Implementation of Ensemble Data Assimilation for a Three-Dimensional Radiation Belt Model
Abstract
Earth's outer radiation belt is very dynamic and undergoes constant changes due to acceleration, loss, and transport processes of the energetic electrons. In this work the ensemble Kalman filter (EnKF) assimilation method is applied to the Versatile Electron Radiation Belt (VERB) code, a three-dimensional radiation belt model developed at the University of California Los Angeles. The VERB model includes radial, pitch angle, and energy diffusion caused by low-latitude and high-latitude chorus, plasma- spheric hiss, and electromagnetic ion cyclotron (EMIC) waves. Assimi- lation methods based on Kalman filtering have been successfully applied to one-dimensional radial diffusion radiation belt models, where it has been shown that assimilating real observational data into the radiation belt models greatly improves the accuracy of electron PSD estimation. In our work we implement the EnKF for assimilation of real electron PSD data into the VERB model. In particular the assimilation is performed locally along the direction of the dominant diffusion of electrons in the model. This will enable the correct assimilation of data to be consistent with the flow of electrons throughout the model. Two set of assimila- tion experiments are presented. The first is an identical-twin experiment, where artificial data is generated from the same model, with the purpose of validating the assimilation method. In the second set of experiments, real PSD observational data from CRRES are assimilated into VERB in order to improve the model estimation of the electron PSD distribution. The results show that data assimilation significantly improves the accu- racy of the VERB model by efficiently including observations to correct the model PSD estimation.
- Publication:
-
AGU Spring Meeting Abstracts
- Pub Date:
- May 2013
- Bibcode:
- 2013AGUSMSM21B..06G
- Keywords:
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- 2774 MAGNETOSPHERIC PHYSICS / Radiation belts;
- 7924 SPACE WEATHER / Forecasting;
- 7984 SPACE WEATHER / Space radiation environment;
- 1910 INFORMATICS / Data assimilation;
- integration and fusion