Solar activity dependence of total electron content derived from GPS observations over Mbarara

Abstract. In this paper, perturbations of the ionospheric Total Electron Content (TEC) are compared with geomagnetic oscillations. Comparison is made for a few selected periods, some during earthquakes in California and Japan and others at quiet periods in Israel and California. Anomalies in TEC were extracted using Global Positioning System (GPS) observations collected by GIL (GPS in Israel) and the California permanent GPS networks. Geomagnetic data were collected in some regions where geomagnetic observatories and the GPS network overlaps. Sensitivity of the GPS method and basic wave characteristics of the ionospheric TEC perturbations are discussed. We study temporal variations of ionospheric TEC structures with highest reasonable spatial resolution around 50 km. Our results show no detectable TEC disturbances caused by right-lateral strike-slip earthquakes with minor vertical displacement. However, geomagnetic observations obtained at two observatories located in the epicenter zone of a strong dip-slip earthquake (Kyuchu, M = 6.2, 26 March 1997) revealed geomagnetic disturbances occurred 6–7 h before the earthquake.

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Equatorial total electron content (TEC) at low and high solar activity

Advances in Space Research ◽

10.1016/j.asr.2008.04.019 ◽

2009 ◽

Vol 43 (11) ◽

pp. 1757-1761 ◽

Cited By ~ 12

Author(s):

O.K. Obrou ◽

M.N. Mene ◽

A.T. Kobea ◽

K.Z. Zaka

Keyword(s):

Solar Activity ◽

Total Electron Content ◽

High Solar Activity ◽

Electron Content ◽

Total Electron

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Annual and semiannual variations of vertical total electron content during high solar activity based on GPS observations

Annales Geophysicae ◽

10.5194/angeo-29-865-2011 ◽

2011 ◽

Vol 29 (5) ◽

pp. 865-873 ◽

Cited By ~ 19

Author(s):

M. P. Natali ◽

A. Meza

Keyword(s):

Solar Activity ◽

Total Electron Content ◽

Principal Component ◽

High Solar Activity ◽

Electron Content ◽

Vertical Total Electron Content ◽

Total Electron ◽

Ionospheric Variability ◽

Low Latitudes ◽

Sudden Decrease

Abstract. Annual, semiannual and seasonal variations of the Vertical Total Electron Content (VTEC) have been investigated during high solar activity in 2000. In this work we use Global IGS VTEC maps and Principal Component Analysis to study spatial and temporal ionospheric variability. The behavior of VTEC variations at two-hour periods, at noon and at night is analyzed. Particular characteristics associated with each period and the geomagnetic regions are highlighted. The variations at night are smaller than those obtained at noon. At noon it is possible to see patterns of the seasonal variation at high latitude, and patterns of the semiannual anomaly at low latitudes with a slow decrease towards mid latitudes. At night there is no evidence of seasonal or annual anomaly for any region, but it was possible to see the semiannual anomaly at low latitudes with a sudden decrease towards mid latitudes. In general, the semiannual behavior shows March–April equinox at least 40 % higher than September one. Similarities and differences are analyzed also with regard to the same analysis done for a period of low solar activity.

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Winter anomaly in NmF2 and TEC: when and where it can occur

Journal of Space Weather and Space Climate ◽

10.1051/swsc/2018036 ◽

2018 ◽

Vol 8 ◽

pp. A45 ◽

Cited By ~ 11

Author(s):

Yury V. Yasyukevich ◽

Anna S. Yasyukevich ◽

Konstantin G. Ratovsky ◽

Maxim V. Klimenko ◽

Vladimir V. Klimenko ◽

...

Keyword(s):

Solar Activity ◽

Meridional Wind ◽

Global Scale ◽

Activity Level ◽

Electron Content ◽

Intensity Increase ◽

Total Electron ◽

Solar Activity Level ◽

Winter Anomaly ◽

Activity Dependence

For the first time, by using a regression procedure, we analyzed the solar activity dependence of the winter anomaly intensity in the ionospheric F2-layer peak electron density (Nm F2) and in the Total Electron Content (TEC) on a global scale. We used the data from global ionospheric maps for 1998–2015, from GPS radio occultation observations with COSMIC, CHAMP, and GRACE satellites for 2001–2015, and ground-based ionosonde data. The fundamental features of the winter anomaly in Nm F2 and in TEC (spatial distribution and solar activity dependence) are similar for these parameters. We determined the regions, where the winter anomaly may be observed in principle, and the solar activity level, at which the winter anomaly may be recorded in different sectors. A growth in geomagnetic disturbance or in the solar activity level is shown to facilitate the winter anomaly intensity increase. Longitudinal variations in the winter anomaly intensity do not conform partly to the generally accepted Rishbeth theory. We consider the obtained results in the context of spatial and solar cycle variations in O/N2 ratio and thermospheric meridional wind. Additionally, we briefly discuss different definitions of the winter anomaly.

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