[P-EM09] Space Weather and Space Climate

[PEM09-P13] Cause and Effects of Relativistic Electron Precipitation at CALET onboard ISS

*Ryuho Kataoka¹、A. Bruno^2,3、L. Blum⁴、G. A. de Nolfo²、S. Nakahira⁵、Shoko Miyake⁶、S. Torii⁷ (1.National Institute of Polar Research、2.NASA/GSFC、3.Catholic University of America、4.University of Colorado Boulder、5.JAXA/ISAS、6.Ibaraki College、7.Waseda University)

キーワード：relativistic electron precipitation, radiation dose, radiation belts

Relativistic electron precipitation (REP) events observed by CALET-CHD instrument at the International Space Station (ISS, orbiting ~400 km altitude) have been interpreted as the manifestation of the wave-particle interaction between electromagnetic ion cyclotron (EMIC) waves and trapped MeV electrons (Kataoka et al., 2016, GRL). From the space weather point-of-view, this presentation will address following questions by reviewing our recent papers: 1) Exposure dose during extravehicular activities on the ISS? 2) Effects on the disappearance of radiation belt MeV electrons? 3) EMIC waves a dominant cause of REP events? Our answers to these questions are: 1) From the quantitative evaluation of the exposure dose during EVA on the ISS, using the MeV electron flux data during REP events, there is no need to be overly concerned (Ueno et al., 2019, Space Weather). 2) Conjunction observations with the Van Allen Probe suggest that a major MeV electron drop-out event was caused by both REP events and the magnetopause shadowing effect at different positions (Bruno et al., 2021, GRL). 3) The plasma waves that caused the REP events were investigated by the conjunction observations with the Arase satellite, and the contribution of whistler mode waves was also clearly identified (Kataoka et al., 2020, JGR Space Physics). The CALET-CHD data are available from ISAS-DARTS. A new web interface for viewing the data is also available here (https://app.darts.isas.jaxa.jp/timeseries/d/lZxZIHSLri4zasawa/maxicalet_bin?orgId=5).
In this presentation, we will also introduce the latest space weather-related activities using CALET-CHD data.