双线偏振多普勒天气雷达遥测降水强度和液态含水量的方法和精度研究

利用雨滴谱的Г分布和散射计算模式,研究了C波段双线偏振多普勒天气雷达遥测降水强度、液态含水量和识别降水粒子相态的方法,给出了利用反射率因子ZH、差分反射率因子ZDR、差传播相移KDP反演降水强度和液态含水量的三种公式以及这三个物理量的关系公式,并从雨滴谱的变化和雷达测量误差两方面比较了几种方法的测雨精度.结果表明:雨滴谱在很大范围变化时,利用ZDR和KDP可以很好地反演出降水强度和液态含水量,它受滴谱分布的影响不大,它的探测精度优于(ZH,ZDR)方法.单参数KDP方法优于传统的Z-R关系方法.同时给出的ZH与ZDR和KDP关系公式也基本不受雨滴谱变化的影响,它可以用于降水粒子相态的识别.双参数方法的测量误差主要来源于雷达测量ZDR和KDP的误差,特别是KDP的误差,改善KDP的测量误差是发挥双线偏振多普勒雷达探测降水强度或液态含水量潜力的关键.     

Uncertainty analysis of CO_2 flux components in subtropical evergreen coniferous plantation

We present an uncertainty analysis of ecological process parameters and CO2 flux components (Reco, NEE and gross ecosystem exchange (GEE)) derived from 3 years’ continuous eddy covariance meas-urements of CO2 fluxes at subtropical evergreen coniferous plantation, Qianyanzhou of ChinaFlux. Daily-differencing approach was used to analyze the random error of CO2 fluxes measurements and bootstrapping method was used to quantify the uncertainties of three CO2 flux components. In addition, we evaluated different ...     

多波束系统横摇、纵倾参数的校正方法

多波束水深测量系统以条幅式测量为特点,比较传统单波束测深发生了巨大的变化,能够进行实时声速、船体姿态等参数的改正.多波束系统换能器安装时存在的纵倾角度偏差(pitch bias)和横摇角度偏差(roll bias)是产生水深测量系统误差的重要来源之一.分析两个参数对水深测量精度的影响,并根据其误差在地形剖面上的表现形式,讨论实测法和剖面重合法两种参数测试的方法,特别是针对剖面重合法参数测试,制作可视化操作界面,大大方便了野外和室内参数调整.测试获取的纵倾、横摇参数输入多波束系统中进行实时水深校正.在室内资料处理中,利用参数校正方法,能够对野外采集资料进行再处理,提高资料质量.     

大尺度水循环模拟系统不确定性研究进展(英文)

The regional hydrological system is extremely complex because it is affected not only by physical factors but also by human dimensions.And the hydrological models play a very important role in simulating the complex system.However,there have not been effective methods for the model reliability and uncertainty analysis due to its complexity and difficulty.The uncertainties in hydrological modeling come from four important aspects:uncertainties in input data and parameters,uncertainties in model structure,uncertainties in analysis method and the initial and boundary conditions.This paper systematically reviewed the recent advances in the study of the uncertainty analysis approaches in the large-scale complex hydrological model on the basis of uncertainty sources.Also,the shortcomings and insufficiencies in the uncertainty analysis for complex hydrological models are pointed out.And then a new uncertainty quantification platform PSUADE and its uncertainty quantification methods were introduced,which will be a powerful tool and platform for uncertainty analysis of large-scale complex hydrological models.Finally,some future perspectives on uncertainty quantification are put forward.     

Exploring the sensitivity of coastal inundation modelling to DEM vertical error

As sea level is projected to rise throughout the twenty-first century due to climate change, there is a need to ensure that sea level rise (SLR) models accurately and defensibly represent future flood inundation levels to allow for effective coastal zone management. Digital elevation models (DEMs) are integral to SLR modelling, but are subject to error, including in their vertical resolution. Error in DEMs leads to uncertainty in the output of SLR inundation models, which if not considered, may result in poor coastal management decisions. However, DEM error is not usually described in detail by DEM suppliers; commonly only the RMSE is reported. This research explores the impact of stated vertical error in delineating zones of inundation in two locations along the Devon, United Kingdom, coastline (Exe and Otter Estuaries). We explore the consequences of needing to make assumptions about the distribution of error in the absence of detailed error data using a 1 m, publically available composite DEM with a maximum RMSE of 0.15 m, typical of recent LiDAR-derived DEMs. We compare uncertainty using two methods (i) the NOAA inundation uncertainty mapping method which assumes a normal distribution of error and (ii) a hydrologically correct bathtub method where the DEM is uniformly perturbed between the upper and lower bounds of a 95% linear error in 500 Monte Carlo Simulations (HBM+MCS). The NOAA method produced a broader zone of uncertainty (an increase of 134.9% on the HBM+MCS method), which is particularly evident in the flatter topography of the upper estuaries. The HBM+MCS method generates a narrower band of uncertainty for these flatter areas, but very similar extents where shorelines are steeper. The differences in inundation extents produced by the methods relate to a number of underpinning assumptions, and particularly, how the stated RMSE is interpreted and used to represent error in a practical sense. Unlike the NOAA method, the HBM+MCS model is computationally intensive, depending on the areas under consideration and the number of iterations. We therefore used the HBM+ MCS method to derive a regression relationship between elevation and inundation probability for the Exe Estuary. We then apply this to the adjacent Otter Estuary and show that it can defensibly reproduce zones of inundation uncertainty, avoiding the computationally intensive step of the HBM+MCS. The equation-derived zone of uncertainty was 112.1% larger than the HBM+MCS method, compared to the NOAA method which produced an uncertain area 423.9% larger. Each approach has advantages and disadvantages and requires value judgements to be made. Their use underscores the need for transparency in assumptions and communications of outputs. We urge DEM publishers to move beyond provision of a generalised RMSE and provide more detailed estimates of spatial error and complete metadata, including locations of ground control points and associated land cover.     

