On the basis of low altitude DMSP satellite particle data, character istics of polar rain, cusp and plasma mantle are examined during the asymmetric polar rain enhancement period. Obtained results are summarized as follows: (I) From the comparison between number fl ux of cusp and polar rain precipitations, the cusp fl ux does not increase correlatively with the increasing of polar rain fl ux. This result suggests that sources of precipitating particles are quite different from each other. ( 2 )

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... Low energy pulsive electrons (plasma mantle) are occasionally observed in the polar rain region. These plasma mantle particles are observed in both hemispheres and the polar rain enhancement shows hemispheric asymmetry. The mixing of polar rain and plasma mantle may be occurred due to the movement of plasma mantle by electric field drift.