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- Title
Characterizing Radiation‐Belt Energetic Electron Precipitation Spectra: A Comparison of Quasi‐Linear Diffusion Theory With In Situ Measurements.
- Authors
Reidy, J. A.; Horne, R. B.; Glauert, S. A.; Clilverd, M. A.; Meredith, N. P.; Rodger, C. J.; Ross, J. P.; Wong, J.
- Abstract
High energy electron precipitation from the Earth's radiation belts is important for loss from the radiation belts and atmospheric chemistry. We follow up investigations presented in Reidy et al. (2021, https://doi.org/10.1029/2020ja028410) where precipitating flux is calculated inside the field of view of the POES T0 detector using quasi‐linear theory and pitch angle diffusion coefficients (Dαα) from the British Antarctic Survey (BAS). These results showed good agreements at >30 keV for L* >5 on the dawnside but the flux were too low at higher energies. We have investigated the effect of changing parameters in the calculation of the precipitating flux to improve the results for the higher energies using comparisons of in situ flux and cold plasma measurements from GOES‐15 and RBSP. We find that the strength of the diffusion coefficients rather than the shape of the source spectrum has the biggest effect on the calculated precipitation. In particular we find decreasing the cold plasma density used in the calculation of Dαα increases the diffusion and hence the precipitation at the loss cone for the higher energies, improving our results. The method of calculating Dαα is also examined, comparing co‐located rather than averaged RBSP measurements. We find that the method itself has minimal effect but using RBSP derived Dαα improved our results over using Dαα calculated using the entire BAS wave data base; this is potentially due to better measurements of the cold plasma density from RBSP than the other spacecraft included in the BAS wave data base (e.g., THEMIS). Plain Language Summary: High energy particles trapped in the Earth's radiation belt can enter the atmosphere, known as particle precipitation, and collide with atmospheric particles, which can change the atmospheric chemistry. This input into our atmosphere is key to understanding the effects of space weather on our climate system variability but is difficult to quantify. Reidy et al. (2021, https://doi.org/10.1029/2020ja028410) calculated the precipitation that would be measured by a low‐Earth orbiting satellite using wave‐particle theory and diffusion coefficients from a radiation belt model. Diffusion coefficients describe the amount of diffusion of the trapped radiation belt particle population driven by different sources (e.g., chorus waves). Reidy et al. (2021, https://doi.org/10.1029/2020ja028410) found good agreement between the calculated and measured precipitation for lower energy particles but found there was something missing for the higher energies. This paper investigates the impact of changing certain parameters within the calculations, finding the cold plasma density to be key in improving the results at higher energies. Key Points: Decreasing the cold plasma density increases calculated electron precipitation at the higher energiesCalculated precipitation for a low Earth orbiting detector is weakly dependent on the source spectrumRBSP derived diffusion coefficients provide more diffusion for precipitating particles than those derived from a larger wave database
- Subjects
BRITISH Antarctic Survey; LOW temperature plasmas; RADIATION belts; SPACE environment; ATMOSPHERIC chemistry; PLASMA density; PRECIPITATION (Chemistry); CHEMICAL weathering; ELECTRON diffusion
- Publication
Journal of Geophysical Research. Space Physics, 2024, Vol 129, Issue 1, p1
- ISSN
2169-9380
- Publication type
Article
- DOI
10.1029/2023JA031641