English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

This paper is a further extension of our latest observations and modeling by\udHayakawa et al. (2005a), in which we discovered the anomalous behavior of Schumann\udresonance observed in Japan, in possible association with the Chi-chi\udearthquake in Taiwan. Schumann resonance\udintensity changes associated with a localized decrease in the lower ionospheric\udheight over the earthquake epicenter are modeled. The knee model of the vertical\udconductivity profile of the ionosphere describes the regular Earth-ionosphere\udcavity, and the modified knee model is introduced for the\uddisturbance. The localized ionosphere modification is of a Gaussian radial\uddependence; it has a 1-Mm radius, and the decrease reaches 20 km in the\udlower ionosphere height over the epicenter of the earthquake (Taiwan). The\uddiffraction problem in the Earth-ionosphere cavity with a localized\uddisturbance is resolved by using the Stratton-Chu integral equation. This\udsolution is constructed for the case of natural resonance oscillations\uddriven by independent random sources distributed worldwide. The data of\udthe Optical Transient Detector (OTD) are used to introduce the source\uddistribution. A pronounced increase in the intensity of the Schumann resonance\udis obtained around the fourth mode frequency (up to 20%) when\udthunderstorms are concentrated in Central America. The worldwide\uddistribution of lightning strokes blurs and slightly reduces the effect\ud(15% increase in intensity) for the observer in Japan and the localized\udnonuniformity positioned over Taiwan. A clear qualitative similarity is\udobtained in relation to the experimental data, indicating that records collected in Japan\udmay be explained by the impact of a localized decrease in the lower\udionosphere over the epicenter of the earthquake. It is admitted that the\udassumed conductivity decrease could only be caused by a severe change in the\udionization in the middle atmosphere. It is not in the scope of this paper to\uddiscuss the possible mechanism, but rather to show that a closer and\udquantitative agreement with the experiment yields information about the form\udand size of the ionospheric modification and about the distribution of global\udthunderstorm activity during measurements

Model modifications in Schumann resonance intensity caused by a localized ionosphere disturbance over the earthquake epicenter