Heliospheric Observations of Solar Disturbances and Their Potential Role in the Origin of Geomagnetic Storms
Abstract
Ground-based interplanetary scintillation observations began heliospheric studies in the early 1960's using remote-sensing techniques. These were followed by coronagraph and Helios photometer white-light observations, and kilometric radio observations. The first solar wind in situ observations were measured by the Mariner 2 spacecraft three decades ago. These observations show heliospheric features which corotate with the Sun, as well as those which only occur as single events. For an observer at Earth both types of features can manifest themselves as abrupt time variations in the heliospheric plasma magnetic field, density, and velocity. On the corotating side, recent studies have shown that active regions are associated with sustained outflows of plasma at 1 AU in the form of a dense, slow-speed solar wind component which can interact with the less dense coronal hole regions of the solar wind. Recent work shows that the heliospheric manifestations of coronal mass ejections provide a significant portion of the solar wind mass (>15%) and energy outflow at solar maximum. Both of these types of features have implications in terms of their potential for magnetospheric interaction. We are now poised to take advantage of several technological advances currently underway which will undoubtedly play a key role in complete heliospheric plasma characterization in terms of fundamental interplanetary medium parameters from the Sun outward.
- Publication:
-
Geophysical Monograph Series
- Pub Date:
- 1997
- DOI:
- 10.1029/GM098p0059
- Bibcode:
- 1997GMS....98...59J