A Kalman filter technique to estimate relativistic electron lifetimes in the outer radiation belt
A Kalman filter technique to estimate relativistic electron lifetimes in the outer radiation belt
复制标题
用于估计外辐射带中相对论电子寿命的卡尔曼滤波技术
DOI：
10.1029/2007ja012583
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发表时间：
2007
影响因子：
--
通讯作者：
R. Thorne
中科院分区：
文献类型：
--
作者：
D. Kondrashov;Y. Shprits;M. Ghil;R. Thorne
[1]数据同化的目的是将不完整和不准确的观测数据与物理模型的动力学信息顺利地融合在一起，已成为理解和预测气象、海洋和气候过程的一个日益重要的工具。随着空间观测越来越丰富，空间物理模型越来越复杂，可以使用先进的数据同化方法分析辐射带的动力学过程。我们使用扩展卡尔曼滤波器和观测的组合释放和辐射效应卫星（CRRES）估计的相对论电子的寿命在磁暴在地球的外辐射带。该模型是一个控制相空间密度的线性抛物型偏微分方程。这个方程包含经验系数，这些系数并不为人所知，我们希望沿着估计相空间密度本身。同化方法首先验证模型模拟的数据，这使我们能够可靠地估计的特征寿命的电子。然后，我们将该方法应用于CRRES测量，并表明它是有用的，在突出系统的参数估计由日冕物质抛射（CME）和共转相互作用区域（CIR），分别驱动的风暴之间的差异。这些差异是由于在不同的物理制度的加速和损失过程的复杂，竞争的影响。本文所述的技术接下来可以应用于约束更复杂的辐射带和环电流模型，以及磁层物理学的其他领域。
[1] Data assimilation aims to smoothly blend incomplete and inaccurate observational data with dynamical information from a physical model, and has become an increasingly important tool in understanding and predicting meteorological, oceanographic and climate processes. As space-borne observations become more plentiful and space-physics models more sophisticated, dynamical processes in the radiation belts can be analyzed using advanced data assimilation methods. We use the Extended Kalman filter and observations from the Combined Release and Radiation Effects Satellite (CRRES) to estimate the lifetime of relativistic electrons during magnetic storms in the Earth's outer radiation belt. The model is a linear parabolic partial differential equation governing the phase-space density. This equation contains empirical coefficients that are not well-known and that we wish to estimate, along with the phase-space density itself. The assimilation method is first verified on model-simulated data, which allows us to reliably estimate the characteristic lifetime of the electrons. We then apply the methodology to CRRES measurements and show it to be useful in highlighting systematic differences between the parameter estimates for storms driven by coronal mass ejections (CMEs) and by corotating interaction regions (CIRs), respectively. These differences are attributed to the complex, competing effects of acceleration and loss processes during distinct physical regimes. The technique described herein may be applied next to constrain more sophisticated radiation belt and ring current models, as well as in other areas of magnetospheric physics.