河西走廊东部近57年不同等级冷空气时空变化特征及寒潮分析

利用河西走廊东部5个国家气象观测站1961—2017年的日最低气温,统计分析其5个等级冷空气的时空变化和降温幅度,并用NCEP月平均500 hPa位势高度场、风场分析本地寒潮显著极端年的特征。结果表明:(1)冷空气年均日数:Ⅰ级最多,Ⅳ和Ⅴ级基本接近,Ⅲ级最少。空间分布Ⅰ级偏北沙漠区少、中部平原区多;其余四级分布均为偏北沙漠区偏多。时间分布Ⅱ、Ⅳ和Ⅴ级春季4—5月最多,夏季最少;Ⅲ级集中在夏季7—8月;Ⅰ级月季出现频率接近,夏季8月略多。(2)年降温日数Ⅴ和Ⅳ级呈明显减少趋势,Ⅰ～Ⅲ级线性不明显,但Ⅰ和Ⅱ级增多。年均降温频数的年代际差异不大,整体呈先降后升,但其主要周期有差异。(3)平均降温幅度季节变化只有Ⅴ级明显,Ⅳ级相近,而Ⅰ～Ⅲ级最大分别出现在春季、秋季和夏季;Ⅴ级24 h、48 h、72 h最大降温幅度分别为9.9、12.2、14.3 ℃。(4)寒潮次数有12个极端年,显著偏多(少)年寒潮天数差异10月最大,夏季较小。河西走廊东部500 hPa位势高度场在显著偏多年为明显的西北气流控制,配合负距平中心;乌拉尔山脊前有极地干冷空气输送有利于寒潮天气发生。偏少年以纬向平直西风气流为主,有明显的正距平高度,冷空气下滑少降温不易发生。     

Geothermobarometry of mafic granulites and metapelite from the Palghat Gap, South India: petrological evidence for isothermal uplift and rapid cooling

The Palghat Gap region is located near the centre of the large southern Indian granulite terrane. at the northern edge of the Kodaikanal charnockite massif. The dominant rock types in the region are hornblende-biotite ± orthopyroxene gneisses and charnockites along with minor amounts of intercalated mafic granulite, metapelite and calc-silicate. The P-T estimates from garnetiferous mafic granulites and metapelite samples are generally in the range 9-10 kbar and 800-900 C using both conventional thermobarometric methods and the TWEEQU thermobarometry program. These P-T estimates, which should be taken as minimum values, are among the highest yet reported for South Indian and Sri Lankan granulites. The occurrence of orthopyroxene + plagioclase symplectites around embayed garnet grains in the mafic granulites and cordierite rims around garnet grains in metapelite suggest an isothermal decompression-type path. Similarly, a core-rim P-T trajectory indicates c. 3 and 7 kbar decompression at high temperature in the mafic granulites and metapelite, respectively. In both rock types, the key to the determination of the retrograde P-T path was the recognition of small amounts of second generation plagioclase with a more anorthitic composition than the matrix plagioclase. The preservation of high garnet-pyroxene temperatures in the mafic granulites (despite small garnet grain size) suggests rapid cooling of the terrane. Calculated minimum cooling rates range from 8 to 80 C Ma^-1. Such cooling rates are more rapid than those associated with normal isostatic processes and suggest that the terrane was tectonically exhumed at high temperature.     

Chronology and cooling history of the Tianmenshan pluton in South Jiangxi Province and their geological significance

Geochronological studies on the crust-derived Tianmenshan pluton were undertaken by SHRIMP zircon U-Pb dating and Ar-Ar dating of biotite, muscovite and K-feldspar, giving a petrogenetic age of 167 Ma. Owing to the closure systems in different minerals, the cooling history of the pluton can be determined with an age-temperature diagram. The late hydrothermal event has been recognized, which is related probably with mineralization. In terms of the comparative geochronological and petrologic records, it is concluded that there are some constrains on tectonic evolution and that the formation of the Tianmenshan pluton proceeded in a transition period from Indosinian post-orogeny extension to strong compressive tectonics. And the timing of the hydrothermal event matches the compressive climax of the Yanshanian orogeny. The temporal gap between granite emplacement and wolframite mineralization could last 10-20 Ma owing to the low cooling rate of the pluton.     

