Flux enhancement mechanism of the outer radiation belt electrons associated with coronal hole streams

HR: 0800h
AN: SM21A-0316 [Abstracts]
TI: Flux enhancement mechanism of the outer radiation belt electrons associated with coronal hole streams
AU: * Miyoshi, Y
EM: miyoshi@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Chikusa, Nagoya, 464-8601, Japan
AU: Kataoka, R
EM: ryuho@riken.jp
AF: RIKEN (The Institute of Physics and Chemical Research), Hirosawa, Wako, 351-0198, Japan
AB: The Earth’s outer radiation belt electrons increase when the magnetosphere is surrounded by the high speed solar wind stream, while the southward interplanetary magnetic field (IMF) is also known as an important factor for the flux enhancement. In order to distinguish the two different kinds of solar wind parameter dependence statistically, we investigate the response of the outer belt to stream interaction regions (SIRs). We classify the SIR events from 1994 to 2005 into two groups according to so-called “spring-toward fall-away” (STFA) rule: (A) IMF sector polarity after the stream interface is toward in spring or away in fall, and (B) vice versa. According to the Russell-McPherron effect, the groups A and B have a significant negative and positive offset of the IMF Bz after the stream interface. Comparing the groups A and B, by superposing about the stream interface, only IMF Bz dependence can be obtained because the other solar wind parameters change in the same manner. As a result, the greatest flux enhancement is found in the high-speed streams with a southward offset of the IMF Bz, indicating that only the solar wind speed by itself is not a sufficient condition for the large flux enhancement. Based on the obtained dependence on the STFA rule and the solar wind speed, it is possible to operate a probabilistic space weather forecast of relativistic electrons at geosynchronous orbit for secure satellite operations. The probability is defined by the number of events with daily maximum flux above the NOAA alert levels, and the stream interface is used as a precursor of coming coronal hole stream in the forecast algorithm. We report how it works and evaluate the skill score of our test operation of the probabilistic forecast.
DE: 2774 Radiation belts
DE: 2784 Solar wind/magnetosphere interactions
DE: 2788 Magnetic storms and substorms (7954)
DE: 7845 Particle acceleration
DE: 7924 Forecasting (2722)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting