Ionospheric response to X-class solar flares in the ascending half of the subdued solar cycle 24

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• 作者：Rumajyoti Hazarika ; Bitap Raj Kalita…
• 关键词：X ; class solar flare ; EUV ; TEC.
• 刊名：Journal of Earth System Science
• 出版年：2016
• 出版时间：August 2016
• 年：2016
• 卷：125
• 期：6
• 页码：1235-1244
• 全文大小：4,050 KB
• 刊物类别：Earth and Environmental Science
• 刊物主题：Earth sciences
  Geosciences
  Extraterrestrial Physics and Space Sciences
  
• 出版者：Springer India
• ISSN：0973-774X
• 卷排序：125

文摘

The signature of 11 X-class solar flares that occurred during the ascending half of the present subdued solar cycle 24 from 2009 to 2013 on the ionosphere over the low- and mid-latitude station, Dibrugarh (27.5∘N, 95∘E; magnetic latitude 17.6∘N), are examined. Total electron content (TEC) data derived from Global Positioning System satellite transmissions are used to study the effect of the flares on the ionosphere. A nonlinear significant correlation (R2 = 0.86) has been observed between EUV enhancement (ΔEUV) and corresponding enhancement in TEC (ΔTEC). This nonlinearity is triggered by a rapid increase in ΔTEC beyond the threshold value ∼1.5 (×1010 ph cm−2 s−1) in ΔEUV. It is also found that this nonlinear relationship between TEC and EUV flux is driven by a similar nonlinear relationship between flare induced enhancement in X-ray and EUV fluxes. The local time of occurrence of the flares determines the magnitude of enhancement in TEC for flares originating from nearly similar longitudes on the solar disc, and hence proximity to the central meridian alone may not play the dominating role. Further, the X-ray peak flux, when corrected for the earth zenith angle effect, did not improve the correlation between ΔX-ray and ΔTEC.