DOI: 10.7910/dvn/c2mhth
title: Near-Earth Interplanetary Coronal Mass Ejections Since January 1996

description: This list of near-Earth interplanetary coronal mass ejections (ICMEs), believed to be the interplanetary manifestations of the coronal mass ejections seen near the Sun by coronagraphs, is based on, and updated from, &lt;a href="http://onlinelibrary.wiley.com/doi/10.1029/2002JA009817/full"&gt;Cane and Richardson,&lt;b&gt; Interplanetary coronal mass ejections in the near-Earth solar wind during 1996–2002&lt;/b&gt;, JGR [2003]&lt;/a&gt;, and &lt;a href="https://link.springer.com/article/10.1007/s11207-010-9568-6"&gt; Richardson and Cane, &lt;b&gt;Near-Earth Interplanetary Coronal Mass Ejections During Solar Cycle 23 (1996--2009): Catalog and Summary of Properties&lt;/b&gt;, Solar Physics, [2010]&lt;/a&gt;.
description: Data description/Footnotes
(a) The time of the associated geomagnetic storm sudden commencement (typically related to the arrival of a shock at Earth) if reported in the NGDC file storm2.ssc (currently only to 2011) or the Service International des Indices Geomagnetique. Some other SSCs have been identified using abrupt increases in the 1-minute SYM-H geomagnetic index. Otherwise, 'A' indicates the time of shock passage at ACE (e.g., in the ACE List of Disturbances and Transients or the Kasper/Stevens/CfA Shock list), 'W' indicates the time of a shock at the WIND spacecraft (from the Kasper/Stevens list or inspection of Wind plasma/field data), and 'S' indicates the time of a possible shock identified by the SOHO CELIAS/MTOF/PM "Shockspotter" program. If no shock or SC is reported or evident from these sources, 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). See Richardson and Cane, Solar Physics, (2010) for further details. 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 (&gt; 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 CfA Interplanetary Shock Database (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 (d) above) or (occasionally, or for recent events) that by our assessment, the ICME has the clear features of a magnetic cloud but a magnetic cloud may not have been reported. 'H' indicates an event reported by Huttunen et al. Ann Geophys. (2005) 23:1-17 that is not listed by Lepping. '1' indicates that the ICME shows evidence of a rotation in field direction, but lacks some other characteristics of a magnetic cloud, for example an enhanced magnetic field. '0' indicates that the ICME is not a reported magnetic cloud, and lacks most of the typical features of a magnetic cloud, such as a smoothly rotating, enhanced magnetic field.

(m) The minimum value of the geomagnetic Dst index during the period between the disturbance and ICME trailing edge (or slightly thereafter if storm peak is generated by the trailing regions of the ICME). 'P' indicates a "provisional" value, and 'Q' that real time ("quicklook") data from the WDC for Geomagnetism, Kyoto, are used. (Note that quicklook Dst values at the WDC are revised after they are initially posted, so the quoted values for recent ICMEs may be subject to revision.) Otherwise values are "final". 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 (o). Note that a range may be given when there are several CMEs listed, and that the transit speed may be overestimated for later CMEs that may not be associated with the initial disturbance.

(o) Probable coronal mass ejection (CME) associated with the ICME, observed by the LASCO coronagraphs on the SOHO spacecraft or (S) by STEREO. 'H' indicates that the CME had a 360 deg. angular extent (i.e. a halo CME) in the CDAW catalog. 'W' denotes a CME association from Woods et al. [2017]. 'D' is an association from, or consistent with, the CCMC DONKI Database that typically takes STEREO and near-Earth coronagraph observations (if available) and ENLIL+cone ICME modeling into consideration. Note that multiple DONKI CME may have estimated Earth arrival times that are consistent with the in situ observations, but it is possible that not all these CMEs may contribute to the structures actually observed. Generally, the CME time in DONKI has been adjusted to the time of the corresponding CME in the CDAW catalog, if this can be identified, for consistency with the pre-DONKI events. '?' 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. Note that the absence of an associated CME, especially for more recent events, may indicate that this information has still to be compiled, and may be added later. A few associations were identified in collaboration with other members of the ISSI Working Team "Understanding the Origins of Problem Geomagnetic Storms".

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

General Comments
This list of near-Earth interplanetary coronal mass ejections (ICMEs), believed to be the interplanetary manifestations of the coronal mass ejections seen near the Sun by coronagraphs, is based on, and updated from, Cane and Richardson, Interplanetary coronal mass ejections in the near-Earth solar wind during 1996–2002, JGR [2003], and Richardson and Cane, Near-Earth Interplanetary Coronal Mass Ejections During Solar Cycle 23 (1996--2009): Catalog and Summary of Properties, Solar Physics, [2010]. It 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 cycle 23 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 (&gt; 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]. In the current updated and revised list, we have incorporated the ACE/SWICS composition and charge state data (discussed in relation to ICMEs by Richardson and Cane [2004], though note the caveats in Richardson and Cane, [2010]). 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 have removed the sudden commencement size (which is available on request if required). Provisional Dst values in the original list have been updated to final. A few errors in the original list have also been corrected. This revised list is discussed in detail in Richardson and Cane, Near-Earth Interplanetary Coronal Mass Ejections During Solar Cycle 23 (1996--2009): Catalog and Summary of Properties, Solar Physics, [2010].

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.

This catalog is a work in progress and subject to revision!

We acknowledge all the various experimenters who have made their data available through the ACE Science Center and other sources. Portions of this work were supported by a NASA Heliophysics Guest Investigator Grant and by the ACE mission.
description: This data set is also available from the ACE Science Center at 
https://izw1.caltech.edu/ACE/ASC/DATA/level3/icmetable2.htm