面球谐函数与引潮位展开

本文定义了一组一般意义下的完全规格化的面球谐函数Ｃｍｎ（θ,λ）与Ｓｍｎ（θ,λ）,并且给出了它们的递推公式．它们构成球面上的正交函数系,对于地球物理以及地球自转研究与计算,特别是对一些需要得到解析结果的计算或符号计算极为重要．用其表示引潮位公式,不...     

引潮位展开中的面球谐函数及其递推公式

为了引潮位展开,文中定义了一种完全规格化的面球谐函数,同时根据勒让德（Ｌｅｇｅｎｄｒｅ）函数以及契比雪夫（Ｃｈｅｂｙｓｈｅｖ）多项式之递推公式,导出一组面球谐函数的递推公式．据此改进引潮位计算程序,使引潮位展开在ＰＣ－５８６计算机上只需要不到１０ｍｉｎ时间即可完成．完全规格化的面球谐函数可以起到规格化的作用,没有必要再继续采用杜德森（Ｄｏｏｄｓｏｎ）规格化．即使采用,也没有必要使用严格的小数值,取其相近的整数值即可．以完全规格化的缔合球谐函数代替Ｄｏｏｄｓｏｎ规格化,并借助面球谐函数的递推公式,使引潮位的表达式更加简洁、规范．文中对高精度潮汐计算中的一些重要问题进行了讨论,指出以往在Ｄｏｏｄｓｏｎ常数归算上存在的误区,还就天体与测站坐标系统的一致性问题进行了讨论．     

引潮位展开中的面球谐函数及其递推公式

为了引潮位展开,文中定义了一种完全规格化的面球谐函数,同时根据勒让德（Ｌｅｇｅｎｄｒｅ）函数以及契比雪夫（Ｃｈｅｂｙｓｈｅｖ）多项式之递推公式,导出一组面球谐函数的递推公式．据此改进引潮位计算程序,使引潮位展开在ＰＣ－５８６计算机上只需要不到１０ｍｉｎ时间即可完成．完全规格化的面球谐函数可以起到规格化的作用,没有必要再继续采用杜德森（Ｄｏｏｄｓｏｎ）规格化．即使采用,也没有必要使用严格的小数值,取其相近的整数值即可．以完全规格化的缔合球谐函数代替Ｄｏｏｄｓｏｎ规格化,并借助面球谐函数的递推公式,使引潮位的表达式更加简洁、规范．文中对高精度潮汐计算中的一些重要问题进行了讨论,指出以往在Ｄｏｏｄｓｏｎ常数归算上存在的误区,还就天体与测站坐标系统的一致性问题进行了讨论．     

精密引潮位展开及某些诠释

作者再次改进了引潮位展开,潮波振幅给到小数后第六位,共3070个潮波.文中论述了引潮位展开的精度,同时给出为了保证潮汐计算的高精度而所需引入的各项改正及其说明.     

精密引潮位展开及某些诠释

作者再次改进了引潮位展开,潮波振幅给到小数后第六位,共3070个潮波.文中论述了引潮位展开的精度,同时给出为了保证潮汐计算的高精度而所需引入的各项改正及其说明.     

新的引潮位完全展开

Doodson进行引潮位展开时的原始数据采自Brown及Newcomb表,其黄赤交角系采用1900年1月1日之值。目前Brown系数已重新计算,黄赤交角每世纪相对变化5×10-4;地球轨道偏心率每世纪相对变化25×10-4。由此引起的潮波振幅长趋势变化已可辨别,这就是所谓潮波振幅的时间依赖问题。作者采用EJC表及2000.0年的黄赤交角和地球轨道偏心率数值,重新用计算机演绎了引潮位展开式,解决了时间依赖问题。文中给出了属于J2000.0系统的引潮位完全展开表。     

