场向电流随亚暴位相的变化

THE RELATIONSHIP BETWEEN FIELD-ALIGNED CURRENT AND SUBSTORM PHASE

利用ＩＳＥＥ１和２卫星测量的磁场数据，计算了电离层中的场向电流．依据每个场向电流事件所伴随的亚暴位相，分别计算了一区和二区场向电流强度、密度及电流片厚度在亚暴成长相、膨胀相和恢复相的平均值及中间值．其结果，从成长相到膨胀相，一区和二区场向电流的强度和密度增加，从膨胀相到恢复相，其值减小．平均说来，一区的电流强度约是二区的１．４倍．电流片厚度的变化在上述期间内与电流强度及密度的变化趋势相反．

ISEE 1 and 2 measurements of magnetic changes across nightside fieldaligned currents (FACs) in the inner magnetosphere are examined to determine the average ionospheric extrapolated characteristics and properties of regin 1 and 2 currents as a function of substorm phase. The properties of these currents studied include current intensity, density and layer width. It is found that there is a close relation between FACs and substorm phase. Both region 1 and region 2 currents intensity reach their peak during the expansion phase. The average value of intensity in region 1 is about 1.4 times greater in region 2. The current densities in region 1 and 2 behave same with current intensity, i.e from the growth phase to expansion phase, the density increases and from the expansion phase to the recovery phase it decreases.