Cosmic Ray Modulation and Its Significance for Extraterrestrial Climate Driving

Horst Fichtner [hf@tp4.rub.de], Ruhr-Universität Bochum, Germany.

            The modeling of the transport of cosmic rays in the heliosphere hasevolved from pure test particle simulations to more consistent treatments. Improvements comprise an explicit and simultaneous treatment of the plasma turbulence with which the cosmic ray particles interact, the considerationof a non-spherical modulation volume resembling the large-scale heliosphere,and the dynamics of the heliosphere on various time-scales. The state-of-the-art of the modeling is reviewed, and the importance of an understanding of the physics of the outer heliosphere is pointed out. There is increasing evidence that there exist interstellar-terrestrialrelations and that the heliosphere's effectivity to serve as a protectingshield for the Earth, specifically against neutral atoms and cosmic rays,is varying in time. The cosmic ray forcing of the terrestrial climate will be described, and the criteria how to discriminate it from solar forcing will be discussed.