18 Result(s)
within
Takuya Tsu**o
Earth Sciences
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Article
Open AccessMonitoring of equatorial plasma bubbles using aeronautical navigation system: a feasibility study
It has long been known that field-aligned irregularities within equatorial plasma bubbles (EPBs) can cause long-range propagation of radio waves in the VHF frequencies such as those used for TV broadcasting th...
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Article
Open AccessStatistical analysis for EUV dynamic spectra and their impact on the ionosphere during solar flares
The X-rays and extreme ultraviolet (EUV) emitted during solar flares can rapidly change the physical composition of Earth’s ionosphere, causing space weather phenomena. It is important to develop an accurate u...
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Article
Open AccessPropagation characteristics of sporadic E and medium-scale traveling ionospheric disturbances (MSTIDs): statistics using HF Doppler and GPS-TEC data in Japan
We carried out a statistical analysis of the propagation characteristics of Es and Medium-Scale Traveling Ionospheric Disturbances (MSTIDs) by combining data of HF Doppler (HFD) sounder and Total Electron Cont...
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Article
Open AccessSpace weather benchmarks on Japanese society
We surveyed the relationship between the scale of space weather events and their occurrence rate in Japan, and we discussed the social impact of these phenomena during the Project for Solar–Terrestrial Environ...
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Article
Open AccessModel-based reproduction and validation of the total spectra of a solar flare and their impact on the global environment at the X9.3 event of September 6, 2017
We attempted to reproduce the total electron content (TEC) variation in the Earth's atmosphere from the temporal variation of the solar flare spectrum of the X9.3 flare on September 6, 2017. The flare spectrum...
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Article
Open AccessStatistical analysis of ionospheric total electron content (TEC): long-term estimation of extreme TEC in Japan
Ionospheric total electron content (TEC) is one of the key parameters for users of radio-based systems, such as the Global Navigation Satellite System, high-frequency communication systems, and space-based rem...
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Article
Open AccessSolar activity dependence of medium-scale traveling ionospheric disturbances using GPS receivers in Japan
In order to reveal solar activity dependence of the medium-scale traveling ionospheric disturbances (MSTIDs) at midlatitudes, total electron content (TEC) data obtained from a Global Positioning System (GPS) r...
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Article
Open AccessStatistical analysis of short-wave fadeout for extreme space weather event estimation
Solar flares trigger an increase in plasma density in the ionosphere including the D region, and cause the absorption of radio waves, especially in high-frequency (HF) ranges, called short-wave fadeout (SWF). ...
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Article
Open AccessA monitoring network for anomalous propagation of aeronautical VHF radio waves due to sporadic E in Japan
We introduce a network observation of anomalous long-distance propagation of aeronautical navigation (NAV) very high-frequency (VHF) radio waves due to sporadic E layer (Es). The system has been operative sinc...
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Article
Open AccessDaytime F-region irregularity triggered by rocket-induced ionospheric hole over low latitude
Unexpected daytime F-region irregularities following the appearance of an ionospheric hole have been observed over low latitude. The irregularities developed initially above the F-region peak height (~ 360 km)...
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Article
Open AccessEffects of pre-reversal enhancement of E × B drift on the latitudinal extension of plasma bubble in Southeast Asia
We investigated the effects of the F region bottomside altitude (h’F), maximum upward E × B drift velocity, duration of pre-reversal enhancement and the integral of upward E × B drift on the latitudinal extension...
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Article
Open AccessAirglow-imaging observation of plasma bubble disappearance at geomagnetically conjugate points
We report the first observation of the disappearance of a plasma bubble over geomagnetically conjugate points. It was observed by airglow imagers at Darwin, Australia (magnetic latitude: −22°N) and Sata, Japan...
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Article
Open AccessObservations of GPS scintillation during an isolated auroral substorm
This paper reports simultaneous observations of ionospheric scintillation during an auroral substorm that were made using an all-sky full-color digital single-lens reflex (DSLR) camera (ASC) and a Global Posit...
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Article
Open AccessGiant ionospheric disturbances observed with the SuperDARN Hokkaido HF radar and GPS network after the 2011 Tohoku earthquake
Giant ionospheric disturbances induced by the 2011 off the Pacific coast of Tohoku Earthquake (Mw 9.0) on 11 March 2011 are studied by using data from the SuperDARN Hokkaido HF radar and GPS receiver network (GEO...
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Article
Open AccessTEC prediction with neural network for equatorial latitude station in Thailand
This paper describes the neural network (NN) application for the prediction of the total electron content (TEC) over Chumphon, an equatorial latitude station in Thailand. The studied period is based on the ava...
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Article
Open AccessIonospheric multiple stratifications and irregularities induced by the 2011 off the Pacific coast of Tohoku Earthquake
A strong earthquake with a magnitude of 9.0 occurred at 1446:23 JST on March 11, 2011, in Japan. Ionospheric disturbances were detected at 1500 JST at four ionosonde stations. An irregular distortion of echo t...
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Article
Medium-scale traveling ionospheric disturbances observed by GPS receiver network in Japan: a short review
Medium-scale traveling ionospheric disturbances (MSTID) are wave-like perturbations of the ionospheric plasma with wavelengths of several hundred kilometres and velocities of several hundred metres per second....
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Article
Open AccessStatistical study of medium-scale traveling ionospheric disturbances observed with the GPS networks in Southern California
Using global positioning system (GPS) data taken from 350 dual-frequency GPS receivers in Southern California in 2002, we investigated two-dimensional maps of total electron content (TEC) perturbations with a ...
