Open AccessTerannual variation in the F 2 layer peak electron density ( N m F 2 ) at middle latitudes
Author(s) -
Xu Jiyao,
Ma Ruiping,
Wang Wenbin
Publication year - 2012
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 - 10.1029/2011ja017191
Subject(s) - daytime , oscillation (cell signaling) , ionosonde , longitude , middle latitudes , atmospheric sciences , amplitude , northern hemisphere , ionosphere , latitude , solar cycle , f region , southern hemisphere , climatology , electron density , physics , environmental science , electron , geology , geodesy , geophysics , plasma , solar wind , chemistry , biochemistry , quantum mechanics
Ionosonde data from 33 stations in three longitude sectors from 1969 to 1986 have been used to study the seasonal variations of ionospheric F 2 layer peak electron densities ( N m F 2 ). We found that there is a periodic oscillation in daytime N m F 2 with a period of 4 months (terannual). Our analysis shows that there is a very good phase match between the annual and semiannual oscillations and the terannual oscillations. These three oscillations vary with solar activity in the same way: large amplitudes during solar maximum. The amplitude of the terannual oscillation is also correlated with the product of the amplitudes of annual and semiannual oscillations. These suggest that the terannual oscillation might be related to the nonlinear interaction between the annual and semiannual oscillations. In addition, the terannual oscillation is stronger in the midlatitude region in the Northern Hemisphere than in the Southern Hemisphere. Furthermore, there are large differences in the ionospheric seasonal variations between daytime and nighttime. No obvious terannual oscillation signature is seen in the nighttime F 2 layer.