New Astronomy 60 (2018) 22–32 Contents lists available at ScienceDirect New Astronomy journal homepage: www.elsevier.com/locate/newast Solar flares associated coronal mass ejection accompanied with DH type II radio burst in relation with interplanetary magnetic field, geomagnetic storms and cosmic ray intensity MARK Harish Chandra, Beena Bhatt* Department of Applied Science, M.M.M. University of Technology, Gorakhpur-273010, India A R T I C L E I N F O A B S T R A C T Keywords: Solar flare Coronal mass ejection DH type II radio burst In this paper, we have selected 114 flare-CME events accompanied with Deca-hectometric (DH) type II radio burst chosen from 1996 to 2008 (i.e., solar cycle 23). Statistical analyses are performed to examine the relationship of flare-CME events accompanied with DH type II radio burst with Interplanetary Magnetic field (IMF), Geomagnetic storms (GSs) and Cosmic Ray Intensity (CRI). The collected sample events are divided into two groups. In the first group, we considered 43 events which lie under the CME span and the second group consists of 71 events which are outside the CME span. Our analysis indicates that flare-CME accompanied with DH type II radio burst is inconsistent with CSHKP flare-CME model. We apply the Chree analysis by the superposed epoch method to both set of data to find the geo-effectiveness. We observed different fluctuations in IMF for arising and decay phase of solar cycle in both the cases. Maximum decrease in Dst during arising and decay phase of solar cycle is different for both the cases. It is noted that when flare lie outside the CME span CRI shows comparatively more variation than the flare lie under the CME span. Furthermore, we found that flare lying under the CME span is more geo effective than the flare outside of CME span. We noticed that the time leg between IMF Peak value and GSs, IMF and CRI is on average one day for both the cases. Also, the time leg between CRI and GSs is on average 0 to 1 day for both the cases. In case flare lie under the CME span we observed high correlation (0.64) between CRI and Dst whereas when flare lie outside the CME span a weak correlation (0.47) exists. Thus, flare position with respect to CME span play a key role for geo-effectiveness of CME. 1. Introduction Solar flare is a burst on the sun, occurred due to sudden release of magnetic energy stored in the sun atmosphere. Solar flare emits energy over a wide range of wavelength extending from Radio, Visible, EUV, Xrays and gamma-rays together with particle emission. It is known that occurrence of solar flares is not uniform and their distribution around the sun shows a strong asymmetry between the hemispheres (Rusin et al., 1979; Badrudin et al. 1983). Coronal Mass ejections, also known as CMEs, are main source of solar activity. It is most energetic and largest phenomenon associated with the eruption of plasma and magnetic field from the Sun into the space and is main cause of GSs if CMEs are directed towards Earth (Gopalswamy et al., 2007). MacQueen and Fisher (1983) found that flare associated CMEs shows higher speed and little acceleration in the corona. A lot of work has been done in this area out of which some recent reviews on CMEs are reported in Gopalswamy (2004), 2006a, b), * Corresponding author. E-mail address: beenabhatt999@gmail.com (B. Bhatt). http://dx.doi.org/10.1016/j.newast.2017.10.001 Received 4 July 2017; Received in revised form 20 August 2017; Accepted 4 October 2017 Available online 05 October 2017 1384-1076/ © 2017 Elsevier B.V. All rights reserved. Kahler (2006) and Kunow et al. (2006). CMEs associated with decameter hectometric (DH type II) radio burst are recorded in the frequency range of 1–14 MHz by the Radio and plasma wave (WAVES) experiment on board the Wind Space Craft. CMEs associated with DH type II radio burst (also known as Radio Loud) have speed 1115 km/s which is nearly 2.4 times the average speed of all CMEs (470 km/s). Lara et al. (2003) studied CMEs associated with DH type II radio burst and observed that CMEs are more