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Evidence for a Latitudinal Gradient of the Cosmic Ray Intensity Associated with a Change in the Tilt of the Heliospheric Current Sheet

Christon, S. P. and Stone, E. C. and Hoeksema, J. T. (1986) Evidence for a Latitudinal Gradient of the Cosmic Ray Intensity Associated with a Change in the Tilt of the Heliospheric Current Sheet. Geophysical Research Letters, 13 (8). pp. 777-780. ISSN 0094-8276. http://resolver.caltech.edu/CaltechAUTHORS:20140429-142718506

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Abstract

Since mid-1985, the average flux of >70 MeV/nucleon cosmic rays at Voyager 2 (r_2 ∼ 17 AU, Θ_2 ∼ 0°) has been ∼3-5% greater than that at Voyager 1 (r_1 ∼ 24 AU, Θ_1 ∼ 26°N). This is the first direct observation over such a large radial range in which the galactic cosmic ray flux closer to the sun is higher than the flux farther from the sun for an extended period of time. This observation is consistent with the presence of a negative latitudinal gradient G_Θ=−0.36 ± 0.05 (or −0.60 ± 0.08) %/deg, assuming a coexistent radial gradient G_r of 1 (or 2) %/AU. We suggest that the appearance of this persistent negative latitudinal gradient may be due to the abrupt, large decrease of the heliospheric current sheet tilt to ∼20° in early 1985.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1029/GL013i008p00777DOIArticle
http://onlinelibrary.wiley.com/doi/10.1029/GL013i008p00777/abstractPublisherArticle
Contact Email Address:dmiles@caltech.edu
Additional Information:Copyright 1986 by the American Geophysical Union. (Received June 2, 1986; accepted June 23, 1986) We are grateful to R.E. Vogt for his contributions to the Cosmic Ray Subsystem on the Voyager spacecraft. We appreciate the contributions of the other Voyager Cosmic Ray Subsystem team members consisting of scientists and engineers at the California Institute of Technology, the Goddard Space Flight Center, the University of Arizona, and the University of New Hampshire. Work at Caltech was supported in part by the National Aeronautics and Space Administration under contract JPL 49-556-63120-0-2600 and under grant NGR 05-002-160. Work at Stanford was supported in part by the National Aeronautics and Space Administration under Grant NGR5-020-559, the Office of Naval Research under contract N00014-76-C-0207, and the Atmospheric Sciences Section of the National Science Foundation under Grant ATM77-20580.
Group:Space Radiation Laboratory
Funders:
Funding AgencyGrant Number
JPL49-556-63120-0-2600
NASANGR 05-002-160
NASANGR5-020-559
ONRN00014-76-C-0207
NSFATM77-20580
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory1986-06
Record Number:CaltechAUTHORS:20140429-142718506
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ID Code:45321
Collection:CaltechAUTHORS
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Deposited On:29 Apr 2014 22:26
Last Modified:29 Apr 2014 22:26

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