Ionospheric <i>F</i><sub>2</sub> region perturbed by the 25 April 2015 Nepal earthquake

Sun, Yihe; Liu, Jann Yenq; Lin, Chi Yen; Tsai, Heng; Chang, Loren C.; Chen, Chao Yen; Chen, Chia-Hung

doi:10.1002/2015ja022280

Cited by 44 publications

(44 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is well known that an acoustic shock wave forms ahead if an object moves faster than the local sound speed. The sound speed ranges from 600 m/s to 800 m/s at the F region of ionosphere (Liu et al, ; Sun et al, ; Figure S1). A detailed description of the computation of the sound speed from the NRLMSISE00‐simulated neutral temperature and density (Picone et al, ) can be found in Figure S1 of the supporting information.…”

Section: Resultsmentioning

confidence: 99%

Ionospheric Bow Wave Induced by the Moon Shadow Ship Over the Continent of United States on 21 August 2017

Sun

Liu

Lin

et al. 2018

Geophysical Research Letters

View full text Add to dashboard Cite

A moon shadow of the total solar eclipse swept through the continent of United States (CONUS) from west to east on 21 August 2017. Massive total electron content (integration of electron density from 0 km to 20,200 km altitude) observations from 2,255 ground‐based Global Navigation Satellite System receivers show that the moon shadow ship generates a great ionospheric bow wave front which extends ~1,500 km away from the totality path covering the entire CONUS. The bow wave front consists of the acoustic shock wave due to the supersonic/near‐supersonic moon shadow ship and the significant plasma recombination due to the reduction in solar irradiation within the shadow area. The deep bow wave trough (−0.02 total electron content unit (1 TECU = 1016 el m−2) area) nearly coincides with the 100% obscuration moving along the totality path over the CONUS through the entire eclipse period. The supersonic moon shadow ship induces a bow wave crest in front of the ship (~80% obscuration). It is the first time to find the acoustic shock wave‐formed bow wave trough and crest near the totality.

show abstract

Section: Resultsmentioning

confidence: 99%

Ionospheric Bow Wave Induced by the Moon Shadow Ship Over the Continent of United States on 21 August 2017

Sun

Liu

Lin

et al. 2018

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…Finally, the vertical electron density profile from COSMIC radio occultation observations has captured the induced ion density perturbations around 300 to 440 km altitudes. Sun et al () have attributed the observed changes in RO profile to rapid uplift of F 2 layer peak altitude. On the contrary, we have shown that the observed ion density perturbations in the RO profile are mainly due to the horizontal progression of occultation (tangent) point through the positive and negative phases of southward propagating CTID as demonstrated in Figure .…”

Section: Discussionmentioning

confidence: 98%

Coseismic Traveling Ionospheric Disturbances during the M_w 7.8 Gorkha, Nepal, Earthquake on 25 April 2015 From Ground and Spaceborne Observations

et al. 2017

View full text Add to dashboard Cite

Coseismic traveling ionospheric disturbances (CTIDs) and their propagation characteristics during Mw 7.8 Gorkha earthquake in Nepal on 25 April 2015 have been investigated using a suite of ground‐based GPS receivers and broadband seismometers along with the spaceborne radio occultation observations over the Indian subcontinent region. Depletion in vertical total electron content, a so called ionospheric hole, is observed near the epicenter ~9–11 min after the onset of earthquake. A positive pulse preceding the depletion, similar to N‐shaped perturbation, propagating with an apparent velocity of ~2.4 km/s is observed on the south. Further, the CTIDs in the southward direction are found to split in to fast (~2.4–1.7 km/s) and slow (~680–520 m/s) propagating modes at epicentral distances greater than ~800 km. However, the velocities of fast mode CTIDs are significantly smaller than the surface Rayleigh wave velocity (~3.7 km/s), indicating that they are not the true imprint of Rayleigh wave, instead, can probably be attributed to the superimposed wave front formed by the mixture of acoustic waves excited by main shock and propagating Rayleigh wave. The southward CTIDs are found to propagate at F2 region altitudes of ~300–440 km captured by Constellation Observing System for Meteorology, Ionosphere and Climate radio occultation observations. The CTIDs with periods of ~4–6 min are observed in all directions with significantly larger amplitudes and faster propagation velocities in south and east directions. The observed azimuthal asymmetry in the amplitudes and velocities of CTIDs are discussed in terms of the alignment with geomagnetic field and nature of surface crustal deformation during the earthquake.

