CoLM 模拟土壤温度和湿度最敏感参数的研究

合理的参数估计是提高陆面模式模拟能力的关键,而其过高的维数极大地增加了合理估计的难度。参数的敏感性分析,旨在针对目标变量找出最敏感的参数,从而实现在有限计算机资源条件下,对参数进行合理估计。本文以Common Land Model(CoLM)为研究对象,利用Morris 方法定性地从40 个参数中筛选出影响土壤温度和土壤湿度的敏感参数,并通过Sobol' 方法从敏感性顺序和各敏感参数的累积贡献率两个方面,对Morris 方法分析结果进行验证。在此基础上,本研究还利用Sobol' 方法对已筛选的参数做定量敏感性分析,最终确定参数的主效应、交互效应和总效应。研究结果表明,Morris 方法可以基于少量样本实现复杂的陆面模式的参数筛选,而Sobol' 方法的结果又从定量的角度描述了每个敏感参数对模型响应的影响程度,并且两种方法结论一致。     

Improving resolution of gravity data with wavelet analysis and spectral method

Gravity data are the results of gravity force field interaction from all the underground sources. The objects of detection are always submerged in the background field, and thus one of the crucial problems for gravity data interpretation is how to improve the resolution of observed information. The wavelet transform operator has recently been introduced into the domain fields both as a filter and as a powerful source analysis tool. This paper studied the effects of improving resolution of gravity data with wavelet analysis and spectral method, and revealed the geometric characteristics of density heterogeneities described by simple shaped sources. First, the basic theory of the multiscale wavelet analysis and its lifting scheme and spectral method were introduced. With the experimental study on forward simulation of anomalies given by the superposition of six objects and measured data in Songliao plain, Northeast China, the shape, size and depth of the buried objects were estimated in the study. Also, the results were compared with those obtained by conventional techniques, which demonstrated that this method greatly improves the resolution of gravity anomalies. Translated from Progress in Geophysics, 2007, 22(1): 112–120 [译自: 地球物理学进展]     

专家更需做调查——从经验适用性和调查全面性看评判结果和工程决策

依据笔者等负责和参与的中国不同地区多个重大地质工程咨询和技术服务项目,对前期工程地质勘察工作中出现地质条件误判、漏判等问题,进行了案例剖析。在此基础上对专家经验的适用性进行探讨,对工程地质条件观察全面性和科学推断的合理性关系进行了讨论,提出了深入全面认识地质模型的重要性。希望能籍这些工程勘察过程中暴露出来的对规划、选址决策有重大影响的地质问题,引起对专家经验慎重性应用的重视。     

深部水热型地热潜力区的GIS预测模型——以土耳其西安纳托利亚地区为例

开发地热资源有着很大的不确定性和很高的经济风险,需要建立可靠的数学预测模型以确定潜在地热区。通过对地震震中、断层、布格重力异常、磁异常和红外遥感5个与地热密切相关的因素进行整合,建立了地热潜力区的数学预测模型;并以土耳其西安纳托利亚地区为例,对模型的优劣性进行分析评价。运用指数叠加模型和证据权重模型分别建立地热潜力区图,预测成功指数表明证据权重模型的预测结果更为准确。其中,中高潜力区总面积为26 529 km²,占总面积的31.14%,包含39个地热点,占总地热点的50.65%。预测结果显示潜在地热区位于Ayd?n,Denizli,Manisa和Bal?kesir,其中前2个地区的地热已经被开发利用。本研究可以在地热勘探阶段确定潜在地热区,降低经济风险。     

应用趋势分析建立蔡家营矿床的物性分布模式

在河北蔡家营铅锌银矿区有代表性的Ｖ矿带，选取了一条钻探剖面，作物性研究。采集了３１２块标本，测试了磁化率、剩余磁化强度及密度等物性参数；结合地面重磁测量，用趋势分析方法，建立该矿床物性分布模式为本区建立质－地球物理分布模型提供了物性依据。     

