中文摘要：

通常卫星探测到的关于行星际空间磁场的数据都是在GSE坐标系（地心太阳黄道坐标系）里表示出来的．磁云是行星际日冕物质抛射事件的一个重要子集，它们的边界认证一直是磁云研究中感兴趣的问题之一．通过讨论坐标系转换确定磁云边界的方法，由磁云的磁通量管特征建立磁云自然坐标系，然后把行星际空间的磁场转换到磁云自然坐标系里．在磁云自然坐标系里磁云作为一个磁通量管的结构能够清晰地显示出来．结合磁云的等离子体特征就可以比较容易地把磁云和背景太阳风分辨出来，即确定了磁云的边界．

英文摘要：

Magnetic clouds （MCs） belong to an important subset of interplanetary coronal mass ejections. The study of MC boundary is correlated with many other problems and interests many investigators at all times. This paper discusses a method that the interplanetary magnetic field data are converted into a cloud natural coordinate system in which the profile of the MC as a flux tube is displayed clearly, combining the plasma properties, the boundaries of the cloud can be identified easier. The establishment of cloud coordinate system is based on that MCs are flux ropes with approximately constant a force-free field configurations. Six observed magnetic clouds are analyzed using the method, and the resuits show that the method is feasible and can reduce the ambiguities of Identification of Magnetic Cloud Boundaries.