中文核心期刊
CNKI期刊全文数据库
中国科学引文数据库(CSCD)源期刊
中国科技论文统计源期刊
万方数据知识服务平台
英国《科学文摘》(SA)
美国化学文摘(CA)
俄罗斯《文摘杂志》(AJ)
德国《天文学与天体物理学文摘》(AAA)
英国《中国天文学和天体物理学》(SCI收录)全文摘译期刊之一
《中国学术期刊文摘》
《中国物理文摘》
《中国天文学文摘》

Chinese Journal of Space Science ›› 2020, Vol. 40 ›› Issue (6): 969-979.doi: 10.11728/cjss2020.06.969

• Research Articles • Previous Articles    

Statistical Investigation on the Galactic Cosmic Rays and Solar Wind Variation Based on ACE Observations

GUO Xiaocheng, CAO Shihao, XIONG Ming   

  1. State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190;College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049
  • Received:2020-01-14 Revised:2020-09-25 Published:2020-12-09

Abstract: Galactic Cosmic Rays (GCRs) are originated from the interstellar medium and modulated by the heliospheric magnetic field when they enter the heliosphere. Based on the GCR and plasma observations from ACE spacecraft, the relation between the GCR counts and the solar wind parameters during the recent two periods of solar minimum (the years of 2007.0-2009.0 and 2016.5-2019.0) was analyzed by means of the Superposed Epoch Analysis (SEA) method. The results indicate that GCRs are strongly modulated by the Corotating Interaction Regions (CIR) in solar wind, the Stream Interfaces (SI) sandwiched between fast and slow solar wind are closely related with the depression of GCR counts. The mechanism of the GCR variation is investigated through the empirical diffusion coefficients. The so-called "snow-plough" effect of GCR variation prior to the SI crossing appears during the first period, then the GCR counts decrease after the crossing, which corresponds to the sudden drop of diffusion coefficient at the SI. However, this effect is not observed for the second period, the decrease of GCR counts are simply caused by the enhancement of the diffusion coefficient after the SI crossing. Moreover, Heliospheric Current Sheet (HCS) correlate with GCR counts well, the GCRs drift along the current sheet and then accumulate to a pileup structure, which is physically balanced between their diffusion and drift effects. Finally, based on the observation and Parker transport theory, we discuss the physical mechanism of the GCR variation for the crossings of SIs and HCS, and proposed that the interplay between drift and diffusion determines the GCR distribution and variation at a heliocentric distance of 1AU.

Key words: Galactic Cosmic Rays (GCR), Corotating interaction regions, Stream Interfaces (SI), Heliospheric current sheet

CLC Number: