Near-Earth Interplanetary Coronal Mass Ejections in 1996-2007

Compiled by Ian Richardson(1) and Hilary Cane(2),

Astroparticle Physics Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA

(1) Also at CRESST and The Department of Astronomy, University of Maryland, College Park;

(2) Also at The School of Mathematics and Physics, University of Tasmania, Hobart, Tasmania, Australia.

Revised May 16, 2008

Footnotes

(a) The time of the associated geomagnetic storm sudden commencement (typically related to the arrival of a shock at Earth) if reported. Otherwise, 'A' indicates the time of shock passage at ACE (e.g., in the ACE List of Disturbances and Transients or Justin Kasper's Shock list (unfortunately no longer on-line at this time)) while 'W' indicates the time of a shock at the WIND spacecraft (from the Kasper list) if not also reported at ACE. If no shock or SC is reported, the estimated arrival time of the disturbance (which in some cases is the ICME leading edge) is given to the nearest hour. Typical features we look for are increases in the solar wind speed, magnetic field strength and density that are more gradual than those associated with shocks.

(b) Estimated start and end times of the ICME based primarily on plasma and magnetic field observations. See Cane and Richardson, JGR, 2003 for additional information on the methods used to identify ICMEs. The times are estimated to ~ the nearest hour.

(c) Start and end times of the associated interval of abnormal solar wind composition/charge states (e.g., enhanced O7/O6, Mg/O, Fe charge states) estimated from ACE/SWICS data in hours relative to the start and end times of the ICME based on plasma/field observations as in (b). A positive (negative) value means that the compositional signature starts after (before) the ICME leading edge or ends after (before) the ICME trailing edge. 'ns' indicates that there is no clear compositional/charge state signature, while 'nc' means that there is no change or the boundary is not clear in the compositional data (for example, between two adjacent ICMEs with similarly elevated ion charge states). No SWICS data are available until February, 1998.

(d) Start and end times of the magnetic clouds reported by Lepping or Huttunen et al. Ann Geophys. (2005) 23:1-17 (see also (l)) in hours relative to the ICME leading or trailing edges. In a few cases, there are 2 magnetic clouds reported during the interval of interest. Magnetic clouds are structures associated with a subset of ICMEs defined by Burlaga and co-workers as having enhanced (> 10 nT) magnetic fields that rotate smoothly through a large angle, low proton temperatures, and low plasma beta (e.g., Klein and Burlaga [1982]; Lepping et al. [1990]).

(e) Evidence of BiDirectional suprathermal Electron strahls (BDE) in ACE/SWEPAM Observations. If data are unavailable from SWEPAM (data commence on 10/22/97), observations from the 3-D P instrument on WIND are referred to. "SEP" indicates that an intense solar energetic particle event was in progress at the time of ICME passage and electron flows therefore cannot be determined.

(f) Evidence of Bidirectional energetic Ion Flows (BIF) in 0.5 -4.0 MeV ion observations from the IMP 8 Goddard Medium Energy instrument. '...' indicates no data, low particle intensities, or when IMP 8 was inside the Earth's bow shock.

(g) The "quality" of the boundary times (`1' indicating the most reliable) based on assessment of the various data sets, including plasma, magnetic field and solar wind composition/charge states. 'W' indicates that the overall ICME signatures are particularly weak.

(h) Increase in solar wind speed at the upstream disturbance (shock/wave) estimated from 1 hour averaged solar wind data. 'S' indicates that a forward fast shock has been reported in the ACE List of Disturbances and Transients or Kasper Shock list (including ACE and WIND observations).

(i) Mean ICME speed, based on solar wind speed observations during the period from (b) to (c) above.

(j) Maximum solar wind speed during the period from the disturbance (a) to the trailing edge of the ICME (c).

(k) Mean magnetic field strength in the ICME, based on the interval from (b) to (c), to the nearest 1 nT.