A 70-year groundwater recharge record from sandy loess in northwestern China and its climatic implications

The processes and rates of groundwater recharge in arid and semiarid environments are highly related to local climate parameters, particularly precipitation. The chloride profile of an unsaturated zone in an arid and semiarid region can be used to infer the recharge history and past changes in climate, by extension. In this study, a 17-m chloride profile was collected from the sandy loess in the northwestern Chinese Loess Plateau, which also lies in the transition zone between desert and loess. A 71-year groundwater recharge history was reconstructed using the chloride mass balance method with an annual Cl^? input of 0.84 g/m²/year. The reconstructed history revealed a long-term decline in recharge with multiple shorter-term oscillations. Five recharge stages between 1938–1946, 1947–1955, 1956–1975, 1976–2000, and 2001–2008 AD were identified, where the lowest average recharge value was 25.1 mm/a in 1976–2000 AD and the highest was 71.7 mm/a in 1947–1955 AD. Climate conditions during these five periods were also inferred based on the reconstructed recharge rates with the knowledge that high recharge corresponds to more humid climates. The climate over the past 71 years generally became drier in the study area, despite some fluctuations. The reconstructed recharge rates, calculated from 1/Cl^? in the profile, exhibited the same variability as annual precipitation measured in the region, both in long- and short-term oscillations over the period from 1955 to 2008. The chloride concentration variations in the profile, indicating changes in recharge flux, also well correlated with annual precipitation anomalies in the region to the east of 100°E in China for the whole study period. These comparisons verified that it is feasible to study not only groundwater recharge, but also past climate change using a chloride profile from the sandy loess area. The results suggested that unsaturated zones of sandy loess may be valuable archives for reconstructing recharge history and regional paleoclimate changes in the region.     

Stable water isotopes of precipitation in China simulated by SWING2 models

The stable water isotope ratio in precipitation is a useful tracer of atmospheric circulation. Such observations, however, are very limited in space and time. To solve this problem, many isotope-enabled general circulation models (GCMs) are used to help the interpretation of isotope proxies. In this paper, several isotope-enabled GCMs released by the second Stable Water Isotope Intercomparison Group (SWING2) were selected to assess the spatial pattern of deuterium (δD) and the deuterium excess (d) of precipitation in China. The isotopic data of the Global Network of Isotopes in Precipitation (GNIP) and the Chinese Network of Isotopes in Precipitation (CHNIP) were also applied to verify the simulations. The results indicate that these models accurately simulate the spatial characteristics of δD and d of precipitation in China. The correlation between the observations and simulations for LMDZ is the highest among these models, while the root-mean-square (RMS) and standard deviation are not perfect. In addition, LMDZ is worse than other models in capturing the low signal in certain regions, such as CAM, GISS_E, and MIROC. For the monthly variation, most SWING2 models underestimate δD of the precipitation but overestimate the value of d, except for isoGSM. The simulated monthly variation of the water isotopes from SWING2 models is in general similar to the observations, and the trend corresponds to the monthly variation in the Northern Hemisphere. Moreover, all models are good at illustrating the temperature and precipitation amount effects, while they exhibit varying skills in interpreting the altitude and continental effects.     

福厦线粉喷桩复合地基有限元分析

结合福建省第一条省内高速铁路福厦线的设计,通过三维Biot固结有限元数值模拟,探讨了粉喷桩处治深厚层 软基的变形特性,并就施工参数、路基参数等对软基沉降的影响进行了参数敏感性分析。其研究成果对工程实践具有一定的 指导意义。     

边坡工程加固需求度评价及其应用

稳定程度不足的边坡通常都需要进行加固。但在加固系统设计时工程师们必须搞清边坡的哪些部位应进行重点加固 ,哪些部位只需要一般加固 ,甚至不需要加固 ,以便合理地布置加固措施。在工程地质力学综合集成方法论 (EGMS)的基础上 ,作者提出了边坡工程加固需求度 (DRD)的概念及其应用方法。