Geochemical characteristics,cooling history and mineralization significance of Zhangtiantang pluton in South Jiangxi Province,P.R. China

The zircon SHRIMP dating of the Zhangtiantang granite gave an age of 159±7 Ma., which shows that the granite was produced at the early Late Jurassic. The Ar-Ar plateau ages of biotite and K-feldspar from the Zhangtiantang pluton are 153.2±1.1 Ma and 135.8±1.2 Ma, respectively. The Ar-Ar anti-isochrone ages of biotite and K-feldspar are 152.5±1.7Ma and 135.4±2.7Ma, respectively. The ages represent the isotopic closure ages of minerals in the pluton. The Zhangtiantang granites are regarded as peraluminous crust-derived type granites to possess the typical geochemical characteristics of calc-alkaline rocks on continental margin, with enriched Si, K, Al (average value of A/CNK as 1.18), HREE, Rb, U, and Th, heavily depleted V, Cr, Co, Ni, Ti, Nb-Ta, Zr, Sr, P, and Ba, strongly negative Eu and common corundum normative (average value of C as 1.84). The εNd_(t) values of the Zhangtiantang granite are −5.84 to −7.79, and t _2DM values are 1.69 to 1.83 Ga, which indicates partial melting of continental-crust metamorphic sedimentary rocks during the Middle Proterozoic. The cooling history of the Zhangtiantang granitic pluton indicates that the cooling velocity of pluton was faster (about 67°C/Ma) from zircon (158 Ma) to biotite (152 Ma), and was slower (about12°C/Ma) from biotite (152.5 Ma) to K-feldspar (135.8 Ma). It can be deduced that the temporal gap (about 10 Ma) between the granite formmation and W-Sn mineralization in South China may be related to ordinary magma-hydrothermal processes by the variational cooling curve of the pluton. The Zhangtiantang pluton was formed in a compressive setting, with differentiation evolution and mineralization occurring in a relative relaxation setting.     

A 3D discrete FEM iterative algorithm for solving the water pipe cooling problems of massive concrete structures

Water pipe cooling has been widely used for the temperature control and crack prevention of massive concrete structures such as high dams. Because both under‐cooling and over‐cooling may reduce the efficiency of crack prevention, or even lead to great harm to structures, we need an accurate and robust numerical tool for the prediction of cooling effect. Here, a 3D discrete FEM Iterative Algorithm is introduced, which can simulate the concrete temperature gradient near the pipes, as well as the water temperature rising along the pipes. On the basis of the heat balance between water and concrete, the whole temperature field of the problem can be computed exactly within a few iteration steps. Providing the pipe meshing tool for building the FE model, this algorithm can take account of the water pipe distribution, the variation of water flow, water temperature, and other factors, while the traditional equivalent algorithm based on semi‐theoretical solutions can only solve problems with constant water flow and water temperature. The validation and convergence are proved by comparing the simulated results and analytical solutions of two standard second‐stage cooling problems. Then, a practical concrete block with different cooling schemes is analyzed and the influences of cooling factors are investigated. In the end, detailed guidance for pipe system optimization is provided. Copyright © 2015 John Wiley & Sons, Ltd.     

Partial melting during tectonic exhumation of a granulite terrane: an example from the Larsemann Hills, East Antarctica

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.     

黄海海雾WRF数值模拟中垂直分辨率的敏感性研究

基于WRF模式探究不同垂直分辨率下模式对黄海海雾的模拟表现。将3种垂直分层方案（35η、44η与63η）和2种边界层方案（YSU、MYNN）组合,对10次海雾做模拟研究。统计分析了水平雾区与雾顶高度对垂直分辨率的敏感性,并利用1次典型个例剖析了雾顶长波辐射与雾体湍流的作用。统计结果显示,提高垂直分辨率能显著改进水平雾区的模拟效果,改善明显的个例在不同垂直分辨率试验下的雾顶高度差异也较大;YSU方案相比于MYNN方案更敏感,从35η层增至44η层其试验个例的击中率（POD）和公正预兆得分（ETS）的平均改进率分别提高了13.29%和10.22%。典型个例研究结果揭示,模式对雾顶长波辐射和雾体湍流作用的模拟程度强烈依赖垂直分辨率：粗垂直分辨率给出的湍流强度很弱,导致模拟失败;雾顶存在“云水含量增多→长波辐射增强→降温加大→云水含量增多”的正反馈过程,细垂直分辨率比粗垂直分辨率更容易维持与增强此反馈;只有细垂直分辨率才能模拟出雾顶长波辐射冷却产生的贯穿雾体直抵海面、强度不弱于近海面机械湍流的浮力湍流,它导致雾体降温而出现符合观测事实的海温高于气温的现象。     

