The cusps have traditionally been described as narrow funnel-shaped regions that provide a focus of the Chapman-Ferraro currents that flow on the magnetopause, a boundary between the cavity dominated by the geomagnetic field (i.e., the magnetosphere) and the external region of the interplanetary medium. From low-altitude satellite and ground-based measurements the cusp appears to behave in much the manner predicted for the responses of the narrow funnel-shaped structure to changes in the upstream interplanetary medium. Measurements at higher altitudes have been reported by past and recent missions such as the Russian Interball satellites, the US/NASA Hawkeye, Polar, and IMAGE satellites, and the joint European Space Agency/NASA Cluster suite of four satellites, all in mid- to high-altitude polar orbits. From these measurements, the cusp no longer is confined to a narrow region near local noon but appears to encompass a large portion of the dayside high-latitude magnetosphere. An unexpected result is that the cusp appears to be a major source region of energetic charged particles for the magnetosphere.
This special issue will provide a comprehensive set of overview papers that will focus on the properties of the cusp as a function of altitude. It will provide a forum in which outstanding problems or controversies associated with the cusp and neighboring boundary regions can be openly discuss and documented. We hope that it will be possible for the publisher, KLUWER ACADEMIC PUBLISHERS to publish this issue as a separate book that can serve as a reference volume on the subject matter.
Once the details of the proposed special issue have been worked out with Kluwer and the journal editor, Dr. Michael Rycroft, we will advertise the special issue and will accept and include papers that focus on the topic of the special issue. Please contact the editors, Ted Fritz (fritz@buasta.bu.edu/617 353 7446) or Shing Fung (shing.fung@gsfc.nasa.gov/301 286 6301), regarding your possible interest. Manuscripts would need to be in a near final draft form by the middle of October.