Survey of intense Sun–Earth connection events (1995–2003) C.J. Farrugia a,b, * , H. Matsui a , H. Kucharek a , V.K. Jordanova a,b , R.B. Torbert a,b , K.W. Ogilvie c , D.B. Berdichevsky d , C.W. Smith a,b , R. Skoug e a Space Science Center, University of New Hampshire, 39 College Road, Morse Hall Room 414, Durham, NH 03824, USA b Department of Physics, University of New Hampshire, 39 College Road, Morse Hall Room 414, Durham, NH 03824, USA c NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA d L-3 Government Services Inc., Space Science Section at NASA/GSFC, Greenbelt, MD 20771, USA e Los Alamos national Laboratory, Los Alamos, NM 87545, USA Received 14 October 2004; received in revised form 12 May 2005; accepted 12 May 2005 Abstract We survey the interplanetary (IP) configurations associated with the largest energy and/or power inputs to the magnetosphere in 1995–2003, i.e., from the last 2 years of solar cycle 22 to the descending phase of solar cycle 23. We work in the ‘‘’’ formulation of [Perreault, P., Akasofu, S.-I. A study of geomagnetic storms, Geophys. J.R. Astron. Soc., 54, 547, 1978]. Using this, we calculate the energy extracted by the magnetosphere from the solar wind, and the powering of the magnetosphere by the solar wind. We carry out a statistical survey to obtain the distribution of power deposition and energy input during this 9-year period. Large events are then defined as those whose energy exceeds 10 J m 2 and/or whose power exceeds 0.3 mW m 2 . We then correlate the large events with the strength of geomagnetic disturbances they elicited, as measured by the Dst storm index. Finally, the large events are classified in terms of the IP structures involved. Ó 2005 COSPAR. Published by Elsevier Ltd. All rights reserved. Keywords: Strongly geoeffective configurations in cycle 23; Interacting ejecta as cause of intense storms 1. Introduction The aim of his work is twofold. The first is to relate the interplanetary (IP) power and energy input to the magnetosphere to inner-magnetospheric disturbances as measured by the Dst index. The second is to isolate the ‘‘large events’’, suitably defined, and identify the cor- responding IP structures. The investigation spans the 9 years 1995–2003 when coverage of the IP medium by the WIND and ACE probes is complete. We work in the formulation of Perreault and Aka- sofu (1978), who defined an ‘‘energy coupling func- tion’’, , as an empirically determined fraction of the solar wind Poynting flux through the dayside magne- topause. Quantity  is defined by  = 1/l 0 V p B 2 sin 4 (h/ 2), where V p is the solar wind speed, B is the strength of the IP magnetic field (IMF), h is the IMF clock an- gle, i.e., the polar angle in the GSM (YZ) plane, and l 0 is the permeability of free space. From general con- siderations of reconnection, Kan and Lee (1979), fol- lowing Sonnerup (1974), showed that  is proportional to the power extracted from the solar wind by the magnetosphere. Following Freeman and Farrugia (1999), we have included l 0 as in the original definition of Perreault and Akasofu, but we have omitted the length scale L 0 =7R E . Parameter  has units of energy flow, i.e., power per unit area. Its inte- gral over time is then the energy per unit area depos- ited in the magnetosphere. 0273-1177/$30 Ó 2005 COSPAR. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.asr.2005.05.051 * Corresponding author. Tel.: +1 603 862 4596; fax: +1 603 862 0311. E-mail address: charlie.farrugia@unh.edu (C.J. Farrugia). www.elsevier.com/locate/asr Advances in Space Research 38 (2006) 498–502