Two attempts of study of seismic source from teleseismic data by simulated annealing non-linear inversion

Two seismic source studies usingteleseismic data are performed by Simulated Annealing(SA), a non-linear inversion method. The Very FastSimulated Annealing (VFSA) algorithm is used and onlyteleseismic data are inverted. We have designed a fastand efficient way of multiple direct problemevaluation, which is based on pre-calculating theelementary Green's function. During the process we setthe values of the inversion control parameters(temperature, number of iterations) and modified thecooling schedule. In the current version, theinversion seeks for the point source mechanism, thedepth of the source, the scalar moment and the sourcetime function (STF). The method is applied to twoearthquakes: 18 Nov. 1992 in Greece, M 5.9 and 14 Sep.1995 in Mexico, M7.3. The calculation is performed ona simple 1D model of the structure. For the firstearthquake the inversion recovered the solution fairlywell; for the second the solution was less acceptable.However, we do not consider this fact to be a failureof the method, but a consequence of an inadequatemodel of the source and of the medium structure. Acasual attempt of reliability determination was alsoperformed; the obtained values of errors arereasonable, except for a few cases when the methodfailed.     

多接收电感耦合等离子体质谱Cu同位素测定中的干扰评估

多接收电感耦合等离子体质谱（MC—ICP—MS）是高精度测定铜同位素的新方法,然而在测定中也可能存在干扰。为此对MC—ICPMS Cu同位素测定中的可能干扰进行了评估。主要包括以下方面的内容：（1）对所用标准物质和试剂进行了纯化,所用标准物质和试剂对Cu同位素的同质异位素干扰可以忽略;（2）运用K和／参数进行了讨论,其中K为样品中的Cu浓度与标准溶液中Cu浓度的比值,f为在一定Cu浓度的标准溶液中干扰信号相对于^63Cu真实信号的比值。理论模拟表明,当K值小于1时,即使在质量为63处的干扰很小,对ε^65 Cu的影响也可能很大;（3）通过对理论模拟结果与实际测定结果的对比,发现对所用的试剂而言质量数为65的干扰可以忽略不计;（4）实际测定结果表明,当样品中Cu的浓度是标样中Cu的浓度的0．5～4倍时,测试获得的样品的ε^65值与其真值在误差范围内一致;（5）对潜在的基质效应重点研究了Fe和Co对Cu同位素测定的影响。实验结果表明,当Fe／Cu〈100,Co／Cu〈7时,Fe,Co不影响Cu同位素比值的测定;（6）10个月的重现性研究结果为ε^65=3．5±1．0（2SD）。该测定值在误差范围内与文献报道的值一致     

Urban stormwater thermal gene expression models for protection of sensitive receiving streams

Thermal impact of typical high‐density residential, industrial, and commercial land uses is a major concern for the health of aquatic life in urban watersheds, especially in smaller, cold, and cool‐water streams. This is the first study of its kind that provides simple easy‐to‐use equations, developed using gene expression programming (GEP) that can guide the assessment and the design of urban stormwater management systems to protect thermally sensitive receiving streams. We developed 3 GEP models using data collected during 3 years (2009–2011) from 4 urban catchments; the first GEP model predicts event mean temperature at the inlet of the pond; the second model predicts the stormwater temperature at the outlet of the pond; and the third model predicts the temperature of the stormwater after flowing through a cooling trench and before discharging to the receiving stream. The new models have high correlation coefficients of 0.90–0.94 and low prediction uncertainty of less than 4% of the median value of the predicted runoff temperatures. Sensitivity analysis shows that climatic factors have the highest influence on the thermal enrichment followed by the catchment characteristics and the key design variables of the stormwater pond and the cooling trench. The general method presented here is easily transferable to other regions of the world (but not necessarily the exact equations developed here); also through sensitivity and parametric analysis, we gained insight on the key factors and their relative importance in modelling thermal enrichment of urban stromwater runoff.