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81.
Tianjun Zhou Bo Wu A. A. Scaife S. Brönnimann A. Cherchi D. Fereday A. M. Fischer C. K. Folland K. E. Jin J. Kinter J. R. Knight F. Kucharski S. Kusunoki N.-C. Lau Lijuan Li M. J. Nath T. Nakaegawa A. Navarra P. Pegion E. Rozanov S. Schubert P. Sporyshev A. Voldoire Xinyu Wen J. H. Yoon N. Zeng 《Climate Dynamics》2009,33(7-8):1051-1068
A multi-model set of atmospheric simulations forced by historical sea surface temperature (SST) or SSTs plus Greenhouse gases and aerosol forcing agents for the period of 1950–1999 is studied to identify and understand which components of the Asian–Australian monsoon (A–AM) variability are forced and reproducible. The analysis focuses on the summertime monsoon circulations, comparing model results against the observations. The priority of different components of the A–AM circulations in terms of reproducibility is evaluated. Among the subsystems of the wide A–AM, the South Asian monsoon and the Australian monsoon circulations are better reproduced than the others, indicating they are forced and well modeled. The primary driving mechanism comes from the tropical Pacific. The western North Pacific monsoon circulation is also forced and well modeled except with a slightly lower reproducibility due to its delayed response to the eastern tropical Pacific forcing. The simultaneous driving comes from the western Pacific surrounding the maritime continent region. The Indian monsoon circulation has a moderate reproducibility, partly due to its weakened connection to June–July–August SSTs in the equatorial eastern Pacific in recent decades. Among the A–AM subsystems, the East Asian summer monsoon has the lowest reproducibility and is poorly modeled. This is mainly due to the failure of specifying historical SST in capturing the zonal land-sea thermal contrast change across the East Asia. The prescribed tropical Indian Ocean SST changes partly reproduce the meridional wind change over East Asia in several models. For all the A–AM subsystem circulation indices, generally the MME is always the best except for the Indian monsoon and East Asian monsoon circulation indices. 相似文献
82.
East Asian summer monsoon simulation by a 20-km mesh AGCM 总被引:1,自引:0,他引:1
East Asian summer monsoon climate simulated by a global 20-km mesh atmospheric general circulation model (AGCM) forced by
the global sea surface temperature during the period 1979–1998 is investigated. In comparison with a lower resolution (180-km
mesh) model experiment, it is revealed that the 20-km mesh AGCM shows the superiority in simulating orographic rainfall not
only its location but also its amount. The Baiu frontal structure is also better simulated in the higher resolution model,
which leads to stronger Baiu rainfall. The 20-km model also shows more intense extremes in precipitation. Interannual variability
of June–August mean precipitation and seasonal march of the monsoon rain band are also investigated.
This paper is a contribution to the AMIP-CMIP Diagnostic Sub-project on General Circulation Model Simulation of the East Asian
Climate, coordinated by W.-C. Wang. 相似文献
83.
Nguyen Dinh Duong Shoji Takeuchi 《ISPRS Journal of Photogrammetry and Remote Sensing》1997,52(6):253-260
The image analysis system ASEAN (Advanced System for Environmental ANalysis with Remote Sensing Data) was designed and programmed by a software development group, ImaSOFr, Department of Remote Sensing Technology and GIS, Institute for Geography, National Centre for Natural Science and Technology of Vietnam under technical cooperation with the Remote Sensing Technology Centre of Japan and financial support from the National Space Development Agency of Japan. ASEAN has been in continuous development since 1989, with different versions ranging from the simplest one for MS-DOS with standard VGA 320×200×256 colours, through versions supporting SpeedStar 1.0 and SpeedStar PRO 2.0 true colour graphics cards, up to the latest version named WinASEAN, which is designed for the Windows 3.1 operating system. The most remarkable feature of WinASEAN is the use of algorithms that speed up the image analysis process, even on PC platforms. Today WinASEAN is continuously improved in cooperation with NASDA (National Space Development Agency of Japan), RESTEC (Remote Sensing Technology Center of Japan) and released as public domain software for training, research and education through the Regional Remote Sensing Seminar on Tropical Eco-system Management which is organised by NASDA and ESCAR In this paper, the authors describe the functionality of WinASEAN, some of the relevant analysis algorithms, and discuss its possibilities of computer-assisted teaching and training of remote sensing. 相似文献
84.
