森林下垫面陆面物理过程及局地气候效应的数值模拟试验   总被引：5，自引：0，他引：5  

刘树华  邓毅  胡非  梁福明  刘和平  王建华 《气象学报》2005,63(1):1-12

文中基于大气边界层和植被冠层微气象学基本原理 ,建立了一个森林植被效应的陆面物理过程和二维大气边界层数值模式。并应用该模式进行了植被和土壤含水量等生物和生理过程在陆面过程和局地气候效应方面的数值模拟试验。所得数值模拟试验结果与实际情况相吻合。结果表明 ,应用该模式可获得植被温度、植被冠层内空气温度、地表温度日变化特征 ;森林下垫面大气边界层风速、位温、比湿、湍流交换系数的时空分布和日变化特征。该模式还可应用于不同下垫面 ,模拟陆面物理过程与大气边界层相互作用机制及其局地气候效应的研究 ,这将为气候模式与生物圈的耦合研究奠定一个良好的基础。  相似文献   

100MPa压力下温度和水对干酪根结构状态影响的实验研究   总被引：1，自引：0，他引：1  

曾贻善  吴朝东 《岩石学报》2005,21(1):245-250

为了实验验证变质沉积物中的碳质物拉曼光谱地质温度计的可用性,利用冷封口式高温高压水热系统将焊封金管内的干酪根于100MPa压力和温度(250-700℃)、有水和无水条件下处理24小时,激光拉曼探针(LRM)分析表明,实验所得碳质物的一级和二级拉曼谱特征(拉曼峰的存在、峰的位置、宽度、高度和面积)随温度系统地变化,所得碳质物的D/O比值随温度升高而减小,但在D/O比-温度关系图上-500℃处有一拐点(极小)。实验条件下处理的干酪根的显微富利叶变换红外谱(micro-FTIR)分析表明,脂族C-H和芳族C-H吸收峰的相对强度在500℃左右急剧变化以及在700℃的实验产物中仍存在含氢的功能团。高温高压条件下,水的存在不利于碳质物的石墨化(有序化)。  相似文献   

Redox state of iron in peralkaline rhyolitic glass/melt: X-ray absorption micro-spectroscopy experiments at high temperature     

N. Métrich  J. Susini  F. Farges  D. Massare  S. Lequien 《Chemical Geology》2006,231(4):350-363

Assessing the ferric-ferrous ratio in magmas prior to eruption remains a challenging task. X-ray absorption near-edge structure (μXANES) spectra were collected at the iron K-edge in water-rich peralkaline silicic melt/glass inclusions trapped in quartz. These experiments were carried out between 800 and 20 °C. The chemical environment of iron was also determined in the naturally quenched samples (glass inclusions and matrix glass) and in the peralkaline rhyolitic reference glasses, with variable [Fe³⁺ / ∑Fe] ratios.In the reference glasses, both the intensity of the pre-peaks (Fe²⁺, Fe³⁺) and site geometry of iron change as the oxidation state increases. Fourfold-coordinated Fe³⁺ prevails in highly oxidised peralkaline silicic glasses, using alkalis for charge balance. The position of the pre-edge centroid of the 1s-3d transition correlates with the Fe³⁺ / ΣFe ratios that allowed calibration of the redox state of iron of our natural samples.At high temperatures, Fe²⁺ dominates in the pre-edge structure of melt inclusions. Upon cooling down to 20 °C, the intensity of the Fe³⁺ peak increases, the centroid position of the pre-edge features shifts by nearly 0.5 eV and the main edge moves slightly towards higher energies. The slower the cooling rate, the higher the ferric iron contribution. Iterative μXANES experiments performed on the same samples show that the process is reversible. However, this apparent oxidation of iron upon cooling is an artefact of changes in Fe coordination. It implies that the [Fe³⁺ / ΣFe] ratio of glassy samples, measured at 20 °C, may be overestimated by a factor > 1.7, and that this ratio cannot be reliably retrieved by probing naturally cooled glass inclusions, and most silicate glasses. High temperature μXANES experiments led first to an assessment of the ferric-ferrous ratio in the water-rich peralkaline melt in pre-eruptive magmatic conditions and second to the determination of the corresponding oxygen fugacity at 740 °C.  相似文献   