新的引潮位完全展开

Doodson进行引潮位展开时的原始数据采自Brown及Newcomb表,其黄赤交角系采用1900年1月1日之值。目前Brown系数已重新计算,黄赤交角每世纪相对变化5×10^{-4;地球轨道偏心率每世纪相对变化25×10-4。由此引起的潮波振幅长趋势变化已可辨别,这就是所谓潮波振幅的时间依赖问题。作者采用EJC表及2000.0年的黄赤交角和地球轨道偏心率数值,重新用计算机演绎了引潮位展开式,解决了时间依赖问题。文中给出了属于J2000.0系统的引潮位完全展开表。}     

精密引潮位展开的精度评定

文中介绍了一个新的引潮位展开,含有潮波3070项及一些新的信息;潮波振幅给至小数点后第6位.为了与精密引潮位比较,专门建立了一套标准数据,其精度为±0.001μGal.按照这一标准数据,我们评价了精密引潮位展开的精度,并给出了其余差及功率谱分析的结果.结果表明,对于潮汐重力,精密引潮位展开的精度,可达±0.005μGal.     

超高阶扰动场元的计算方法

空间重力测量技术的飞速发展为超高阶全球重力场模型的建立提供了条件和更迫切的应用需求.本文从完全规格化缔合勒让德函数及其一、二阶导数的标准前向列递推公式出发,研究了超高阶扰动场元球谐展开式中完全规格化缔合勒让德函数及其一、二阶导数的数值特征,改进了上述标准前向列递推关系式,提出了在微机上计算超高阶扰动场元的实用方法,避免了数字溢出.     

基于Clenshaw技术计算大地水准面差距的快速算法

随着超高阶重力场位模型的建立与精化,其计算效率也逐渐凸显起来.本文比较了Clenshaw算法和标准向前列递推算法的适用性,并分析了Clenshaw求和计算全球大地水准面差距的适用范围.在Clenshaw求和技术基础上,进行如下算法改进:将球谐函数级数和的形式以矩阵形式替代,算法运算过程中以向量化计算代替循环计算.在计算前360阶、420阶、480阶、……、直至前1500阶的大地水准面差距时,改进后的Clenshaw算法要比改进前算法的运算耗时减少了三分之一左右,也就是运算效率至少提升了33%.     

应用精密引潮力位展开建立刚体地球章动序列

通过对Melchior P.潮汐与章动理论的改进,给出了高阶日月引潮力位引起的岁差章动力矩,建立了刚体地球极移和章动的联合动力学方程,由此对天球中间极（CIP）进行了严格的理论定义. 在各阶潮汐力矩的作用下,得到CIP轴岁差章动的表达式. 通过推导发现,奇数阶引潮力位产生的岁差章动力矩使得黄经章动和交角章动出现了异向项（即：黄经章动出现了cos项,交角章动出现了sin项）. 最后利用郗钦文精密引潮力位展开,建立了737项刚体地球章动序列. 新的章动序列是IERS2003采用的刚体地球章动序列REN2000（包含678个日月章动项）的一个补充.     

An evaluation method of hydrocarbon generating potential of highly mature and over-mature marine carbonate

How to restore the residual organic carbon and residual hydrocarbon-generating potential is discussed based on the hydrocarbon degradability of source rock. The results indicate there is linear function relationship between the restoring coefficient of residual organic carbon (K_c) and the vitrinite reflectance (R _o%) of various kinds of source rock, but the relationship is secondary functional between the restoring coefficient of residual hydrocarbon-generating potential (K_s) and the vitrinite reflectance (R _o%). It is pointed out thatKc = (1 -Dresidual)/(1 -D _primary),Ks= Kc (D _primary/D _residual). The restoration of residual organic carbon and hydrocarbon-generating potential of the Cambrian and Ordovician highly mature marine carbonate in the Tarim Basin and North China region shows that the lower limit value of hydrocarbon generating potential and the organic matter abundance of carbonate source rock are basically the same as that of clastic rock. The technical difficulty in hydrocarbon generating evaluation of highly mature and overmature carbonate is solved.     

