|
A solar eclipse offers a rare opportunity to observe how the sun affects the ionospheric structures. The main purpose of this paper is to study the ionospheric response to a solar eclipse that occurred in Asia on October 24, 1995. Although its path of totality passed over southern Asia, the associated region of partial eclipse covered almost all of Asia. We have collected ionosonde data from six stations in the region. Its purpose is to investigate how the ionosphere responded to this eclipse, especially because the region included the equatorial anomaly region. After processing these data, we find that geomagnetic field is a dominant force in causing the depression in Nmax following a solar eclipse in the equatorial anomaly region. The deviations in Nmax are plotted as contours using time after the first contact as the horizontal axis and geomagnetic latitude as the vertical axis. The results reveal three effects: (1) For the region with geomagnetic latitudes higher than 20 degrees the Nmax increa-sed slightly immediately following the first contact for about 30 minutes. (2) In response to the eclipse, the largest depression occurring roughly 11/2 hours after the maximum obscuration was observed at approximately 14 degrees geomagnetic latitude even though the percent obscuration of the sun at latitudes lower than 14 degrees was larger. (3) Around 6 hours after the maximum phase another secondary depression in Nmax was observed for geomagnetic latitudes lower than 14 degrees. Here we have to emphasize that these effects must cover at least two of these six stations. Physical mechanisms that may be responsible for causing these effects are proposed and examined in conclusion.
|