Vincent Maget

Characterizing Solar Energetic Particles Access to any Earth-Space Location

A consistent tool that completely characterizes the Earths magnetic shielding at any location in space has been developed. The formalism of transmissivity helps the user to rapidly compute and estimate the transmitted SEP flux along any orbit. The model and first results (comparison to SAC-C/ICARE measurements) are presented. In particular, the geomagnetic shielding at GPS-like altitude is focused on and comparison plots of transmitted flux obtained when using different transmission functions for example orbits are analyzed.

Improvements of FLUKA Calculation of the Neutron Albedo

This paper presents Monte-Carlo simulations based on the Fluka code aiming to calculate the contribution of the neutron albedo at a given date and altitude above the Earth chosen by the user. Results consist of a two-parameter distribution, the neutron energy and the angle to the tangent plane of the sphere containing the orbit of interest, and are provided by geographical position above the Earth at the chosen altitude. In this paper, a major improvement was introduced with respect to the previous model concerning the filtering of incoming cosmic rays hitting the upper atmosphere. This more accurate estimation of neutron albedo is of prime importance for the radiation belts modelers because it constitutes the main source of protons >40 MeV of the inner radiation belt.

Improved outer boundary conditions for outer radiation belt data assimilation using THEMIS‐SST data and the Salammbo‐EnKF code

Over the last decade, efforts have been made in the radiation belt community to develop data assimilation tools in order to improve the accuracy of radiation belts models. In this paper we present a new method to correctly take into account the outer boundary conditions at L* = 8 in such an enhanced model of the radiation belts. To do that we based our work on the Time History of Events and Macroscale Interactions during Substorms/Solid State Telescope data set. Statistics are developed to define a consistent electron distribution at L* = 8 (in both equatorial pitch angle and energy), and a variance-covariance matrix is estimated in order to more realistically drive the Monte Carlo sampling required by the Ensemble Kalman Filter (EnKF). Data processing is first described as well as caveats avoided, and then the use of these information in a machinery such as the EnKF is described. It is shown that the way the Monte Carlo simulations are performed is of great importance to realistically reproduced outer boundary distribution needed by the physic-based Salammbo model. Finally, EnKF simulations are performed and compared during September 2011 in order to analyze the improvements gained using this new method of defining outer boundary conditions. In particular, we highlight in this study that such a method provides great improvement in the reconstruction of the dynamics observed at geosynchronous orbit, both during quiet and active magnetic conditions.