Current Science

Open Access Open Access  Restricted Access Subscription Access

Extreme space weather events of solar cycle 24: X-class solar flares and their impact on the low-latitude D-region ionosphere


Affiliations
1 KSK Geomagnetic Research Laboratory, Indian Institute of Geomagnetism, Prayagraj 211 506, India., India
2 Department of Physics, Babasaheb Bhimrao Ambedkar University, Lucknow 226 025, India., India
3 K. Banerjee Centre of Atmospheric and Ocean Studies, University of Allahabad, Prayagraj 221 002, India., India
 

X-class solar flares, which occurred in the daytime from 2008 to 2016 during solar cycle 24, were studied for their influence on the lower ionosphere over the low-equatorial Indian region. To understand the D-region behaviour during flare events, we used the very low frequency (VLF) navigational transmitter NWC (19.8 kHz) signal recorded at Pryagraj, Uttar Pradesh, India. A total of seven parameters were estimated: (i) the magnitude of X-ray flux, (ii) VLF signal rising amplitude perturbation (SRAP), (iii) X-ray flux and NWC signal start time difference (STD), (iv) peak time difference (PTD), (v) Wait’s ionospheric parameters h′ (reference height), (vi) β (sharpness factor) and (vii) D-region electron density difference (EDD) to determine the overall effect of solar flares on the D-region. The results suggest that three parameters (X-ray flux, SRAP and h′) show a decreasing trend through the linear fit line, two parameters (β and EDD) show an increasing trend, while the remaining two parameters show a mixed trend (decrease during low activity and increase during high activity). Further, the trend line during the diurnal variation shows an increasing trend for X-ray flux, PTD and h′, and a decreasing trend for SRAP, STD, β and EDD. Deviation in the case of individual events may indicate the dependence of these parameters on the seasons as well. The present study will provide the base for more robust analysis and modelling work in the future to understand the complexity of ionospheric change during flare events, and to develop a predictive model for space weather mitigation.

Keywords

D-Region Ionosphere, Space Weather, Solar Cycle, Solar Flares, Trend Line, Vlf Waves.
User
Notifications
Font Size

  • Hargreaves, J. K., The Solar–Terrestrial Environment, Cambridge University Press, New York, USA, 2003, p. 420.

  • Maurya, A. K., Singh, R., Kumar, S., Kumar, D. V. and Veenadhari, B., Wave-like signatures in the D-region ionosphere generated by solar flares. In Proceedings of the IEEE General Assembly and Scientific Symposium, XXXI URSI, 2014, pp. 1–4; 10.1109/URSIGASS. 2014.6929796.

  • Maurya, A. K. et al., Low–mid latitude D region ionospheric perturbations associated with 22 July 2009 total solar eclipse: wave-like signatures inferred from VLF observations. J. Geophys. Res.: Space Phys., 2014, 119, 8512–8523; doi:10.1002/2013JA019521.

  • Singh, R. et al., D-region ionosphere response to the total solar eclipse of 22 July 2009 deduced from ELF–VLF tweek observations in the Indian sector. J. Geophys. Res.., 2011, 116, A10301, 1–9; http://dx.doi.org/10.1029/2011JA016641.

  • Selvakumaran, R. et al., Solar flares induced D-region ionospheric and geomagnetic perturbations in the Indian sector. J. Atmos. Sol.– Terr. Phys., 2015, 123, 102–112; doi:10.1016/j.jastp.2014.12.009.

  • Rakov, A. and Uman, M. A., Lightning: Physics and Effects, Cambridge University Press, New York, USA, 2006, p. 320.

  • Maurya, A. K. et al., Morphological features of tweeks and nighttime D region ionosphere at tweek reflection height from the observations in the low-latitude Indian sector. J. Geophys. Res., 2012, 117, A05301; http://dx.doi.org/10.1029/2011JA016976.

  • Maurya, A. K. et al., Night-time D region electron density measurements from ELF–VLF tweek radio atmospherics recorded at low latitudes. J. Geophys. Res., 2012, 117, A11308; http://dx.doi.org/ 10.1029/2012JA017876.

  • Kumar, S., Kumar, A., Menk, F., Maurya, A. K., Singh, R. and Veenadhari, B., Response of the low-latitude D region ionosphere to extreme space weather event of 14–16 December 2006. J. Geophys. Res.: Space Phys., 2015, 120, 788–799; doi:10.1002/2014JA020751.

  • Bhatnagar, A. and Livingston, W., Fundamentals of Solar Astronomy, World Scientific Series, Singapore, 2005, p. 374.

  • Mitra, A. P., Ionospheric Effects of Solar Flares, D. Reidel Publishing Company, Dordrecht-Holland, The Netherlands, 1974, p. 220.

  • Zigman, V., Grubor, D. and Sulic, D., D-region electron density evaluated from VLF amplitude ∆t during X-ray solar flares. J. Atmos. Sol.–Terr. Phys., 2007, 69(7), 775–792.

  • Thomson, N. R., Rodger, C. J. and Clilverd, M. A., Large solar flares and their ionosperic D region enhancements. J. Geophys. Res., 2005, 110, A06306; http://dx.doi.org/10.1029/2005JA011008.