On the impossibility of measuring the general relativistic part of the terrestrial acceleration of gravity with superconducting gravimeters     

Lorenzo Iorio 《Geophysical Journal International》2006,167(2):567-569

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GRAPES模式动力框架的长期积分特征   总被引：4，自引：2，他引：4       下载免费PDF全文

胡江林沈学顺  张红亮杨学胜 王盘兴 《应用气象学报》2007,18(3):276-284

通过考虑动量表面拖曳并利用牛顿松弛方法将温度松弛到纬向对称的温度场, 对GRAPES模式的动力框架进行了长期时间积分试验。通过统计分析其积分结果表明:GRAPES模式的动力框架可以模拟出大气环流的基本特征; 随着分辨率的提高, GRAPES模式动力框架的模拟结果显示出收敛的特性; 虽然GRAPES模式动力框架采用的是能量不守衡的半隐式半拉格朗日时间积分方案, 但长期时间积分试验表明其能量基本保持稳定。这些结果显示使用GRAPES模式动力框架作大气环流和气候研究的大气动力框架是可行的, 同时也为进一步改进GRAPES模式动力框架提供了线索和依据。  相似文献   

Extraction of water and solutes from argillaceous rocks for geochemical characterisation: Methods, processes and current understanding     

Elisa Sacchi  Jean-Luc Michelot  Helmut Pitsch  Philippe Lalieux  Jean-François Aranyossy 《Hydrogeology Journal》2001,9(1):17-33

This paper summarises the results of a comprehensive critical review, initiated by the OECD/NEA "Clay Club," of the extraction techniques available to obtain water and solutes from argillaceous rocks. The paper focuses on the mechanisms involved in the extraction processes, the consequences on the isotopic and chemical composition of the extracted pore water and the attempts made to reconstruct its original composition. Finally, it provides some examples of reliable techniques and information, as a function of the purpose of the geochemical study. Electronic Publication  相似文献   

一次路径偏北南折的秋季江淮气旋成因分析          下载免费PDF全文

刘雪映  高山红 《山东气象》2018,38(1):17-26

2015年11月5—8日发生的一次江淮气旋具有与以往过程不同的特征,发生时间晚、路径偏北东移、途经山东半岛后又南折,导致山东半岛连续降水36 h,降水时段内累积降水量最大接近50 mm。为揭示上述特点的成因,利用FNL（Final Analysis Data of Global Forecast System）再分析数据进行了天气形势分析,结果表明：副热带高压位置偏北且强度较强是导致气旋过程发生时间偏晚、路径偏北东移的重要原因,而副热带高压的异常变化与2015年强厄尔尼诺事件有很强的关联性。借助WRF（Weather Research and Forecasting）数值试验探究了气旋过程路径偏北又南折的原因,发现：1）黄海的高海温有利于海面水汽通量向上输送,积云对流加强,潜热释放促进江淮气旋增强发展;高空西南气流对增强气旋的控制较弱,导致气旋没有一直向北移动,中途发生南折。2）黄海南部海温较北部偏高约4 ℃,低空大气南、北部之间形成的能量锋区对江淮气旋的南折有指向作用;同时对流层低层偏北风的存在以及副热带高压的短时南撤为气旋的南折提供了动力环境。  相似文献   

Basal slip and texture development in calcite: new results from torsion experiments     