Shoji Arai 《Contributions to Mineralogy and Petrology》1975,52(1):1-16
The Tari-Misaka ultramafic complex, which is emplaced into the Paleozoic sediments and thermally metamorphosed by two younger granitic masses, is divided into four zones on the basis of the mineral assemblage. They are, in order of increasing metamorphic grade: Zone I antigorite-olivine-orthopyroxene-clinopyroxene. Zone II olivine-talc. Zone III olivine-anthophyllite. Zone IV olivine-orthopyroxene. Strongly serpentinized clinopyroxene-bearing harzburgite in Zone I is similar to ordinary Alpine-type harzburgite. In Zonne II, two kinds of olivine are recognized. One is Mg-rich olivine (Fo93 to Fo97) with opaque inclusions and is probably a recrystallization product of serpentine with talc. The other is Fe-rich olivine (Fo88 to Fo93) free of opaque inclusions and is probably a relic of the primary peridotite. Olivine in Zone III and Zone IV is also relatively Mg-rich (Fo91 to Fo95). Chromitite in Zone IV commonly has an assemblage, olivine+cordierite+Mg-Al spinel (Mg/Mg+Fe2+, more than 0.9). Enstatite is rare and coexists with less magnesian Mg-Al spinel (Mg/Mg+Fe2+, less than 0.9). Petrological and mineralogical characters of the ultramafic rocks can be well explained by thermal metamorphism of strongly serpentinized peridotite by granitic intrusion. Metamorphic zones are consistent with the experimental results in the system MgO-SiO2-H2O. The assemblage olivine+cordierite indicates that the metamorphism occurred at relatively low pressures (<3kb). 相似文献
85.
Shoji?NishimotoEmail author Hidekazu?Yoshida Yoshihiro?Asahara Tadahiko?Tsuruta Masayuki?Ishibashi Nagayoshi?Katsuta 《Contributions to Mineralogy and Petrology》2014,167(1):960
Episyenite is a quartz-depleted vuggy rock resulting from hydrothermal alteration of granitic rocks. This is the first report of its existence in an island arc, which is identified in a deep drill core of the Toki Cretaceous granite distributed in central Japan. In order to understand the petrographical features of the episyenite, neutron porosity measurement, geochemical analysis, microscopic observation, and X-ray computed tomography scanning were carried out. The results show remarkably high porosity (35.4 %) due to interconnecting vugs and the removal of quartz, plagioclase, and biotite. The Rb–Sr isotopic results and the paragenetic sequence of secondary minerals in the vugs suggest that the hydrothermal alteration process can be divided into an episyenitization stage and a later hydrothermal stage. At the episyenitization stage (70.6 ± 3.1 Ma) ca. 6 million years after the emplacement of the unaltered granite (76.3 ± 1.5 Ma), dissolution of quartz, biotite, and plagioclase occurred and was followed by the precipitation of albite, vermicular chlorite, and platy calcite. The episyenitization is considered as a local alteration of the Toki granite in an isotopically closed system. At the later hydrothermal stage, illite and secondary quartz precipitated from circulating meteoric-derived water in the dissolution vugs. Superimposing alteration at the later hydrothermal stage is limited, which results in the preservation of the episyenite in an almost primitive condition. 相似文献
86.
Recent studies on mineralogy, geochronology, fluid inclusion and stable isotope (Pb, Os, S, C, O, Sr) characteristics were reviewed to determine constraints for genetic models of the Chilean manto‐type copper deposits. The Chilean manto‐type deposits are divided into the two geologic categories of the northern areas (Arica–Iquique, Tocopilla–Taltal) and the central areas (Copiapó, La Serena, Santiago). The former is distributed in the coastal range composed of Jurassic andesite‐dominated volcano‐sedimentary piles and younger plutonic intrusions, and yields chalcocite (‐digenite) and bornite as the principal hypogene copper sulfides. The latter is hosted mostly in Lower Cretaceous volcano‐sedimentary sequences, and has chalcopyrite‐rich mineral associations. The fluid inclusion data indicate that the primary copper mineralization was commonly generated in the temperature range 150–360°C under low‐pressure conditions near the boiling curve, mediated with relatively saline brines. Generally, homogeneous Pb and S isotope compositions for primary copper minerals imply direct magma source or leaching of igneous rocks. Pb and Os isotope data published for some deposits, however, suggest that ore‐forming metals were derived mainly from the volcano‐sedimentary host rocks. The noticeably negative isotope ratios of primary sulfide sulfur and hydrothermal calcite carbon of some central area deposits indicate influx of sedimentary rock components, and the high 87Sr/86Sr initial ratios of hydrothermal calcite from the Tocopilla–Taltal area deposits imply contribution of the contemporaneous seawater or marine carbonates. These isotopic constraints imply a formation mechanism in which the Chilean manto‐type copper deposits formed epigenetically in the process of hydrothermal interaction of non‐magmatic surface‐derived brine with the volcano‐sedimentary host rocks, which is inferred to have been induced by a deep‐seated plutonic complex as the possible heat source. 相似文献
87.
Ishimaru Satoko; Arai Shoji; Ishida Yoshito; Shirasaka Miki; Okrugin Victor M. 《Journal of Petrology》2007,48(2):395-433
88.
