Observations of the ionosphere in the equatorial anomaly region using WISS during the total solar eclipse of 22 July 2009

Zhang, Xinmiao; Zhao, Zhengyu; Zhang, Yuannong; Zhou, Chen

doi:10.1016/j.jastp.2010.04.012

Cited by 11 publications

(13 citation statements)

References 36 publications

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“…Moreover, Ratnam et al [2012], for annular SE of 15 January 2010 observed time delay of~68 min at the altitude range of 60-80 km at a low latitude station, in India. The longer delay times (~1-2 h) have also been reported by various workers at E to F region ionosphere heights [Zhang et al, 2010;Yadav et al, 2013].…”

Section: Eclipse Day Wave-like Signaturessupporting

confidence: 80%

Low‐mid latitude D region ionospheric perturbations associated with 22 July 2009 total solar eclipse: Wave‐like signatures inferred from VLF observations

Maurya¹,

Phanikumar

Singh³

et al. 2014

JGR Space Physics

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We present first report on the periodic wave-like signatures (WLS) in the D region ionosphere during 22 July 2009 total solar eclipse using JJI, Japan, very low frequency (VLF) navigational transmitter signal (22.2 kHz) observations at stations, Allahabad, Varanasi and Nainital in Indian Sector, Busan in Korea, and Suva in Fiji. The signal amplitude increased on 22 July by about 6 and 7 dB at Allahabad and Varanasi and decreased by about 2.7, 3.5, and 0.5 dB at Nainital, Busan, and Suva, respectively, as compared to 24 July 2009 (normal day). The increase/decrease in the amplitude can be understood in terms of modal interference at the sites of modes converted at the discontinuity created by the eclipse intercepting the different transmitter-receiver great circle paths. The wavelet analysis shows the presence of WLS of period~16-40 min at stations under total eclipse and of period~30-80 min at stations under partial eclipse (~85-54% totality) with delay times between~50 and 100 min at different stations. The intensity of WLS was maximum for paths in the partially eclipsed region and minimum in the fully eclipsed region. The features of WLS on eclipse day seem almost similar to WLS observed in the nighttime of normal days (e.g., 24 July 2009). The WLS could be generated by sudden cutoff of the photo-ionization creating nighttime like conditions in the D region ionosphere and solar eclipse induced gravity waves coming to ionosphere from below and above. The present observations shed additional light on the current understanding of gravity waves induced D region ionospheric perturbations.

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Section: Eclipse Day Wave-like Signaturessupporting

confidence: 80%

Low‐mid latitude D region ionospheric perturbations associated with 22 July 2009 total solar eclipse: Wave‐like signatures inferred from VLF observations

Maurya¹,

Phanikumar

Singh³

et al. 2014

JGR Space Physics

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“…The D region ionospheric response time of ~ 4–13 min estimated between the first encounter of three SEs with respective TRGCPs and start of decrease in the amplitude is consistent with observations by Clilverd et al . [] but are shorter than the response times (~1–2 h) found by several researchers [ Altadill et al ., ; Zhang et al ., ; Yadav et al ., ] for SEs effect in the E and F region ionosphere.…”

Section: Discussionmentioning

confidence: 98%

“…The major portion of solar radiation during the solar eclipses (SEs) is reduced suddenly, which produces temporal changes in the Earth's atmosphere including ionosphere [e.g., Anderson et al ., ; Antonia et al ., ; Chimonas and Hines , ; Chimonas , ; Singh et al ., ; Afraimovich et al ., ; Clilverd et al ., ; Baran et al ., ; Chandra et al ., ; Zhang et al ., ; Chuo , ; Maurya et al ., , and references therein]. Each SE is different from others in terms of their occurrence time, day and year, location of observing station, percentage of the solar disk occultation, and state of the near Earth's environment [ Baran et al ., ]; therefore, continuous investigations on SEs ionospheric effects, mainly in the lower ionosphere, are needed to better establish the SE effects and their variability.…”

Section: Introductionmentioning

confidence: 99%

Changes in the D region associated with three recent solar eclipses in the South Pacific region

