The energy budget of the magnetosphere-ionosphere (MI) system during 1998-2008 was examined by using Akasofu's epsilon function. The results showed that 1) the yearly average rate of solar wind energy input into the MI system was 4.51 GGJ (GGJ=1018 J), while the yearly average total dissipation was 4.30 GGJ; 2) the energy partitioning in the ring current and polar region was 56%:44%; 3) the energy input and dissipation processes continuously proceeded both in storm-substorm events and less disturbed intervals, suggesting the significant contribution of slow but long-lasting energy process during the less disturbance periods to the total energy budget. In addition, we found in this study an interesting phenomenon "self-adjustment ability" of the MI system which behaves just like a water reservoir. During solar active years, the input energy is more than the dissipated energy, implying that a portion of the input energy is not immediately released, but is stored in the magnetosphere. On the other hand, during less active years, the dissipated energy is more than the input energy, implying that the previously stored energy makes up for the energy input shortage in this period.
太阳风向磁层-电离层(Magnetosphere and Ionosphere,MI)系统输入能量,而输入的能量随后在MI系统中消耗.本文从能量守恒原理出发,讨论太阳风-磁层-电离层(SMI)耦合过程中的能流路径和能量收支的定量关系.主要讨论9个问题:(1)太阳风向MI系统的能量输入,(2)MI系统对能量输入的响应,(3)环电流的能量消耗,(4)极区电离层焦耳加热的能量消耗,(5)极光粒子沉降的能量消耗,(6)磁尾能量的消耗、储存以及返回下游太阳风,(7)平静期间的能量积累与释放,(8)能量在不同能汇中的分配,(9)评价能量函数的准则和方法.