D. J. Barber  H.-R. Wenk  J. Gomez-Barreiro  E. Rybacki  G. Dresen 《Physics and Chemistry of Minerals》2007,34(2):73-84

The deformation behavior of calcite has been of longstanding interest. Through experiments on single crystals, deformation mechanisms were established such as mechanical twinning on in the positive sense and slip on and both in the negative sense. More recently it was observed that at higher temperatures slip in both senses becomes active and, based on slip line analysis, it was suggested that slip may occur. So far there had been no direct evidence for basal slip, which is the dominant system in dolomite. With new torsion experiments on calcite single crystals at 900 K and transmission electron microscopy, this study identifies slip unambiguously by direct imaging of dislocations and diffraction contrast analysis. Including this slip system in polycrystal plasticity simulations, enigmatic texture patterns observed in compression and torsion of calcite rocks at high temperature can now be explained, resolving a long-standing puzzle.  相似文献   

Wave loads on a coastal bridge deck and the role of entrapped air     

《Applied Ocean Research》2015

Wave loading on a coastal bridge deck due to nonlinear waves during a storm, where air may be fully or partially trapped between the girders, is studied through an extensive set of laboratory experiments. Wave cases tested cover a range of shallow-water to intermediate-water depth waves. A range of model elevations is tested to include conditions where the bridge may be partially inundated, to where the model is fully elevated above the still-water level (SWL). The model is constructed to include different percentages of air-relief openings, to capture a range of cases where no air can escape between the girders, to where all the air can escape and the wave can freely interact with the bottom of the bridge deck. Effects of the compressibility of entrapped air as well as the effects of the model scale are investigated through numerical calculations solving the compressible and incompressible Euler's equations, at both the model and prototype scales, by use of the open source CFD software, OpenFOAM. Along with coastal bridges, this research is applicable to other coastal and offshore structures, such as piers, submerged breakwaters and offshore platforms, in which wave loading or entrapped air is of concern.  相似文献   

水母(沙海蜇)降解与营养盐(氮、磷)释放的模拟与实证     

李学刚  宋金明  马清霞  李宁  袁华茂  段丽琴  曲宝晓 《海洋学报(英文版)》2015,34(8):1-12

The aim of this study was to investigate nitrogen and phosphorus released in the process of the decomposition of giant jellyfish in the laboratory and found the evidence to verify the influence of nutrients released by the decomposition of jellyfish on the ecosystem in the field. The release of nitrogen and phosphorus from the decomposition of Nemopilema nomurai was examined in a series of experiments under different incubation conditions such as different p H values, salinity values, temperatures and nitrogen and phosphorus concentrations. The results showed that the complete decomposition of Nemopilema nomurai generally took about 4–8 d. The release of nitrogen and phosphorus from the decomposition of Nemopilema nomurai could be divided into two stages: the early stage and the later stage, although the efflux rate of nitrogen was one order more than phosphorus. In the early stage of the decomposition of Nemopilema nomurai, the concentrations of dissolved nitrogen, dissolved phosphorus, total nitrogen and total phosphorus in seawater increased rapidly, and the concentration of nitrogen could reach the highest level in the whole degradation process. In the later stage of the decomposition, the concentrations of dissolved nitrogen and total nitrogen declined slowly, while the concentration of phosphorus in water could reach a maximum in the degradation process. High p H, low salinity,high temperature and N/P will promote the release of nitrogen; low p H is unfavorable to the release of nitrogen but favorable to the release of phosphorus. In addition, we found the concentrations of ammonium and phosphate in the bottom water were higher than those in the surface water during the period of jellyfish bloom in the Jiaozhou Bay, proving that nutrients released by the decomposition of jellyfish have significant influence on nitrogen and phosphorus in the field. For the whole Yellow Sea, nutrients released by jellyfish carcasses may reach up to(2.63±2.98)×107 mol/d of dissolved nitrogen(DN) and(0.74±0.84)×106 mol/d of dissolved phosphorus(DP) during the period of jellyfish bloom. The values are comparable to riverine inputs in a day, but much higher than sediment–water exchange flux in the Yellow Sea. The great amounts of nutrients must have significant influence on the nutrients balance of the Yellow Sea during the period of jellyfish dead and decomposition. Both the experimental data and field observations proved that the decomposition of jellyfish may release a great amount of nutrient to the surrounding environment during the period of jellyfish decomposition.  相似文献