Journal of geomagnetism and geoelectricity最新文献

{"title":"Ionospheric Manifestation of Sc-Associated Magnetic Pulsations in the HF Doppler Frequency Shifts (Recent Results of Studies on Solar Terrestrial Physics Part 4)","authors":"T. Shibata, H. Kataoka, T. Okuzawa","doi":"10.5636/JGG.49.SUPPLEMENT_S179","DOIUrl":"https://doi.org/10.5636/JGG.49.SUPPLEMENT_S179","url":null,"abstract":"Ionospheric manifestation of ssc-associated ULF magnetic pulsations is investigated by analyzing the simultaneous data of HF Doppler frequency shift and magnetic H component on the ground. The theoretical Doppler velocities associated with magnetic pulsations are also calculated using the method of Sutcliffe and Poole (1989). Comparison of the observed phase difference between the ionospheric and magnetic pulsations with the one by theory reveals that in several of the pulsation events the ionospheric response can be controlled by the advection and/or compression mechanisms attributable to the pulsation EM fields.","PeriodicalId":156587,"journal":{"name":"Journal of geomagnetism and geoelectricity","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129428112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Application of Two-Dimensional Wavelet Analysis to Wind Disturbances Observed with MU Radar in the Lower Stratosphere and Troposphere","authors":"T. Shimomai, M. Yamanaka, S. Fukao","doi":"10.5636/JGG.49.SUPPLEMENT_S205","DOIUrl":"https://doi.org/10.5636/JGG.49.SUPPLEMENT_S205","url":null,"abstract":"Orthonormal wavelet analysis is applied for the first time to two-dimensional (time and height) data obtained from three-week continuous MU radar observations in June-July, 1991. It is confirmed that monochromatic wave structures are generally localized both in time and in altitude. We find the dominant temporal scale of wave activity in this case study is 2-4 days. The dominant vertical wavelength seems to decrease from -4 km to - 1 km, upwards through the tropopause-lower stratosphere region, which is almost independent of temporal scales in the 1-4 day range.","PeriodicalId":156587,"journal":{"name":"Journal of geomagnetism and geoelectricity","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129286212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Coupling of Double Tearing Instability with Shear Flow and Solar Flare","authors":"Xu Deng, Jie Wang, Zhiliang Chen","doi":"10.5636/JGG.49.SUPPLEMENT_S15","DOIUrl":"https://doi.org/10.5636/JGG.49.SUPPLEMENT_S15","url":null,"abstract":"The nonlinear behavior of the double tearing mode with shear flow parallel to the magnetic filed is investigated numerically in cylindrical geometry. The double tearing instability is found to be unstable with two peak current density profile, and under the influence of shear flow, it exhibits a complicated behavior in the physical and parameter space. With a Sech form shear flow, it is found that when the velocity shear near the resonant surface is small, the shear flow has a stabilizing effect, but for larger velocity shear, the double tearing modes are destabilized. The Possible physical implications of the coupling of double tearing instability with shear flow for the triggering of solar flares are discussed.","PeriodicalId":156587,"journal":{"name":"Journal of geomagnetism and geoelectricity","volume":"2006 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125561931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ULF/ELF Plasma Waves in the Active Regions of the Magnetosphere (Recent Results of Studies on Solar Terrestrial Physics Part 4)","authors":"J. Blecki","doi":"10.5636/JGG.49.SUPPLEMENT_S131","DOIUrl":"https://doi.org/10.5636/JGG.49.SUPPLEMENT_S131","url":null,"abstract":"","PeriodicalId":156587,"journal":{"name":"Journal of geomagnetism and geoelectricity","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131470288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Auroral Oval Dynamics in Different Spatial Scales","authors":"J. Šafránková, Z. Němeček, O. Santolík","doi":"10.5636/JGG.49.SUPPLEMENT_S151","DOIUrl":"https://doi.org/10.5636/JGG.49.SUPPLEMENT_S151","url":null,"abstract":"The present paper deals with a detail study of the dynamics of the polar cap boundaries. The study involves the data from two satellites of the APEX project, and the data from three DMSP satellites. The APEX (Active Plasma Experiment) satellites moving along the polar orbit provide charged particle measurements in a small