Low ionospheric reactions on tropical depressions prior hurricanes

Nina, Aleksandra; Radovanović, Milan; Milovanović, Boško; Kovačević, Andjelka B.; Bajčetić, Jovan; Popović, L. Č.

doi:10.1016/j.asr.2017.05.024

Cited by 27 publications

(17 citation statements)

References 24 publications

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“…In the last several decades, studies of the lower ionosphere disturbances are mostly based on observations by very low/low frequency (VLF/LF) radio signals [9][10][11][12][13] and processing of the corresponding recorded data in both the time and frequency domains. Increases or decreases of the signal amplitude and/or phase are recorded in many studies focused on research of ionospheric disturbances induced by earthquakes [9], solar activity [14][15][16][17][18], tropical cyclones [19,20], solar eclipse [21,22] etc.…”

Section: Introductionmentioning

confidence: 99%

Reduction of the VLF Signal Phase Noise Before Earthquakes

et al. 2021

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In this paper we analyse temporal variations of the phase of a very low frequency (VLF) signal, used for the lower ionosphere monitoring, in periods around four earthquakes (EQs) with magnitude greater than 4. We provide two analyses in time and frequency domains. First, we analyse time evolution of the phase noise. And second, we examine variations of the frequency spectrum using Fast Fourier Transform (FFT) in order to detect hydrodynamic wave excitations and attenuations. This study follows a previous investigation which indicated the noise amplitude reduction, and excitations and attenuations of the hydrodynamic waves less than one hour before the considered EQ events as a new potential ionospheric precursors of earthquakes. We analyse the phase of the ICV VLF transmitter signal emitted in Italy recorded in Serbia in time periods around four earthquakes occurred on 3, 4 and 9 November 2010 which are the most intensive earthquakes analysed in the previous study. The obtained results indicate very similar changes in the noise of phase and amplitude, and show an agreement in recorded acoustic wave excitations. However, properties in the obtained wave attenuation characteristics are different for these two signal parameters.

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Section: Introductionmentioning

confidence: 99%

Reduction of the VLF Signal Phase Noise Before Earthquakes

et al. 2021

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“…In addition, the obvious ionospheric disturbance in response to the 2015 Typhoon Dujuan in China was observed by analyzing the GPS-derived TEC sequences (Kong et al 2017). Moreover, the close connection between the troposphere and low ionosphere was revealed through analyzing 41 tropical depression events in the North Atlantic Ocean in the period of 2004-2010 (Nina et al 2017). The ionospheric responses to severe weather events can be explained as that the acoustic gravity waves (AGWs) are generated by the powerful convection during severe weather events.…”

Section: Introductionmentioning

confidence: 99%

The ionospheric condition and GPS positioning performance during the 2013 tropical cyclone Usagi event in the Hong Kong region

Liu

2021

Earth Planets Space

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The ionosphere plays a critical role in the electromagnetic waves in communication systems such as the global positioning system (GPS). However, it is suspected that the strong convection during the tropical cyclone (TC) events can be a trigger to anomalous electron density variation in the ionosphere. This study analyzed the variation of three ionosphere-related parameters based on the GPS data including scintillation index S4, cycle slips, and total electron content (TEC) rate (TECR) during the tropical cyclone event (the 2013 TC Usagi) in the Hong Kong region. The results showed that the ionosphere-related parameters had a consistent significant increase on the second day after the Usagi made landfall near Hong Kong. Consequently, the positioning performance of GPS precise point positioning (PPP) and relative positioning modes was degraded. The degradation was ~ 138%, ~ 181%, and ~ 460% in the east (root mean square (RMS) 0.050 m), north (RMS 0.045 m), and up (RMS 0.185 m), respectively, compared with the RMS of 0.021 m in the east, 0.016 m in the north, and 0.033 m in the up on the normal day. Regarding the relative positioning, the positioning errors in the east (RMS 0.134 m) and north (RMS 0.118 m) directions were ~ 7.1 and ~ 7.9 times, respectively, as large as the RMS of 0.019 m in the east and 0.015 m in the north on the normal day. The positioning errors in the up (RMS 0.513 m) direction were ~ 12.2 times larger than the RMS of 0.042 m on the normal day.

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“…The separation of charges in the thundercloud may eventually produce an electric field that becomes so large (around 3 × 10 5 ∼ 4 × 10 5 V m −1 ) that it could initiate the lightning stroke [5]. One fact agreed by most of researchers [6][7][8][9][10][11][12] is the contribution of intense lightning discharges to the global electric circuit (GEC). The substantial role of the lightning and thunderstorm in GEC would justify the need to investigate the charge structure of thunderclouds.…”

Section: Introductionmentioning

confidence: 99%

Lorentz Force Contribution to Thunderstorm's Electrical Characteristics

Sadeghi¹,

Akmal²,

Taghavi³

2021

PIER B

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In this paper, the exerted electric and geomagnetic forces on the electrified hydrometeors in thunderclouds are compared. The parameters of geomagnetic field are acquired from International Geomagnetic Reference Field (IGRF) model. First, the calculations showed that the magnitude of the electric force exerted on a charged hydrometeor dominated the magnitude of the geomagnetic force in troposphere. These results revealed the significance of electric force in the formation of thunderclouds' charge structure. Moreover, as the electric field increases in thunderstorm conditions, (regarding the dependence of the induction mechanism of cloud electrification to the intensity of the electric field), the increased electric field strengthens the induction mechanism of cloud electrification and influences the electrical properties of thunderstorm. Second, using satellite-based/ground-based data and reports, an inverse relation has been revealed between the total geomagnetic field and the mean annual lightning activity in most of the hot spots on the Earth. Moreover, a comparison between the global annual thunder days' map and the map of global total geomagnetic field showed an inverse relation between these two maps. Furthermore, regarding the horizontal and vertical correlation coefficient matrices of the geomagnetic field and the global mean annual lightning activity (in the global tropics and subtropics), approximately in latitudes and longitudes with high lightning density, the reverse relation between the average annual lightning activity and the total geomagnetic field is stronger.

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Low ionospheric reactions on tropical depressions prior hurricanes

Cited by 27 publications

References 24 publications

Reduction of the VLF Signal Phase Noise Before Earthquakes

Reduction of the VLF Signal Phase Noise Before Earthquakes

The ionospheric condition and GPS positioning performance during the 2013 tropical cyclone Usagi event in the Hong Kong region

Lorentz Force Contribution to Thunderstorm's Electrical Characteristics

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