Characterization of the Large-Scale Solar Corona
Abstract
Coronal mass ejections (CMEs) from the Sun constitute one of the primary causes of geomagnetic storms. CMEs also drive shocks, which in turn accelerate solar energetic particles (SEPs) that pose radiation hazards for technological systems in space. With support from AFOSR, researchers from the Catholic University developed an empirical CME arrival (ECA) model that takes as input the CME speed from coronagraph observations and outputs the arrival time of CMEs at 1 AU. This model has recently been extended to predict the arrival time of shocks. This empirical shock arrival model (ESA) predicts the arrival time of interplanetary shocks on Earth based on the remote-sensing observations of CMEs by coronagraphs such as the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) satellite. The input to the model is the sky plane speed measured from coronagraph images of CMEs. An important step in the model is to show that the interplanetary shocks behave like gas-dynamic shocks for a large number of shocks of solar cycle 23. This means the shock arrival can be predicted from CME arrival because there is a definite relation between a CME and its shock. Once the CME speed is measured, the shock travel time from Sun to Earth can be obtained from a table. The ESA model is capable of providing 1-3 day advance warning of the impending arrival of CME-driven shocks on Earth. This is a very useful lead-time for space weather applications. As a result of this study, a complete catalog of all the CMEs observed by the SOHO mission has been created and provided online to the scientific community (http://cdaw.gsfc.nasa.gov/CME_list). This study revealed that long-wavelength radio bursts detected by Wind/WAVES experiment are indicative of a special population of CMEs that are wider and faster than regular CMEs. Further correlative studies were used to improve the empirical CME arrival model to predict the arrival of CMEs at 1 AU.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 05, 2003
- Accession Number
- ADA418377
Entities
People
- J. Brosius
Organizations
- The Catholic University of America