Atmospheric Gravity Waves in the Ionosphere and Thermosphere During the 2017 Solar Eclipse

Lin, Charles; Deng, Yue; Ridley, A. J.

doi:10.1029/2018gl077388

Cited by 29 publications

(54 citation statements)

References 30 publications

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“…Their results showed TIDs with a dominant peak at about 20–30 min and broadly extended to 20–90 min periods, without details about the wavelength of the observed TIDs. A simulation of bow waves during the eclipse (Lin et al, ) reproduced TIDs with a period of 20–30 min and therefore similar characteristics to the bow waves observed by (Zhang et al, ). They also fall within the range of the dominant frequency peak of the TIDs observed by (Nayak & Yigit, ).…”

Section: Introductionsupporting

confidence: 72%

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

et al. 2019

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On the 21 August 2017 the eclipse shadow drastically changed the state of the ionosphere over the United States. This effect on the ionosphere is visible in the total electron content measured by Global Navigation Satellite Systems (GNSS). The shadow moved with the supersonic speed of~1,000 m/s over Oregon to~650 m/s over South Carolina. In order to exhaustively explore the ionospheric signature of the eclipse, we use data of total electron content from~3,000 GNSS stations seeing multiple Global Positioning System (GPS) and Global Navigation Satellite System (GLONASS) satellites to visualize the phenomena. This tremendous dataset allows high-resolution characterization of the frequency content and wavelengths-using an omega-k analysis based on 3-D fast Fourier transform-of the eclipse signature in the ionosphere in order to fully identify traveling ionospheric disturbances (TIDs). We confirm the generation of TIDs associated with the eclipse including TIDs interpreted as bow waves in previous studies. Additionally, we reveal, for the first time, short (50-100 km) and long (500-600 km) wavelength TIDs with periods between 30 and 65 min. The sources of the revealed short wavelength TIDs are co-located with the regions of stronger gradient of the EUV related to sunspots. Our work confirms and describes physical properties of the waves observable in the ionosphere during the Great American Eclipse. Plain Language Summary A total solar eclipse occurred on 21 August 2017 over the UnitedStates with the eclipse shadow reaching supersonic speed. We calculate the differential total electron content to visualize the evolution of the phenomena with incredible high spatial and temporal resolution. Traveling ionospheric disturbances associated with the eclipse with a period of up to 1 hr and wavelengths of 40 to 600 km including bow waves with a period of~25 min and wavelength of~300 km are identified using an omega-k analysis based on 3-D fast Fourier transform. The additionally highlighted shortest (50-100 km) and longest (500-600 km) wavelength traveling ionospheric disturbances have not been observed before. The shortest waves seem to be related to sunspots.

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Section: Introductionsupporting

confidence: 72%

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

et al. 2019

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“…The similarities between the P03, P14, and P32 spectra cannot be explained by this interpretation. However, the three sets of spectra are consistent with the modeling works by Eckermann et al () and Lin et al (), which point to a TID wavefield setup by the eclipse umbra and penumbra.…”

Section: Discussionsupporting

confidence: 89%

“…The authors attributed the wave activity to the eclipse, noting that their results are consistent with Zhang et al () and that the wave activity can be generated by the eclipse of a uniform solar EUV disk. Although the GITM model is too coarse to resolve horizontal wavelengths smaller than 316 km and the variations detected by GAP‐O, the appearance of wave activity due to the eclipse in GITM is consistent with Zhang et al's () results (Lin et al, ) and with the GAP‐O measurements. Indeed, the present measurements would serve to motivate contemporary IT models to reproduce the scales of the observed disturbances for the August 2017 eclipse and to simulate those for future eclipses, such as the 2 July 2019 eclipse.…”

Section: Discussionsupporting

confidence: 88%

Topside Ionospheric Disturbances Detected Using Radio Occultation Measurements During the August 2017 Solar Eclipse

Perry

Watson

Howarth

et al. 2019

Geophysical Research Letters

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The CASSIOPE (also known as Swarm‐E) satellite crossed the path of totality of the August 2017 eclipse at ~640‐km altitude ~10 min following the lunar umbra. Observations from CASSIOPE's Global Positioning System radio occultation receiver reveal total electron content variations of 0.2–0.3 total electron content units in the topside ionosphere—a signature of medium‐scale (100‐200 km) plasma disturbances in the lunar penumbra that were induced by the eclipse. The variations were only observed during the eclipse, their absence on preceding days being consistent with their very low (<10%) statistical occurrence probability. Their spectral characteristics match those of other contemporaneous measurements, and their detection is consistent with the simulated ionosphere‐thermosphere response to the eclipse. To capture the small‐scale size of the variations or to simulate those expected in the upcoming (July 2019) total eclipse, ionosphere‐thermosphere model runs with a spatial resolution of 50 km or better would be required.

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“…Besides geomagnetic storms, solar eclipses are also known to excite AGWs (e.g., Chimonas & Hines, ; Liu et al, ) that alter the IT system (Harding et al, ; Lin et al, ). Liu et al () conclude that the ionospheric perturbations that they observed using ionosondes during the total solar eclipse of 24 October 1995 were most likely due to plasma upflow and downflow induced by rapid temperature increase immediately following the eclipse.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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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.

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Atmospheric Gravity Waves in the Ionosphere and Thermosphere During the 2017 Solar Eclipse

Cited by 29 publications

References 30 publications

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

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

Topside Ionospheric Disturbances Detected Using Radio Occultation Measurements During the August 2017 Solar Eclipse

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

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