Experimental measurements of the streaming potential and seismoelectric conversion in Berea sandstone

The streaming potential across a porous medium is induced by a fluid flow due to an electric double layer between a solid and a fluid. When an acoustic wave propagates through a porous medium, the wave pressure generates a relative movement between the solid and the fluid. The moving charge in the fluid induces an electric field and seismoelectric conversion. In order to investigate the streaming potential and the seismoelectric conversion in the same rock sample, we conduct measurements with Berea sandstone saturated by NaCl solutions with different conductivities. We measure the electric voltage (streaming potential) across a cylindrical sample in NaCl solutions with different conductivities and under different pressures to determine the DC coupling coefficients. We also measure the seismoelectric signals induced by acoustic waves with a Berea sandstone plate at different frequencies and solution conductivities. The pressures of the acoustic waves are calibrated with a standard hydrophone (Brüel & 8103) at different frequencies (15–120 kHz). We calculate the quantitative coupling coefficients of the seismoelectric conversion at DC and at high frequencies with samples saturated by solutions with different conductivities. When the Berea sandstone sample is saturated by the NaCl solution with 0.32 mS/m in conductivity, for example, the DC and seismoelectric coupling coefficients at 15 kHz are 0.024 μV/Pa and 0.019 μV/Pa, respectively. The seismoelectric coupling coefficient is an important and helpful parameter for designing a seismoelectric tool. More experimental measurements of seismoelectric coupling coefficients in the frequency range of 100 Hz to 15 kHz are needed in the future.     

重力位谱分析及重力异常导数换算新方法——余弦变换

为了提高重力异常导数换算的精度,真实有效地反映地质体的异常特征,提出用余弦变换计算异常导数的新方法. 给出并证明了两个定理,利用它们推导出重力位余弦谱一般表达式以及重力异常各阶导数计算公式,建立了位场余弦谱分析理论. 模型实验中发现,用Fourier变换计算的一阶导数与理论导数偏差很大,而余弦变换计算的导数与理论异常导数拟合效果非常好,除边界几个数据因重力异常的有限截断产生的吉布斯效应残留使误差较大外,数据的计算精度均很高,误差为-0.09%～5%.     

鄂尔多斯西缘北段的地壳结构和块体间变形关系

本文对喜马拉雅计划二期部分台站的远震波形数据进行接收函数提取,利用接收函数共转换点叠加方法获得阿拉善地块、鄂尔多斯地块以及银川—河套盆地下方0~80 km深度的速度间断面结构.结果表明：鄂尔多斯地块成层性好,地壳厚度为38~42 km,康拉德界面为18~22 km,阿拉善地区的Moho面深度为38~45 km.河套盆地地壳厚度约52 km,银川断陷盆地和贺兰山下方的Moho面最深为~55 km.鄂尔多斯西缘构造边界下方Moho面变化明显,且黄河断裂为深大断裂直接切割莫霍界面.根据本文的间断面成像结果我们进一步确定阿拉善地块与鄂尔多斯地块分属不同的大地构造单元.与此同时,我们推测贺兰山以西70~80 km范围内和鄂尔多斯地块西缘北段存在地壳增厚变形的可能.

     

Spatiotemporal heterogeneity of actual and potential respiration in two contrasting floodplains

Floodplains are vital components of river ecosystems and play an important role in carbon cycling and storage at catchment and global scales. For efficient river management and conservation, it is critical to understand the functional role of spatiotemporally complex and dynamic habitat mosaics of river floodplains. Unfortunately, the fundamental understanding of mineralization and carbon flux patterns across complex floodplains is still fragmentary. In this study, respiratory potential (i.e., electron transport system activity [ETSA]) was quantified seasonally across different aquatic and terrestrial habitats (wetted channels, gravel bars, islands, riparian forests, and grasslands) of 2 Alpine floodplains differing in climate, altitude, discharge, flow alteration intensity, and land use (So?a [natural flow regime, 12% grassland area] and Urbach [mean annual discharge reduction by 30% due to water abstraction, 69% grassland area]). In situ respiration (R) was measured, and ETSA–R ratios were calculated to examine differences in exploitation intensity of the overall respiratory capacity among floodplain habitats and seasons. ETSA and R provided potential and actual estimates, respectively, of organic matter mineralization in the different floodplain habitats. Hierarchical linear regression across habitat types showed that organic matter, grain sizes <0.063 mm, and water content were the most important predictors of ETSA in both floodplains, and grain sizes 2–0.063 and >8 mm were also highly important for the So?a floodplain. The combination of ETSA and R measurements conducted in contrasting floodplains increased our understanding of the relationships between floodplain habitat heterogeneity, organic matter mineralization and human impacts, that is, structural–functional linkages in floodplains. These data are integral towards predicting changes in floodplain function in response to environmental alterations from increasing human pressures and environmental change.     

