THE RAREFACTIVE SOLITON SOLUTION OF NONLINEAR MAGNETOSONIC WAVE AND KINETIC ALFVEN WAVE,AND THEIR APPLICATION IN THE LOWER CUSP REGIONS

The properties of the rarefactive soliton solution of nonlinear magnetosonicwave and kinetic Alfven wave have been studied in detail. It is found that the electric and magnetic fields, induced by different nonlinear wave are apprantly different in directions and patterns. These results are compared with the observationdata from Freja satellite in the lower cusp region. It is shown that the low frsquency events with density depression are most possibly due to nonlinear kineticAlfven wave.