Introduction to the special section on Sun‐Earth system response to extreme solar and seismic events

Abstract

Extreme solar events such as CMEs (coronal mass ejections) and ICMEs (interplanetary CMEs) offer valuable information about the physical processes involved in coupling the Sun-Earth system through shocks, magnetic reconnection, wave-particle interaction, ring current intensification, geomagnetic storms, electric field intensification, and thermospheric and ionospheric storms. Seismic events including earthquakes and volcanoes provide the opportunity to understand upward coupling of the atmosphere-ionosphere system through possible magnetic/electric fields generated in the lithosphere and atmospheric waves generated in the atmospheric boundary layer during the events. In addition to scientific interest, the studies of the Sun-Earth system responses are of public interest for their effects on satellite systems and astronauts, communication and navigation, power grids and climate, and life and resources. The findings may lead to earthquake precursor and severe space weather prediction.This special section of JGR Space Physics contains a collection of papers studying the Sun-Earth system response to extreme solar and seismic events. The majority of the papers are based on the presentations in a session on this topic organized at the joint AOGS-AGU (WPGM) general assembly held in Singapore during 13-17 August 2012. The collection also contains a few papers from outside the assembly but fall within the theme of the special section.A theoretical study of Alfvén waves by Shukla [2013] provides an alternative mechanism for transferring energy from the surface of the Sun to the corona. By using a two-fluid model, together with Ampère's law, Shukla derives the wave equation for 3-D modified-kinetic Alfvén waves (m-KAWs) in a magnetoplasma. It is shown that the 3-D m-KAWs in magnetized plasma can propagate in the form of Alfvénic tornadoes characterized by plasma density whirls (or rapidly rotating magnetic flux ropes), which can channel electromagnetic wave energy and heat fluxes from the surface of the Sun into the corona through the Alfvénic tornadoes. Yue et al.