Multispectral and Multi‐instrument Observation of TIDs Following the Total Solar Eclipse of 21 August 2017

Abstract

Wave‐like structures in the upper atmospheric nightglow brightness were observed on the night of 22 August 2017, approximately 8 hr following a total solar eclipse. These wave‐like perturbations are signatures of atmospheric gravity waves and associated traveling ionospheric disturbances (TIDs). Observations were made in the red line (OI 630.0 nm) and the green line (OI 557.7 nm) from Carbondale, IL, at 2–10 UTC on 22 August 2017. Based on wavelet analyses, the dominant time period in both the red and green lines was around 1.5 hr. Differential total electron content data obtained from Global Positioning System total electron content measurements at Carbondale, IL, and ionospheric parameters from digisonde measurements at Idaho National Laboratory and Millstone Hill showed a similar dominant time period. Based on these observations and their correlation with geomagnetic indices, the TIDs appear to be associated with geomagnetic disturbances. In addition, by modeling the ionosphere‐thermosphere system's response to the eclipse, it was seen that while the eclipse enhanced the O/N2 ratio and electron density (Ne) at 250 km during our observation period, it did not affect the TIDs. Vertical (7 m/s) and meridional (616 m/s) phase velocities of the TIDs were estimated using cross‐correlation analysis between red and green line brightness profiles and spectral analysis of the differential total electron content keogram, respectively. This provides a method to characterize the three‐dimensional wave properties of TIDs.

First Report of an Eclipse From Chilean Ionosonde Observations: Comparison With Total Electron Content Estimations and the Modeled Maximum Electron Concentration and Its Height

“…The above mentioned authors also detected depletions and enhancements at the 10.1029/2020JA027923 Journal of Geophysical Research: Space Physics geomagnetic conjugate locations of the eclipse in the Southern Hemisphere using this methodology, in concordance with the results of Huba and Drob (2017). Some modeling and observational studies (Aryal et al, 2019;Lei et al, 2018) concentrated on the posteclipse ionospheric response. Lei et al (2018) found small global average TEC perturbations (0.2 TECu) 9 hr after an eclipse.…”

“…Lei et al (2018) found small global average TEC perturbations (0.2 TECu) 9 hr after an eclipse. Alternatively, multiinstrument (GNSS TEC and digisonde) and spectral observations (OI emissions) led Aryal et al (2019) to conclude that it is the prevalent geomagnetic disturbance via enhanced auroral currents/Joule heating that generates AGWs and large-scale traveling ionospheric disturbances (LSTIDs) propagating toward the equator. GITM results show that the associated 10% increases in N and O/N 2 at 250 km present oscillations of 90 min with vertical speeds and wavelengths of 7 m s −1 and 36 km, respectively, and 616 m s −1 and 1,256 km.…”

Short‐ and Long‐Wavelength TIDs Generated by the Great American Eclipse of 21 August 2017

“…Their position does not correspond to thunderstorms occurring during the eclipse ((Mrak, Semeter, Nishimura, et al, )), but around 18:00 UT the position corresponds to that of EUV modulations shown by (Mrak, Semeter, Drob, et al, ). (Aryal et al, ) show that increased geomagnetic activity after the eclipse generated large scale TIDs with a wavelength of more than 1,000 km and a dominant period of 1.5 hr. As our choice of the grid limits the FFT resolution to a maximum wavelength of 600 km we cannot see TIDs of the same type during the day, although Box 4 lies within the same period.…”

Atmospheric gravity waves observed in the nightglow following the 21 August 2017 total solar eclipse}

“…As a result of these changes in the atmospheric composition and dynamics, large-scale disturbances (TIDs) were observed in the ionosphere associated with the eclipse (e.g., Coster et al, 2017). Finally, a wave-like signature of the bow wave generated by the eclipse was observed in the neutral winds by a Fabry-Perot interferometer over São João do Cariri (Harding et al, 2018) and over Carbondale (37.7 o N, 89.2 o W) using airglow red and green lines (Aryal et al, 2019).…”