绝对观测时段对地磁基线值观测质量影响的分析研究

基线值的观测质量是综合评价地磁台观测资料质量的一个重要指标。根据肇庆地磁台2007年9月18日进行的连续46组绝对观测数据．分析研究了相应时段基线值的稳定性及精度。研究结果表明,在磁静日的不同时段进行的绝对观测对基线值的稳定性影响较小,基线值观测精度较高。     

GNSS-A直线测量模式及航迹组合优化分析

海底控制点的GNSS-A定位精度受到测量船相对于海底控制点的航迹影响,本文针对圆形测量模式垂向几何结构较弱的问题,给出了一种新的基于嵌套圆的直线测量模式的分析方法,研究了直线测量模式的参数可估性,并给出了直线测量模式得到唯一解的条件.同时,详细分析了圆形测量模式下要增加十字航迹的原因,推导出圆加十字测量模式下获得海底控制点最优三维点位精度的走航半径约为1.15倍水深.理论分析表明,在圆形测量模式下增加直线航迹能够有效增强其几何结构,提升定位效能.此外,针对是否存在唯一的最优航迹进行了思考,并给出了相应的见解.最后,利用深海实测数据验证了理论推导的结果,圆加十字测量模式较圆形测量模式对海底控制点定位的精度提升可达1.4 cm.

     

基于磁异常反演的磁航向误差实时补偿方法

三轴磁力仪是一种常用的磁场测量工具,在地磁导航、海洋磁测、地磁勘探等领域应用较为广泛。作为一种磁场矢量测量工具,三轴磁力仪的磁测误差主要来源于三轴非正交、敏感轴灵敏度不一致及零偏误差等方面,磁力仪的标定优劣影响磁力仪的测量性能。为解决三轴磁力仪的标定问题,建立了磁力仪误差补偿模型,提出了基于正弦拟合的三轴磁力仪标定方法。将磁力仪沿平面旋转时的三轴输出数据拟合成正弦曲线,利用正弦曲线的幅值、初相角和平移量等信息计算出磁力仪的标定参数。仿真结果表明：该方法无需非线性优化过程即可实现标定参数的求解,得到的标定参数与设定值吻合度高;磁测噪声对三轴灵敏度系数及非正交角的计算结果影响较小。     

微分算子展开与耦合势三维有限体积法快速计算随钻超深前视电阻率测井响应非线性Born逼近

本文将非均质各向异性地层中电磁场耦合势Helmhotz方程分解为各向异性背景场方程与散射场方程,并应用算子展开技术推导出耦合势Born级数解,建立一套三维非均质各向异性地层中随钻超深前视电阻率测井响应各阶散射电磁场与非线性Born逼近的有效计算方法.首先,利用传输线法与二维插值技术确定背景电磁场空间分布,得到零阶Born逼近解,然后根据电磁场耦合势的Born级数解推导出各阶散射电磁场方程与递推关系,通过三维有限体积法实现各阶散射场耦合势方程的离散,在此基础上结合MKL PARDISO并行技术,通过递推方式逐步计算各阶散射电磁场,并根据Born级数部分和确定不同阶次的非线性Born逼近.最后利用数值模拟结果对正演算法加以检验,并深入研究分析各阶散射场的变化特征与Born级数的收敛性质.

     

距离法定量评价储层地质模型的不确定性

针对目前常用的储层地质模型不确定性评价方法存在的主要问题,提出了先用距离函数计算模型之间的差异,再以差异的大小来判断不确定性大小的方法.以WZ油田西区为例,采用相控物性参数建模技术,利用顺序高斯模拟方法建立渗透率的三维模型.对各种度量差异的距离函数进行对比研究和分析,结果显示曼哈顿距离函数和欧氏距离函数能较好地刻画模型之间的差异.选用欧氏距离函数计算模型之间的差异,其原理是先计算每两个模型之间相对应的每一网格节点的渗透率值差的平方和,然后取平方根,得到一个表征各模型之间差异的矩阵.根据该矩阵可得到各个模型之间的差异程度,差异越大,不确定性就越大.最后通过对比模型过井剖面图分析结果与距离矩阵分析结果,说明了本方法的正确性,结果显示该方法能有效评价随机模拟生成的储层地质模型的不确定性.