RECURRENT GEOMAGNETIC STORMS AND RELATIVISTIC ELECTRON ENHANCEMENTS IN THE OUTER MAGNETOSPHERE - ISTP COORDINATED MEASUREMENTS

New, coordinated measurements from the International Solar-Terrestrial Physics (ISTP) constellation of spacecraft are presented to show the causes and effects of recurrent geomagnetic activity during recent sol ar minimum conditions. It is found using WIND and POLAR data that even for modest geomagnetic storms, relativistic electron fluxes are stron gly and rapidly enhanced within the outer radiation zone of the Earth' s magnetosphere. Solar wind data are utilized to identify the drivers of magnetospheric acceleration processes. Yohkoh solar soft X-ray data are also used to identify the solar coronal holes that produce the hi gh-speed solar wind streams which, in turn, cause the recurrent geomag netic activity. It is concluded that even during extremely quiet solar conditions (sunspot minimum) there are discernible coronal holes and resultant solar wind streams which can produce intense magnetospheric particle acceleration. As a practical consequence of this Sun-Earth co nnection, it is noted that a long-lasting E>1MeV electron event in lat e March 1996 appears to have contributed significantly to a major spac ecraft (Anik E1) operational failure.