energetic when they are associated with DH type II radio burst as compare to metric type II radio burst and normal CMEs. Gopalswamy et al. (2001) observed that if CMEs are associated with DH type II radio bursts then they are wider and show faster speed. Hence study of CME associated with DH type II radio burst is very crucial. Recently, Bhatt et al. (2016), has observed that the southern region with 54% events is effective in producing flare - halo CME for DH type II radio burst and for without DH type II radio burst dominance exists in the northern region with 56% events. New Astronomy 60 (2018) 22–32 H. Chandra, B. Bhatt gsfc.nasa.gov/CME_list/radio/waves _type2.html. This website provide the type II bursts data observed by the Radio and Plasma Wave (WAVES) experiment on board the Wind spacecraft and the associated CMEs observed by the Solar and Heliospheric Observatory (SOHO) mission. The type II burst catalogue is derived from the Wind/WAVES catalogue available at http://lep694.gsfc.nasa.gov/waves/waves.html by adding a few missing events. The CME sources (flare position and classes) are also listed, as derived from the Solar Geophysical Data listing or from inner coronal images such as Yohkoh/Soft X-ray Telescope (SXT) and SOHO/Extreme ultraviolet Imaging Telescope (EIT). Excluding those events for which solar flares position angle, class and CMEs properties is not given we found total 114 events. We investigate the flare position with respect to the CME span by using the following formula CSHKP (Carmichael, Strurrock, Hirayama, Kopp and Pneuman) model requires that the flare occurs near the center of CME span. Harison (1986) and Kahler et al. (1989) examined small number of flares and found that flare position does not peak at the centre of CME span. Thus it does not fulfill the requirement of CSHKP model in which flare originate near the centre of CME span. Yashiro et al. (2008b), has done the investigation involving nearly 500 flare-CME pairs in the SOHO era and observed that the flare is typically located below the CME leading edge for limb CMEs, agreeing with CSHKP model. When flare-CME accompanied with DH type II radio burst, Bhatt et al. (2015) has observed that dominance exists in the northern region in both the cases when flare lie under the CME span or outside the CME span with 57% events and 51% events respectively. The first explanation of storm mechanism is given by Dungey (1961). Geomagnetic storms can be defined as disturbances of Earth's magnetosphere caused by interplanetary magnetic field structures. The intensity of the storm is measured by the Disturbance storm time index (Dst) in nT, which is the average change in the horizontal component of Earth magnetic field. The Dst is based on measurement at four magnetometers near equator and depends on average horizontal component of the Earth's magnetic field (Sugiura, 1964). Earlier, it was thought that solar flares were responsible for GSs. However, recently we have seen that CMEs, not flares alone are responsible for GSs. CMEs which originate close to the centre disk of the sun arrive near the Earth thus causing GSs. The fastest ( > 1000 km/s) CMEs typically cause the most intense interplanetary disturbances and in the presence of a southward component Bz at Earth's orbit, they create strongest GSs (Gosling, 1993; Tsurustani, 2001). Echer et al. (2008), analyzed the intense GSs (Dst ≤ 100 nT) and concluded that Magnetic cloud ( MC), sheath field and corotating interaction regions are the main cause of GSs during the decay phase of solar cycle 23. Forbush decrease (Fd) is a rapid depression in the observed galactic cosmic ray intensity followed by a gradual recovery typically lasting about a week (Forbush, 1938). It occurs when the sun releases large burst of matter and magnetic disturbance. Cosmic ray decrease is usually associated with CMEs and ICME (Cane et al., 1996, 1997, 2000). Cane in 1996, studied that 86% of Fd are associated with CMEs and interplanetary shocks. Verma et al. (2009) concluded that halo CME associated with