국내 최대 기계 및 로봇 연구정보

기술보고서

기술보고서 게시판 내용
타이틀	Solar Drivers of 11-yr and Long-Term Cosmic Ray Modulation
저자	Cliver, E. W.;; Richardson, I. G.;; Ling, A. G.
Keyword	ATTITUDE (INCLINATION); CORONAL MASS EJECTION;; COSMIC RAYS;; DIFFUSION COEFFICIENT;; GALACTIC COSMIC RAYS;; HELIOSPHERE;; HIGH SPEED;; MODULATION;; SOLAR ACTIVITY EFFECTS;; SOLAR WIND;; SPECTRA;; SUN;; TIME MEASUREMENT
URL	http://hdl.handle.net/2060/20110023416
보고서번호	GSFC.JA.5411.2011
발행년도	2011
출처	NTRS (NASA Technical Report Server)
ABSTRACT	In the current paradigm for the modulation of galactic cosmic rays (GCRs), diffusion is taken to be the dominant process during solar maxima while drift dominates at minima. Observations during the recent solar minimum challenge the pre-eminence of drift: at such times. In 2009, the approx.2 GV GCR intensity measured by the Newark neutron monitor increased by approx.5% relative to its maximum value two cycles earlier even though the average tilt angle in 2009 was slightly larger than that in 1986 (approx.20deg vs. approx.14deg), while solar wind B was significantly lower (approx.3.9 nT vs. approx.5.4 nT). A decomposition of the solar wind into high-speed streams, slow solar wind, and coronal mass ejections (CMEs;; including postshock flows) reveals that the Sun transmits its message of changing magnetic field (diffusion coefficient) to the heliosphere primarily through CMEs at solar maximum and high-speed streams at solar minimum. Long-term reconstructions of solar wind B are in general agreement for the approx. 1900-present interval and can be used to reliably estimate GCR intensity over this period. For earlier epochs, however, a recent Be-10-based reconstruction covering the past approx. 10(exp 4) years shows nine abrupt and relatively short-lived drops of B to < or approx.= 0 nT, with the first of these corresponding to the Sporer minimum. Such dips are at variance with the recent suggestion that B has a minimum or floor value of approx.2.8 nT. A floor in solar wind B implies a ceiling in the GCR intensity (a permanent modulation of the local interstellar spectrum) at a given energy/rigidity. The 30-40% increase in the intensity of 2.5 GV electrons observed by Ulysses during the recent solar minimum raises an interesting paradox that will need to be resolved.