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Title: A STATISTICAL STUDY OF SOLAR ELECTRON EVENTS OVER ONE SOLAR CYCLE

Abstract

We survey the statistical properties of 1191 solar electron events observed by the WIND 3DP instrument from <1 keV to {approx}>300 keV for a solar cycle (1995 through 2005). After taking into account times of high background, the corrected occurrence frequency of solar electron events versus peak flux exhibits a power-law distribution over three orders of magnitude with exponents between -1.0 and -1.6 for different years, comparable to the frequency distribution of solar proton events, microflares, and coronal mass ejections (CMEs), but significantly flatter than that of soft X-ray (SXR) flares. At 40 keV (2.8 keV), the integrated occurrence rate above {approx}0.29 ({approx}330) cm{sup -2} s{sup -1} sr{sup -1} keV{sup -1} near 1 AU is {approx}1000 year{sup -1} ({approx}600 year{sup -1}) at solar maximum and {approx}35 year{sup -1} ({approx}25 year{sup -1}) at solar minimum, about an order of magnitude larger than the observed occurrence rate. We find these events typically extend over {approx}45 Degree-Sign in longitude, implying the occurrence rate over the whole Sun is {approx}10{sup 4} year{sup -1} near solar maximum. The observed solar electron events have a 98.75% association with type III radio bursts, suggesting all type III bursts may be associated with a solar electron event. Theymore » have a close ({approx}76%) association with the presence of low-energy ({approx}0.02-2 MeV nucleon{sup -1}), {sup 3}He-rich ({sup 3}He/{sup 4}He {>=} 0.01) ion emissions measured by the ACE ULEIS instrument. For these electron events, only {approx}35% are associated with a reported GOES SXR flare, but {approx}60% appear to be associated with a CME, with {approx}50% of these CMEs being narrow. These electrons are often detected down to below 1 keV, indicating a source high in the corona.« less

Authors:
 [1]; ;  [2];  [3]
  1. Department of Geophysics, Peking University, Beijing 100871 (China)
  2. Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450 (United States)
  3. Applied Physics Laboratory, Johns Hopkins University, Laurel, MD (United States)
Publication Date:
OSTI Identifier:
22086448
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 759; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; HELIUM 3; HELIUM 4; ION EMISSION; KEV RANGE; MASS; MEV RANGE; SOFT X RADIATION; SOLAR CYCLE; SOLAR ELECTRONS; SOLAR FLARES; SOLAR PROTONS; SOLAR WIND; SUN

Citation Formats

Wang Linghua, Lin, R. P., Krucker, Saem, and Mason, Glenn M., E-mail: wanglhwang@gmail.com. A STATISTICAL STUDY OF SOLAR ELECTRON EVENTS OVER ONE SOLAR CYCLE. United States: N. p., 2012. Web. doi:10.1088/0004-637X/759/1/69.
Wang Linghua, Lin, R. P., Krucker, Saem, & Mason, Glenn M., E-mail: wanglhwang@gmail.com. A STATISTICAL STUDY OF SOLAR ELECTRON EVENTS OVER ONE SOLAR CYCLE. United States. doi:10.1088/0004-637X/759/1/69.
Wang Linghua, Lin, R. P., Krucker, Saem, and Mason, Glenn M., E-mail: wanglhwang@gmail.com. Thu . "A STATISTICAL STUDY OF SOLAR ELECTRON EVENTS OVER ONE SOLAR CYCLE". United States. doi:10.1088/0004-637X/759/1/69.
@article{osti_22086448,
title = {A STATISTICAL STUDY OF SOLAR ELECTRON EVENTS OVER ONE SOLAR CYCLE},
author = {Wang Linghua and Lin, R. P. and Krucker, Saem and Mason, Glenn M., E-mail: wanglhwang@gmail.com},
abstractNote = {We survey the statistical properties of 1191 solar electron events observed by the WIND 3DP instrument from <1 keV to {approx}>300 keV for a solar cycle (1995 through 2005). After taking into account times of high background, the corrected occurrence frequency of solar electron events versus peak flux exhibits a power-law distribution over three orders of magnitude with exponents between -1.0 and -1.6 for different years, comparable to the frequency distribution of solar proton events, microflares, and coronal mass ejections (CMEs), but significantly flatter than that of soft X-ray (SXR) flares. At 40 keV (2.8 keV), the integrated occurrence rate above {approx}0.29 ({approx}330) cm{sup -2} s{sup -1} sr{sup -1} keV{sup -1} near 1 AU is {approx}1000 year{sup -1} ({approx}600 year{sup -1}) at solar maximum and {approx}35 year{sup -1} ({approx}25 year{sup -1}) at solar minimum, about an order of magnitude larger than the observed occurrence rate. We find these events typically extend over {approx}45 Degree-Sign in longitude, implying the occurrence rate over the whole Sun is {approx}10{sup 4} year{sup -1} near solar maximum. The observed solar electron events have a 98.75% association with type III radio bursts, suggesting all type III bursts may be associated with a solar electron event. They have a close ({approx}76%) association with the presence of low-energy ({approx}0.02-2 MeV nucleon{sup -1}), {sup 3}He-rich ({sup 3}He/{sup 4}He {>=} 0.01) ion emissions measured by the ACE ULEIS instrument. For these electron events, only {approx}35% are associated with a reported GOES SXR flare, but {approx}60% appear to be associated with a CME, with {approx}50% of these CMEs being narrow. These electrons are often detected down to below 1 keV, indicating a source high in the corona.},
doi = {10.1088/0004-637X/759/1/69},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 759,
place = {United States},
year = {2012},
month = {11}
}