X-ray solar flare and related to interplanetary shocks, magnetic clouds or combination of both are mainly responsible for Fd and GSs. Mishra et al. (2008), analyzed the data during the period 1996–2006 and found that Fd ≥ 4% is due to bright solar flare (importance ≥ 1B) in the northern hemisphere. They also observed that almost 88% Fd is associated with halo CME and most of the flares are produced in the 10° −30° latitudinal and longitudinal belts. Recently Kovalyov et al. (2014) have observed that both the solar activity and cosmic rays have one to one correspondence. Cane et al. (2000) found a high correlation coefficient (0.74) between Dst index and Bz. The interplanetary magnetic field (IMF) is a part of Sun magnetic field that is carried outward by the solar wind. The southward component of IMF (Bz) stresses the Earth magnetic field. Tsurutani et al. (1997) observed that there is one to one relationship between Dst index and strength of IMF and concluded that intense storm ( Dst ≤ −100nT) were caused by large southwardly directed magnetic fluid, where Bz ≤ −10nT . The ability of a CME or any IP structure to produce a geomagnetic storm is known as geo effectiveness and such a structure is said to be geo effective. Many authors have studied the geo effectiveness of CMEs directed to Earths (Tsurutani et al. 1997; Farrugia et al., 1997). Kharayat et al. (2016) found a very good correlation coefficient between CRI and Dst index. Thus CME is most effective in causing FD when it is closest to Earth. r3 = ϕF − ϕ3 0.5ω3 (1) where γ3 is flare position under the CME span, θF is position angle of flare, θ3 is central position angle (CPA) of CME and ω3 is angular span of CME. If γ3= ± 1 then the solar flare is located at either leg of CME frontal structure and if γ3 = 0 then the flare is located at the center of the CME span (Yashiro et al., 2008). Solar flares position angle is determined by the formula sin β ⎞ ϕF = tan−1 ⎛⎜ ⎟ tan γ⎠ ⎝ (2) where β is flare heliographic longitude and γ is heliographic latitude. Using the above formulas we found that out of 114 events only 43 flares are under the CME span and 71 are outside the CME span. This is contrary to the result as suggested by CSHKP. Now we have two sets of data:(i) Flare under the CME Span (i.e. 43) and (ii) Flare outside the CME Span (i.e. 71). We apply the Chree analysis by the superposed epoch method to both sets of data to investigate the relationship of these events with IMF, GSs and CRI. The occurrence day of CME is used as zero days. The daily mean values of the Dst index and IMF is taken from the Omniweb data centre (omniweb.gsfc.nasa.gov/form/dx1.html). The pressurecorrected daily mean CRI data were taken from the Moscow Neutron Monitor Station (cr0.izmiran.rssi.ru/mosc/main.htm). 3. Result and discussion In 2008, Yashiro and Gopalswamy studied the position of flare with respect to CME span during 1996–2008 and found the most of the solar flare lie under the CME span. Their result follows the CSHKP flare-CME model but our result does not as 71 (62%) out of 114 lie outside the CME span. Thus we can say that DH type II radio burst play a major role in context of flare position with respect to CME span. Now we discuss the relationship of Flare-CME with Interplanetary parameters. 3.1. Flare-CME and IMF We have studied the relationship between flare-CME and IMF for both the case during 1996 to 2008. We observed that in case when flare lie under the CME span, the ascending phase and descending phase of solar cycle 23 show maximum increase in IMF within 3 to 6 and 2 to 5 days after the CME onset, respectively. Whereas in case when flare lie outside the CME span, the ascending phase and descending phase of solar cycle 23 shows maximum increase in IMF within 1 to 5 and 1 to 4 days after the CME onset, respectively. From the above we conclude that in arise and decay phase of solar cycle the time leg between CME onset and IMF on its peak is almost same for both cases. 