(l) '2' indicates that a magnetic cloud has been reported in association with the ICME (see (f) above) or (occasionally) that by our assessment, the ICME has the clear features of a magnetic cloud but no magnetic cloud has currently been reported. 'H' indicates an event reported by Huttunen et al. Ann Geophys. (2005) 23:1-17 that is not listed by Lepping.

(m) The minimum value of the geomagnetic Dst index during the period between the disturbance and ICME trailing edge. 'P' indicates a provisional value, and 'Q' that real time (Quicklook) data from the WDC for Geomagnetism, Kyoto, are used. See Zhang et al. [2007] for a discussion of the solar and interplanetary drivers of the intense (Dst ≤-100 nT) geomagnetic storms during 1996-2005.

(n) Mean 1 AU transit speed of the disturbance based on the CME association in (r).

(o) Probable coronal mass ejection (CME) associated with the ICME, observed by the LASCO coronagraphs on the SOHO spacecraft. 'H' indicates that the CME had a 360 deg. angular extent (i.e. a halo CME). '?' indicates that the CME association may be doubtful. Times in brackets indicate solar events associated with the ICME during an interval with no coronagraph coverage. 'dg' indicates that there was a LASCO data gap around the expected time of the associated CME.

(p) There are multiple candidate CMEs; the time of the most likely association is listed.

Revision History Since December, 2007

Feb. 12, 2008: Added ICMEs on August 23 and 24, 2005.

May 16, 2008: Updated to May 15 (no events so far in 2008!). SWICS data now available for all 2007. Updated quick look Dst in 2006 to provisional.

General Comments

This list of near-Earth interplanetary coronal mass ejections, believed to be the interplanetary manifestations of the coronal mass ejections seen near the Sun by coronagraphs, was originally motivated by our interest in the effects of ICMEs on energetic particles, including those accelerated by solar flares and interplanetary shocks, and galactic cosmic rays, during this and earlier solar cycles. These effects (e.g., Richardson, I. G., Using energetic particles to probe the magnetic topology of ejecta, in Coronal Mass Ejections, Geophys. Monogr. Ser., vol. 99 edited by N. Crooker, J. A. Joselyn, and J. Feynman, pp. 189-198, AGU, Washington, D. C., 1997; Cane and Lario [2006], and references therein) include short-term "Forbush" depressions in the galactic cosmic ray intensity (e.g., Cane [2000]), bidirectional energetic particle flows, long scattering mean free paths, and unusual particle flow directions. To examine these effects, we need to know when ICMEs are passing the observing spacecraft. Conversely, energetic particle observations can help to indicate when ICMEs are present. Some two dozen in-situ signatures of ICMEs (earlier terms include "shock drivers", "pistons", "ejecta") have been reported in magnetic field, plasma, solar wind composition and charge states, and energetic particles from suprathermal solar wind to galactic cosmic ray energies (e.g., Zurbuchen and Richardson [2006]). Thus, ideally ICME identification should combine as many data sets as possible, such as those available from ACE and other near-Earth spacecraft. Criteria may be set that are likely to identify ICMEs in particular data sets (cf. Table 1 of Zurbuchen and Richardson [2006]).

Our philosophy in making the list has been to combine a number of available data sets and try to assess when ICMEs were probably present in the near-Earth solar wind, using both criteria characteristic of ICMEs and visual inspection of the data, in order to produce as comprehensive a list as possible. In particular, it is important to recognize that we do not limit our list to events that have the characteristics of magnetic clouds, as defined by Burlaga and co-workers, i.e., enhanced (> 10 nT) magnetic fields that rotate smoothly through a large angle, low proton temperature, and low plasma beta (e.g., Klein and Burlaga [1982]; Lepping et al. [1990]). Although these are very important events, since they are generators of many large geomagnetic storms, are easily modeled as flux ropes or more complicated structures, and are an inevitable consequence of current models of CME initiation, they are only a subset of all ICMEs, as the list indicates. It is still unclear whether there is a magnetic cloud structure in all ICMEs, but this is only intercepted in a subset of events, or whether there are ICMEs that do not include magnetic clouds.

