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On a summer maximum in the occurrence frequency of 150 km ( F 1 ) radar echoes over Pohnpei
Author(s) -
Tsunoda Roland T.,
Ecklund Warner L.
Publication year - 2004
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2003gl018704
Subject(s) - longitude , earth's magnetic field , radar , latitude , sporadic e propagation , geology , geophysics , polarization (electrochemistry) , geomagnetic latitude , geodesy , magnetic field , physics , ionosphere , telecommunications , chemistry , quantum mechanics , computer science
Using three and a half years of 50 MHz radar data collected from Pohnpei, Federated States of Micronesia (6.96°N, 158.19°E geographic, 0.3° magnetic dip latitude), we show for the first time that the occurrence frequency of 150 km (or F 1 ) echoes has a broad but conspicuous maximum during northern summer in this longitude sector with minimal activity in other months. Given a seasonal similarity to sporadic E ( E s ), we suggest that an E s ‐layer instability [ Cosgrove and Tsunoda , 2002] generates a polarization electric field (), which maps along geomagnetic field lines to the F 1 region. There, forms thin plasma sheets that provide gradients to excite 3‐m‐scale plasma waves via an interchange process.