2. Data analysis and identification method For the present study we have chosen the data from period 1996 to 2008 (i.e. solar cycle 23) downloaded from the website http://cdaw. 23 New Astronomy 60 (2018) 22–32 H. Chandra, B. Bhatt Fig. 1. Superposed epoch results from −6 to +6 days when flare lie under and outside the CME span. It shows the variation of IMF, Dst and CRI mean value during 1997–2008. decrease during 1 to 2 days. The effect of flare-CME on cosmic rays was studied by many other authors (Harrison, 1995; Cane, 2000; Lara et al., 2005; Shrivastava, 2005). Jothe et al. (2010) observed that CME are responsible for short-term CRI variation. We found that in case when flare lie outside the CME span, CRI shows variations for whole solar cycle from 1997 to 2007. Our results agree with the results of Agrawal et al. (2008). Jothe et al. (2010) found that maximum decrease in CRI is occurred one day after the ICME onset. We noticed that in case when flare lie under the CME span, for both ascending and descending phase maximum decrease in CRI takes place 1 to 3 days after CME onset (except for 2007). Whereas in case when flare lie outside the CME span, the ascending and descending phase of solar cycle 23rd show maximum decrease in CRI 3 to 6 and 1 to 2 days after the CME onset, respectively (except for 2007). For 2007, when flare lie inside or outside the CME span, the time lag between maximum decrease in CRI and CME onset is 5th day for both the phases. We also observed that those event in which flare lie under the CME span are more geoeffective than the event outside of CME span (Fig. 1). 3.2. Flare-CME and GSs Zhang et al. (2007) found that 68% halo CMEs are responsible for producing major GSs. Statistical study of CME and GSs shows that most of GSs are always caused by CMEs (Richardson et al., 2006; Zhang et al. 2007). Tsurutani et al. (1988) observed that magnetized CME plasma on magnetosphere is the cause of intense GSs. We noticed that in case when flare lie under the CME span, both the ascending and descending phase of solar cycle 23rd show maximum decrease in Dst within 3 to 6 days after the CME onset. Whereas in case when flare lie outside the CME span, the ascending and descending phase of solar cycle 23rd show maximum decrease in Dst within 4 to 6 and 2 to 6 days after the CME onset, respectively. 3.3. Flare-CME and CRI Cane et al. (1996) studied the flare-CME effect for short term decrease in CRI and found that 86% Fd associated with CME and CME driven shocks. Agrawal et al. (2008) reported that Fd started with rapid 24 New Astronomy 60 (2018) 22–32 H. Chandra, B. Bhatt Fig. 1a. Superposed epoch results from −6 to +6 days when flare lie under the CME span It shows the variation of IMF and Dst mean value 1997–2008. 25 New Astronomy 60 (2018) 22–32 H. Chandra, B. Bhatt Fig. 1b. Superposed epoch results from −6 to +6 days when flare lie outside the CME span. It shows the variation of IMF and Dst mean value during 1997–2008. 26 New Astronomy 60 (2018) 22–32 H. Chandra, B. Bhatt Fig. 2a. Superposed epoch results from −6 to +6 days when flare lie under the CME span. It shows the variation of IMF and CRI mean value during 1997–2008. 27 New Astronomy 60 (2018) 22–32 H. Chandra, B. Bhatt Fig. 2b. Superposed epoch results from −6 to +6 days when flare lie outside the CME span. It shows the variation of IMF and CRI mean value 1997–2008. 28 New Astronomy 60 (2018) 22–32 H. Chandra, B. Bhatt Fig. 3a. Superposed epoch results from −6 to +6 days when flare lie under the CME span. It shows the variation of CRI and Dst mean value 1997–2008. 29 New Astronomy 60 (2018) 22–32 H. Chandra, B. Bhatt Fig. 3b. Superposed epoch results from −6 to +6 days when flare lie outside the CME span. It shows the variation of CRI and Dst mean value during 1997–2008. 30 New Astronomy 60 (2018) 22–32 H. Chandra, B. Bhatt 4. Relation between IMF, GSs and CRI of solar cycle is different for both the cases. 5. In case of flare lie outside the CME span CRI shows comparatively more variations than the flare lie under the CME span. 6. We found that those events in which flare lie under the CME span are more geoeffective than the events outside of CME span. 7. Maximum decrease in Dst takes place one day after the IMF on its peak for both the cases. 