spatial scale (due to changeable distance between both spacecrafts), up to 2000 km. The large scale changes are studied by the comparison of the APEX and the DMSP (Defense Meteorological Satellite Program) data. Different regions are identified using the characteristics of the precipitating particles in the energy range 0.1-20 keV which have been registered onboard of all satellites. This satellite configuration allows us to determine the evolution of the small structures as well as the motion of the whole precipitating region. The main attention is concentrated on the rising phase of the substorms when the width of the auroral oval decreases with the increasing geomagnetic activity and the velocity of the auroral oval motion can reach 0.2° per minute. The observed phenomena are compared with the changes of the interplanetary magnetic field and the solar wind parameters as provided by the IMP-8 spacecraft.","PeriodicalId":156587,"journal":{"name":"Journal of geomagnetism and geoelectricity","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131426092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Oscillatory Nature of the Magnetosphere II. The EM-Background, Strong Packets of Waves, Resonances","authors":"Y. Al’pert, L. Lanzerotti","doi":"10.5636/JGG.49.SUPPLEMENT_S85","DOIUrl":"https://doi.org/10.5636/JGG.49.SUPPLEMENT_S85","url":null,"abstract":"","PeriodicalId":156587,"journal":{"name":"Journal of geomagnetism and geoelectricity","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122001626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamical Variation of Plasmasphere Revealed by PWS Data onboard the Akebono(EXOS-D)Satellite (Recent Results of Studies on Solar Terrestrial Physics Part 4)","authors":"H. Oya","doi":"10.5636/JGG.49.SUPPLEMENT_S159","DOIUrl":"https://doi.org/10.5636/JGG.49.SUPPLEMENT_S159","url":null,"abstract":"From the upper hybrid frequency data observed by PWS onboard the Akebono satellite, the entire plasma density profile along the satellite paths have been obtained being based on the plasma neutrality condition. The analyses of the plasma density deduced from the upper hybrid frequency reveal the dynamical variation of the plasmaspheric plasma density profile (PPDP). The PPDP variation is especially characterized by the intimate correspondence to the time variation of Dst that indicates the time derivative-coefficient larger than 5 nT/hour. Variation phenomena of PPDP are divided into two categories depending on the phases of Dst variations; these are the phenomena which occur in the phase of the positive time derivative-coefficient (PDC) of Dst; and the phenomena which occur in the phase of the negative time derivative-coefficient (NDC) of Dst. Both in PDC, and NDC phases, the plasmapause structures show the sharpening of their cliff feature of the plasma density distribution, but a few hours later, all these traditionally convinced enhancement effects of the plasma convection in the neighboring plasma sheet regions are taken. over by the effects of plasmapause disruption without depending on the local time of the consideration. These plasmapause disruptions are caused by the exodus of the plasmaspheric plasma in the NDC phase while the hot plasma sheet plasma immigrates into the plasmasphere in the phase of PDC. Because of extreme inhomogeneity of the plasma temperature between the original plasmaspheric warm plasma and hot plasma from the plasma sheet region, there exist sharp discontinuous boundaries across the magnetic field lines in the plasmasphere. The evidence has been detected as the “donkey ears” phenomena by the observation of PWS onboard the Akebono satellite. It is disclosed that the exodus of plasma from the plasmasphere in NDC phase of Dst, and the immigration of plasma into the plasmasphere in PDC phase are caused by E × B drift due to the induction electric field that is strictly related to ∂B/∂t. The arrival of the front of the injected hot plasma delays with times ranging from 15 h to 2.5 h corresponding to the time derivative-coefficient of Dst, respectively from 5 nT/hour to 30 nT/hour. As higher the time derivative-coefficient becomes, the faster the drift velocity is increased; i.e., the delay time of arrival of the hot plasma front from the original plasmapause position to the satellite level becomes short for the fast E × B drift.","PeriodicalId":156587,"journal":{"name":"Journal of geomagnetism and