SM43E-01
Validating SWMF Particle Density and Energy: Initial Results
First principle-based models can be a powerful tool for scientific and operational space weather forecasting and analysis. A key step for improving current models and preparing them for operational use is thorough data-model comparisons. Of particular interest is particle density and energy distribution in the magnetosphere, which are key values for spacecraft surface charging calculations. In this study, we compare particle density and energy spectrum values generated by the Space Weather Modeling Framework (SWMF) to in situ LANL geosynchronous measurements. The SWMF is configured to use a self-consistent ionospheric electrodynamics model, the BATSRUS global MHD model, and the Rice Convection Model (RCM). Coupling these models allows for tracing the magnetic field lines from the MHD solution to provide the RCM with an improved open/closed field line boundary. It also allows for the extraction of the RCM solution along any satellite trajectory by tracing the magnetic field line from the 3D location of the satellite to the 2D RCM ionospheric grid. The SWMF is further configured to run in near-real time on 32 Columbia SGI processors, creating a solution that better reflects the SWMF's capabilities in an operational environment. This study is an extension of previous work to validate the SWMF's modeled magnetic field.
SM43E-02
Validation of Methods for Calculating the Second and Third Adiabatic Invariants
A comprehensive study is done to quantify the accuracy of various methods for computing the second, I, and third, Φ, adiabatic invariants used for analyzing energetic particle motion in the Earth's magnetic field. Two methods are compared: the first available from the ONERA-DESP library (http://wwwe.onecert.fr/craterre/support/compiled.html) and the second provided by Dr. J. Albert from the Air Force Research Laboratory. Differences between the two methods and the intrinsic accuracy of each method based on varying level of convergence criteria are computed as a function of geographic coordinates. Results are presented in a form where they can easily be incorporated into the error budget when analyzing satellite particle detector data typically parameterized by time, position, energy and pitch-angle. Derived quantities, such as the "L- shell" parameter L* , are also computed and variations resulting from different magnetic field models and the time variation of the Earth's dipole moment over time will be shown.
SM43E-03 INVITED
Space Weather Models at the CCMC And Their Capabilities
The Community Coordinated Modeling Center (CCMC) is a US inter-agency activity aiming at research in support of the generation of advanced space weather models. As one of its main functions, the CCMC provides to researchers the use of space science models, even if they are not model owners themselves. The second focus of CCMC activities is on validation and verification of space weather models, and on the transition of appropriate models to space weather forecast centers. As part of the latter activity, the CCMC develops real-time simulation systems that stress models through routine execution. A by-product of these real-time calculations is the ability to derive model products, which may be useful for space weather operators. In this presentation, we will provide an overview of the community-provided, space weather-relevant, model suite, which resides at CCMC. We will discuss current capabilities, and analyze expected future developments of space weather related modeling. http://ccmc.gsfc.nasa.gov
SM43E-04
CME-driven Shock Simulations and Observations: Variability of SEP Abundances, Mechanisms, and Validation
In the past decade, much progress has been made by way of satellite observations regarding the origin and acceleration mechanisms of solar energetic particles (SEPs). In comparison, relatively little work has been done on the side of event-based simulations. In particular in the context of developing quantitative models of SEP fluxes and spectra, it is of great concern to understand their intrinsic possible variability, and to address the question whether the prevalence and efficiency of different contributing mechanisms can be estimated or predicted. Using ACE data, we have selected a number of characteristic "energetic storm particle" (ESP) events, i.e., SEP events in which the CME-driven shock passes the spacecraft, to compare observed local proton flux profiles with those obtained from large-scale hybrid simulations (kinetic ions, electron fluid). The events were selected for relatively undisturbed solar wind, isolation from other events, and flux profiles that clearly indicate local shock acceleration. Interestingly, in the sub-MeV range, we find very little variation of peak proton fluxes with shock normal angle. In our simulations we have investigated the role of seed particles, the acceleration processes at oblique shocks, and other effective mechanisms such as mirroring of energetic ions in downstream converging fields. In addition, shock curvature on various scales can play a role. Via direct comparison with the observed events, we discuss the pertinent acceleration mechanisms and the feasibility of predicting their respective, relative importance and occurrence.
SM43E-05
Simulation of Radiation Belt Diffusion Using SDE (Stochastic Differential Equation) Methods
In this work we seek to improve space weather modeling by developing a useful new numerical tool for radiation belt modeling. Specifically, we make use of a large body of existing mathematical research which shows that radiation belt diffusion equations of the Fokker-Planck form are exactly equivalent to sets of stochastic differential equations (SDEs), and we adopt numerical methods of solving sets of SDEs which in turn provide solutions of the corresponding radiation belt diffusion equation. SDEs will be described and Monte Carlo methods of solution will be presented. The main emphasis is on the SDE methods, but we will also show some recent SDE solutions of the energy-pitch-angle quasilinear diffusion equation for cyclotron-resonant interactions of relativistic electrons with whistler-mode chorus waves.
SM43E-06
Studying Radiation Belt Enhancements using an Adaptive Kalman Filter
The highly energetic electron environment in the inner magnetosphere undergoes dramatic changes caused by wave-particle interactions. Competing physical processes are at play and can either transport energetic electrons, accelerate them, or move them into the loss cone. Radiation belt enhancements through electron accelerations are usually significant during the recovery phase of a geomagnetic storm and can even reach higher flux levels than before the storm. We will present results from studying the radiation belt enhancements using our data assimilation framework that combines phase space density data from several satellites with predictions from a radiation belt diffusion code. This quantitative comparison of data and model output enables us to estimate where forecast and observations drift apart. In addition, our framework can automatically estimate the location of active acceleration regions and the overall efficiency of wave-particle interactions. We will use our recently developed residual method to quantitatively evaluate the effect of different physical processes on the forecast capability of our model. Specifically, we will look at the effect of adding an artificial source term in the shape of a Gaussian distribution to the radial diffusion equation. Our data assimilation framework will then estimate the most likely position of the energetic electron source region, its width and amplitude as a function of L* and time.
SM43E-07
Variations in the ring current and inner-magnetospheric electric field deduced from data assimilation of IMAGE/HENA data
We examine the relationship between the temporal variation of the ring current and that of the inner- magnetospheric electric field during a magnetic storm by using data assimilation of ENA observations into a kinetic ring current simulation. Since the dynamics of ring current ions are strongly controlled by the electric field, it is important to know the electric field in the inner magnetosphere in order to discuss the ring current evolution. However, due to the lack of direct observations, it is basically difficult to know the global distribution of the electric field for each storm event. By applying a data assimilation technique to a kinetic ring current model, we can estimate not only the ring current distribution but also the electric potential distribution and some other parameters on the basis of both observations and physical laws described by the kinetic code. We assimilated ENA observations from the IMAGE satellite into a kinetic ring current model developed by Fok et al. (2001) using the merging particle filter algorithm, and the distributions of the ring current and electric potential provided by this ENA data assimilation was examined. It is indicated that a westward electric field appears around the post- midnight and that it feeds high energy ions into the ring current region. It is also suggested that the variation of this westward electric field substantially controls the high-energy part of the ring current. The possible implications of the results are also discussed.