Kumar

Maurya

et al. 2016

JGR Space Physics

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We estimate D region changes due to 22 July 2009 total solar eclipse (SE), 13–14 November 2012 total SE, and 9–10 May 2013 annular SE, using VLF navigational transmitters signal observations at Suva, Fiji. The North West Cape (NWC) signal (19.8 kHz) showed an amplitude and phase decrease of 0.70 dB and 23° during November SE and 2.0 dB and 90° during May SE. The modeling using Long Wave Propagation Capability code for NWC‐Suva path during November and May SEs showed an increase in average D region reflection height (H′) and sharpness factor (β) by 0.6 and 0.5 km and 0.012 and 0.015 km−1, respectively. The July total SE for JJI‐Suva path showed an increase in H′ of 1.5 km and a decrease in β of 0.055 km−1. The decrease in the electron density calculated using SE time H′ and β is maximum for July total SE and minimum for May annular SE. The effective recombination coefficient estimated from the decay and recovery of signal phase associated with May annular SE was higher (27%) than normal daytime value 5.0 × 10−7 cm−3 s−1 and varied between 1.47 × 10−6 and 1.15 × 10−7 cm−3 s−1 in the altitude 70 to 80 km. Morlet wavelet analysis of signals amplitude shows strong wave‐like signatures (WLS) associated with three SEs with period ranging 24–66 min, but the intensity and duration of WLS show no clear dependence on SE magnitude and type. Apart from the cooling spot, the eclipse shadow can also generate WLS associated with atmospheric gravity waves.

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“…In principal, besides Joule heating and particle precipitation induced by high solar activities in polar region, solar activities like terminator and solar eclipse can also be the potential sources of gravity wave bursts detected in the ionosphere. However, only medium‐scale TIDs (MSTIDs) have been reported so far related to the latter type of source [e.g., Afraimovich et al , 2009; Šauli et al , 2006, 2007; Zhang et al , 2010]. Hence, solar terminator and solar eclipse tend to be not a responsible cause.…”

Section: Summary and Discussionmentioning

confidence: 99%

Evidence of low‐latitude daytime large‐scale traveling ionospheric disturbances observed by high‐frequency multistatic backscatter sounding system during a geomagnetically quiet period

et al. 2012

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[1] Observations from the high-frequency multistatic backscatter sounding radars on a geomagnetically quiet day (minimum D st = À14 nT) captured the anti-equatorward propagation of daytime large-scale traveling ionospheric disturbance (LSTID) at the low-latitude regions. The observed LSTID was characterized approximately by a meridional propagation speed of 347 AE 78 m/s and azimuthal angle of À4.7 AE 27.6 (counterclockwise from north), with a period of 76 min and a wavelength of 1583 AE 354 km by means of maximum entropy cross-spectral analysis. Vertical phase velocity was also evaluated to be <$42 m/s through the Doppler measurements. These results provide evidence that the low-latitude ionosphere can undergo large-scale perturbations even under geomagnetically quiet conditions. We suggest that this observed LSTID could be due to the secondary gravity waves from thermospheric body forces created from the dissipation of primary gravity waves from deep tropospheric convection.Citation: Zhou, C., Z. Zhao, G. Yang, G. Chen, Y. Hu, and Y. Zhang (2012), Evidence of low-latitude daytime large-scale traveling ionospheric disturbances observed by high-frequency multistatic backscatter sounding system during a geomagnetically quiet period,

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Observations of the ionosphere in the equatorial anomaly region using WISS during the total solar eclipse of 22 July 2009

Cited by 11 publications

References 36 publications

Low‐mid latitude D region ionospheric perturbations associated with 22 July 2009 total solar eclipse: Wave‐like signatures inferred from VLF observations

Low‐mid latitude D region ionospheric perturbations associated with 22 July 2009 total solar eclipse: Wave‐like signatures inferred from VLF observations

Changes in the D region associated with three recent solar eclipses in the South Pacific region

Evidence of low‐latitude daytime large‐scale traveling ionospheric disturbances observed by high‐frequency multistatic backscatter sounding system during a geomagnetically quiet period

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