Open AccessSpread‐ F /sporadic E coupling at Chung‐Li, especially for postsunset periods of sunspot maximum years
Author(s) -
Bowman G. G.,
Mortimer I. K.
Publication year - 2003
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2002ja009541
Subject(s) - crest , sporadic e propagation , sunspot , ionosphere , ionogram , geodesy , series (stratigraphy) , anomaly (physics) , ionosonde , geology , atmospheric sciences , astrophysics , physics , mathematics , geophysics , optics , nuclear physics , electron density , paleontology , condensed matter physics , quantum mechanics , magnetic field , electron
Using ionogram‐recorded data, the coupling between spread‐ F occurrence and enhanced E s blanketing frequencies ( f b E s ) (indicative of f o E s changes), has been investigated for an equatorial‐ionospheric‐anomaly crest station, Chung‐Li, for the postsunset periods of sunspot‐maximum years. Apart from the evidence for coupling from inspections of the f ‐plots alone, for the years analyzed (1981, 1982, 1988, and 1989), statistical results of more significance were found from superposed‐epoch analyses. Isolated spread‐ F events of duration of 2 hours or less which started at or before 2200 LT were used as controls on time series. These series were made up of comparisons between 15‐min f ‐plot f b E s values and interpolated monthly median f b E s values. Evidence for coupling was found for the analyses which involved 97 controls. The evidence in the f ‐plots for three events involving E s patches, which investigators have examined in some detail using the VHF radar at Chung‐Li, suggests that these events are also coupled to isolated spread‐ F occurrence.