The cosmic ray modulation in the rigidity range 0.3460 MeV) measured by satellite cosmic ray telescopes with the rigidity dependence of the diffusion coefficient K2(P) proportional to P for P≲10 GV. From this study we found that the hysteresis effect between the integral cosmic ray intensity (E>60 MeV) and the neutron monitor rates at Mount Washington (Pc=1.24 GV) could be explained by assuming that for P?PT, K2(P) changed from K2&agr;P to K2&agr;P2, following the theoretical arguments of Jokipii (1971). Furthermore, PT changes from about 25 GV at solar minimun to about 10 GV later in the solar modulation cycle. The hysteresis effect between the count rates of the Mount Washington and Huancayo (Pc=13.5 GV) monitors is explained on the same basis. |