质子地磁垂直截止刚度在2004年11月7-8日两个时刻处的数值模拟

摘要

利用单粒子轨道理论,在T04和IGRF2000磁场模式建立的磁层模型基础上,应用四阶龙格库塔方法,模拟计算宇宙线带电质子在地球磁层中的运动以及沿天顶方向入射到达地球磁场内的某一特定位置,得到了距地球表面450km高度处全球质子垂直截止刚度在2004年11月7-8日中两个时刻的计算值.根据计算得到的684个不同位置处的截止刚度值,分析了同一时刻地磁垂直截止刚度随磁纬和磁经的变化.与此同时,模拟计算了相同时刻下磁纬为30°,磁经为0°,45°,90°,135°,180°,225°,270°,315°处,地磁有效垂直截止刚度随高度的变化情况.结果表明,在磁纬30°处,其质子有效垂直截止刚度随距离地心高度的变化沿向阳处向磁尾处方向,变化越来越缓慢.%The geomagnetic cut-off rigidity can effectively measure the shielding effect of Earth's magnetic field on cosmic ray particles.In this paper,the single particle orbit theory is used to simulate the movement of cosmic ray protons in the Earth's magnetosphere and the specific location within the magnetic field along the vertical direction to the Earth center.Based on the establishment of T04 and IGRF2000,the fourth-order Runge-Kutta method is used to simulate the trajectories of particles.The vertical cutoff rigidities of global cosmic protons around the height of 450 km above Earth's surface at two moments in November 2004 are calculated.The value change of geomagnetic vertical cutoff rigidity with the magnetic latitude and magnetic longitude is analysed with the help of 684 calculation results at the same moment.The changes of protons vertical cutoff rigidity with the height from Earth's center,at the position of magnetic latitude of 30°,magnetic longitude of 0°,45°,90°,135°,180°,225°,270°,315°,are also simulated.Simulation results show that the change of geomagnetic effective vertical cutoff rigidity with the increasing height from the Earth's center is getting more and more slow along the sunny direction to the magnetic tail.