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Latitudinal and Radial Gradients of Anomalous and Galactic Cosmic Rays in the Outer Heliosphere

Cummings, A. C. and Stone, E. C. and Webber, W. R. (1987) Latitudinal and Radial Gradients of Anomalous and Galactic Cosmic Rays in the Outer Heliosphere. Geophysical Research Letters, 14 (3). pp. 174-177. ISSN 0094-8276. doi:10.1029/GL014i003p00174.

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We have used measurements from instruments on Voyagers 1 and 2 and Pioneer 10 to derive simultaneous radial and latitudinal gradients of anomalous cosmic-ray oxygen during the latter part of 1985. We find that in the energy interval from 7.1-30.6 MeV/nucleon the latitudinal gradient is −3 to −4%/deg. The sign of the latitudinal gradient is opposite to that reported for the last solar cycle when the solar magnetic field polarity was reversed, as predicted by propagation models in which curvature and gradient drifts are significant. The ratios of the radial and latitudinal gradients of anomalous oxygen, anomalous helium, and galactic cosmic rays are similar, also in agreement with drift theory predictions. Based on drift theory, these observed ratios, which are near unity, lead to estimates of κ/β in the range of 3-8 × 10^(22) cm²/sec at 24.9 AU for particles with rigidities of ∼2-3 GV.

Item Type:Article
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URLURL TypeDescription DOIArticle
Cummings, A. C.0000-0002-3840-7696
Stone, E. C.0000-0002-2010-5462
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Additional Information:© 1987 by the American Geophysical Union. We are grateful to R.E. Vogt for his contributions during his tenure as principal investigator for the Voyager CRS. We also appreciate the contributions of the other Voyager CRS team members at Caltech and the Goddard Space Flight Center. We thank J. R. Jokipii for helpful discussions. This work was supported in part by NASA under contracts NAS 7-918 and NAG5-722, and grant NGR 05-002-160.
Group:Space Radiation Laboratory
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NASANGR 05-002-160
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Space Radiation Laboratory1986-11
Issue or Number:3
Record Number:CaltechAUTHORS:20140430-091349465
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ID Code:45343
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Deposited On:30 Apr 2014 22:54
Last Modified:10 Nov 2021 17:02

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