Blar i forfatter Artikler, rapporter og annet (fysikk og teknologi) "Aa, Ercha"

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    • 2022 Tonga Volcanic Eruption Induced Global Propagation of Ionospheric Disturbances via Lamb Waves 

      Zhang, Shun-Rong; Vierinen, Juha; Aa, Ercha; Goncharenko, Larisa P.; Erickson, Philip J.; Rideout, William; Coster, Anthea J.; Spicher, Andres (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-23)
      The Tonga volcano eruption at 04:14:45 UT on 2022-01-15 released enormous amounts of energy into the atmosphere, triggering very significant geophysical variations not only in the immediate proximity of the epicenter but also globally across the whole atmosphere. This study provides a global picture of ionospheric disturbances over an extended period for at least 4 days. We find traveling ionospheric ...

    • Conjugate ionospheric perturbation during the 2017 solar eclipse 

      Zhang, Shunrong; Erickson, Philip J.; Vierinen, Juha; Aa, Ercha; Rideout, William; Coster, Anthea; Goncharenko, Larisa (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-16)
      We report new findings of total electron content (TEC) perturbations in the southern hemisphere at conjugate locations to the northern eclipse on August 21, 2017. We identified a persistent conjugate TEC depletion by 10%–15% during the eclipse time, elongating along magnetic latitudes with at least ∼5° latitudinal width. As the Moon's shadow swept southward, this conjugate depletion moved northward ...

    • Pronounced Suppression and X-Pattern Merging of Equatorial Ionization Anomalies After the 2022 Tonga Volcano Eruption 

      Aa, Ercha; Zhang, Shun-Rong; Wang, Wenbing; Erickson, Philip J.; Qian, Liying; Eastes, Richard W.; Harding, Brian; Immel, Thomas; Karan, Deepak; Daniell, Robert E.; Coster, Anthea J.; Goncharenko, Larisa P.; Vierinen, Juha; Cai, Xuguang; Spicher, Andres (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-05-27)
      Following the 2022 Tonga Volcano eruption, dramatic suppression and deformation of the equatorial ionization anomaly (EIA) crests occurred in the American sector ∼14,000 km away from the epicenter. The EIA crests variations and associated ionosphere-thermosphere disturbances were investigated using Global Navigation Satellite System total electron content data, Global-scale Observations of the ...

    • Significant ionospheric hole and equatorial plasma bubbles after the 2022 Tonga volcano eruption 

      Aa, Ercha; Zhang, Shunrong; Erickson, Philip J.; Vierinen, Juha; Coster, Anthea J.; Goncharenko, Larisa P.; Spicher, Andres; Rideout, William (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-28)
      This paper investigates the local and global ionospheric responses to the 2022 Tonga volcano eruption, using ground-based Global Navigation Satellite System total electron content (TEC), Swarm in situ plasma density measurements, the Ionospheric Connection Explorer (ICON) Ion Velocity Meter (IVM) data, and ionosonde measurements. The main results are as follows: (a) A significant local ionospheric ...

    • Simultaneous Global Ionospheric Disturbances Associated With Penetration Electric Fields During Intense and Minor Solar and Geomagnetic Disturbances 

      Zhang, Shun-Rong; Nishimura, Yukitoshi; Vierinen, Juha-Pekka; Lyons, Larry R.; Knipp, Delores J.; Gustavsson, Björn Johan; Waghule, Bhagyashree V.; Erickson, Philip J.; Coster, Anthea J.; Aa, Ercha; Spicher, Andres (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-29)
      A new observational phenomenon, named Simultaneous Global Ionospheric Density Disturbance (SGD), is identified in GNSS total electron content (TEC) data during periods of three typical geospace disturbances: a Coronal Mass Ejection-driven severe disturbance event, a high-speed stream event, and a minor disturbance day with a maximum Kp of 4. SGDs occur frequently on dayside and dawn sectors, with ...

    • Traveling Ionospheric Disturbances in the Vicinity of Storm-Enhanced Density at Midlatitudes 

      Zhang, Shunrong; Nishimura, Yukitoshi; Erickson, Philip J.; Aa, Ercha; Kil, Hyosub; Deng, Yue; Thomas, Evan; Rideout, William; Coster, Anthea J.; Kerr, Robert; Vierinen, Juha (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-08)
      This study provides first storm time observations of the westward-propagating medium-scale traveling ionospheric disturbances (MSTIDs), particularly, associated with characteristic subauroral storm time features, storm-enhanced density (SED), subauroral polarization stream (SAPS), and enhanced thermospheric westward winds over the continental US. In the four recent (2017–2019) geomagnetic storm ...