This proposal requests support for three closely related studies of the ionosphere and magnetosphere above Antarctica. In chronological order, the first task proposed is continuing analysis of X-ray and electric field data obtained by balloon-borne sensors flown from Siple Station in 1980-81 and from South Pole in 1985-86. The focus of this analysis will be on ULF waves. A statistical survey of the ratio of the electric to magnetic field strength as a function of frequency, magnetic activity, magnetic local time, and latitude will be made. The second task proposed is analysis of data obtained by experiments flown as part of the Japanese Polar Patrol Balloon (PPB) Program from Syowa Station in 1990-91 and 1992-93. This program involves the launch of long-duration zero-pressure balloons onto circumpolar flight paths. The University of Houston provided three-axis double probe electric field experiments for a flight in 1990-91 and two flights in 1992-93. Excellent data were obtained for a total of 30 balloon days. It is anticipated that we will be conducting both a statistical convection study and individual event studies. Comparison of these data with data obtained simultaneously by R. H. Holzworth during ELLBO and by ground-based electric field meters at South Pole are also planned.
The third task proposed is a continuation of our flight program. There are a number of long-duration balloons (LDB) launched from McMurdo each year that spend most of their observing time at latitudes that place them either in the geomagnetic polar cap or the auroral zone. We propose to build and fly a series of ``target of opportunity'' add-on experiment packages that can be attached to essentially any LDB payload that has sufficient spare lift capacity to accomodate our small experiment. For the summer of 1996-97, the JAYCEE payload, R. Jeff Wilkes, University of Washington, PI, has the available lift. Preliminary conversations with staff at the National Scientific Balloon Facility indicate that it appears easy to accomodate a three axis electric field experiment with on-board recorder as part of this payload. Two payloads would be built each year, with one being a spare for the first year, and the idea being to look for two or more available rides in subsequent years. The proven ability of the U. S. Program to recover the on-board data recorders will provide for a two order of magnitude increase in time resolution compared with the ARGOS telemetry system used on the PPB's. The experience that is obtained launching LBD's that carry electric field experments will assist in planning the resumption of the PPB program, which is presently envisioned for McMurdo in the austral summer of 1999-2000.
The electric field data that are obtained will be used to study the responses of the high latitude convection pattern to IMF variations, the electric fields of ULF waves, high latitude impulsive events, and to search for differences between the convection pattern over the austral polar cap and auroral zone in the years 1996-1999 and that measured in the 1985-86, 90-91 and 92-93 campaigns. A major emphasis will be placed on following the temporal and spatial development of events from WIND and IMP 8, to POLAR and FAST, and then to the balloon data, data from the Southern Hemisphere Auroral Radar Experiment (SHARE) and data from ground arrays such as PENGUIn and SESAME. These studies will lead to better understanding of global convection patterns and auroral electrodynamics.