Long-term measurement of solar EUV/UV fluxes for thermospheric-ionospheric (T/I) modelling and for space weather investigations

On 18/19 June 1998 the 1st TIGER Symposium was held in Freiburg/Germany. After presentation and discussion of 28 invited and contributed talks, the symposium agreed to establish a longterm TIGER Program within the framework of the SCOSTEP International Solar Cycle Study Working Group 1, Panel 2. This decision is based on the general agreement that, for thermospheric-ionospheric research as well as for a broad range of commercial applications in space, the improvement of existing thermospheric-ionospheric (T/I) models is absolutely necessary to meet scientific goals. There are 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 and/or weather and what is their significance? How does solar forcing compare with that from other sources such as increasing concentrations of radiatively-active gases and atmospheric aerosols? How sensitive is the Earth's climate to changes in solar radiation? What time scales of solar variability are significant to climate? How might solar variability in these wavelengths affect global warming projections? Are there signatures of solar influences in the upper atmosphere that are distinct from anthropogenic effects? To meet these goals, coordinated work on the following topics is required and is discussed in detail below: 1. 1.|Measurement and modelling of solar EUV/UV radiation 2. 2.|Measurement and modelling of the solar wind (particles) originated energy T/I influx 3. 3.|Measurement of relevant thermospheric-ionospheric parameters 4. 4.|Modelling of the thermosphere/ionosphere 5. 5.|Fundamental physical investigations of photoenergetic atomic and molecular processes To make substantial progress in developing a complete understanding of the T/I processes, it is necessary to envisage solar cycle and 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.