4DSVD分析误差与样本选取方法和样本容量的关系初探

分析误差与样本选取方法和样本容量的关系是4DSVD同化方法一个亟需研究的重要问题。获得支撑大气模式空间和观测空间吸引子的基向量是4DSVD研究的关键部分,样本的好坏和样本容量的范围是决定4DSVD基向量和分析结果质量的一个重要前提条件。首先利用Lorenz28变量模式,用4DSVD方法做了一些简单三维同化试验,探讨了Lorenz28变量模式的分析误差与样本容量和样本选取方法的关系。数值试验结果表明,对一个具体的模式,有限的样本容量就能够获得较高精度的分析结果;在模式系统和观测系统不变情况下,用一定样本容量得到的支撑模式空间和观测空间的基向量具有很好的稳定性,即一旦获得一组较好的基向量,在观测系统和模式系统不变的情况下,对同化任何时刻的观测适用;分析结果对选取方法没有太大的依赖性,但具体的样本容量要视不同模式和样本选取方法而定。用WRF模式做的4DSVD四维观测系统模拟试验结果表明,若样本选取方法得当,所需要的样本容量要远远小于模式自由度。4DSVD要真正获得较高精度的分析结果,需要的条件是尽可能的在吸引子上取样并选取充足的样本容量;间隔取样可以一定程度上减少计算量。根据数值试验结果提出了4DSVD在实际同化时样本选取的一些初步的方法。     

沈阳春夏季大气冰核浓度的观测研究

为了解沈阳地区大气冰核浓度的时空分布状况,2010年起开始对沈阳地区的大气冰核浓度分布进行观测和研究.地面采用Bigg型混合云室法和滤膜法进行冰核气溶胶的采样测量,高空利用辽宁省人工影响天气办公室租用的人工增雨飞机进行滤膜法采样.采样滤膜的处理都是统一在活化温度-15℃及冰面过饱和度20％、水面过饱和度3％的湿度条件下进行的.根据取得的部分观测资料,给出了沈阳春夏季大气冰核的浓度及冰核温度谱分布参数,分析了冰核浓度在3～6月各月以及在不同天气状况下的分布特征,初步给出了大气冰核浓度的尺度谱分布及其随高度的变化.     

The effect of membrane filtration on estimates of microbial ATP in New Zealand freshwaters

Concentrations of microbial ATP in 15 New Zealand lakes were determined using 2 extraction techniques. ATP was found in both the paniculate (>0.45 μm) and dissolved (<0.45 μm) fractions of the water samples. Higher concentrations of paniculate ATP were obtained when ATP was extracted directly from freshwater samples rather than following pre‐concentration on to membrane filters. Recovery of particulate ATP declined with increasing volumes of sample filtered. The magnitude of the filtration effect varied unpredictably between lakes and within lakes with time. Corrections for the presence of dissolved ATP were necessary before estimates of particulate ATP could be made by the direct extraction technique. Concentrations of dissolved ATP up to 1.2 μg L^‐1 were observed. The direct extraction technique is recommended for more accurate determination of particulate ATP in New Zealand freshwaters.     

Undisturbed Strata Succession Sampling Technology and the Engineering Geological Characteristics of an Atoll in the Southern South China Sea

Coral reef calcareous sediment, a special category of rock-soil material, has representative geological structure and environmental characteristics. It is widely distributed in shallow areas of the tropical ocean; therefore the exploration instruments and technologies for engineering geology studies of coral reef calcareous sediments are very different from those used in land or deep-sea. Obtaining undisturbed cores from the Holocene unconsolidated stratum of coral reefs has been a key problem in the field of marine geology and environment surveying. The authors have designed a novel floating drilling platform equipped with a drilling machine, and successfully achieved undisturbed cores from both reef flats (with water depth 0.5 to 2 m) and a enclosed lagoon (with water depth 2–12 m) of Yongshu Reef (9°32–9°42 N, 112°52–113°04 E), southern South China Sea. Based on the detailed observation on the cores and the analysis from engineering geology, Yongshu Reef was split into reef three engineering geological zones: leading edge, reef flat (including outer reef flat, middle reef flat and inner reef flat) and lagoon. The sediments are classified in the stratum as fine sand, medium sand, coarse sand, gravel and weak-cemented reef limestone.     