geoelectricity","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121896232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Polarization Characteristics of Io-Related Jovian Decametric Radiations (Recent Results of Studies on Solar Terrestrial Physics Part 4)","authors":"H. Misawa, H. Oya, M. Iizima","doi":"10.5636/JGG.49.SUPPLEMENT_S67","DOIUrl":"https://doi.org/10.5636/JGG.49.SUPPLEMENT_S67","url":null,"abstract":"Polarization measurements of Io-related Jovian decametric radiations (DAM's) were made in a frequency range from 20.5 to 25.5 MHz at the Zao observatory of Tohoku University, Japan. In the analyses of axial ratios of polarization ellipses, the following two factors were particularly investigated which were expected to deform the original axial ratios of Io-related DAM's; i.e., i) interferences caused by reflected wave components from ground, and ii) mutual cross-talks between one free-space mode wave to another free-space mode wave in anisotropic magnetized plasma along the ray paths. Totally 20 Io-related radio storms and 2 non-Io-A radio storms were selected for the analyses. Our major results are as follows: i) Most of Io-related DAM events indicate highly right-handed (RH) elliptical polarization and the mean value of the axial ratios for RH events is -0.31 ± 0.09 (standard deviation). ii) Io-A and 10-13 related DAM events indicate the significant difference in their axial ratios; i.e., -0.35 ± 0.08 and -0.26 ± 0.06 for RH Io-A and RH Io-B related DAM events, respectively. iii) Io-related DAM events indicate slightly more linear polarization than non-Io-A DAM events.","PeriodicalId":156587,"journal":{"name":"Journal of geomagnetism and geoelectricity","volume":"123 18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127708617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Frequency Spectra of Wind Velocity Fluctuations between 1 hour and 1 month in the Atmospheric Boundary Layer over Equatorial Indonesia","authors":"H. Hashiguchi, S. Fukao, M. Yamanaka, T. Tsuda","doi":"10.5636/JGG.49.SUPPLEMENT_S187","DOIUrl":"https://doi.org/10.5636/JGG.49.SUPPLEMENT_S187","url":null,"abstract":"Frequency power spectra are analyzed from zonal and meridional wind velocities observed continuously in a height range below 2.5 km with the Kyoto University Boundary Layer Radar (BLR) in Serpong, Indonesia (6.4°S, 106.7°E). We find that (i) the spectral slope in a period range from a few hours to a few days is approximately -1; (ii) the power spectral densities in the rainy season are at least about two times larger than those in the dry season; (iii) the diurnal component is dominant both in dry and rainy seasons; (iv) components with periods of about 4 and 10 days are probably associated with mixed Rossby-gravity wavelike cloud clusters and Kelvin wavelike super cloud clusters, respectively; and (v) the power spectral amplitudes increase at least one order of magnitude from the bottom to the top of the equatorial Planetary Boundary Layer (PBL), and the values at the top of the PBL are comparable to those in the upper troposphere over mid-latitudes. The last feature suggests that the equatorial PBL is probably a major source of kinetic energy of the earth's atmosphere.","PeriodicalId":156587,"journal":{"name":"Journal of geomagnetism and geoelectricity","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122281475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Small-Scale Anti-Parallel Field-Aligned Currents and Plasma Density Dips:Signatures of the″Alfvenic Shocks″ (Recent Results of Studies on Solar Terrestrial Physics Part 4)","authors":"M. Forster, D. Popescu","doi":"10.5636/JGG.49.SUPPLEMENT_S43","DOIUrl":"https://doi.org/10.5636/JGG.49.SUPPLEMENT_S43","url":null,"abstract":"“Electrostatic Shocks” and field-aligned currents are associated with discrete auroral arcs and low-altitude particle acceleration. We show that accounting for the two new elements with respect to the previous “static” and “Alfven wave” models, namely the transverse wave-guide for shear Alfven waves and plasma density dip in the center of the structure, is necessary in order to explain the basic features of this phenomenon. The characteristics dimensions of the structure correspond to the “stirring scales” of the auroral turbulence.","PeriodicalId":156587,"journal":{"name":"Journal of geomagnetism and geoelectricity","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130447957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}