Tiger: A program for thermospheric-ionospheric geospheric research

Abstract The primary goals of the TIGER Program as defined in current knowledge of the terrestrial thermospheric-ionospheric (T/I) system are presented in this Special Edition of the Journal Physics and Chemistry of the Earth. The 1 st and the 2 nd TIGER Symposia were held in Freiburg (1998) and in St. Petersburg (1999), respectively, and the participants decided to summarize this field of space research combining the results of both symposia in a review-type survey. The TIGER Program was established within the framework of the SCOSTEP International Solar Cycle Study, Working Group 1, Panel 2. This decision is based on the general agreement that the improvement of existing thermospheric-ionospheric (T/I) models is absolutely necessary to meet scientific and engineering goals for thermospheric-ionospheric research as well as for a broad range of commercial applications in space. There are also a number of scientific questions underlying the goal of understanding solar EUV/UV variability such as what are the primary mechanisms by which solar ultraviolet (UV), extreme ultraviolet (EUV), and soft X-ray (XUV) irradiance variations affect terrestrial global climate change, including the upper atmosphere and space weather. The improvement of T/I models requires coordinated work on the following topics: • ⊎ Measurement and modeling of solar EUV/UV radiation • ⊎ EUV/UV Space Instrumentation • ⊎ Modeling of the solar wind originated energy T/I influx and Space Weather • ⊎ T/I modeling and measurement of relevant T/I parameters from space • ⊎ Measurements from ground • ⊎ Basic physical investigations to support T/I modeling To make substantial progress in developing a more complete understanding of the T/I processes, it is necessary to envisage solar cycle and even longer timescales. This can be done in the global change context by making use of a broad range of worldwide existing resources with respect to manpower, experience, hardware, methods, flight opportunities, and funding resources. The TIGER Program aims to facilitate the coordination of these existing and planned activities and to help define missing links for achieving the scientific goals.