10th National Science Symposium. February 11, 2018
Organized by Christ College, Rajkot. Subject:
SPACE WEATHER EVENTS WITH HALO CORONAL MASS EJECTION IN 23RD AND 24TH SOLAR CYCLE
Kunjal Dave 1, Miral Bhatt 2, R. M. Jadhav 3*
1,2Research Scholar, C. U. Shah University, Wadhwan, Surendranagar, 363030, Gujarat
3Assistant Professor, Gujarat College of Arts and Science College, Ahmedabad, 380006, Gujarat
*Corresponding author:
ABSTRACT:The effects of solar storms like solar flare, coronal mass ejection (CME), solar bursts etc. have been found to have major effects in recent decades, on terrestrial magnetic field. The earth’s magnetosphere is affected by halo coronal mass ejection in various ways one such way has been disturbing satellite electronics besides effects on technological society. We report the properties of halo coronal mass ejection observed by CDAW Data Center Solar Physics Laboratory (Code 671) Heliophysics Science Division NASA / Goddard Space Flight Center Greenbelt Maryland USA. Comparison between solar events occurred in last two (23rd and 24th) solar cycles is done to understand solar terrestrial relations. Various spacecraft data for solar events, interplanetary medium are used and ground based magnetic field measurements were used to correlate. Some conclusions from the study are presented here. Several correlation studies have been done in this study which includes plotting CME linear speed, ambient solar wind speed, sunspot number etc vs. Magnetic storm index. The study suggests that for a big magnetic storm (less than 100 nT) to occur very high initial linear speed is not necessary however reasonably high speed is required. Ambient solar wind speed is also an important parameter.
Keywords: Coronal Mass Ejection, Dst index, geomagnetic storms
10th National Science Symposium. February 11, 2018
Organized by Christ College, Rajkot. Subject:
1. INTRODUCTION
Coronal mass ejections (CMEs) are found to be the primary source of transient interplanetary (IP) disturbances such as magnetic clouds, ejecta and shock waves [1]. The CMEs originating on the solar disk and quickly expanding to a projected size larger than the occulting disk of coronagraphs are known as a halo CME because they appears to surround the occulting disk (fully or partially) [2, 3]. In recent decades, effects of solar storms like solar flare, coronal mass ejection (CME), solar bursts etc. have been found to have major effects on terrestrial magnetic field. In recent times, use of geostationary satellites has been increasing manifold in communication and other purposes. These satellites are placed in geostationary orbits where changes in magnetic field may affect their operation. Such changes have been affecting humankind as well.In present times, use of communication satellite is abundant and study of events that may affect its working is important. Such study had been done in various ways like theoretical modelling, statistical forecasting, real-time tracking of events etc is being done to estimate possible effects and precautionary steps that may be taken to prevent damage. We report the properties of halo coronal mass ejection observed by CDAW Data Center Solar physics Laboratory (Code 671) Heliophysics Science Division NASA / Goddard Space Flight Center Greenbelt Maryland USA.
2. DATA ANALYSIS
Coronal Mass Ejection linear speed is obtained from Coronagraph images taken using LASCO/C2 onboard SOHO spacecraft. It is derived from height vs time plot. We have taken only full halo CMEs which are earth directed. This was done to ensure considering geo-effective CMEs. Magnetic storm is characterized by many parameters however Dst is the most available and important parameter. Geomagnetic storms (Dst magnitude <-50nT) occurred during year 1996 to 2013, we have classified geomagnetic storms with respect to their Dst magnitude in four categories according to Loewe and Prolss [4,5], a geomagnetic storm can be weak (Dst > -50nT), moderate (-100nT < Dst ≤-50nT), intense (Dst ≤-100nT), and severe (Dst ≤-200 nT). So, we took data from World data centre – 2 which provides Final as well as provisional data. It is a combination of values taken at many ground station magnetometers across the world. Yearly Plot of Linear speed vs. Dst index for last two solar cycles is plotted and shown in figure 1 below.
3. RESULTS AND DISCUSSION
We have plotted linear speed of Coronal Mass Ejection versus minimum Dst index occurrence in next 3-4 days. The 11-year Solar Cycle has been studied for a very long time sunspot data is known to possibly data back to the ancient Chinese astronomers however the sun-earth connection is relatively new [4].
10th National Science Symposium. February 11, 2018
Organized by Christ College, Rajkot. Subject:
We have plotted this considering all CMEs in a year from 1996 onwards for solar cycle 23 and 24. The graphs shows relatively high slope of the linear fit during solar minimum years (1996, 1997, 1998, 1999, 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2013) fig 1 and 2. This means linear speeds were more correlated with geomagnetic storms at the earth. However, when the solar activity started increasing the slope found to be decreased indicating less correlation and during solar maximum (2000, 2002, 2012) the slope was lowest fig 1 and 2. This would mean that even with high CME velocities, geomagnetic storms could not be produced for many cases. This would also mean that during high solar activity other parameters play bigger role in producing storm at other.
4. CONCLUSION
There is less correlation between solar and terrestrial parameters during solar maximum. During solar minimum years CME speed and Dst index are better correlated. There was a period when there was no correlation between the two during transition period of solar minimum to maximum.
ACKNOWLEDGEMENT
I thank C U Shah University and Gujarat Arts and Science College for providing administrative and infrastructural facilities for doing this work.
REFERENCES
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[2]Howard, R. A., D. J. Michels, N. R. Sheeley and M. J. Koomen, The observations of a coronal transient directed at Earth, Astrophys. J., 263, L101, 1982.
[3]N. Gopalswamy, A. Lara, R. P. Lepping, M. L. Kaiser, D. Berdichevsky, and O. C. St. Cyr, Interplanetary acceleration of coronal mass ejections, Geophysical Research Letters, Vol. 27, no. 2, Pages 145-148, January 15, 2000.
[4]Balveer S. Rathore, Subhash C. Kaushik, K. A. Firoz, D. C. Gupta, A. K. Shrivastava, Krishna Kant Parashar, and Ram Mohan Bhaduriya, A Correlative Study of Geomagnetic Storms Associated with Solar Wind and IMF Features During Solar Cycle 23, International Journal of Applied Physics and Mathematics, Vol. 1, No. 2, September 2011.
[5]C. A. Loewe and G.W. Prolss, “Classification and mean behavior of magnetic storms,” J. Geophys. Res. 102, 14209, 1997.