8. In case flare lie outside the CME span event we found a good anti correlation (−0.52) between IMF and Dst. 9. The time leg between IMF Peak value and Fd, CRI and Dst is one day for both the cases. 10. In case flare lie under the CME span we observed high correlation (0.64) between CRI and Dst whereas in other case when flare lie outside the CME span a weak correlation (0.47) exists. We have analyzed the relationship between IMF, GSs and CRI for both the cases and findings are as follows: 4.1. IMF and GSs It is observed that the southward IMF is responsible for intense storms (Tsurutani, 2001; Zhang et al., 2006). Tiwari et al. (2011) found a strong (0.78) correlation between Ap-index and IMF B. Ap-index is also the measure of GSs. We have studied the association between IMF and GS (Fig. 1a and b) for both the cases and found that the maximum decrease in Dst takes place on average one day after the IMF on its peak. Therefore we conclude that time leg between IMF Peak value and Dst on maximum decrease is one day. Verma et al. (2012) found that magnetic field strength and plasma density start to increase before the onset of GSs. Our finding matches the finding of Verma. We calculated the correlation coefficient between IMF and GSs for both the cases during 1996–2008 and found that in case when flare lie under the CME span the correlation coefficient is very weak (i.e. −0.37) whereas in other case when flare lie outside the CME span we found a good anti correlation (i.e. −0.52). This indicates that flare position with respect to CME span affect the association between IMF and Dst. Acknowledgement The authors would like to thank the excellent Wind/WAVES and ground based radio spectrograph teams for providing the type-II data in online catalogs. Reference Agarwal, R., Mishra, R.K., 2008. Astrophysics 51, 269. Badruddin, Yadav, R.S., Yadav, N.R., 1983. Indian J. Radio Space Phys. 2, 124. Bhatt, B., Prasad, L., Chandra, H., Garia, S., 2016. Astrophys. Space Sci. 361, 265. Bhatt, B., Prasad, L., Mathpal,, Hema, Mathpal, R., 2015. Astrophysics 58, 420. Cane, H.V., Richardson, I.G., Von Rosenving, T.T., 1996. J. Geophys. Res. 21561. 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IMF and CRI Selvamurugan and Rao (2006) found that the Galactic cosmic rays remain less influenced by the IMF during the minimum phase of solar cycle (when the total IMF is < 5–6 nT). It is observed that one nT increase in IMF magnitude leads to ∼ 0.2% decrease in CRI (Maltsev et al., 2003). In our study we observed that for both the cases Fd takes place on average one day after the IMF on its maximum i.e., the time leg between IMF Peak value and Fd is one day (Fig. 2a and b). In this aspect our result matches the result of Agarwal et al. (2008). The correlation coefficient between IMF and CRI for both the cases is found very weak during the period 1996–2008 which is an agreement to the results of Selvamurugan and Rao (2006). 4.3. CRI and GSs We have studied the relationship between CRI and Dst for both the case during 1996 to 2008 and found that in both the case maximum decrease in CRI takes place on average within 0 to 1 day after the Dst on its maximum decrease or we can say that the time leg between CRI and Dst is 0 to 1 day. This is similar with the finding of Kharayat et al. (2016). In case when flare lie under the CME span we found a high correlation (0.64) between CRI and Dst whereas in other case when flare lie outside the CME span a weak correlation (0.47) is found between CRI and Dst. Our result findings are agreed with the finding of Kharayat et al. (2016) and Firoz et al. (2010) (Fig.. 3). 5. Conclusions 1. Out of total114 flare-CME events associated with DH type II radio burst only 43 flares lie under the CME span while other 71 lie outside the CME span during 1996 to 2008. 2. Our selected events do not follow the CSHKP flare-CME model. 3. 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