INTERNATIONAL SOLAR-TERRESTRIAL-ENERGY-PROGRAM AND THE UK PARTICIPATION

The Solar Terrestrial Energy Programme (STEP) aims to improve our gene ral understanding of how mass, energy and momentum are transferred bet ween the various regions that form the Solar Terrestrial environment. STEP began in 1990 and will continue until 1997, during which time a n umber of major new spacecraft and ground-based projects will become op erational. Six Working Groups form the basis of STEP, covering topics such as the Sun as a source of energy and disturbance, energy and mass transfer through the interplanetary medium and the magnetosphere-iono sphere system, ionosphere-thermosphere coupling and response to energy and momentum inputs, middle atmosphere responses to forcing from abov e and below, solar variability effects in the human environment, and i nformatics. A Royal Astronomical Society Geophysics Discussion meeting took place in March 1992 to draw to the attention of UK scientists th e diverse nature of STEP and the opportunities offered by STEP. This p aper consists of individual sections prepared by the speakers at the m eeting and which cover most of the STEP Working Group topics. The main aims of each section are to provide a ''benchmark'' for the present s tatus of the research area and to look ahead to the possible contribut ions that UK scientists can make during STEP.