show abstract

“…Sun et al (2016) have investigated the ionospheric density perturbation induced by 25 April 2015 Nepal earthquake using FORMOSAT-3/COSMIC (F3/C) and suggested that ionospheric density is perturbed by quake induced acoustic wave speed of 800 m/s near peak altitude (hmF2). These results were in agreement with theoretical pressure oscillations.…”

Section: Journal Of Geophysical Research: Space Physicsmentioning

confidence: 99%

On the Co‐Seismic Ionospheric Disturbances (CIDs) in the Rapid Run Ionosonde Observations Over Allahabad Following M_w 7.8 Nepal Earthquake on April 25, 2015

Sripathi

Singh

Tiwari³

et al. 2020

JGR Space Physics

View full text Add to dashboard Cite

We present high-resolution ionosonde observations at Allahabad (25.43°N, 81.84°E) near anomaly crest location in India along with GPS TEC to investigate the possible signatures of co-seismic disturbances (CIDs) in the ionosphere during M w 7.8 Nepal Earthquake that occurred at 06:11:26 UT on 25 April 2015. The epicenter of the earthquake (28.147°N, 84.708°E) was located at~77 km north-west of Kathmandu with a shallow depth of 15 km. The mechanical shock disturbances produce Rayleigh waves and Rayleigh wave induced acoustic gravity waves (AGWs) during earthquake which propagate into the ionosphere and produced plasma density fluctuations due to collisions. The manifestation of these waves produces 'wiggles' or 'cusps' in the ionograms known as Multiple-Cusp Signatures (MCS). The detection of multiple cusps in the ionograms at Allahabad indicates the altitude structure of Rayleigh wave and it's induced AGWs. To confirm co-seismic signatures in ionosonde further, we scaled the ionograms at isodensity and iso-heights along with foF2 (MHz) and h'F (km). The periodogram and wavelet analysis suggest the presence of acoustic gravity waves and gravity waves with frequencies in the range of 0.7-1.5 mHz over the altitude range of 180-250 km. The foF2 variations show wave like oscillations having frequency of 0.5 mHz after the onset of earthquake. The GPS TEC also show signatures of co-seismic perturbations having frequencies in the range of 2-4 mHz and are propagated to southward with a speed of 0.5-1.0 km/s. These results suggest that there exists a good coupling between seismic activity and ionized density perturbations after Nepal earthquake.

show abstract

Ionospheric F₂ region perturbed by the 25 April 2015 Nepal earthquake

Cited by 44 publications

References 40 publications

Ionospheric Bow Wave Induced by the Moon Shadow Ship Over the Continent of United States on 21 August 2017

Ionospheric Bow Wave Induced by the Moon Shadow Ship Over the Continent of United States on 21 August 2017

Coseismic Traveling Ionospheric Disturbances during the M_w 7.8 Gorkha, Nepal, Earthquake on 25 April 2015 From Ground and Spaceborne Observations

On the Co‐Seismic Ionospheric Disturbances (CIDs) in the Rapid Run Ionosonde Observations Over Allahabad Following M_w 7.8 Nepal Earthquake on April 25, 2015

Contact Info

Product

Resources

About

Ionospheric F2 region perturbed by the 25 April 2015 Nepal earthquake

Cited by 44 publications

References 40 publications

Ionospheric Bow Wave Induced by the Moon Shadow Ship Over the Continent of United States on 21 August 2017

Ionospheric Bow Wave Induced by the Moon Shadow Ship Over the Continent of United States on 21 August 2017

Coseismic Traveling Ionospheric Disturbances during the Mw 7.8 Gorkha, Nepal, Earthquake on 25 April 2015 From Ground and Spaceborne Observations

On the Co‐Seismic Ionospheric Disturbances (CIDs) in the Rapid Run Ionosonde Observations Over Allahabad Following Mw 7.8 Nepal Earthquake on April 25, 2015

Contact Info

Product

Resources

About

Ionospheric F₂ region perturbed by the 25 April 2015 Nepal earthquake

Coseismic Traveling Ionospheric Disturbances during the M_w 7.8 Gorkha, Nepal, Earthquake on 25 April 2015 From Ground and Spaceborne Observations

On the Co‐Seismic Ionospheric Disturbances (CIDs) in the Rapid Run Ionosonde Observations Over Allahabad Following M_w 7.8 Nepal Earthquake on April 25, 2015