First observational study during a solar eclipse event on variations in the horizontal winds simultaneously in the troposphere-stratosphere-mesosphere-lower-thermosphere region over the equatorial station Thumba (8.5°N, 77°E)

Abstract

The longest annular solar eclipse of the millennium occurred on 15 January, 2010, and was visible over the equatorial station Thumba (8.5 • N, 77• E) around noon time. A host of experiments were carried out to study the variations due to the solar eclipse event on various geophysical parameters, from the Earth's surface to ionospheric heights. The present study focuses on the variation in the horizontal winds in the height regions of 0-65 km and 80-100 km, using GPS-sondes, rocket-sondes and meteor wind radar. The observations were made during, and after, the maximum obscuration on the day of the eclipse, as well as at the same time on a control day. The observations showed a strengthening/weakening of winds along with directional changes both in zonal and meridional winds in the selected height domains. A drastic change from easterly to westerly is observed at 98 km during, and after, the maximum phase, but, for the meridional wind, the reversal is observed only after the maximum phase. Variations due to the eclipse were also observed around the tropopause and stratopause in both wind components. However, the observed changes in winds around the tropopause and stratopause could not be attributed unambiguously to the eclipse as day-to-day wind variability is not available in these height regions. The significance of the present study lies in reporting the variations in the horizontal wind components from the ground to the 100-km height region (with a gap around 65-80 km), and the characteristics of the atmospheric waves generated due to the mid-day annular solar eclipse.

Ionospheric Response to the December 14, 2020 Total Solar Eclipse in South America

“…Also, nonstationary oGW can be triggered by wind fluctuations (Chunchuzov, 1994) which are observed in the collected wind data. Nevertheless, other sources of GWs are also plausible, such as triggering of GWs due to the combined effect of wind shears and sudden temperature changes in the lower atmosphere (Ramkumar et al., 2013). This work highlights the necessity of further modeling using 3D simulations including topography to fully understand the generation and propagation of GWs during this and other solar eclipses.…”

“…The temperature perturbation was set to −4% which is equivalent to a maximum perturbation of −11°C at ∼50 km but only of −7°C at ∼90 km (Figure 7a, shaded region). Lower atmospheric adiabatic heating effects were disregarded (Ramkumar et al., 2013) because we found that temperature perturbations in the troposphere did not produce large changes in TC. Previous studies show that eclipse‐induced wind perturbations can vary significantly.…”

GNSS Observations of Ionospheric Variations During the 21 August 2017 Solar Eclipse

“…We suggest that this TEC enhancement over the Rocky Mountains is caused by processes triggered by the eclipse, perhaps due to large temperature changes on the ground that induced or enhanced locally produced atmospheric waves in the mountain region. Large changes in mesosphere-lower thermosphere (MLT) zonal winds during eclipses have been observed by Ramkumar et al (2013). They observed a reversal of zonal winds at 98 km during the maximum phase of the January 2010 eclipse at local noon.…”

Gravity wave signatures in the dip equatorial ionosphere‐thermosphere system during the annular solar eclipse of 15 January 2010

“…Ramkumar et al . [], studying the same event over Trivandrum, reported enhanced gravity wave amplitudes with short vertical wavelengths of 2–8 km throughout the troposphere and stratosphere. They have also reported enhancement in amplitudes of periods in the range of 80–100 min using meteor radar data in the mesosphere/lower thermosphere (MLT) region.…”

“…Further, Ramkumar et al . [] have also reported that the wave propagates upward from the region below 80 km and downward from the region above 98 km indicative of the fact that there are two source regions one above 100 km and one below 80 km height region. The present study is in agreement with the above observations.…”