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91.
Uncertainty Estimate of Surface Irradiances Computed with MODIS-, CALIPSO-, and CloudSat-Derived Cloud and Aerosol Properties 总被引:1,自引:0,他引:1
Seiji Kato Norman G. Loeb David A. Rutan Fred G. Rose Sunny Sun-Mack Walter F. Miller Yan Chen 《Surveys in Geophysics》2012,33(3-4):395-412
Differences of modeled surface upward and downward longwave and shortwave irradiances are calculated using modeled irradiance computed with active sensor-derived and passive sensor-derived cloud and aerosol properties. The irradiance differences are calculated for various temporal and spatial scales, monthly gridded, monthly zonal, monthly global, and annual global. Using the irradiance differences, the uncertainty of surface irradiances is estimated. The uncertainty (1σ) of the annual global surface downward longwave and shortwave is, respectively, 7?W?m?2 (out of 345?W?m?2) and 4?W?m?2 (out of 192?W?m?2), after known bias errors are removed. Similarly, the uncertainty of the annual global surface upward longwave and shortwave is, respectively, 3?W?m?2 (out of 398?W?m?2) and 3?W?m?2 (out of 23?W?m?2). The uncertainty is for modeled irradiances computed using cloud properties derived from imagers on a sun-synchronous orbit that covers the globe every day (e.g., moderate-resolution imaging spectrometer) or modeled irradiances computed for nadir view only active sensors on a sun-synchronous orbit such as Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation and CloudSat. If we assume that longwave and shortwave uncertainties are independent of each other, but up- and downward components are correlated with each other, the uncertainty in global annual mean net surface irradiance is 12?W?m?2. One-sigma uncertainty bounds of the satellite-based net surface irradiance are 106?W?m?2 and 130?W?m?2. 相似文献
92.
Yuki Abe Takahiro Ohkura Takuo Shibutani Kazuro Hirahara Mamoru Kato 《Journal of Volcanology and Geothermal Research》2010
Aso Volcano experienced a huge pyroclastic eruption 90 thousand years ago, and formed a large caldera (18 km × 25 km). In order to test the hypothesis of a magma body in the mid and lower crust that has been suggested geophysically and geochemically, we investigated seismic velocity discontinuities and velocity structure beneath Aso Caldera using receiver functions and a genetic algorithm inversion. We confirm the existence of the Moho at depths between 30 km and 35 km and a large velocity anomaly should exist in the deep portion of the crust beneath Aso Caldera, from imaging of receiver functions observed only at stations outside the caldera. As a result of a more detailed examination with GA inversion, a low velocity layer is detected at depths between 10 km and 24 km beneath the western part of the caldera. S-wave velocity of the layer is estimated to be 2.0–2.4 km/s. We estimate that the low velocity layer contains at most 15% melt or 30% aqueous fluid. The layer exists near the Conrad and at the same depths as the swarm of the low frequency earthquakes and a compressional and dilatational deformation source which are expected to be caused by fluid movement beneath the middle-eastern part of the caldera. Fluid contained in the layer might be related with huge pyroclastic eruptions of Aso Volcano. 相似文献
93.
—A tectonic state of a locked subduction is considered to be a possible source of a future interplate earthquake. Discriminating an actually locked state to verify its extent is therefore essential in constructing an accurate prospect against the forthcoming earthquake. Micorearthquake seismicity is an effective tool for such an analysis because it is considered to be a faithful indicator of the stress state, and is expected to exhibit a characteristic pattern in the area where the locked state in the subduction appears with a certain stress concentration. Focusing on the microearthquake seismicity around the Tokai district in central Japan, where a large interplate earthquake is feared to occur, we tried to identify such an area of locked subduction on the Philippine Sea plate, possibly related to the future earthquake. We investigated the microearthquake seismicity from various perspectives. First, the hypocenter distribution was analyzed to identify the extent of the locked area. The characteristic profile of the distribution was presumed to represent a stress concentrated area induced from the mechanical contact between both plates. The second approach is to interpret stress patterns reflected in focal mechanisms. The locked state was recognized and verified by a comparison of the P-axis distribution pattern with that expected from a model imaging a partially locked subduction. The third approach is to monitor the temporal change of the seismic wave spectrum. Analyzing predominant frequencies of P and S waves and monitoring their changes for a period of 10 years, we found a trend of gradual increase common to both waves. This means an increase of stress drop in microfracturings, and in its turn implies accumulation of stress around the focus area. The rate of the stress change converted from the frequency change was compared with the result derived from a numerical simulation. The simulation, performed on the basis of a constitutive friction law for a stick sliding on the plate interface, computed a changing rate of the maximum shear stress around the locked zone and showed its spatial variation along the subduction axis. Thus the simulated result indicated a certain compatibility with the observed one. Although ambiguities and uncertainties still exist in the study, all the results derived here seem to indicate an identical conclusion that the plate subduction is actually locked in this region at present. 相似文献
94.
