On the solar origin of interplanetary disturbances observed in the vicinity of the Earth

Abstract

Abstract. The solar origin of 40 interplanetary disturbances observed in the vicinity of the Earth between January 1997 and June 1998 is investigated in this paper. Analysis starts with the establishment of a list of Interplanetary Mass Ejections or ICMEs (magnetic clouds, flux ropes and ejecta) and of Interplanetary Shocks measured at WIND for the period for which we had previously investigated the coupling of the interplanetary medium with the terrestrial ionospheric response. A search for associated coronal mass ejections (CMEs) observed by LASCO/SOHO is then performed, starting from an estimation of the transit time of the interplanetary perturbation from the Sun to the Earth, assumed to be achieved at a constant speed (i.e. the speed measured at 1 AU). EIT/SOHO and Nançay Radioheliograph (NRH) observations are also used as proxies in this identification for the cases when LASCO observations do not allow one to firmly establish the association. The last part of the analysis concerns the identification of the solar source of the CMEs, performed using a large set of solar observations from X-ray to radio wavelengths. In the present study, this association is based on a careful examination of many data sets (EIT, NRH and Hα images and not on the use of catalogs and of Solar Geophysical Data reports). An association between interplanetary disturbances and LASCO/CMEs or proxies on the disk is found for 36 interplanetary events. For 32 events, the solar source of activity can also be identified. A large proportion of cases is found to be associated with a flare signature in an active region, not excluding of course the involvement of a filament. Conclusions are finally drawn on the propagation of the disturbances in the interplanetary medium, the preferential association of disturbances detected close to the Earth's orbit with halos or wide CMEs and the location on the solar disk of solar sources of the interplanetary disturbances during that period.

A logistic regression model for predicting the occurrence of intense geomagnetic storms

“…However, the characteristics of the solar sources of intense/super-intense geomagnetic storms that influence their interplanetary properties and the mode of their influence are not yet well understood. Recently, a number of studies on solar sources of severe geomagnetic storms have been carried out to understand the solar-terrestrial relationship (Feynman and Gabriel, 2000;Plunkett et al, 2001;Wang et al, 2002;Zhang et al, 2003;Vilmer et al, 2003;Schwenn et al, 2005;Srivastava, 2005). Such understanding can give us important parameters for forecasting the occurrence of intense/super-intense geomagnetic storms well in advance.…”

Predicting the occurrence of super-storms

“…We now know that CMEs are the major causes of geomagnetic activity at the Earth (Feynman and Gabriel, 2000;Plunkett et al, 2001;Wang et al, 2002;Zhang et al, 2003;Vilmer et al, 2003;Srivastava and Venkatakrishnan, 2004). Intense geomagnetic activity can also occur due to fast streams originating from coronal holes (Klein and Burlaga, 1982;Sheeley et al, 1976).…”

Sources of SEP Acceleration during a Flare – CME Event

“…Selection of model should be based on the knowledge of coronal conditions in the propagation region, but the available information is often insufficient, see Pohjolainen et al (2007). Standard coronal density models such as Saito (1970) and Newkirk (1961), and "hybrid" models such as Vršnak, Magdalenić, and Zlopec (2004), which is a mixture of the five-fold Saito model for coronal densities and the Leblanc, Dulk, and Bougeret (1998) model for IP densities, can be used to describe the undisturbed high corona at frequencies lower than ≈200 MHz (corresponding electron density n e 4×10 8 cm −3 ). For the highfrequency emission at 500 -400 MHz (corresponding electron density n e ≈ 2-3×10 9 cm −3 ), we need high-density models such as the ten-fold Saito or a scale height method, to describe densities in active region loops or streamer regions.…”

“…Recently, the role of CME interaction in SEP production has also been discussed (e.g., Gopalswamy et al, 2002;Kahler, 2003;Wang et al, 2005, and references therein). One of the difficulties in determining the relevant processes lies in the uncertainties of timing.…”

“…CMEs are associated with flares, filament eruptions, shocks, radio bursts, solar energetic particle (SEP) events, and have been found to be the primary cause of major geomagnetic disturbances and changes in the solar wind flow (see, e.g., Schwenn et al, 2005;Vilmer et al, 2003;Mann et al, 2003;Gopalswamy et al, 2002;Leblanc et al, 2001;Gosling, 1997).…”