Global change: the solar influence

The variable outputs of the Sun that influence the Earth´s atmosphere include electromagnetic radiation, the solar wind, and energetic particles emitted by flares and other disturbances. Irregularities in the solar wind can also modulate galactic cosmic rays that impact the Earth. In addition, there are variations in the solar energy at the top of the atmosphere caused by long-term changes in the Earth´s orbital elements. All of these variations are currently being imposed on an atmosphere whose composition and thermal structure is changing as a result of trace-gas increases from man´s activities. There is need for a next-generation climate model that extends from the ground to the thermosphere that can be used to study the effects of solar variability on a changing atmosphere. Such a model will probably require an increase in present-day computational power by a factor of 10 to 100