Aaron J. Ridley

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[1] The Space Weather Modeling Framework (SWMF) provides a high-performance flexible framework for physics-based space weather simulations, as well as for various space physics applications. The SWMF integrates numerical models of the Solar Corona, Upper Atmosphere into a high-performance coupled model. The components can be represented with alternative(More)
[1] We present a three-dimensional (3-D) numerical ideal magnetohydrodynamics (MHD) model describing the time-dependent expulsion of a coronal mass ejection (CME) from the solar corona propagating to 1 astronomical unit (AU). The simulations are performed using the Block Adaptive Tree Solar-Wind Roe Upwind Scheme (BATS-R-US) code. We begin by developing a(More)
— We compare the performance of the extended Kalman filter, the unscented Kalman filter, and two extensions of the H∞ filter when applied to discrete-time nonlinear state estimation problems with nondifferentiable dynamics. We compare the performance of all the estimation techniques on simple nonlinear examples and finally consider state estimation of(More)
[1] In late October and early November 2003 a series of some of the most powerful solar eruptions ever registered shook the heliosphere. These ''Halloween storms'' damaged 28 satellites, knocking two out of commission, diverted airplane routes, and caused power failures in Sweden, among other problems. This paper presents a 4-day end-to-end simulation of(More)
I. INTRODUCTION While the classical Kalman filter provides a complete and rigorous solution for state estimation of linear systems under Gaussian noise, the estimation problem for nonlinear systems remains a problem of intense interest. Although rigorous solutions to the nonlinear problem have been studied, these results are either too narrow in(More)
Space-environment simulations, particularly those involving space plasma, present significant computational challenges. Global computational models based on magnetohydrodynamics equations are essential to understanding the solar system's plasma phenomena, including the large-scale solar corona, the solar wind's interaction with planetary magnetospheres,(More)
The Space Weather Modeling Framework (SWMF) has been developed to provide NASA and the modeling community with a high-performance computational tool with " plug-and-play " capabilities to model the physics from the surface of the Sun to the upper atmosphere of the Earth. Its recently released working prototype includes five components for the following(More)
— We compare several reduced-order Kalman filters for discrete-time LTI systems based on reduced-order error-covariance propagation. These filters use combinations of balanced model truncation and complementary steady-state covariance compensation. After describing each method, we compare their performance through numerical studies using a compartmental(More)
— A nonlinear asymptotic observer for a discrete-time nonlinear system is considered. The observer is based on a Kalman filter that uses the state dependent Riccati equation (SDRE) to obtain the filter gain. Unlike the Extended Kalman Filter, the SDRE-based Kalman filter does not involve the evaluation of a Jacobian at every time step. The convergence(More)