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1.
Recent observational studies on solar flares made by solar radio groups in Japan during the period around the maximum of Cycle 21 are briefly reviewed. Much attention is paid especially to comparison studies of microwave observations with hard X-ray and -ray observations. 相似文献
2.
Takeo Kosugi 《Solar physics》1981,71(1):91-105
A well-developed multiple impulsive microwave burst occurred on February 17, 1979 simultaneously with a hard X-ray burst and a large group of type III bursts at metric wavelengths. The whole event is composed of several subgroups of elementary spike bursts. Detailed comparisons between these three classes of emissions with high time resolution of 0.5 s reveal that individual type III bursts coincide in time with corresponding elementary X-ray and microwave spike bursts. It suggests that a non-thermal electron pulse generating a type III spike burst is produced simultaneously with those responsible for the corresponding hard X-ray and microwave spike bursts. The rise and decay characteristic time scales of the elementary spike burst are 1 s, 1 s and 3 s for type III, hard X-ray and microwave emissions respectively. Radio interferometric observations made at 17 GHz reveal that the spatial structure varies from one subgroup to others while it remains unchanged in a subgroup. Spectral evolution of the microwave burst seems to be closely related to the spatial evolution. The spatial evolution together with the spectral evolution suggests that the electron-accelerating region shifts to a different location after it stays at one location for several tens of seconds, duration of a subgroup of elementary spike bursts. We discuss several requirements for a model of the impulsive burst which come out from these observational results, and propose a migrating double-source model. 相似文献
3.
Urban change detection related to earthquakes using an adaptive nonlinear mapping of high-resolution images 总被引:1,自引:0,他引:1
Kosugi Y. Sakamoto M. Fukunishi M. Wei Lu Doihara T. Kakumoto S. 《Geoscience and Remote Sensing Letters, IEEE》2004,1(3):152-156
We propose a nonlinear mapping method for detecting geographical changes. In our system, two images photographed at different points of time are checked based on an iterative nonlinear mapping. The system automatically extracts feature changes of aerial imageries by computing distribution of the image matching score. We evaluate the change detection ability by using the receiver operating characteristic under misregistration cases, including rotational misalignments. 相似文献
4.
A model describing the three‐dimensional matrix flow along a slope with rock fragments or impermeable blocks was developed. The model was combined with modified Picard's iteration to ensure mass conservation in the unsaturated flow. We found that rock fragments obstruct water flow along the slope. The groundwater table must be raised to provide a sufficient pore water pressure gradient to facilitate water flow, but higher pore water pressure may induce slope failure. We also conducted a bench‐scale laboratory flume experiment to examine the effects of impermeable blocks on downstream seepage flow. In addition, a numerical experiment was conducted to examine how different arrangements of impermeable blocks affect downstream seepage flow and pore water pressure. This research demonstrated that the hydraulic phenomena were affected when impermeable blocks were present, and pore water pressure increased as the position of impermeable blocks was lowered. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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We have developed a new method for synthesizing hard X-ray maps from the raw data of the Solar X-ray Telescope (SXT) aboard Hinotori. Using this method we analyzed five typical SXT events and summarized their images in a movie with a time resolution of about 8 s (half spin period of the satellite). The movie clearly shows that (1) three different classes of bursts, i.e., the gradual thermal burst, the multiple impulsive burst, and the extended outburst, have different structures and show quite different variations from each other, and that (2) the source of the extended outburst is located in the corona above 104 km and its shape appears to be a large loop. 相似文献
7.
Ayaka Sakabe Ken Hamotani Yoshiko Kosugi Masahito Ueyama Kenshi Takahashi Akito Kanazawa Masayuki Itoh 《Theoretical and Applied Climatology》2012,109(1-2):39-49
Very few studies have conducted long-term observations of methane (CH4) flux over forest canopies. In this study, we continuously measured CH4 fluxes over an evergreen coniferous (Japanese cypress) forest canopy throughout 1?year, using a micrometeorological relaxed eddy accumulation (REA) system with tuneable diode laser spectroscopy (TDLS) detection. The Japanese cypress forest, which is a common forest type in warm-temperate Asian monsoon regions with a wet summer, switched seasonally between a sink and source of CH4 probably because of competition by methanogens and methanotrophs, which are both influenced by soil conditions (e.g., soil temperature and soil moisture). At hourly to daily timescales, the CH4 fluxes were sensitive to rainfall, probably because CH4 emission increased and/or absorption decreased during and after rainfall. The observed canopy-scale fluxes showed complex behaviours beyond those expected from previous plot-scale measurements and the CH4 fluxes changed from sink to source and vice versa. 相似文献
8.
Morphological characteristics of snow ripples formed by drifting snow were investigated as functions of wind velocity in a cold wind tunnel at -15 °C. Wave-length, wave height and migration rate of snow ripples increased from 5 to 20 cm, 3 to 5 mm and 1 to 8 cm/min, respectively, with increasing wind velocity from 5 to 7 m/s. Measured size distributions of snow particles in snow ripples showed sorting of large particles in ridges, suggesting that the snow ripple migration is caused by creeping of large particles. The snow drift rate caused by creep, that is, by the ripple migration, was estimated to amount, at least, to 6% of the total snow drift rate. 相似文献
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10.
T. Kosugi K. Makishima T. Murakami T. Sakao T. Dotani M. Inda K. Kai S. Masuda H. Nakajima Y. Ogawara M. Sawa K. Shibasaki 《Solar physics》1991,136(1):17-36
The Hard X-ray Telescope (HXT) is a Fourier-synthesis imager; a set of spatially-modulated photon count data are taken from 64 independent subcollimators and are Fourier-transformed into an image by using procedures such as the maximum entropy method (MEM) or CLEAN. The HXT takes images of solar flares simultaneously in four energy bands, nominally 15 (or 19)–24, 24–35, 35–57, and 57–100 keV, with an ultimate angular resolution as fine as 5 arc sec and a time resolution 0.5 s. Each subcollimator has a field of view wider than the solar disk. The total effective area of the collimator/detector system reaches 70 cm2, about one order of magnitude larger than that of the HINOTORI hard X-ray imager. Thanks to these improvements, HXT will for the first time enable us to take images of flares at photon energies above 30 keV. These higher-energy images will be compared with lower-energy ones, giving clues to the understanding of nonthermal processes in solar flares, i.e., the acceleration and confinement of energetic electrons. It is of particular importance to specify the acceleration site with regard to the magnetic field figuration in a flaring region, which will be achieved by collaborative observations between HXT and the Soft X-ray Telescope on board the same mission.After the launch the name of SOLAR-A has been changed to YOHKOH. 相似文献