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991.
In this paper we document the correlationship between sea surface temperature(SST) and low level-winds such as sea level wind and 850 hPa wind in the South China Sea(SCS) based on COADS(1958-1987) and ECMWF objective analysis data(1973-1986).Further statistical analyses tell us that there is a fixed SCS basin mode for variations both of SST and low-level winds in the region on the interannual time scale due to air-sea interactions.A simplified,coupled model that is designed following the McCreary and Anderson's(1985) model and includes the feedback between the upper ocean and the circulation of East Asian monsoon demonstrates an interannual oscillation in the coupled air-sea system,which is similar to the observations in the SCS. 相似文献
992.
A coupled model,which is employed to study the dominating factor and key area of El Nino cycle formation,consists of a dynamical ocean model and a statistical atmospheric model.The coupled model with seasonal forcing successfully reproduces the El Nino event cycle which exhibits quasi-regular oscillations with a preferred period of about 4 years.The results show that the heat content(HC) is transported between the eastern and the western tropical Pacific areas.The spatial distribution of HC anomalies for four phases of the whole cycle clearly shows a possible formation mechanism of El Nino.Experiments further suggest that sea surface temperature in the tropical Pacific and HC in the central tropical Pacific are the most important factors and the central tropical Pacific is the most important area for determining formation of El Nino cycle. 相似文献
993.
本文研究适用于ICF实验的CT技术,并已用于“星光Ⅱ”装置的激光等离子体的实验X光测量,重建出X光的三维分布,获得了有意义的结果,表明该技术在ICF实验中的应用的可能性。 相似文献
994.
第14届世界无损检测大会工业CT的层析成像技术 总被引:2,自引:0,他引:2
介绍了新近14届世界无损检测大会有关情况,并对工业CT的发展动态进行了简要的分析。 相似文献
995.
996.
在河北省怀来县后郝窑地区,对地下气体运移变化的影响因素进行了野外模拟实验研究。选择3个试验点,对地下气体的扩散作用,物理化学影响因素及水压效应等进行了模拟实验,主要研究H2,CO2气体运移变化机制。实验研究表明,H2,CO2气体运移变化机制不尽相同,水压效应对H2,CO2等地下气体运移影响相当明显 相似文献
997.
华北夏季旱涝的前期环流异常及其与北太平洋海温的关系 总被引:10,自引:1,他引:10
文章分析了华北地区夏季旱涝的前期春季大气环流和北太平洋海温异常(SSTA)分布特征,探讨SSTA与异常环流的关系,并用OSU-AGCM进行黑潮地区热源异常强迫的数值试验.结果表明,当春季北极低涡明显减弱,欧亚大陆中高纬度地区纬向环流加强,西太平洋副高位置偏北偏西,且存在负PNA型异常环流时,华北地区夏季多雨涝;反之则少雨干旱.此时,西北太平洋和赤道东太平洋SST分别存在较大的正、负异常,它们与春季环流异常密切相关,黑潮区SSTA对北半球副热带及其以北的大气环流产生显著影响,正的SSTA是造成华北夏涝年的前期春季异常环流形势的重要因素. 相似文献
998.
砂岩岩脉(岩墙、岩床)的一种可能成因——冲蚀沟槽的充填 总被引:2,自引:0,他引:2
钟建华 《沉积与特提斯地质》1997,17(2):32-36
黄河三角洲的边滩、心滩上发育了大量冲蚀沟槽(冲槽).这些冲蚀沟槽深数厘米至1m~2m,宽数厘米至数米,长数十厘米至十几、二十余米,但以深数十厘米,宽数厘米至十余厘米,长数米者多见。形态多样,有直立板片状、直立楔状、“⊥”状、梯形状、“U”形状及树枝状等,其内有时被风成砂充填。经成岩作用后,它们便会转变成砂岩岩脉(岩墙、岩床)。因此,冲蚀沟槽的(砂)充填可能是一种砂岩岩脉(岩墙、岩床)的形成方式. 相似文献
999.
Advances in energy-dispersive X-ray fluorescence 总被引:1,自引:0,他引:1
Utz Kramar 《Journal of Geochemical Exploration》1997,58(1):73-80
Recently, two new instruments for X-ray fluorescence analysis (XRF) with interesting features for geochemical applications came to the market. Both instruments were designed to improve the peak to background ratio, the principal factor limiting the sensitivity of XRF. Total reflection XRF (TXRF) was designed to analyse extremely small sample amounts. An instrument, using polarised X-rays (P-XRF) for excitation, is designed to reduce scattered background in spectra of bulk samples. The performance of both instruments was compared with conventional XRF-methods and ICP/MS. Results for GXR-1, GXR-2, GXR-3, GXR-4 and GXR-6 obtained with TXRF and P-XRF are in good agreement with literature data. The effective amount of sample, analysed by TXRF was 200 μg only and detection limits of ~ l μg/g were achieved. P-XRF shows considerable improved detection limits (0.25–0.5 μg/g) for bulk samples for elements with atomic numbers 42–51 (Mo-Sb) compared with conventional XRF-methods. 相似文献
1000.
Partial melting during tectonic exhumation of a granulite terrane: an example from the Larsemann Hills, East Antarctica 总被引:23,自引:0,他引:23
C. J. CARSON R. POWELL C. J. L. WILSON & P. H. G. M. DIRKS 《Journal of Metamorphic Geology》1997,15(1):105-126
Anatectic migmatites in medium- to low-pressure granulite facies metasediments exposed in the Larsemann Hills, East Antarctica, contain leucosomes with abundant quartz and plagioclase and minor interstitial K-feldspar, and assemblages of garnet–cordierite–spinel–ilmenite–sillimanite. Qualitative modelling in the system K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–O2, in conjunction with various P–T calculations indicate that the high-grade retrograde evolution of the terrane was dominated by decompression from peak conditions of c. 7 kbar at c. 800 °C to 4–5 kbar at c. 750 °C. Extensive partial melting during decompression involved the replacement of biotite by the assemblage cordierite–garnet–spinel within the leucosomes. These leucosomes represent the site of partial melt generation, the cordierite–garnet–spinel–ilmenite assemblage representing the solid products and excess reactants from the melting reaction. The extraction and accumulation of this decompression-generated melt led to the formation of syntectonic pegmatites and extensive granitic plutons. Leucosome development and terrane decompression proceeded during crustal transpression, synchronous with upper crustal extension, during a progressive Early Palaeozoic collisional event. Subsequent retrograde evolution was characterized by cooling, as indicated by the growth of biotite replacing spinel and garnet, thin mantles of cordierite replacing spinel and quartz within metapelites, and garnet replacing orthopyroxene and hornblende within metabasites. P–T calculations on late mylonites indicate lower grade conditions of formation of c. 3.5 kbar at c. 650 °C, consistent with the development of late cooling textures. 相似文献