Accumulation phenomena in fluvial processes and the corresponding stochastic model     

Jing  Huan  Zhong  Deyu  Zhang  Hongwu  Shi  Xufang  Wang  Yanjun 《地理学报(英文版)》2020,30(6):1021-1040

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A dendroclimatological study of east- and west-facing slopes in mountainous areas subjected to strong air pollution (the Sudetes,Central Europe)     

Magdalena Opała-Owczarek  Marek Błaś  Mieczysław Sobik  Michał Godek 《自然地理学》2019,40(2):186-208

The Sudetes Mountains (Central Europe) were under a particularly intense long-term air pollution load during the 1970s and 1980s. Intense industrial activity in this area led to large-scale forest dieback and reductions in tree growth rates, potentially limiting the use of tree-ring data from this region in dendroclimatic research. In this paper, ring-width chronologies were constructed for 493 Norway spruce trees (Picea abies L. Karst.) from 17 sampling sites within five major mountain ranges in the Sudetes Mountains of Poland. Growth-climate response data indicate that April?July temperatures are the main factor affecting radial growth of trees in the study area. Our data also indicate the strong influence of slope aspect on temperature signal strength. The lowest correlation values were obtained for sites located on western slopes with effective fog deposition, which are strongly affected by pollution. An appropriate sampling strategy resulted in the creation of a temperature-sensitive proxy record (rAMJJ = 0.70), exceptional for areas under strong pressure from human activity. Based on a regional master chronology, growing season (April?July) temperatures over the past 200 years were then reconstructed. Four warm and four cold periods were distinguished and compared with other reconstructions and long-term instrumental data.  相似文献   

光滑表面内孤立波光学遥感图像的实验研究     

梅源  王晶  黄松松  牟海迪  陈旭 《海洋学报(英文版)》2019,38(6):124-131

基于光学遥感图像的内孤立波参数反演是一项重要的工作。本文在实验室条件下提出一种新方法用于模拟光滑表面情况下内孤立波的光学遥感成像。基于二维内波水槽、LED平板面光源和CCD相机搭建仿真光学遥感系统探测内孤立波。水平表面的光学遥感图像和垂向内孤立波传播图像被同时探测，旨在探讨在光滑表面下，光学遥感与内孤立波的响应。结果表明，内孤立波传播经过时，CCD1相机获得暗纹，暗纹的特性随光源入射角的变化而变化。光学遥感特征参数和垂向波要素相对应。实验还显示光学遥感图像的暗纹宽度与内孤立波的半波宽度在不同内孤立波振幅下呈现正相关关系。该系统有着现象清晰，重复性高的优点，为定量研究光学遥感成像机理提供科学依据。  相似文献   

改进的最优窗宽理论对年径流量的插值预测研究——以黄河利津等站为例          下载免费PDF全文

匡晓为  朱伟军  洪梅  白成祖 《大气科学学报》2018,41(2):258-266

针对小样本数据造成年径流量预测效果不理想的情况,以及非对称和非正态资料的处理问题,引入信息扩散和模糊映射思想,同时运用遗传算法改进最优窗宽理论,建立了新的扩散插值模型。该模型通过对零散数据点的信息进行模糊扩散,进而实现对有限数据点信息向其邻近区域点的概率插值。选取黄河利津站为例,根据其近70 a(1942—2011年)径流量实测数据,进行了缺损数据的插值和预测试验,同时与正态扩散插值模型进行对比分析,结果表明:1)预测值能较好地模拟实际径流序列的波形变化,对丰水年(如2007年)和枯水年(如2009年)的预报都比较准确;2)中长期预报(10a)平均相对误差仅为11.59%,相较传统方法有较大的改进;3)以黄河流域2个站点(花园口和兰州)和长江流域的3个站点(朱沱、宜昌和大通)年径流量预测试验以及海温资料的插值试验作为补充,验证了该算法的有效性和普适性。该模型可为实际水文数据资料的客观分析和中长期预报提供参考。  相似文献   

