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Anomalous cosmic rays: Observations

Cummings, A. C. and Stone, E. C. (1999) Anomalous cosmic rays: Observations. Advances in Space Research, 23 (3). pp. 509-520. ISSN 0273-1177. doi:10.1016/S0273-1177(99)80005-2.

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The latitudinal gradients of galactic cosmic ray protons and anomalous cosmic ray (ACR) helium appear to be symmetrical about a plane displaced ∼10° south of the heliographic equator, similar to the displacement of the heliospheric current sheet (HCS). The radial gradient of ∼10 MeV/nuc ACR oxygen in the outer heliosphere is correlated with the amplitude of the tilt of the HCS. The form of the correlation depends on the magnetic polarity of the solar cycle. The observed radial gradients are the basis for an empirical model that reasonably describes the modulation of ∼2–3 GV ACR oxygen at low heliographic latitudes over a 25-year period.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Cummings, A. C.0000-0002-3840-7696
Stone, E. C.0000-0002-2010-5462
Additional Information:© 1999 COSPAR. Published by Elsevier Science Ltd. We appreciate the website at the Wilcox Solar Observatory ( from which the tilt angle data were extracted. We also obtained IMP 8 solar wind speed data from the website maintained by the Space Plasma Group of the Massachusetts Institute of Technology ( We thank W. R. Webber for providing the P10 oxygen data from 1978 onwards. This work was supported by NASA under contract NAS7-918 and grant NAGW-1919.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory1999-58
Issue or Number:3
Record Number:CaltechAUTHORS:20140226-111247648
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Official Citation:A.C Cummings, E.C Stone, Anomalous cosmic rays: Observations, Advances in Space Research, Volume 23, Issue 3, 1999, Pages 509-520, ISSN 0273-1177, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44015
Deposited By: Tony Diaz
Deposited On:28 Feb 2014 16:11
Last Modified:10 Nov 2021 16:46

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