, the EOF patterns and long-term observations of ionosondes are assimilated to get the observed EOF amplitudes, which are further used to construct the Chinese Ionospheric Maps (CIMs) of the layer parameters. In contrast with the IRI-07 model, the mapped CIMs successfully capture the inherent temporal and spatial variations of the ionospheric layer parameters. Finally, comparison of the modeled (EOF and IRI-07 model) and observed values reveals that the EOF model reproduces the observation with smaller root-mean-square errors and higher linear correlation coefficients. In addition, IRI discrepancy at the low latitude especially for f o F 2 is effectively removed by EOF model.

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The geomagnetic storm time response of GPS total electron content in the North American sector

et al. 2016

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Over the last two decades, maps of GPS total electron content (TEC) have improved our understanding of the large perturbations in ionospheric electron density which occur during geomagnetic storms. However, previous regional and global studies of ionospheric storms have performed only a limited separation of storm time, local time, longitudinal, and seasonal effects. Using 13 years of GPS TEC data, we present a complete statistical characterization of the ionospheric response to geomagnetic storms for midlatitudes in the North American sector where dense ground receiver coverage is available. The rapid onset of a positive phase is observed across much of the dayside and evening ionosphere followed by a longer‐lasting negative phase across all latitudes and local times. Our results show clear seasonal variations in the storm time TEC, such that summer events tend to be dominated by the negative storm response while winter events exhibit a stronger initial positive phase with minimal negative storm effects. We find no discernable difference between spring and fall equinox events with both being equivalent to the average storm time response across all seasons. We also identify a prominent magnetic declination effect such that stronger dayside positive storm effects are observed in regions of negative declination (i.e., eastern North America). On the nightside, asymmetries in the TEC response are observed near the auroral oval and midlatitude trough which may be attributed to thermospheric zonal winds pushing plasma upward/downward along field lines of opposite declination.

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Ionospheric symmetry caused by geomagnetic declination over North America

Cited by 26 publications

References 33 publications

EOF analysis and modeling of GPS TEC climatology over North America

EOF analysis and modeling of GPS TEC climatology over North America

Modeling Chinese ionospheric layer parameters based on EOF analysis

The geomagnetic storm time response of GPS total electron content in the North American sector

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