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Ann. Geophys., 22, 3109-3121, 2004
www.ann-geophys.net/22/3109/2004/
© European Geosciences Union 2004
Analysis of the seasonal variations of equatorial plasma bubble occurrence observed from Haleakala, Hawaii
J. J. Makela1, B. M. Ledvina2, M. C. Kelley2, and P. M. Kintner2
1E.O. Hulburt Center for Space Research, Code 7607, Naval Research Lab., Washington, District of Columbia 20375, USA
2School of Electrical and Computer Engineering, Cornell University, Ithaca, New York, 14853, USA
Abstract. Over 300 nights of airglow and GPS scintillation data collected between January 2002 and August 2003 (a period near solar
maximum) from the Haleakala Volcano, Hawaii are analyzed to obtain the seasonal trends for the occurrence of equatorial plasma
bubbles in the Pacific sector (203° E). A maximum probability for bubble development is seen in the data in April (45%)
and September (83%). A broad maximum of occurrence is seen in the data from June to October (62%). Many of the bubbles
observed from June through August occur later in the evening, and, as seen in the optical data, tend to be "fossilized". This
suggests that the active growth region during these months is to the west of the observing location. These seasonal trends are
consistent with previous data sets obtained both from other ground-based and satellite studies of the occurrence of equatorial
bubbles in the Pacific sector. However, our data suggests a much greater probability of bubble occurrence than is seen in other
data sets, with bubbles observed on over 40% of the nights studied.
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