WIND Observation of Magnetic Cloud Boundary Layer and Discontinuity

82 boundary layer events in magnetic cloud between 1995.2---2003.8 were analyzed, using the data measured by WIND instruments. It is suggested from the results that: (1) Among the types of the directional discontinuity (DD), the distribution of RD (Rotational Discontinuity), TD (Tangential Discontinuity), ED (Either Discontinuity), ND (Neither Discontinuity) is 37:18:44:1. It is different from 51:12:35:2 in solar wind. (2) The ratio of TD at boundary of Magnetic Cloud Boundary Layers (MCBL) is high, that is 20 percents of all the DD. And the relative variety of temperature and density at either side of discontinuity is |ΔN/N| = 0.24 and |ΔT/T|= 0.19, that is higher than the average inside the MCBL. It has much more TD' characters. The number of DD in MCBL per day is 1.87 times than that in solar wind; (3) The distribution of DD' normal direction in θ-φ plane is likely a sinusoid structure, the center of which is θ = - 24.90 º, φ =217.49 º that points to opposite direction to the sun. It is rather than a simple isotropy distribution. The preliminary results suggest that discontinuities are the important structures in MCBL which has different distribution of DD' type. This paper could provide some evidences for analyzing the formation of MCBL.