Origin of Neoproterozoic ophiolitic peridotites in south Eastern Desert, Egypt, constrained from primary mantle mineral chemistry 总被引:1,自引:0,他引:1
The ophiolitic peridotites in the Wadi Arais area, south Eastern Desert of Egypt, represent a part of Neoproterozoic ophiolites of the Arabian-Nubian Shield (ANS). We found relics of fresh dunites enveloped by serpentinites that show abundances of bastite after orthopyroxene, reflecting harzburgite protoliths. The bulk-rock chemistry confirmed the harzburgites as the main protoliths. The primary mantle minerals such as orthopyroxene, olivine and chromian spinel in Arais serpentinites are still preserved. The orthopyroxene has high Mg# [=Mg/(Mg + Fe2+)], ~0.923 on average. It shows intra-grain chemical homogeneity and contains, on average, 2.28 wt.% A12O3, 0.88 wt.% Cr2O3 and 0.53 wt.% CaO, similar to primary orthopyroxenes in modern forearc peridotites. The olivine in harzburgites has lower Fo (93?94.5) than that in dunites (Fo94.3?Fo95.9). The Arais olivine is similar in NiO (0.47 wt.% on average) and MnO (0.08 wt.% on average) contents to the mantle olivine in primary peridotites. This olivine is high in Fo content, similar to Mg-rich olivines in ANS ophiolitic harzburgites, because of its residual origin. The chromian spinel, found in harzburgites, shows wide ranges of Cr#s [=Cr/(Cr + Al)], 0.46?0.81 and Mg#s, 0.34?0.67. The chromian spinel in dunites shows an intra-grain chemical homogeneity with high Cr#s (0.82?0.86). The chromian spinels in Arais peridotites are low in TiO2, 0.05 wt.% and YFe [= Fe3+/(Cr + Al + Fe3+)], ~0.06 on average. They are similar in chemistry to spinels in forearc peridotites. Their compositions associated with olivine’s Fo suggest that the harzburgites are refractory residues after high-degree partial melting (mainly ~25?30 % partial melting) and dunites are more depleted, similar to highly refractory peridotites recovered from forearcs. This is in accordance with the partial melting (>20 % melt) obtained by the whole-rock Al2O3 composition. The Arais peridotites have been possibly formed in a sub-arc setting (mantle wedge), where high degrees of partial melting were available during subduction and closing of the Mozambique Ocean, and emplaced in a forearc basin. Their equilibrium temperature based on olivine?spinel thermometry ranges from 650 to 780 °C, and their oxygen fugacity is high (Δlog ?O2?=?2.3 to 2.8), which is characteristic of mantle-wedge peridotites. The Arais peridotites are affected by secondary processes forming microinclusions inside the dunitic olivine, abundances of carbonates and talc flakes in serpentinites. These microinclusions have been formed by reaction between trapped fluids and host olivine in a closed system. Lizardite and chrysotile, based on Raman analyses, are the main serpentine minerals with lesser antigorite, indicating that serpentines were possibly formed under retrograde metamorphism during exhumation and near the surface at low T (<400 °C). 相似文献
89.
L.G Austin K Shoji V.K Bhatia F.F Aplan 《International Journal of Mineral Processing》1974,1(2):107-123
The Alyavdin equation for batch grinding data is: where P(χ,t) is the weight fraction less than size χ after grinding time t, c (χ) is constant with t and p is a constant close to one. It is shown that this equation is illogical (except for a single size of feed) unless c (χ) varies with P(χ,0), which makes the equation of little utility. A new empirical equation is developed for finite size intervals: which reduces to the Alyavdin equation for a single size of feed, and which gives consistent computations for any feed size distribution. Techniques are given for determining Ki, γ values from sets of batch grinding data. The values are then used to predict size distributions for other times and other feed size distributions. The equation was quite successful in predicting size distributions in batch milling: (a) providing the feed size distribution was not un-natural, that is, not truncated or (b) if a truncated feed was used, the values of Ki and γ are determined from size distributions of grinding of the same type of feed. Thus, Ki, γ are not, unfortunately, completely independent of the starting feed size distribution. 相似文献
90.
We found extremely high-Mg# (=Mg/(Mg + total Fe) atomic ratio) ultramafic rocks in Avacha peridotite suite. All the high-Mg#
rocks have higher modal amounts of clinopyroxene than ordinary Avacha peridotite xenoliths, and their lithology is characteristically
heterogeneous, varying from clinopyroxenite through olivine websterite to pyroxene-bearing dunite. The Mg# of minerals is
up to 0.99, 0.98 and 0.97 in clinopyroxene, orthopyroxene and olivine, respectively, decreasing progressively toward contact
with dunitic part, if any. The petrographical feature of pyroxenes in the high-Mg# pyroxenite indicates their metasomatic
origin, and high LREE/HREE ratio of the metasomatic clinopyroxene implies that the pyroxenites are the products of reaction
between dunitic peridotites and high-Ca, silicate-rich fluids. The lithological variation of the Avacha high-Mg# pyroxenites
from clinopyroxenite to olivine websterite resulted from various degrees of fluid-rock reaction coupled with fractional crystallization
of the high-Ca fluids, which started by precipitation of high-Mg# clinopyroxene. Such fluids were possibly generated originally
at a highly reduced serpentinized peridotite layer above the subducting slab. The fluids can reach the uppermost mantle along
a shear zone as a conduit composed of fine-grained peridotite that developed after continent-ward asthenospheric retreats
from the mantle wedge beneath the volcanic front. The fluids are incorporated in mantle partial melts when the magmatism is
activated by expansion of asthenosphere to mantle wedge beneath the volcanic front. 相似文献