Improved estimators of correlation and R2 for skewed hydrologic data

ABSTRACT

The coefficient of determination R² and Pearson correlation coefficient ρ = R are standard metrics in hydrology for the evaluation of the goodness of fit between model simulations and observations, and as measures of the degree of dependence of one variable upon another. We show that the standard product moment estimator of ρ, termed r, while well-behaved for bivariate normal data, is upward biased and highly variable for bivariate non-normal data. We introduce three alternative estimators of ρ which are nearly unbiased and exhibit much less variability than r for non-normal data. We also document remarkable upward bias and tremendous increases in variability associated with r using both synthetic data and daily streamflow simulations from 905 calibrated rainfall–runoff models. We show that estimators of ρ = R accounting for skewness are needed for daily streamflow series because they exhibit high variability and skewness compared to, for example, monthly/annual series, where r should perform well.     

安徽省沙坪沟钼矿钼的分析质量监控

通过对安徽省沙坪沟钼矿床矿石物质成分及结构、构造的分析,发现矿石中辉钼矿常呈细小鳞片状、浸染状分布于细脉中。针对岩芯易沿含矿裂纹破裂造成鳞片状辉钼矿丢失,本矿区全部采用金刚石刀具切割分取岩芯。制样过程试验中将样品无缩分粗碎、中碎至Ф〈-1．0mm,进行了K值试验,取0．5。缩分后密封棒磨6小时（充分混匀、磨碎）至-200目。分析了该矿区伴生元素不干扰测定的情况,不加Fe：O。载体,刚玉坩埚-Na2O2熔矿,降低空白值,严格质量监控,采用硫氰酸盐分光光度法测定钼量,获得的结果稳定可靠。本试验成果可为从事同类型大型钼矿的分析测试和质量监控提供参考。     

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线性抽样及分形理论在景观异质性研究中的应用

景观异质性是景观生态学研究的核心,对景观格局、动态和功能具有决定作用。将线性抽样与分形理论相结合的方法应用于景观空间异质性的表达中,相比于传统方法,可以定量表达景观类型在空间序列中的组合规律,而该组合规律可以作为指标来测度景观空间异质性的高低。景观类型在空间序列中的组合越复杂,则景观的空间异质性越高。该方法以景观类型空间序列的线形图像为基础,利用分形理论计算线形图像的分维,以分维数值的大小来表达景观空间异质性的高低。但样线的布设方法、分维计算方法以及景观分类系统的不同都会对分维数值产生影响。以妫水河流域为试验区,对该方法的适用性进行验证,结果表明,该方法可以有效表达景观空间异质性的高低。     

Guidelines for sampling bedload transport with minimum uncertainty

The stability of river channels and their suitability as habitat for aqueous organisms is strongly controlled by the rate of bedload transport. Quantification of bedload transport rates in rivers is difficult, not only because of the temporal variation in transport, but also because of the cross‐channel variation in transport. The objectives of this study were: (i) to determine the effect of cross‐channel variation in bedload transport on the uncertainty of width‐integrated transport rates; and to use this knowledge (ii) to improve guidelines for bedload sampling. This was done through a thorough statistical evaluation of stochastic and systematic uncertainties involved in bed‐load transport measurements. Based on this evaluation, new guidelines are presented for determination of the number of samples and sampling positions across the channel that are required for bedload measurements in several types of sand‐bed rivers and gravel‐bed rivers. The guidelines relate to bedload measurements made with pressure‐difference (Helley‐Smith type) samplers that require numerous bedload samples of short duration at several positions across the channel. The results show that generally more sampling positions across the channel are required in gravel‐bed rivers than in sand‐bed rivers. For gravel‐bed rivers with unknown cross‐channel distribution of transport, at least 10 sampling positions are recommended, whereas for most sand‐bed rivers five positions suffice. In addition, at least 12 short‐duration samples are required at each position to obtain bedload estimates with uncertainties below 20%. If the same level of uncertainty is desired in the case of high spatial and temporal variation in transport rates, the number of short‐duration samples needed per sampling position increases to 40.     

空气反循环连续取样钻进技术在紫金山金铜矿区的应用

紫金山金铜矿矿产勘查中使用空气反循环连续取样钻进工艺,解决破碎地层、缺水地区钻探取样难、施工成本高的问题。介绍了机具的配套、钻进工艺流程及施工注意事项,特别是针对紫金山金铜矿区破碎、漏失地层,为提高钻进效率,采用正反循环2种潜孔锤钻进,获得了高的采样率,提高了施工效率,大幅度降低了施工成本。