ICME

ICME
Name	ICME
Abbreviation	ICME

ICME

ICME is an acronym referring to a major class of transient phenomena that propagate from the outer atmosphere of a star into surrounding space. It is central to studies that connect solar physics, heliophysics, planetary science, space weather, and astrophysical plasmas. Researchers in institutions such as the NASA, European Space Agency, NOAA, Space Weather Prediction Center, and multiple university groups use observations from observatories like the Solar and Heliospheric Observatory, Parker Solar Probe, Solar Dynamics Observatory, and Hinode to analyze these events.

Definition and Overview

In heliophysics literature, ICME denotes a coherent, large-scale expulsion of magnetized plasma originating in the stellar corona that travels through the heliosphere. Definitions in publications from the American Geophysical Union, Royal Astronomical Society, AGU Fall Meeting, and specialized journals such as Journal of Geophysical Research often emphasize magnetic field structure, plasma composition, and kinematic properties. Typical descriptions compare these expulsions to structures observed during campaigns by missions like Voyager 2 and Ulysses, noting links to filament eruptions, flares catalogued by the Geostationary Operational Environmental Satellite series, and signatures recorded by the International Solar-Terrestrial Physics program.

History and Development

The conceptual development traces through early coronagraph observations and in situ detections. Groundbreaking work followed Carrington Event analyses and coronagraph imaging from the Mauna Loa Solar Observatory and later from SOHO instruments. The term and formal classification matured during coordinated studies involving Helios 1, Helios 2, and later during the International Living With a Star initiative. Seminal papers by researchers affiliated with Stanford University, University of California, Berkeley, and Harvard-Smithsonian Center for Astrophysics integrated magnetic cloud models from teams linked to the Max Planck Institute for Solar System Research and observational campaigns at Lockheed Martin Solar and Astrophysics Laboratory.

Types and Classification

Researchers categorize these expulsions into subtypes such as magnetic clouds, flux ropes, ejecta without clear flux rope signatures, and stealth events. Classification schemes used by groups at NOAA Space Weather Prediction Center and in compilations like the Coordinated Data Analysis Workshop series rely on parameters derived from instruments on ACE, WIND, and STEREO. Catalogs maintained by observatories including CDAW Data Center and universities like Boston University list events as fast, slow, halo, partial-halo, or stealth based on speed profiles, angular width measured by instruments such as LASCO, and association with solar surface features seen by TRACE and SDO.

Causes and Mechanisms

The driving mechanisms are studied in frameworks developed at institutions such as Princeton University, University of Colorado Boulder, and Cambridge University. Leading models invoke magnetic reconnection in complex active regions, flux emergence, and loss of equilibrium in coronal filaments. Theoretical foundations draw on work by researchers associated with the Kavli Institute for Theoretical Physics, Institut d'Astrophysique de Paris, and the National Center for Atmospheric Research employing magnetohydrodynamic simulations validated against data from facilities including RHESSI, Hinode, and IRIS.

Detection and Observation

Detection relies on remote-sensing and in situ measurements. Remote imaging comes from coronagraphs and extreme-ultraviolet imagers aboard SOHO, STEREO, and SDO; in situ plasma and field measurements derive from ACE, WIND, Parker Solar Probe, and Voyager 1. Analytical techniques developed at Johns Hopkins University Applied Physics Laboratory, Los Alamos National Laboratory, and NASA Goddard extract signatures such as enhanced helium abundance, charge-state anomalies, depressed proton temperatures, and coherent magnetic rotations. Campaigns coordinated with observatories like Mount Wilson Observatory and Big Bear Solar Observatory support multiwavelength characterization.

Impacts and Effects

These expulsions interact with planetary magnetospheres, ionospheres, and atmospheres, producing geomagnetic storms, auroral displays monitored by programs such as SuperMAG, and disruptions to spacecraft systems and power grids studied after events affecting entities like the Hydro-Québec network. Effects documented in case studies include satellite anomalies reported by operators at Intelsat, Iridium Communications, and navigation errors in Global Positioning System receivers. Societal and technological impacts are subjects of assessment by organizations including National Academies of Sciences, Engineering, and Medicine and World Meteorological Organization.

Mitigation and Forecasting

Mitigation and forecasting combine observational networks, modeling centers, and operational agencies. Forecast systems developed at NOAA, UK Met Office, and research groups at University of Michigan and Cornell University use heliospheric propagation models validated against datasets from OMNIWeb and missions like STEREO and Parker Solar Probe. Operational alerts leverage instruments on GOES-R series and predictive products coordinated through initiatives such as the International Space Environment Service. Ongoing improvements draw on advances at laboratories including Los Alamos National Laboratory, Sandia National Laboratories, and collaborations under programs like COSPAR.

Category:Heliophysics