海岸破碎带植物消浪数值模拟研究     

刘达  黄本胜  邱静  谭超 《海洋工程》2016,34(2):16-23

沿海防浪林能形成柔性的植物消浪体系,可以有效降低风暴潮灾害。由于防浪林消浪效果受波浪、近岸水深及植物等多重因素的影响,消浪机理较为复杂,以往的系统研究成果较少。本文以立面二维自由面紊流模型为工具,建立了基于植物冠层特征的多孔介质模型,精细地模拟了破碎波对植物带的冲击,并与物理模型试验结果进行了对比验证,计算分析了植物带宽度、植物密度、滩地水深等因素对消浪效果的影响。  相似文献   

黄河三角洲埕岛近岸海域悬浮泥沙运动   总被引：8，自引：2，他引：8  

冯秀丽  吴世强  林霖  刘涛  周松望 《海洋科学》2003,27(12):66-70

根据1998年9月8日和1999年3月19日两次对埕北海域进行的10个站位的同步海流、悬浮泥沙观测资料，进行该海区的悬浮泥沙输运趋势分析，发现该海区含沙量较大。从整个海区来看，底层含沙量大于表层含沙量，该海区泥沙含量普遍表现为东南部的泥沙含量高于西北部的泥沙含量；由单宽输沙量的计算及有关资料分析可以得出，秋季泥沙运移趋势是由东南向到西北向，而春季泥沙的运移趋势是由东北向到西南向；含沙量是随流速的加大而增加，含沙量的峰值稍滞后于流速的峰值；该海区为冲蚀海区，悬浮泥沙产生的平均年7中刷量为2cm／a，在本海区的地形塑造中占次要地位。  相似文献   

Ontogenetic Shifts in Resource Use and Shoaling Tendency Related to Body Size in Red Sea Goatfish (Parupeneus forsskali, Mullidae)     

Franz  Uiblein 《Marine Ecology》1991,12(2):153-161

Abstract. Red Sea goatfish show marked behavioral differences related to body size in food searching, substrate use, and shoaling tendency. While smaller fish mainly use their barbels to search for food hidden in the upper sediment layers or in crevices of corals, the largest fish frequently burrow with their mouths in deeper layers of the sediment. The conspecific shoaling tendency decreases with increasing size. Only smaller-sized fish are found in mixed-species shoals. The data are discussed with regard to the relations between ontogenetic changes in body size, resource utilization, and socialization patterns.  相似文献   

Scour below pipelines and around vertical piles in random waves     

Dag Myrhaug  Hvard Rue 《Coastal Engineering》2003,48(4):227-242

An approach by which the scour depth and scour width below a fixed pipeline and scour depth around a circular vertical pile in random waves can be derived is presented. Here, the scour depth formulas by Sumer and Fredsøe [ASCE J. Waterw., Port, Coastal Ocean Eng. 116 (1990) 307] for pipelines and Sumer et al. [ASCE J. Waterw., Port, Coastal Ocean Eng. 114 (1992) 599] for vertical piles as well as the scour width formula by Sumer and Fredsøe [The Mechanics of Scour in the Marine Environment, World Scientific, Singapore, 2002] for pipelines combined with describing the waves as a stationary Gaussian narrow-band random process are used to derive the cumulative distribution functions of the scour depths and width. Comparisons are made between the present approach and random wave scour data. Tentative approaches to related random wave scour cases are also suggested.  相似文献   

Singularity and Breaking of the Third Order Stokes Waves     

孙孚  高山  王伟  钱成春 《中国海洋工程》2003,17(1)

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Time-based signal characteristics as predictors of fish size and species for a side-looking hydroacoustic application in a river   总被引：1，自引：1，他引：1  

Burwen  Debby L; Fleischman  Steven J; Miller  James D; Jensen  Mark E 《ICES Journal of Marine Science》2003,60(3):662-668

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