The impact of the January 15, 2010, annular solar eclipse on the equatorial and low latitude ionospheric densities

Choudhary, R. K.; St.-Maurice, J.-P.; Ambili, K. M.; Sunda, Surendra; Pathan, B. M.

doi:10.1029/2011ja016504

Cited by 47 publications

(50 citation statements)

References 33 publications

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“…In other eclipse cases, a reduction ranging from 0.2 to 4 TECU has been reported (Afraimovich et al, 2002;Krankowski et al, 2008). Choudhary et al (2011), for the solar eclipse of 15 January 2010, have reported a larger decrease in the VTEC at Hyderabad as compared to that for Bangalore and Trivandrum, whereas the obscuration at Hyderabad, Bangalore and Trivendrum was 67.5, 77.1 and 84.3 % respectively. The VTEC at Trivendrum recovered to the mean value by 18:00 IST (∼ 2 h and 50 min after the eclipse), whereas at Hyderabad VTEC did not recover even up to 20:00 IST.…”

Section: Annmentioning

confidence: 99%

Ionospheric response to total solar eclipse of 22 July 2009 in different Indian regions

Kumar

Singh

2013

Ann. Geophys.

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The variability of ionospheric response to the total solar eclipse of 22 July 2009 has been studied analyzing the GPS data recorded at the four Indian low-latitude stations Varanasi (100% obscuration), Kanpur (95% obscuration), Hyderabad (84% obscuration) and Bangalore (72% obscuration). The retrieved ionospheric vertical total electron content (VTEC) shows a significant reduction (reflected by all PRNs (satellites) at all stations) with a maximum of 48% at Varanasi (PRN 14), which decreases to 30% at Bangalore (PRN 14). Data from PRN 31 show a maximum of 54% at Kanpur and 26% at Hyderabad. The maximum decrement in VTEC occurs some time (2–15 min) after the maximum obscuration. The reduction in VTEC compared to the quiet mean VTEC depends on latitude as well as longitude, which also depends on the location of the satellite with respect to the solar eclipse path. The amount of reduction in VTEC decreases as the present obscuration decreases, which is directly related to the electron production by the photoionization process. The analysis of electron density height profile derived from the COSMIC (Constellation Observing System for Meteorology, Ionosphere & Climate) satellite over the Indian region shows significant reduction from 100 km altitude up to 800 km altitude with a maximum of 48% at 360 km altitude. The oscillatory nature in total electron content data at all stations is observed with different wave periods lying between 40 and 120 min, which are attributed to gravity wave effects generated in the lower atmosphere during the total solar eclipse

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Section: Annmentioning

confidence: 99%

Ionospheric response to total solar eclipse of 22 July 2009 in different Indian regions

Kumar

Singh

2013

Ann. Geophys.

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“…There is so far no observational evidence to support this prediction. Aside from the short-lived effect, some studies noted a high occurrence rate of the counter electrojet on the day of eclipse (Tomás et al 2008;Choudhary et al 2011). This seems to be related to the fact that a solar eclipse, by definition, occurs at new moon, which favors the occurrence of the counter electrojet (e.g., Rastogi 1974).…”

Section: Storm Effectmentioning

confidence: 99%

“…As an alternative approach, Choudhary et al (2011) first calculated a linear regression between H and Dst, and then subtracted it from H . Here, we introduce a modified version of this Dst correction technique.…”

Section: Correction For the Dst Fieldmentioning

confidence: 99%

Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

2016

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A record of the geomagnetic field on the ground sometimes shows smooth daily variations on the order of a few tens of nano teslas. These daily variations, commonly known as Sq, are caused by electric currents of several μA/m 2 flowing on the sunlit side of the Eregion ionosphere at about 90-150 km heights. We review advances in our understanding of the geomagnetic daily variation and its source ionospheric currents during the past 75 years. Observations and existing theories are first outlined as background knowledge for the nonspecialist. Data analysis methods, such as spherical harmonic analysis, are then described in detail. Various aspects of the geomagnetic daily variation are discussed and interpreted using these results. Finally, remaining issues are highlighted to provide possible directions for future work.

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“…It has been discussed earlier by St.-Maurice et al (2011) in terms of eclipsed-induced Pre-reversal-enhancement (PRE) generated through a superposition of the low (cooling) and high pressure (solar heating) wind systems during the eclipse. Later, Choudhary et al (2011) also supported their arguments by retrieving the direction and amplitude of the plasma drift at the equator from a numerical 1-D model.…”

Section: Fig 5 Depicts the F-region Parameters (Top Three Panels) Atmentioning

confidence: 75%

“…The availability of global geomagnetic and interplanetary parameters, local magnetometer, ionosonde, and the large array of GPS receivers gave us an opportunity to investigate these objectives with a modern multi-instrument study. The comprehensive presentations of Rastogi (1989), Choudhary et al (2011), Madhav Haridas and Manju (2012, and Manju et al (2012Manju et al ( , 2014 motivated to investigate the peculiar ionospheric aspects of the exceptional eclipse configuration during the period.…”

Section: Introductionmentioning

confidence: 99%

Impact of the 15 January 2010 annular solar eclipse on the equatorial and low latitude ionosphere over the Indian region

Panda¹,

Gedam²,

Rajaram³

et al. 2015

Journal of Atmospheric and Solar-Terrestrial Physics

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a b s t r a c tThe annular solar eclipse of 15 January 2010 over southern India was studied with a multi-instrument network consisting of magnetometer, ionosonde and GPS receivers. The presence of a counter electrojet (weakened or westward zonal electric field) during the eclipse and adjacent days suggests the strong gravitational tidal effect associated with the exceptional Sun-Moon-Earth alignment around the eclipse day. With a strong backup of magnetometer recordings on the day of eclipse, its adjacent days and the normal electrojet day, it is argued that the regular eastward electric field for the whole day at the equator was not just weakened, but actually was flipped for several hours by the influence of enhanced lunar tides. The effect of flipping the electric field was clearly seen in the equatorial ionosonde data and through the large array of GPS receivers that produced the total electron content (TEC) data. The main impact of flipping the electric field was poor feeding of equatorial ionization anomaly (EIA) due to the severely weakened fountain effect on the eclipse day, with the regular anomaly crest shifting towards the equator. The equatorial ionosonde profile was also showing an enhanced F2 region peak in spite of a reduced vertical TEC. While the plasma density depletion at the lower F region altitude over the equator was due to the temporary lack of photo-ionization, the reductions in high altitude plasma density beyond the equator were caused by the electrodynamics taking place around the eclipse. The important finding of this analysis is that the electrodynamical consequences on the low latitude ionosphere were mainly due to the combination of eclipse and lunar tides which were far more significant and influenced the EIA density rather than eclipse alone. Based on these findings, it is argued that the prevailing lunar tidal impact also needs to be taken into account while seeking to understand the electrodynamical impact of the solar eclipse on the low latitude ionosphere.

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The impact of the January 15, 2010, annular solar eclipse on the equatorial and low latitude ionospheric densities

Cited by 47 publications

References 33 publications

Ionospheric response to total solar eclipse of 22 July 2009 in different Indian regions

Ionospheric response to total solar eclipse of 22 July 2009 in different Indian regions

Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

Impact of the 15 January 2010 annular solar eclipse on the equatorial and low latitude ionosphere over the Indian region

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