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

Journal of Earth system science

Bitap Raj Kalita1¹  Pradip Kumar Bhuyan1¹  Rumajyoti Hazarika1¹ 

[1] Centre for Atmospheric Studies, Dibrugarh University, Dibrugarh 786 004, India$$

关键词: X-class solar flare;    EUV;    TEC;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

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 ($R^2$ =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 foundthat 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 longitudeson 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 thecorrelation between ΔX-ray and ΔTEC.

【 授权许可】

Unknown