| We analyzed 82 boundary layer events in magnetic cloud between 1995.2– 2003.8, and the data were measured by WIND instruments. We suggests that: (1)The distribution of DDs (Directional Discontinuity) type: RD (Rotational Discontinuity): TD(Tangential Discontinuity): ED (Either Discontinuity):ND (Neither Discontinuity) 37:18:42:1 is different from that 51:12:35:2 in solar wind. (2)The ratio of TDs at boundary of magnetic cloud boundary layers (MCBLs) is high, that is 20 percents of all the DDs. And the relative variety of temperature and density at either side of discontinuity isΔN /N=0.24 andΔT /T=0.19, that is higher than the average inside the MCBL. It is shows much TDs'character. The number of DDs in MCBL per day is 1.87 times than that in solar wind; (3)The distribution of DDs'normal direction inθ?φplane is likely a sinusoid structure, which the center isθ=-24.90,Φ=217.49 that points to opposite direction to the sun. It is rather than a simple isotropy distribution. (4)And comparison between MCBL, magnetic hole (MH) and magnetic decrease (MD) shows that MCBL inclines to have more abundance and complicated discontinuities. It has close relationship with dynamic inside. The first step results suggest that discontinuities are the important structures in MCBL which has different distribution of DDs'type. This paper could provide some evidences for analyzing the formation of MCBL. |
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