使用地磁脉动参数定量预报地球同步轨道相对论电子通量的建模研究

Quantitative Prediction of Relativistic Electron Flux at Geosynchronous Orbit With Geomagnetic Pulsations Parameters

磁层超低频波(ULF波)对种子电子的加速机制是磁层相对论电子产生的一个重要机制,而地磁脉动参数可以作为此机制的有效指标.本文采用地磁脉动参数作为输入参数,借鉴线性预测滤波器技术,构建一个多参量非线性函数,进而利用此函数以及卡尔曼滤波技术,建立一个地球同步轨道相对论电子通量日积分值预报模式,提供提前一天的预报值.使用2004年数据对该模式进行训练,预报结果的预报效率为0.73,线性相关系数为0.85.使用2005-2006年的数据对该模式进行测试,预报值与实测值之间的线性相关系数为0.83,预报效率为0.69,相比Persistence模式具有较大提升,与仿REFM模式的预报效率相当.

Ultra-Low Frequency （ULF） waves can accelerate the seed electrons produced with sub storm injection, which is one of the main mechanisms for relativistic electron in the magnetosphere. Based on the previous studies, the Pil pulsation＇s duration is a good indicator for seed electrons. The Pc5 pulsation＇s duration and spectra power are good indicators for the efficiency of acceleration. In this paper, geomagnetic field data observed by Memambetsu observatory are used to extract Pil pulsations. The geomagnetic field data observed by GOES-12 satellite and SODANKYLA observa- tory are used to extract Pc5 pulsations. With these geomagnetic pulsation parameters, a prediction model for relativistic electron flux at geosynchronous orbit is established to provide the value of aday in advance. There are two steps. First, referencing the linear prediction filter, a multi-parameter nonlinear function has been built to give a preliminary prediction value for relativistic electron flux at GEO orbit. Then, a Kalman filter is used to correct this preliminary value with the history relativis- tic electron flux. The data during 2004 is used to train this model. The prediction efficiency of this year is 0.73 and the linear correlation coefficient is 0.85. In the test with data during 2005-2006, the prediction efficiency is 0.69 and the linear correlation coefficient is 0.83, which is a large promotion compared with Persistence model and closed to the imitation REFM model. On one hand, the re- sults show that the ULF wave acceleration mechanism is one of the main mechanisms for relativistic electron. On the other hand, the magnetic pulsation parameters can be well instead of the solar wind speed parameter, which would help to establish a new relativistic electron flux prediction model with ground stations.