Before the launch of ACE (August, 1997), and during occasional ACE data gaps, we have referred to observations from other spacecraft including IMP 8 and WIND, and the OMNI near-Earth solar wind database.

Our original list, for 1996-2002, appeared in Cane and Richardson [2003]. We have subsequently revised the list every few months to include later events, incorporate the ACE/SWICS composition and charge state data (discussed in relation to ICMEs by Richardson and Cane [2004]), update Dst values to final, and correct a few errors in the original list. These revisions have been distributed to interested researchers on request. In this current revision, we have reviewed all the original event identifications, removing a few events with particularly weak signatures. A few events have also been added. For example, the SWICS charge state data may confirm an event for which the other signatures previously considered were marginal. There are still some events that we have retained in the list, indicated by 'W' in the "Quality" column, that have relatively weak signatures. Overall, we estimate that potential events with marginal signatures that might or might not be included in the list constitute ~10% of the total number of events. We have also added several parameters to those in the original list, and removed the sudden commencement size (which is available on request if required).

At times of high solar activity, several ICMEs may pass by in rapid succession. Although we have tried to identify individual ICMEs, it is possible that a given ICME interval may include more than one ICME. There are also a few extended ICMEs for which it is unclear whether they consist of one ICME or multiple ICMEs. We have been cautious about following the line of argument that "there are x preceding halo CMEs observed by LASCO so there should be evidence of x ICMEs near the Earth" since we are aware that some reported halo CMEs do not reach the Earth and there are many ICMEs (cf. the list) that do not have clear CME counterparts. Thus we do not necessarily expect a one-to-one association between halo CMEs and subsequent ICMEs.

A well-known problem when identifying ICMEs using different data sets is that the boundaries may not agree exactly, or some signatures may be completely absent. Reasons presumably include event to event variations in the conditions at the Sun during CME ejection, the different physical processes that give rise to the various signatures and which may occur at the Sun (e.g., composition/charge states, formation of magnetic clouds), during ICME expansion in the solar wind (e.g., abnormally low proton temperatures), or depend on the magnetic field line topology and connection to the Sun (e.g., energetic particle decreases and bidirectional flows) that may be influenced by reconnection between field lines in the ICME and ambient solar wind. In the above list, we give first the estimated ICME start and end times based predominantly on solar wind plasma and magnetic field observations, with consideration of other data sets, essentially as given in the Cane and Richardson [2003] list. We also give the estimated offsets from these times for the boundaries suggested by signatures in the SWICS plasma composition and charge state data (e.g., enhanced oxygen and iron charge states, Mg/O) and for reported magnetic clouds. Although in many events, these boundaries are essentially co-located (to within an accuracy of an hour or so), there are other events where the boundaries appear to be substantially different. We also indicate the offset times of the boundaries of the reported magnetic clouds, which are often determined primarily by the need to choose an interval of "well-behaved" magnetic field to input to a model.

The list is still a work in progress and subject to revision, but probably is close to our "final" list for cycle 23.

We acknowledge all the various experimenters who have made their data available through the ACE Science Center and other sources. This work is supported by a NASA Heliophysics Guest Investigator Grant.

Please send comments, questions or corrections to Ian Richardson (ian.g.richardson@nasa.gov).

Our Related References:

Richardson, Cane and von Rosenvinge, Prompt arrival of solar energetic particles from far eastern events - The role of large-scale interplanetary magnetic field structure, JGR [1991].

Richardson, Farrugia, and Burlaga, Energetic ion observations in the magnetic cloud of 14-15 January 1988 and their implications for the magnetic field topology, 22nd Int. Cosmic Ray Conf. [1991].

