All the details of ionospheric disturbances following the 2011 Tohoku Earthquake were first revealed by the high-resolution GPS total electron content observation in Japan. The initial ionospheric disturbance appeared as sudden depletions following small impulsive TEC enhancements ~7 minutes after the earthquake onset, near the epicenter. Then, concentric waves appeared to propagate in the radial direction with a velocity of 138–3,457 m/s. Zonally-extended enhancements of the TEC also appeared in the west of Japan. In the vicinity of the epicenter, short-period oscillations with a period of ~4 minutes were observed. This paper focuses on the concentric waves. The concentric pattern indicates that they had a point source. The center of these structures, termed the “ionospheric epicenter”, was located about 170 km from the epicenter in the southeast direction. According to the propagation characteristics, these concentric waves could be caused by atmospheric waves classified into three types: acoustic waves generated from a propagating Rayleigh wave, acoustic waves from the ionospheric epicenter, and atmospheric gravity waves from the ionospheric epicenter. The amplitude of the concentric waves was not uniform and was dependent on the azimuth of their propagation direction, which could not be explained by previously-proposed theory.

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Ionospheric disturbances detected by GPS total electron content observation after the 2011 off the Pacific coast of Tohoku Earthquake

The dual frequency radio signals of the Global Positioning System (GPS) allow measurements of the total number of electrons, called total electron content (TEC), along a ray path from GPS satellite to receiver. We have developed a new technique to construct two-dimensional maps of absolute TEC over Japan by using GPS data from more than 1000 GPS receivers. A least squares fitting procedure is used to remove instrumental biases inherent in the GPS satellite and receiver. Two-dimensional maps of absolute vertical TEC are derived with time resolution of 30 seconds and spatial resolution of 0.15° × 0.15° in latitude and longitude. Our method is validated in two ways. First, TECs along ray paths from the GPS satellites are simulated using a model for electron contents based on the IRI-95 model. It is found that TEC from our method is underestimated by less than 3 TECU. Then, estimated vertical GPS TEC is compared with ionospheric TEC that is calculated from simultaneous electron density profile obtained with the MU radar. Diurnal and day-to-day variation of the GPS TEC follows the TEC behavior derived from MU radar observation but the GPS TEC is 2 TECU larger than the MU radar TEC on average. This difference can be attributed to the plasmaspheric electron content along the GPS ray path. This method is also applied to GPS data during a magnetic storm of September 25, 1998. An intense TEC enhancement, probably caused by a northward expansion of the equatorial anomaly, was observed in the southern part of Japan in the evening during the main phase of the storm.

A new technique for mapping of total electron content using GPS network in Japan

An object of the present invention is to provide a charging member in which a toner, an additive for use in the toner, or the like is hard to adhere to the surface even under repeated use for a long time, and hence the charging and image output are made stable for a long time even if the charging member is used in the DC contact charging method, and a process cartridge and an electrophotographic apparatus having the charging member. The present invention provides a charging member comprising a support, a conductive elastic layer formed on the support, and a surface layer formed on the conductive elastic layer, characterized in that the surface layer contains a polysiloxane having a fluoroalkyl group and an oxyalkylene group, and a process cartridge and an electrophotographic apparatus having the charging member.

Charging member, process cartridge, and electrophotographic apparatus

Geodesy, the oldest science, has become an important discipline in the geosciences, in large part by enhancing Global Positioning System (GPS) capabilities over the last 35 years well beyond the satellite constellation's original design. The ability of GPS geodesy to estimate 3D positions with millimeter-level precision with respect to a global terrestrial reference frame has contributed to significant advances in geophysics, seismology, atmospheric science, hydrology, and natural hazard science. Monitoring the changes in the positions or trajectories of GPS instruments on the Earth's land and water surfaces, in the atmosphere, or in space, is important for both theory and applications, from an improved understanding of tectonic and magmatic processes to developing systems for mitigating the impact of natural hazards on society and the environment. Besides accurate positioning, all disturbances in the propagation of the transmitted GPS radio signals from satellite to receiver are mined for information, from troposphere and ionosphere delays for weather, climate, and natural hazard applications, to disturbances in the signals due to multipath reflections from the solid ground, water, and ice for environmental applications. We review the relevant concepts of geodetic theory, data analysis, and physical modeling for a myriad of processes at multiple spatial and temporal scales, and discuss the extensive global infrastructure that has been built to support GPS geodesy consisting of thousands of continuously operating stations. We also discuss the integration of heterogeneous and complementary data sets from geodesy, seismology, and geology, focusing on crustal deformation applications and early warning systems for natural hazards.

Physical applications of GPS geodesy: a review.

The recent tsunamigenic earthquake in Tohoku (11 March 2011) strongly affirms, one more time after the Sumatra event (26 December 2004), the necessity to open new paradigms in oceanic monitoring Detection of ionospheric anomalies following the Sumatra tsunami demonstrated that ionosphere is sensitive to the tsunami propagation Observations supported by modeling proved that tsunamigenic ionospheric anomalies are deterministic and reproducible by numerical modeling via the ocean/neutral-atmosphere/ionosphere coupling mechanism In essence, tsunami induces internal gravity waves propagating within the neutral atmosphere and detectable in the ionosphere Most of the ionospheric anomalies produced by tsunamis were observed in the far field where the tsunami signature in the ionosphere is clearly identifiable In this work, we highlight the early signature in the ionosphere produced by tsunamigenic earthquakes and observed by GPS, measuring the total electron content, close to the epicenter We focus on the first hour after the seismic rupture We demonstrate that acoustic-gravity waves generated at the epicenter by the direct vertical displacement of the source rupture and the gravity wave coupled with the tsunami can be discriminated with theoretical support We illustrate the systematic nature of those perturbations showing several observations: nominally the ionospheric perturbation following the tsunamigenic earthquakes in Sumatra on 26 December 2004 and 12 September 2007; in Chile on 14 November 2007; in Samoa on 29 September 2009; and the recent catastrophic Tohoku-Oki event on 11 March 2011 Based on the analytical description, we provide tracks for further modeling efforts and clues for the interpretation of complex--and thus often misleading--observations The routine detection of the early ionospheric anomalies following the rupture highlights the role of ionospheric sounding in the future ocean monitoring and tsunami detection