Multi-objective and multi-scheme research on water and sediment regulation potential of reservoirs in the upper Yellow River

The problems of the deteriorating relation between water and sediment, and the escalating conflict between water supply and demand in the upper Yellow River(YR), need to be addressed. Reservoirs of Longyangxia, Liujiaxia, and Heishanxia(Long-Liu-Hei) in the upper YR are taken as the research object, and a multi-objective, water-sediment optimal operation model for cascade reservoirs Long-Liu-Hei has been developed. This operation model considers the comprehensive requirements of water supply, po...     

Spatiotemporal variations and abrupt changes of potential evapotranspiration and its sensitivity to key meteorological variables in the Wei River basin,China

Evapotranspiration is an important component of hydrological cycle and a key input to hydrological models. Therefore, analysis of the spatiotemporal variation of potential evapotranspiration (PET) will help a better understanding of climate change and its effect on hydrological cycle and water resources. In this study, the Penman–Monteith method was used to estimate PET in the Wei River basin (WRB) in China based on daily data at 21 meteorological stations during 1959–2008. Spatial distribution and temporal trends of annual and seasonal PET were analysed by using the Spline interpolation method and the Mann–Kendall test method. Abrupt changes were detected by using the Pettitt test method. In order to explore the contribution of key meteorological variables to the variation of PET, the sensitivity coefficients method was employed in this study. The results showed that: (1) mean annual and seasonal PET in the WRB was generally decreasing from northeast to southwest. Summer and spring made the major contributions to the annual values; (2) annual and seasonal PET series in most part of the WRB exhibited increasing trends; (3) abrupt changes appeared in 1993 for annual and spring PET series for the entire basin, while summer value series was detected in the late 1970s. (4) Relative humidity was the most sensitive variable for PET in general for the WRB, followed by wind speed, air temperature and solar radiation. In the headwater and outlet of the WRB, relative humidity and air temperature were the most sensitive variables to PET, while relative humidity and wind speed were more influential in most part of the middle‐lower region. Copyright © 2011 John Wiley & Sons, Ltd.     

云闪放电对云内电荷和电位分布影响的数值模拟

我们应用改进的随机闪电参数化方案,对两次雷暴的起、放电过程进行了二维125 m和250 m分辨率云闪模拟试验,分析表明高分辨率模拟的云闪通道几何结构、延伸范围和最大垂直电场变化等特征与观测结果更为一致,并且揭示了云闪放电重新配置云内电荷分布和空间电荷中和过程的一种新的物理图像：(1) 云闪的直接物理效应是在已有的空间电荷区内沿着放电通道沉积异极性电荷、形成复杂的空间电荷分布,有效地导致云中电位和场强绝对值及静电场能量剧烈下降,使放电终止.其中：放电后在闪电通道经过主要区域,电位降到±30 MV之间,垂直电场强度也降到±20 kV·m-1之间,一次正或负云闪估计消耗掉107～1010 J静电能;(2) 云中电荷中和不是正、负空间电荷简单地直接相互抵消的瞬态过程,而是广泛分布的云中空间电荷与通道沉积的异极性电荷通过湍流交换、平流输送、重力沉降以及起电等多种因素逐渐混合并部分被中和的一个后续慢过程,其弛豫时间典型值在14～44 s之间,在此期间通道感应电荷总量下降到50%以下.并残余部分电荷参与后续放电前高空间电荷密度和强电场的重建过程.