Shock metamorphism of the lunar samples is discussed. All types of lunar glasses formed by various-size collision-type impact are found as impact glass, ropy glass and agglutinates. The agglutinates bonded by crystal and glassy materials contain hydrogen and helium from the solar wind components. Lunar shocked minerals of plagioclase and silica show anomalous compositions and densities. There are typical two formation processes on planetary materials formed by shock events; that is (1) shocked quartz formed by silica-rich target rocks (esp. on evolved planets of the Earth and Mars), and (2) shocked silica with minor Al contents formed from plagioclase-rich primordial crusts of the Moon. The both shocked silica grows to coarse-grain normal crystals after high-temperature metamorphism which cannot distinguish the original main formation event of impact process. 相似文献
Solar Physics - Plasma motions at the initial phases of flares observed in the high resolution soft X-ray spectrometers are summarized. Blue-shifted components of highly ionized metal ions suggest... 相似文献
In this study, we constructed a perturbed physics ensemble (PPE) for the MIROC5 coupled atmosphere–ocean general circulation model (CGCM) to investigate the parametric uncertainty of climate sensitivity (CS). Previous studies of PPEs have mainly used the atmosphere-slab ocean models. A few PPE studies using a CGCM applied flux corrections, because perturbations in parameters can lead to large radiation imbalances at the top of the atmosphere and climate drifts. We developed a method to prevent climate drifts in PPE experiments using the MIROC5 CGCM without flux corrections. We simultaneously swept 10 parameters in atmosphere and surface schemes. The range of CS (estimated from our 35 ensemble members) was not wide (2.2–3.2?°C). The shortwave cloud feedback related to changes in middle-level cloud albedo dominated the variations in the total feedback. We found three performance metrics for the present climate simulations of middle-level cloud albedo, precipitation, and ENSO amplitude that systematically relate to the variations in shortwave cloud feedback in this PPE. 相似文献
In association with the large solar flare of April 15, 2001, the Chacaltaya neutron monitor observed a 3.6σ enhancement of the counting rate between 13:51 and 14:15 UT. Since the enhancement was observed beginning 11 min before the GLE, solar neutrons must be involved in this enhancement. The integral energy spectrum of solar neutrons can be expressed by a simple power law in energy with the index γ=-3.0±1.0. On the other hand, an integral energy spectrum of solar protons has been obtained in the energy range between 650 MeV and 12 GeV. The spectrum can also be expressed by a power law with the power index γ=-2.75±0.15. The flux of solar protons observed at Chacaltaya (at 12 GeV) was already one order less than the flux of the galactic cosmic rays. It may be the first simultaneous observation of the energy spectra of both high-energy protons and neutrons. Comparing the Yohkoh soft X-ray telescope images with the observed particle time profiles, an interesting picture of the particle acceleration mechanism has been deduced. 相似文献
The temperature distribution at depth is a key variable when assessing the potential of a supercritical geothermal resource as well as a conventional geothermal resource. Data-driven estimation by a machine-learning approach is a promising way to estimate temperature distributions at depth in geothermal fields. In this study, we developed two methodologies—one based on Bayesian estimation and the other on neural networks—to estimate temperature distributions in geothermal fields. These methodologies can be used to supplement existing temperature logs, by estimating temperature distributions in unexplored regions of the subsurface, based on electrical resistivity data, observed geological/mineralogical boundaries, and microseismic observations. We evaluated the accuracy and characteristics of these methodologies using a numerical model of the Kakkonda geothermal field, Japan, where a temperature above 500 °C was observed below a depth of about 3.7 km. When using geological and geophysical knowledge as prior information for the machine learning methods, the results demonstrate that the approaches can provide subsurface temperature estimates that are consistent with the temperature distribution given by the numerical model. Using a numerical model as a benchmark helps to understand the characteristics of the machine learning approaches and may help to identify ways of improving these methods.
Laboratory measurements of ultrasonic wave propagation in tuffaceous sandstone (Kimachi, Japan) and granite (Iidate, Japan) were performed during increasing fracturing of the samples. The fracturing was achieved by unconfined uniaxial compression up to and beyond the point of macrofracture of the specimen using a constant low strain rate. The observed variation of wave velocity (up to 40 per cent) due to the development of micro- and macrofractures in the rock is interpreted by rock models relating velocity changes to damage and crack density. The calculated density of the newly formed cracks reaches higher values for the sandstone than for the granite. Using the estimated crack densities, the attenuation behaviour is interpreted in terms of different attenuation mechanisms; that is, friction and scattering. Rayleigh scattering as described by the model of Hudson (1981 ) may explain the attenuation qualitatively if the largest plausible crack dimensions are assumed in modelling. 相似文献
Seawater samples were collected in the North Pacific along 175°E during a cruise of the Northwest Pacific Carbon Cycle Study (NOPACCS) program in 1994. Many properties related to the carbonate system were analyzed. By using well-known ratios to correct for chemical changes in seawater, the CO2 concentration at a given depth was back calculated to its initial concentration at the time when the water left the surface in winter. We estimated sea-surface CO2 and titration alkalinity (TA) in present-day winter, from which we evaluated the degree of air-sea CO2 disequilibrium in winter was. Using a correction factor for air-sea CO2 disequilibrium in winter, we reconstructed sea-surface CO2 in pre-industrial times. The difference between the back-calculated initial CO2 and sea-surface CO2 in pre-industrial times should correspond to anthropgenic CO2 input. Although the mixing of different water masses may cause systematic error in the calculation, we found that the nonlinear effect induced by the mixing of different water masses was negligible in the upper layer of the North Pacific subtropical gyre along 175°E. The results of our improved method of assessing the distribution of anthropogenic CO2 in that region show marked differences from those obtained using the previous back-calculation method. 相似文献