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From Sumatra 2004 to Tohoku-Oki 2011: The systematic GPS detection of the ionospheric signature induced by tsunamigenic earthquakes

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 trace was observed at Kokubunji, which is the nearest station to the epicenter and is 440 km from it. Multiple-cusp-type trace indicating extra stratification was observed at Wakkanai and Yamagawa, which are 870 and 1410 km away from the epicenter. A small wavy fluctuation was observed at Okinawa 1910 km away from the epicenter. The real height analysis of the ionograms showed a vertical structure with a scale size of 20~30 km.

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Ionospheric multiple stratifications and irregularities induced by the 2011 off the Pacific coast of Tohoku Earthquake

[1] After the magnitude 9.0 earthquake off the Pacific coast of Tohoku (near the east coast of Honshu, Japan), which occurred on 11 March 2011, an unusual multiple-cusp signature (MCS) was observed in ionograms at three ionosonde stations across Japan. To investigate the general characteristics of MCSs, we examined ionograms obtained during the period 1957 to 2011 from five ionosonde stations in Japan after earthquakes with a seismic magnitude of 8.0 or greater. A total of 43 such earthquakes occurred after 1957, as recorded in the database of the United States Geological Survey. MCSs were observed in 8 of 43 earthquakes, allowing us to investigate the specific conditions of MCS appearance. The appearance of MCSs at different epicentral distances exhibits traveling characteristics at a velocity of ∼4.0 km/s, which is in the range of Rayleigh waves. There is a ∼7 min offset in delay time after the earthquake at each epicentral distance in the travel-time diagram. This offset is consistent with the propagation time of acoustic waves from the ground to the ionosphere launched by Rayleigh waves. MCSs in ionograms provide a snapshot of vertical disturbances induced by a wave because the sweep time for the whole ionospheric echo traces is much shorter than the propagation time of acoustic waves. The vertical scale of the disturbances is 10∼30 km, which corresponds to an acoustic wave period of 20∼50 s at ionospheric heights.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2012JA017952

Rayleigh wave signature in ionograms induced by strong earthquakes

[1] Using monthly medians of ionosonde observations taken over a period including more than four solar cycles (1958–2003) at Kokubunji (35.71°N, 139.49°E), Japan and a linear regression model to eliminate solar and geomagnetic effects, we derive the long-term trends of critical frequencies (foE, foF1, and foF2), the E region height (h′E), and the F2 peak height (hmF2). The results show increasing trends for foE (+0.002 MHz/yr), h′E (+0.189 km/yr), and foF1 (+0.0107 MHz/yr) and decreasing trends for foF2 (−0.0058 MHz/yr at noon and −0.0016 MHz/year at midnight) and hmF2 (−0.398 km/yr at noon and −0.505 km/year at midnight). We have also analyzed seasonal and diurnal trend variations. These trends differed for various times of day and months, even with altering signs (except for hmF2). An interesting phenomenon was observed for the first time; that is, the morphologies of the overall seasonal trend variations of foE and foF1 were opposite each other to some extent, although the trends remained positive. A similar phenomenon was found for the seasonal trend variation of hmF2 between local noon and midnight. In addition, comparison of the results from four regression models indicated that the differences induced by linear and quadratic models are slightly significant for foF2 but not for other parameters. On the basis of the average of foF2 data obtained over 5 hours around noon, we have assessed the performance of each of these regression models. The performance differed depending on the month. The results showed that the quadratic model and the linear model that took saturation into consideration performed better than the linear ones which did not consider saturation. In addition, it was indicated that the effect of geomagnetic activity was not significant in regression models at this station.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2004JA010572

Long-term ionospheric trends based on ground-based ionosonde observations at Kokubunji, Japan

PROBLEM TO BE SOLVED: To provide electrocatalyst for a fuel cell using a new carrier and providing a fuel cell with higher output density than that of the conventional electrocatalyst for the fuel cell when used for the fuel cell. SOLUTION: This electrocatalyst for the fuel cell is characterized in having the carrier composed of a carbon material including mesoporous carbon particles in one part and a catalyst layer carried by the carrier. The mesoporous carbon particle has a smaller pore size distribution than that of a general carbon material so as to exhibit favorable dispersion of the catalyst carried and to reduce the wastefulness of the catalyst carried in the pore. The mixing of the carbon material except for the mesoporous carbon particles can solve a problem of insufficient diffusion of reaction gas, when the mesoporous carbon particle is singularly used so as to efficiently form a network of electron transfer and reduce the inner DC resistance of the fuel cell. COPYRIGHT: (C)2004,JPO

Hisao Kato

Papers

Ionospheric disturbances detected by GPS total electron content observation after the 2011 off the Pacific coast of Tohoku Earthquake

Ionospheric multiple stratifications and irregularities induced by the 2011 off the Pacific coast of Tohoku Earthquake

Rayleigh wave signature in ionograms induced by strong earthquakes

Long-term ionospheric trends based on ground-based ionosonde observations at Kokubunji, Japan

Electrocatalyst for fuel cell and fuel cell