The Variation of Stresses due to Aseismic Sliding and its Effect on Seismic Activity 总被引:2,自引:0,他引:2
— Numerical simulation of recurring large interplate earthquakes in a subduction zone is conducted to explore the effects of aseismic sliding on the variation of stresses and the activity of small earthquakes. The frictional force obeying a rate- and state-dependent friction law is assumed to act on the plate interface in a 2-D model of uniform elastic half-space. The simulation results show that large earthquakes repeatedly occur at a constant time interval on a shallow part of the plate interface and that aseismic sliding migrates from the upper aseismic zone as well as from the lower aseismic zone into the central part of the seismogenic zone before the occurrence of a large interplate earthquake. This spatiotemporal variation of aseismic sliding significantly perturbs the stresses in the overriding plate and in the subducting oceanic plate, leading to the precursory seismic quiescence in the overriding plate and the activation of the intermediate-depth earthquakes of down-dip tension type. After the occurrence of a large interplate earthquake, the activity of the intermediate-depth earthquakes of down-dip compression type in the subducting slab is expected to increase and migrate downward. This is because the downward propagation of postseismic sliding causes the downward migration of compressional-stress increase in the down-dip direction of the plate interface. The simulation result further indicates that episodic events of aseismic sliding may occur when the spatial distributions of friction parameters are significantly nonuniform. The variation of stresses due to episodic sliding is expected to cause seismicity changes. 相似文献
95.
The paper provides a detailed analysis for the second-order diffraction of monochromatic waves. For the second-order potential on the free surface, the paper proposed a forward prediction method for computing the integration on the free surface. By this method we only need to run the infinity integration on the free surface directly for a few points; a one-step quadrature can then be applied successively outward from the body for potentials at other points. For wave diffraction from a body of revolution with a vertical axis, the paper derives a new integral equation, which can cancel the leading singularity in the derivative of ring Green's functions automatically. To obtain accurate results, different approaches are also used to deal with singularities in the ring Green's functions in the integration on both the body surface and free surface. The method has been implemented for bodies of revolution with vertical axes, but the theory is also available for arbitrary bodies.A numerical examination is made to validate the numerical code by comparing the second-order forces and moments on uniform and truncated cylinders and second-order diffraction potentials on the free surface with some published results. The comparison shows that the present results are in good agreement with those published. The method is also used to compute the second-order wave elevation around uniform and truncated cylinders. 相似文献
96.
97.
The innermost region of slim accretion disks with standard viscosity is unstable against axisymmetric radial inertial acoustic perturbations under certain conditions. Numerical simulations are performed in order to demonstrate behaviors of such unstable disks. It is shown that oscillations with the period of 10–3 (M
BH/M
) s can be excited near the inner edge of the disks, whereM
BH is the mass of the central object. This kind of unstable disks is a possible origin of the periodic X-ray time variabilities with period of 104s observed in a Seyfert galaxy NGC 6814. 相似文献
98.
Single crystalline San Carlos olivine (1 mm cube) was transformed to (Mg,Fe)2SiO4β-phase at 13.5–15 GPa, 1030–1330 °C for 0–600 min using a multi-anvil high pressure apparatus. The α-β transformation occurred
by incoherent surface nucleation and interface-controlled growth and recovered partially transformed samples showed sharply
defined reaction rim. The growth rate of the β-phase rim significantly decreased with time and the growth eventually ceased.
TEM observations revealed that many dislocations were created in both the relict olivine just near the α-β interface and the
β-phase in the rim, which show evidence for deformation caused by interfacial stresses associated with the misfit elastic
strain of the transformation. The observed tangled dislocation texture in β-phase suggested that the β-phase rim was hardened
and relaxation of the interfacial stress was retarded. This probably caused a localized pressure drop in the relict olivine
and decreased the growth rate. Time-dependent growth rates of β-phase is possibly controlled by the rheology of β-phase, which
must be considered for the prediction of the olivine metastability in the subducting slabs.
Received: 24 January 1997 / Revised, accepted: 24 July 1998 相似文献
99.
A. G. Rodnikov A. G. Gainanov B. V. Yermakov V. M. Kovylin V. A. Seliverstov Ya. B. Smirnov P. A. Stroev Yu. K. Shchukin T. Kato H. Shimamura 《Marine Geophysical Researches》1985,7(3):379-387
The paper presents the results of geological-geophysical research carried out during the Soviet-Japanese cooperative study of the structure and dynamics of the Earth's crust and upper mantle in the transition zone from the Pacific Ocean to the Asian continent. The 300 km deep geological-geophysical section of the tectonosphere (geotraverse) has been compiled on the basis of combined interpretations of seismic, geological, petrographic, gravimetric, magnetometric, electromagnetic and heat flow measurements. Estimates were made of deep temperatures along the geotraverse and of the depths of the partial melting level that can be identified with the upper boundary of the asthenosphere. 相似文献
100.
Giant Megamullion in the Parece Vela Backarc Basin 总被引:1,自引:0,他引:1
Ohara Yasuhiko Yoshida Tsuyoshi Kato Yukihiro Kasuga Shigeru 《Marine Geophysical Researches》2001,22(1):47-61
We present results of high-resolution bathymetric studies of the extinct intermediate-spreading Parece Vela Basin in the northwestern Pacific, where we have identified an extremely large mullion structure, here termed a giant megamullion. We find that the giant megamullion is nearly an order of magnitude larger than the similar structures in the slow-spreading Mid-Atlantic Ridge (`megamullions'). The giant megamullion has slightly elevated mantle Bouguer anomaly, and yields serpentinized peridotites and gabbros, suggesting that they are exposing oceanic crust and upper mantle. An off-axis rugged `chaotic terrain' was also identified in the Parece Vela Basin. The terrain consists of isolated and elevated blocks capped by corrugated axis-normal lineations, and associated deeps. We thus interpret it as analogues to the Mid-Atlantic Ridge megamullions. We propose that amagmatic tectonics producing the giant megamullion and the chaotic terrain occupied a significant part in crustal construction in the Parece Vela Basin evolution. 相似文献