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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
earth and planetary sciences
Precursors of the forbush decrease on 2006 december 14 observed with the Global Muon Detector Network (GMDN)
Astrophysical Journal, Volume 715, No. 2, Year 2010
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Description
We analyze the precursor of a Forbush decrease (FD) observed with the Global Muon Detector Network on 2006 December 14. An intense geomagnetic storm is also recorded during this FD with the peak Kp index of 8+. By using the "two-dimensional map" of the cosmic ray intensity produced after removing the contribution from the diurnal anisotropy, we succeed in extracting clear signatures of the precursor. A striking feature of this event is that a weak loss-cone (LC) signature is first recorded more than a day prior to the storm sudden commencement (SSC) onset. This suggests that the LC precursor appeared only 7 hr after the coronal mass ejection eruption from the Sun, when the interplanetary (IP) shock driven by the interplanetary coronal mass ejection was located at 0.4 AU from the Sun. We find the precursor being successively observed with multiple detectors in the network according to the Earth's spin and confirmed that the precursor continuously exists in space. The long lead time (15.6 hr) of this precursor which is almost twice the typical value indicates that the interplanetary magnetic field (IMF) was more quiet in this event than a typical power spectrum assumed for the IMF turbulence. The amplitude (-6.45%) of the LC anisotropy at the SSC onset is more than twice the FD size, indicating that the maximum intensity depression behind the IP shock is much larger than the FD size recorded at the Earth in this event. We also find the excess intensity from the sunward IMF direction clearly observed during ∼ 10 hr preceding the SSC onset. It is shown that this excess intensity is consistent with the measurement of the particles accelerated by the head-on collisions with the approaching shock. This is the first detailed observation of the precursor due to the shock reflected particles with muon detectors. © 2010. The American Astronomical Society. All rights reserved.
Authors & Co-Authors
Fushishita, A.
Japan, Matsumoto
Shinshu University
Kuwabara, Takao
United States, Newark
The Bartol Research Institute
Kato, Chihiro
Japan, Matsumoto
Shinshu University
Yasue, S.
Japan, Matsumoto
Shinshu University
Bieber, John William
United States, Newark
The Bartol Research Institute
Evenson, Paul Arthur
United States, Newark
The Bartol Research Institute
Rockenbach, M.
Brazil, Sao Jose Dos Campos
Instituto Nacional de Pesquisas Espaciais
Dal Lago, Alisson
Brazil, Sao Jose Dos Campos
Instituto Nacional de Pesquisas Espaciais
Schuch, Nelson Jorge
Brazil, Sao Jose Dos Campos
Instituto Nacional de Pesquisas Espaciais
Tokumaru, Munetoshi
Japan, Nagoya
Nagoya University
Duldig, Marcus Leslie
Australia, Hobart
Australian Antarctic Division
Humble, John E.
Australia, Hobart
University of Tasmania
Sabbah, Ismail S.
Saudi Arabia, Jeddah
King Abdulaziz University
Egypt, Alexandria
Faculty of Science
Al-Jassar, Hala Khalid
Kuwait, Kuwait City
Kuwait University
Sharma, Madan M.
Kuwait, Kuwait City
Kuwait University
Munakata, Kazuoki
Japan, Matsumoto
Shinshu University
Statistics
Citations: 29
Authors: 16
Affiliations: 9
Identifiers
Doi:
10.1088/0004-637X/715/2/1239
ISSN:
0004637X
e-ISSN:
15384357
Research Areas
Mental Health