Richardson and Reames, Bidirectional ~ 1 MeV/amu ion intervals in 1973-1991 observed by the Goddard Space Flight Center instruments on IMP 8 and ISEE 3/ICE, Astrophys. J. Supp. [1993].

Cane, Richardson, von Rosenvinge, Cosmic ray decreases and particle acceleration in 1978-1982 and the associated solar wind structures, JGR [1993].

Richardson and Cane, Signatures of shock drivers in the solar wind and their dependence on the solar source location, JGR [1993].

Cane, Richardson, von Rosenvinge, Wibberenz, Cosmic ray decreases and shock structure: A multispacecraft study, JGR [1994].

Richardson and Cane, Regions of abnormally low proton temperature in the solar wind (1965–1991) and their association with ejecta, JGR [1995].

Richardson and Cane, Particle flows observed in ejecta during solar event onsets and their implication for the magnetic field topology, JGR [1996].

Richardson, Farrugia and Cane, A statistical study of the behavior of the electron temperature in ejecta, JGR [1997].

Cane, Richardson and St. Cyr, The interplanetary events of January-May, 1997 as inferred from energetic particle data, and their relationship with solar events, GRL [1998].

Richardson and Cane, Bidirectional ˜1 MeV Ion Flows Observed by IMP 8 Over Two Solar Cycles, 26th Int. Cosmic Ray Conf. [1999].

Cane, Richardson and St. Cyr, Coronal mass ejections, interplanetary ejecta and geomagnetic storms, GRL [2000].

Richardson, Dvornikov, Sdobnov, Cane, Bidirectional particle flows at cosmic ray and lower (~1 MeV) energies and their association with interplanetary coronal mass ejections/ejecta, JGR [2000].

Cane, Coronal Mass Ejections and Forbush Decreases, Space Sci. Rev. [2000].

Lepri et al., Iron charge distribution as an identifier of interplanetary coronal mass ejections, JGR [2001].

Cane and Richardson, Interplanetary coronal mass ejections in the near-Earth solar wind during 1996–2002, JGR [2003].

Richardson and Cane, Identification of interplanetary coronal mass ejections at 1 AU using multiple solar wind plasma composition anomalies, JGR [2004].

Richardson and Cane, The fraction of interplanetary coronal mass ejections that are magnetic clouds: Evidence for a solar cycle variation, GRL [2004].

Richardson and Cane, A Survey of Interplanetary Coronal Mass Ejections in the Near-Earth Solar Wind during 1996-2005, Solar Wind 11 [2005].

Richardson and Cane, The ~150 day quasi-periodicity in interplanetary and solar phenomena during cycle 23, GRL [2005].

Zurbuchen and Richardson, In-Situ Solar Wind and Magnetic Field Signatures of Interplanetary Coronal Mass Ejections, Space Sci. Rev. [2006].

Cane and Lario, An Introduction to CMEs and Energetic Particles, Space Sci. Rev. [2006].

Forsyth et al., ICMEs in the Inner Heliosphere: Origin, Evolution and Propagation Effects, Space Sci. Rev. [2006].

Wimmer-Schweingruber et al., Understanding Interplanetary Coronal Mass Ejection Signatures, Space Sci. Rev. [2006].

Riley et al., On the Rates of Coronal Mass Ejections: Remote Solar and In Situ Observations, Astrophys. J. [2006].

Richardson and Cane, Interplanetary Coronal Mass Ejections During 1996-2007, Proc. 30th Int. Cosmic Ray Conf., Merida, Mexico

Zhang, Richardson, et al., Solar and interplanetary sources of major geomagnetic storms (Dst less than -100 nT) during 1996–2005, JGR [2007]. Correction to paper table.

Richardson and Zhang, Multiple-step geomagnetic storms and their interplanetary drivers, GRL [2008].

Zhang, Poomvises and Richardson, Sizes and relative geoeffectiveness of interplanetary coronal mass ejections and the preceding shock sheaths during intense storms in 1996–2005, GRL [2008].