Natural hazard effects on ionospheric parameters&nbsp;detected by various space geodetic techniques

Mahdi Alizadeh; Zahra Foroodi; Yaser Rahmani; Harald Schuh

doi:https://doi.org/10.5194/iag-comm4-2022-35

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iag-comm4-2022-35

https://doi.org/10.5194/iag-comm4-2022-35

2nd Symposium of IAG Commission 4 “Positioning and Applications”

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Natural hazard effects on ionospheric parameters detected by various space geodetic techniques

Mahdi Alizadeh^1,2, Zahra Foroodi¹, Yaser Rahmani^1,4, and Harald Schuh^2,3

Mahdi Alizadeh et al.

¹K.N.Toosi University of Technology, Department of Geodesy, Tehran, Iran
²German Research Centre for Geosciences (GFZ), Potsdam, Germany
³Institute of Geodesy and Geoinformation Sciences, Technische Universität Berlin, Berlin, Germany
⁴Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT, USA

Natural hazards, that occur in the lower part of the Earth's atmosphere, the troposphere, are affecting higher atmosphere layers. Many of these phenomena, such as thunderstorms, heavy rainfalls, tsunamis, or volcanic eruptions create acoustic waves (AWs), and internal gravity waves (IGWs) in the atmosphere. These waves considerably affect the propagation of radio waves traveling through the ionosphere via transferring energy to this layer, causing significant variations in its parameters.

In this paper, IGWs generated by thunderstorms and tsunamis are investigated. For this task, we used double-frequency measurements from the Global Navigation Satellite Systems (GNSS) along with radio occultation (RO) measurements from Low Earth Orbiting (LEO) satellites, such as Formosat3/ COSMIC (F3/C) and SWARM.

The average increase of ionospheric irregularity amplitudes under severe thunderstorm conditions was 30% compared to calm conditions (non-lightning days). The Rate of TEC Index (ROTI) on high thunderstorm days showed an average increase of 25% within the lower ionosphere. In addition, a significant increase in amplitude and activity of IGWs and IAWs during the thunderstorms was observed.

In the case of tsunamis, the critical frequency of the F2 layer (foF2) showed clear disturbances at the GNSS ground stations due to the tsunami-generated IGWs. During the tsunami, the Ionospheric Electron Density (IED) decreased in altitudes below approximately 300km by 27%. However, above this height, the IEDs increased by 64% up to about 750 km altitude, with a maximum amount of 3.77 × 105 elec/cm3 at 355 km altitude. The average increase of ROTI during the arrival of the tsunami to the stations was 8%.

Keywords: Natural hazards, ionospheric parameters, thunderstorm, tsunami, internal gravity waves, troposphere-ionosphere vertical coupling.

How to cite: Alizadeh, M., Foroodi, Z., Rahmani, Y., and Schuh, H.: Natural hazard effects on ionospheric parameters detected by various space geodetic techniques, 2nd Symposium of IAG Commission 4 “Positioning and Applications”, Potsdam, Germany, 5–8 Sep 2022, iag-comm4-2022-35, https://doi.org/10.5194/iag-comm4-2022-35, 2022.