  • Grubor, D., Sulic, D. and Zigman, V., Influence of solar X-ray flares on the earth ionosphere wave guide. Serb. Astron., 2005, 171, 29–35.

  • Zhang, D. H., Mo, X. H., Cai, L., Zhang, W., Feng, M., Hao, Y. Q. and Xiao, Z., Impact factor for the ionospheric total electron content response to solar flare irradiation. J. Geophys. Res.: Space Phys., 2011, 116, A04311; https://doi.org/10.1029/2010JA016089.

  • Le, H., Liu, L., Chen, Y. and Wan, W., Statistical analysis of ionospheric responses to solar flares in the solar cycle 23. J. Geophys. Res.: Space Phys., 2013, 118, 576–582; https://doi.org/10.1029/ 2012JA017934.

  • Pant, P., Relation between VLF phase deviations and solar X-ray fluxes during solar flares. Astrophys. Space Sci., 1993, 209, 297–306.

  • Bouderba, Y., NaitAmor, S. and Tribeche, M., Study of the solar flares effect on VLF radio signal propagating along NRK–ALG path using LWPC code. J. Geophys. Res., 2016, 121, 6799–6807; doi:10.1002/2015JA022233.

  • Thomson, N. R., Rodger, C. J. and Dowden, R. L., Ionosphere gives size of greatest solar flare. Geophys. Res. Lett., 2004, 31, L06803; http://dx.doi.org/10.1029/2003GL019345.

  • Cohen, M. B., Inan, U. S. and Paschal, E. W., Sensitive broadband ELF/VLF radio reception with the AWESOME instrument. IEEE Trans. Geosci. Remote Sensing, 2010, 48(1), 3–7; doi:10.1109/ TGRS.2009.2028334.

  • Singh, R. et al., Initial results from AWESOME VLF receivers: setup in low latitude Indian region under IHY2007/UNBSSI program. Curr. Sci., 2010, 98(3), 398–405.

  • Clilverd, M. A., Rodger, C. J., Thomson, N. R., Lichtenberger, J., Steinbach, P., Cannon, P. and Angling, M. J., Total solar eclipse effects on VLF signals: observation and modeling. Radio Sci., 2001, 36(4), 773–788.

  • Ferguson, J. A., Computer programs for assessment of long-wavelength radio communications (Version 2.0). Space and Naval Warfare Systems Center, San Diego, CA, USA, 1998, p. 327.

  • Wait, J. R. and Spies, K. P., Characteristics of the Earth Ionosphere Wave Guide for VLF Radio Waves, National Bureau of Standards Technical Note, US Government Printing Office, Boulder, Colorado, 1964, p. 300.

  • Valnicek, B. and Ranzinger, P., X-ray emission and D-region ‘sluggishness’. Bull. Astron. Inst. Czechoslov, 1972, 23, 318–322.


Abstract Views: 272

PDF Views: 143




  • Extreme space weather events of solar cycle 24: X-class solar flares and their impact on the low-latitude D-region ionosphere

Abstract Views: 272  |  PDF Views: 143

Authors

K. Venkatesham
KSK Geomagnetic Research Laboratory, Indian Institute of Geomagnetism, Prayagraj 211 506, India., India
Ajeet K. Maurya
Department of Physics, Babasaheb Bhimrao Ambedkar University, Lucknow 226 025, India., India
Rajesh Singh
KSK Geomagnetic Research Laboratory, Indian Institute of Geomagnetism, Prayagraj 211 506, India., India
Suneet Dwivedi
K. Banerjee Centre of Atmospheric and Ocean Studies, University of Allahabad, Prayagraj 221 002, India., India

Abstract


X-class solar flares, which occurred in the daytime from 2008 to 2016 during solar cycle 24, were studied for their influence on the lower ionosphere over the low-equatorial Indian region. To understand the D-region behaviour during flare events, we used the very low frequency (VLF) navigational transmitter NWC (19.8 kHz) signal recorded at Pryagraj, Uttar Pradesh, India. A total of seven parameters were estimated: (i) the magnitude of X-ray flux, (ii) VLF signal rising amplitude perturbation (SRAP), (iii) X-ray flux and NWC signal start time difference (STD), (iv) peak time difference (PTD), (v) Wait’s ionospheric parameters h′ (reference height), (vi) β (sharpness factor) and (vii) D-region electron density difference (EDD) to determine the overall effect of solar flares on the D-region. The results suggest that three parameters (X-ray flux, SRAP and h′) show a decreasing trend through the linear fit line, two parameters (β and EDD) show an increasing trend, while the remaining two parameters show a mixed trend (decrease during low activity and increase during high activity). Further, the trend line during the diurnal variation shows an increasing trend for X-ray flux, PTD and h′, and a decreasing trend for SRAP, STD, β and EDD. Deviation in the case of individual events may indicate the dependence of these parameters on the seasons as well. The present study will provide the base for more robust analysis and modelling work in the future to understand the complexity of ionospheric change during flare events, and to develop a predictive model for space weather mitigation.

Keywords


D-Region Ionosphere, Space Weather, Solar Cycle, Solar Flares, Trend Line, Vlf Waves.

References





DOI: https://doi.org/10.18520/cs%2Fv124%2Fi7%2F812-819