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These proceedings are based upon introductory talks, research reports and discussions from the NATO Advanced Workshop on the "Morphology and Dynamics of the Polar Cusp", held at Lillehammer, Norway, 7-12 May, 1984. The upper atmosphere at high latitudes is called the "Earth's win dow to outer space". Through various electrodynamic coupling process es as well as through direct transfer of particles many geophysical effects displayed there are direct manifestations of phenomena occurring in the deep space. The high latitude ionosphere will also exert a feedback on the regions of the magnetosphere and atmosphere to which it is coupled, acting as a momentum and energy source and sink, and a source of particles. Of particular interest are the sections of the near space known as the Polar Cusp. A vast portion of the earth's magnetic field envelope is electrically connected to these regions. This geometry results in a spatial mapping of the magnetospheric pro cesses and a focusing on to the ionosphere. In the Polar Cusps the solar wind plasma has also direct access to the upper atmosphere. The polar regions are thus of extreme importance when it comes to under standing the physical processes in the near space and their effect on our environment. The Introductory Talks given at this workshop provided a common background for discussing and understanding the physics of the Polar Cusp. By this book we will make the information which thus was provid ed to the participants of the workshop accessible to a wider audience.
List of contents
Plasma and field observations in the exterior cusp, entry layer, and plasma mantle.- Plasma composition and flow characteristics in the magnetospheric boundary layers connected to the polar cusp.- Simulation of solar wind-magnetosphere interaction.- Electron injection in the polar cusp.- Ion injection and acceleration in the polar cusp.- Average electron precipitation in the polar cusps, cleft and cap.- The characteristics of a persistent auroral arc at high latitude in the 1400 MLT sector.- The effects of magnetosheath electrons on charge exchange, radiation trapping and other atomic and molecular processes in the mid-day polar cusp thermosphere.- The HeI 3889Å line in polar cleft spectra.- Modelling of cusp auroras: The relative impact of solar EUV radiation and soft electron precipitation.- Polar cusp dynamics.- Large- and small-scale dynamics of the polar cusp region.- Polar cusp features observed by DMSP satellites.- Optical-particle characteristics of the polar cusp.- Characteristics of large-scale Birkeland currents in the cusp and polar regions.- Dayside high-latitude ionospheric current systems.- Small scale intense field aligned current sheets in the northern polar cusp.- Interferometer observations of ion and neutral dynamics in the polar cusp.- Neutral parcel transport in the high latitude F-region.- Observations of plasma structure and transport at high latitudes.- Interplanetary magnetic field effects on high latitude ionospheric convection.- Structure in the DC and AC electric fields associated with the dayside cusp region.- Low frequency waves at the dayside auroral oval.- Incoherent-scatter radar observations of the cusp.- High-resolution observations of electric fields and F-region plasma parameters in the cleft ionosphere.- Observations of theunstable E-region in the polar cusp.- Observations of the cusp with topside sounders.- Definition of the cusp.- Future cusp experiments and their coordination.- Summary.
