VENTILATION FLOW IN A BAROCLINIC VORTEX RELATED TO TROPICAL CYCLONE MOTION*

The tropical cyclone motion is numerically simulated with a quasi-geostrophic baroclinic model.The flow field of a tropical cyclone is decomposed into its axisymmetric and asymmetric components.The relation between the ventilation flow vector and the motion vector of the tropical cyclone is investigated.The results of numerical experiments indicate:(1) There are both large-scale beta gyres and small-scale gyres in the asyrnmetric flow field.(2) The interaction between small-scale gyres and large-scale beta gyres leads to the oscillation of translation speed and translation direction for the tropical cyclone.(3) There are the large deviations between the ventilation flow vector calculated by means of Fiorino and Elsberry's method and the motion vector of tropical cyclone.(4) The ventilation flow vector computed using the improved method closely correlates with the motion vector of the tropical cyclone.     

Elimination of hydraulic effects for cassiterite in a Malaysian Stream

Geochemical patterns for elements, such as Sn, W and Au, present in drainage sediments as resistate heavy minerals are often erratic and difficult to interpret. To investigate the source of these problems and develop methods of eliminating them we have compared the behavior of Sn, present as cassiterite, and associated pathfinder elements downstream from a small primary Sn deposit in Perak, Peninsular Malaysia.Dispersion trains for the pathfinder elements are characterized by smooth decay patterns and differences in concentrations between high- and low-energy environments, characterized by coarse-and medium-grained sands respectively, are not significant. In contrast, Sn (and magnetite) concentrations are extremely erratic with significantly higher concentrations in high- compared to low-energy environments. As a result the dispersion train for Sn exhibits no regular decay pattern away from its source. These findings suggest that the action of the stream is analogous to that of sluice box, with light minerals being winnowed away and cassiterite, together with magnetite, accumulating. For all but the finest sizes this process, which is most efficient in high-energy environments, causes considerable local variability in Sn content of the sediments. However, because the hydraulic behavior of cassiterite and magnetite is similar, but magnetite is not associated with the primary mineralization, the Sn/magnetite ratio can be used to eliminate Sn anomalies resulting from local variations in hydraulic conditions.The concept of hydraulic equivalence of cassiterite and magnetite was extended to examining the relationship between Sn and different size fractions of the light minerals that constitute the bulk of most sediments. Greatest contrast is obtained when the Sn content of the −270 mesh (−53 μm) fraction is re-expressed as its hydraulic equivalent concentration in −65 + 100 mesh (−212 + 150 μm) material.For exploration purposes it is concluded that: (1) providing cassiterite is present in the fine size fractions, sampling of this material will reduce hydraulic effects, thereby reducing data variability, and can also increase the length of the anomalous dispersion train; and (2) hydraulic effects can also be reduced by re-expressing Sn concentrations as ratios to magnetite (provided this is not associated with the primary Sn mineralization) or a hydraulically equivalent size fraction of the light minerals that constitute the bulk of the sediment. Similar principles probably apply to the interpretation of geochemical data for other elements dispersed in drainage sediments as heavy minerals; this warrants further investigation.     

Study of Dynamic Waveform Inversion with Computer

This paper has done the spectrum analysis of deformity waveform and it’s each frequency element is rectified with measuring system frequency response curve by positive and inverse Fourier transform theoretical. If all of rectified frequency elements of waveform are superposed then real waveform would be obtained. This paper has done theoretical analysis and a practical method is introduced.     

北京地区暴雨时各层温、湿、风的统计特征

本文分析了北京45个日雨量大于100毫米暴雨的探空,发现在暴雨出现时各层空气异常潮湿而不稳定,并且风有一定强度的垂直切变,尤其是边界层有强切变。当暴雨临近时,R_i数变小,湍流发展,这也是形成暴雨的一个重要原因。我们还发现暖湿空气活动是暴雨形成的有利条件,在暴雨形成过程中是否容易发生不稳定能释放,不在于是否大,而在于低层暖湿空气能否及早抬升达到自由对流高度,以及600毫巴是否足够高。文中所给定量结果为理论工作和预报工作提供了依据或参考。     

中国北方沙尘灾害特点及其下垫面状况的遥感监测

2000年春季,中国北方地区多次受到沙尘灾害的影响,对生产、生活活动造成了多方面的不利影响。采用遥感和GIS技术进行沙尘灾害的过程监测、空间特点分析和下垫面状况分析是一个有效的技术方法,通过对沙尘灾害发生、发展的环境条件的了解,可以减轻沙尘天气的危害、防治等一系列决策措施的制定、实施提供客观、及时的空间信息,有助于制定和实施区域生态环境保护措施,以便减少沙尘天气的次数和减轻灾害性天气的危害程度。     

山东归来庄金矿区g(Au/Ag)的空间信息统计学特征

空间信息统计学是一门集数学、空间信息科学及计算机技术于一体,在时空域内对区域化变量的随机性与结构性进行定量研究的技术。以山东归来庄金矿床为例,对其g(AuAg)异常进行空间信息统计学研究。利用指示克立格法研究g(AuAg)的空间变异结构特征,建立空间结构模型。在对结构模型和估计方案进行交叉验证后,对g(AuAg)的空间分布进行估计。根据g(AuAg)的空间分布规律,探讨其与Au空间分布的关系,并对今后该区的找金工作提出建议。     

箱法在草地温室气体通量野外实验观测中的应用研究

利用静态箱法采样,配以气相色谱仪法分析对草地N2O、CH4和CO2温室气体通量进行了较系统的现场测量,同时对箱体内外温度进行同步观测。在对野外原位观测实验数据进行定量分析的基础上,论证了静态箱法对草原土壤-植被系统的N2O、CH4和CO2通量测量的适用性和科学性,讨论了实验结果的可靠性。     

90年代中国省级区域经济与环境协调度分析

在阐述经济环境协调度理论的基础上,建立了环境承载力与经济发展水平之间的协调度模型。并通过对90年代我国省级区域的实证分析,发现我国空间区域经济环境协调度基本符合“U”型曲线,区域经济发展模式大多以牺牲环境为代价,特别是中西部地区的问题比较严重。     

东天山戈壁荒漠景观区地球化学勘查中某些工作方法的研究

通过东天山地区地球化学勘查中某些方法的试验,研究了一套适宜于戈壁荒漠景观中地球化学勘查的工作方法.（1）查明了盛行风对岩屑异常特征的影响程度;（2）推荐消除风成沙影响的合理采样粒级;（3）利用水溶态铜、金异常指示被运积物掩盖的铜、金矿体;（4）明确了荒漠区盐磐层不会阻碍在残积物覆盖区发现矿致岩屑异常和在运积物覆盖区发现后生晕.     

模糊数学分析方法在水环境评价中的应用

本文应用模糊数学原理，以淮河上游长台关站水质监测资料为依据，选择5个评价参数，用模糊概念进行推理，经过运算得出综合评价结果，与一般评价方法相比更接近客观。