Premium
The Response Time of Equatorial Ionization Anomaly Crest: A Unique Precursor to the Time of Equatorial Spread F Initiation
Author(s) -
Aswathy R. P.,
Manju G.,
Sunda Surendra
Publication year - 2018
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2018ja025469
Subject(s) - crest , ionosonde , tec , solstice , anomaly (physics) , context (archaeology) , atmospheric sciences , solar cycle , magnitude (astronomy) , total electron content , ionosphere , local time , environmental science , geology , physics , geodesy , astrophysics , solar wind , latitude , plasma , geophysics , electron density , mathematics , statistics , optics , paleontology , condensed matter physics , quantum mechanics
The time delay with which the magnitude and location of the total electron content (TEC) at the equatorial ionization anomaly (EIA) crest responds to the mean height of the F layer ( h m F 2 ) is examined seasonally using the ionosonde data at Trivandrum and the Global Positioning System data at different stations in the EIA region for low and high solar activity years. The study brings out the fact that for the low solar activity year, the crest TEC responds fastest in winter solstice compared to other seasons. Further, the response time of the crest is found to decrease with solar activity. The seasonal variation in the EIA response time is attributed to the modulation by meridional neutral winds, whereas the solar activity variation seems to be basically controlled by the diffusion times and the background ionization gradients in the respective epochs. The derived relationship between EIA crest location/magnitude and h m F 2 for any season can be used for prediction purposes. Furthermore, this study for the first time establishes the relation of EIA response time to equatorial spread F (ESF) start time, for days when the F layer is in the neutral dynamically controlled domain. The deleterious effects of ESF irregularities on communication and navigation systems are well known, and the above result is significant in this context. The present study has the potential to be extended into a model to predict the ESF start time, from the EIA response time, earlier in the day.