By using the lightning data (LPATS data) of June through August (during the years from 1997 to 2001) observed in the Gunma area of Japan, we have performed an analysis on the temporal evolution of percentage of positive and negative lightning discharges and lightning current in different geological regions (mountain, hill, and plain areas) with a special reference to the dissipating stage. As the result, it is found that both the percentage of positive lightning discharges and the lightning current show increases toward the dissipating stage of lightning for Japanese summer thunderstorms, which can be utilized to judge whether the lightning activity is in the dissipating stage.
This study proves the measurement capability of a Ka-band frequency modulated continuous wave (FMCW) Doppler weather radar (KaDR) developed for the Japanese cloud seeding experiments for precipitation augmentation (JCSEPA) research project. To continuously monitor precipitation and clouds with reduced maintenance costs, KaDR uses a traveling wave tube (TWT) transmitter which is originally designed for satellite communication. The TWT produces signals with a frequency of 35.25 GHz (8-mm wavelength) and a peak power of 100 W. Because the peak power of the TWT was small compared with conventional Ka-band weather radars which use transmission tubes, KaDR transmits FMCW in order to attain enough sensitivity and range resolution. Using the dataset collected from 1700 JST 25 October to 0300 JST 26 October 2009 at Shigaraki MU Observatory (34°51'N, 136°06'E, 386 m above the sea level), the equivalent radar reflectivity factor (Ze) and Doppler velocity (Vd) measured by KaDR were compared with micro ran radar (MRR). To evaluate Ze (Vd) measured by KaDr, a correlation coefficient and regression line were computed using a scatter plot between the two Zes (Vds). High correlation coefficient of 0.904 (0.912) and regression slope of 1.023 (1.038) between the two Zes (Vds) demonstrate the capability of KaDR to measure Ze and Vd quantitatively.
Changes are modeled of parameters of the global electric circuit caused by the giant gamma ray burst arrived at the Earth's dayside on December 27 2004. Modification of the air conductivity by gamma rays alters the leakage current of the Earth.ionosphere cavity and causes a discrete radio pulse. Electric parameters of the air at the tropopause-troposphere altitudes play the key role. ELF spectrum of the “parametric” current moment is 'red' or 'white' depending on the particular model. Sample spectra and waveforms are presented of the parametric Q-burst.
In this paper we use a long-term record of the Schumann resonance (SR) intensity observed in Nakatsugawa, Japan and global lightning activity to study the global temperature change. The cumulative magnetic field energy from the first and second modes of SR intensity for 4 years is derived for two horizontal components. The monthly dependence of field energy is compared with the global lightning and temperature data for the corresponding time period. As a result SR energy is found to be correlated well with the temperature in the middle latitude and global lightning activity. Furthermore the principal component analysis (PCA) is applied to extract the periodical component in each data set. The annual component of SR energy has a significant correlation with the middle latitude temperature, whilst the semi-annual component of the SR energy has a significant correlation with low latitude temperature. The correlation pattern varies with magnetic components and the contribution from African and Asian thunderstorm activity to the global SR is studied.
Many observations have been conducted to clarify the relation between electromagnetic phenomena and seismic activities. We have been observing seismic electromagnetic waves in FM broadcasting frequency band from 76 MHz to 90 MHz using PLL type synthesized digital FM tuners since 1998. We are operating thirteen observatories in Japan. From observations at Ibaraki by the dual frequency method using two different frequencies, nine events of co-seismic electromagnetic waves were observed for seven years from January 1, 2002 to December 31, 2008. Received electromagnetic levels rose up at the same moment of arrival of seismic waves. Further, we examined the relation between the co-seismic broadband electromagnetic waves and the seismic parameters. It was confirmed that the detected peak electromagnetic levels were well correlated with the peak ground accelerations of the earthquakes.
The appearance of ionospheric perturbations in possible association with earthquakes (EQs) seems to be confirmed on the basis of both event and statistical studies, but the generation mechanism of those seismo-ionospheric perturbations is not well understood, though a few possible hypotheses have been proposed. Two hypotheses are promising candidates; one is so-called chemical channel, in which radon emanation results in the change in atmospheric conductivity, then in the atmospheric electric field, leading to the redistribution of ionospheric plasma, and the other is the excitation of atmospheric oscillations due to some precursory changes of ground surface, which propagate upward and induce the ionospheric perturbation. We support the second chemical channel atmospheric oscillation channel chemical channel, so that in this paper we present several evidences (or facts) in support of this hypothesis. First, we present some case studies of the enhancement of AGW (atmospheric gravity wave) modulation in subionospheric VLF/LF propagation data, and then a recent statistical treatment of this AGW modulation in VLF/LF data is reported. Further studies on the satellite observation and also on the satellite-ground coordinated measurements are presented in order to indicate the AGW as the agent of lithosphere-ionosphere coupling. Finally, our equipment recently developed to measure the Doppler-shift of a short-distance subionospheric LF signal is used to indicate the direct evidence of the AGW hypothesis.