Influence of the Tidal Wind System on the Frequency of Sporadic‐E Occurrence

Abstract

Sporadic‐E (ES) data from Japan were presented to show the temporal variations in sporadic‐E blanketing frequency (ƒbES), virtual height (h′ES), and frequency of occurrence. Tidal winds were substituted into the wind‐shear theory of ES to calculate electron density profiles and determine the influence of the tidal winds in the asymmetry of the ES occurrence variation. Results showed that the tidal wind model used was not strong enough to significantly influence the formation of molecular ion ES layers, but that the winds did have the proper orientation to accumulate and layer metallic ions in the late afternoon. The role of metallic ions in afternoon ES will have to be established.

Height and critical frequency variations of the sporadic-E layer at midlatitudes

“…On a short time scale of a few hours, or less, the wind pattern is often modified by gravity waves that may interact with the tide (Nygré n et al, 1990) but, here, we are mainly interested by interaction between tides and long period planetary waves. Harris and Taur (1972) have proposed a model of the prevailing wind and tides based on the analysis of rocket trails by Woodrum et al (1969). In their model the diurnal component of the eastward velocity of the tide is given by…”

A comparison of FORMOSAT-3/COSMIC radio occultation and ionosonde measurements in sporadic E detection over mid- and low-latitude regions

“…Reddy and Matsushita (1969) studied Es layers at mid and low latitudes utilizing the ionosonde to establish a more detailed understanding of temporal and latitudinal variations of them. Subsequently, until the 1990s, numerous studies typically focused on examining the diurnal and seasonal variations of Es by utilizing ionosonde observations (Axford & Cunnold, 1966;Harris and Taur, 1972;Chandra and Rastogi, 1975;Saksena, 1976;MacDougall, 1978;Baggaley, 1984).…”