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Global distribution of neutral wind shear associated with sporadic E layers derived from GAIA
Author(s) -
Shinagawa H.,
Miyoshi Y.,
Jin H.,
Fujiwara H.
Publication year - 2017
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2016ja023778
Subject(s) - wind shear , aeronomy , thermosphere , atmospheric sciences , ionosphere , atmosphere (unit) , sporadic e propagation , environmental science , lapse rate , shear (geology) , f region , local time , seasonality , meteorology , geophysics , geology , wind speed , physics , mathematics , statistics , petrology
There have been a number of papers reporting that the statistical occurrence rate of the sporadic E ( E s ) layer depends not only on the local time and season but also on the geographical location, implying that geographical and seasonal dependence in vertical neutral wind shear is one of the factors responsible for the geographical and seasonal dependence in E s layer occurrences rate. To study the role of neutral wind shear in the global distribution of the E s layer occurrence rate, we employ a self‐consistent atmosphere‐ionosphere coupled model called GAIA (Ground‐to‐topside model of Atmosphere and Ionosphere for Aeronomy), which incorporates meteorological reanalysis data in the lower atmosphere. The average distribution of neutral wind shear in the lower thermosphere is derived for the June–August and December–February periods, and the global distribution of vertical ion convergence is obtained to estimate the E s layer occurrence rate. It is found that the local and seasonal dependence of neutral wind shear is an important factor in determining the dependence of the E s layer occurrence rate on geographical distribution and seasonal variation. However, there are uncertainties in the simulated vertical neutral wind shears, which have larger scales than the observed wind shear scales. Furthermore, other processes such as localization of magnetic field distribution, background metallic ion distribution, ionospheric electric fields, and chemical processes of metallic ions are also likely to make an important contribution to geographical distribution and seasonal variation of the E s occurrence rate.