HR: 0830h
AN: SH21B-0113    [PDF]
TI: Long-Term Decline of South Pole Neutron Rate
AU: * Bieber, J W
EM: john@bartol.udel.edu
AF: University of Delaware, Bartol Research Institute, Newark, DE 19716
AU: Clem, J
EM: clem@bartol.udel.edu
AF: University of Delaware, Bartol Research Institute, Newark, DE 19716
AU: Evenson, P
EM: penguin@bartol.udel.edu
AF: University of Delaware, Bartol Research Institute, Newark, DE 19716
AU: Pyle, R
EM: pyle@bartol.udel.edu
AF: University of Delaware, Bartol Research Institute, Newark, DE 19716
AU: Lal, D
EM: dlal@ucsd.edu
AF: Univ California San Diego, Scripps Inst of Oceanography, La Jolla, CA 92093-0244
AU: Desilets, D
EM: ddesilet@hwr.arizona.edu
AF: University of Arizona, Dept Hydrology and Water Resources, Tucson, AZ 85721
AU: Lopate, C
EM: lopate@ulysses.sr.unh.edu
AF: University of New Hampshire, Inst Study of Earth, Oceans, and Space, Durham, NH 03824-3525
AB: The count rate recorded by a neutron monitor at South Pole, Antarctica displays a long-term decline over the 22-year span from 1965 to 1987. The neutron rate follows an 11-year cycle with maxima at times of low solar activity, but the 1987 peak rate was approximately 9% lower than the 1965 peak rate based on 27-day averages. This change is much larger than that recorded by any other neutron monitor. We suggest that the South Pole monitor, owing to its unique position at both high latitude and high altitude (2820 m), has enhanced sensitivity at $\sim$1-2 GV relative to a sea level monitor and may be responding to a change in the intensity of primary cosmic rays in this rigidity region. Measurements of cosmic rays made aboard stratospheric balloons and on the IMP 8 spacecraft support the possibility of a long-term change in cosmic ray intensity. This work was supported by NSF grant ATM-0000315.
UR: http://www.bartol.udel.edu/~neutronm/
DE: 1650 Solar variability
DE: 2104 Cosmic rays
DE: 2114 Energetic particles, heliospheric (7514)
DE: 7536 Solar activity cycle (2162)
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting