An empirical model of electron pitch angle distributions in the outer radiation belt based on Van Allen Probes data

Cite as:

Smirnov, Artem; Shprits, Yuri; Allison, Hayley; Aseev, Nikita; Drozdov, Alexander; Kollmann, Peter; Wang, Dedong; Saikin, Anthony (2022): An empirical model of electron pitch angle distributions in the outer radiation belt based on Van Allen Probes data. V. 1.1. GFZ Data Services. https://doi.org/10.5880/GFZ.2.7.2022.001

Status

I N R E V I E W : Smirnov, Artem; Shprits, Yuri; Allison, Hayley; Aseev, Nikita; Drozdov, Alexander; Kollmann, Peter; Wang, Dedong; Saikin, Anthony (2022): An empirical model of electron pitch angle distributions in the outer radiation belt based on Van Allen Probes data. V. 1.1. GFZ Data Services. https://doi.org/10.5880/GFZ.2.7.2022.001

Abstract

Here, we present an empirical model of the equatorial electron pitch angle distributions, based on the Magnetic Electron Ion Spectrometer (MagEIS) instrument aboard the Van Allen Probes. The model was created for energies from 37 keV up to 2.65 MeV. The model uses the solar wind dynamic pressure as a driving parameter and has a continuous dependence on Lm, magnetic local time and activity. It works for L-shells from 3.05 up around 5.95. For each channel of the MagEIS instrument, there are two files with model coefficients, one for Pdyn <5.5-6 nPa (e.g., “Pijk_246_keV.dat’) , and the second one for very high dynamic pressure values above 5.5 nPa (e.g., “Pijk_246_keV_HIGH.dat’). The script to read both file types is provided (“read_coefs.py”), and the data format is explained in the readme file.

Methods

The model is based on fitting the pitch angle distributions with Fourier sine series up to degree 5. This gives three model coefficients, namely A1, A3 and A5, which are the modeled as a quadratic function of the solar wind dynamic pressure for each bin of 0.2L-1hr MLT. Then, the quadratic trend coefficients are expanded in L, sin(MLT) and cos(MLT), which ensures a continuous dependence on L, MLT and activity for each of the energy channels.

Authors

Smirnov, Artem;GFZ German Research Centre for Geosciences, Potsdam, Germany
Shprits, Yuri;GFZ German Research Centre for Geosciences, Potsdam, Germany
Allison, Hayley;GFZ German Research Centre for Geosciences, Potsdam, Germany
Aseev, Nikita;GFZ German Research Centre for Geosciences, Potsdam, Germany
Drozdov, Alexander;University of California, Los Angeles (UCLA), CA, Los Angeles, USA
Kollmann, Peter;Johns Hopkins University Applied Physics Laboratory
Wang, Dedong;GFZ German Research Centre for Geosciences, Potsdam, Germany
Saikin, Anthony;University of California, Los Angeles (UCLA), CA, Los Angeles, USA