Climatology of postsunset equatorial spread F over Jicamarca
Abstract
We use radar observations from 1996 to 2006 to study the climatology of postsunset equatorial 3-m spread F irregularities over Jicamarca during all seasons. We show that the spread F onset times do not change with solar flux and that their onset heights, which occur near the altitude of the evening F region velocity vortex, increase linearly from about 260 to 400 km from solar minimum to solar maximum. Higher onset heights generally lead to stronger radar echoes. During the equinox, spread F onset occurs near vertical drift evening reversal times, while during the December solstice, they occur near the drift reversal times close to solar minimum and near the time of the prereversal velocity peak for high solar flux conditions. On average, radar plume onset occurs earlier with increasing solar flux in all seasons. Plume onset and peak altitudes increase with solar activity, and the peak heights are generally highest during the equinox. The F region upward drift velocities that precede spread F onset increase from solar minimum to solar maximum and are approximately proportional to the maximum prereversal drift peak velocities.
Description
Date
2009-07
Keywords
Equatorial ionosphere , Ionospheric irregularities , Ionospheric disturbances
Citation
Chapagain, N. P., Fejer, B. G., & Chau, J. L. (2009). Climatology of postsunset equatorial spread F over Jicamarca. Journal of Geophysical Research: Space Physics, 114 (A7), A07307. https://doi.org/10.1029/2008JA013911
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Publisher
American Geophysical Union