Are ionospheric storms the same during different solar cycles?
Abstract
The ionosphere's response to geomagnetic storms has been studied since the earliest days of terrestrial space physics. In terms of temporal coverage, the largest data sets used extensively have been from the global network of ionosondes. Many previous investigations examined the behavior of the F layer's maximum electron density (Nmax)—often contrasting the difference seen between storms that occur during solar maximum years versus those during solar minimum years. We report on the first attempt to study systematically the patterns of ionospheric disturbance seen during different solar cycles. We select two midlatitude sites with long‐term consistency in data: Wallops Island (Virginia) and Hobart (Tasmania)—stations with comparable geographic and geomagnetic coordinates—but in different hemispheres and widely separated longitude sectors. We compare average ionospheric storm patterns using over 200 moderate to severe geomagnetic storms within each of solar cycle #20 (October 1964 to June 1976) and cycle #23 (May 1996 to December 2008). We compute average patterns of ΔNmax(%), measured with respect to monthly mean conditions, following storm and local time. The overall results show remarkable consistency in characteristic patterns of an ionospheric storm: a short positive phase that occurs during the daytime hours on the first day of a storm, with a prolonged negative phase on subsequent days. Statistical differences occur in the overall magnitudes and longevities of these patterns, consistently showing that cycle #23 had less severe ionospheric storms. An analysis of geomagnetic indices shows that degrees of disturbance were, in fact, lower during solar cycle #23 than cycle #20.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Oct 01, 2013
- Source ID
- 10.1002/2013ja019102
Entities
People
- Angela G. Marusiak
- Clara Narvaez
- Michael Mendillo
Organizations
- Boston University
- National Science Foundation
- Office of Naval Research