Heterogeneous Saltation: Theory, Observation and Comparison   总被引：7，自引：0，他引：7  

Yaping Shao  Masao Mikami 《Boundary-Layer Meteorology》2005,115(3):359-379

In the theory of saltation, under development since the 1940s, it is often assumed that saltation is homogeneous, i.e., saltating particles are uniform in size and follow identical trajectories. This assumption is a limitation to the development of saltation theory. In this paper, as in some other studies made since the 1980s, we are concerned with the saltation of multi-sized particles in turbulent flows, a process that we refer to as heterogeneous saltation. The theory deals with several questions, including the variation of particle size distribution with height, the entrainment rates of particles in different size ranges, and the associated profiles of saltation flux, particle momentum flux and particle concentration. It is hypothesised that saltation is dynamically similar and ‘universal’ similarity functions can be established. The similarity function for saltation flux is presented. Field observations are carried out at the southern fringe of the Takla Makan Desert in April 2002. Measurements of streamwise saltation flux of 32 particle size groups are made using a sand particle counter, together with measurements of wind speed and other atmospheric variables. These data are used to validate the saltation theory, by examining whether the observed saltation flux and particle size distribution can be reproduced. It is shown that the theory is promising in predicting these quantities.  相似文献   

Indirect Indicators of Gas HydrateOccurrence within Submarine Sediments     

Zhao Xingmin Wu Bihao Institute of Mineral Deposits  Chinese Academy of Geological Sciences  Beijing Wang Yaping Experimental Institute  Chinese Academy of Geological Sciences  Beijing Lu Zhenquan Institute of Mineral Deposits  Chine 《中国地质大学学报(英文版)》2000,11(4)

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人工示踪沙实验的原理与进展   总被引：6，自引：0，他引：6  

贾建军  高抒  汪亚平 《海洋通报》2000,19(2):80-89

人工示踪沙实验是进行沉积物搬运研究的一咱独立方法,已有近５０年的发展历史。人工示踪沙实验有三种主要方法（即空间积分法、时间积扮法和连续投放法）,可用以获得活动层厚度、垂向和水平系数、输运率等定量参数,并进行不同输沙公式进行对比验证,在海底稳定性分析、港湾冲淤、工程措施影响评价等方面都有应用价值。通过加强实验的物理边界、沉积物活动层厚度、实验的时空尺度、充分混合状态、示踪沙加收率、沉积特搬运过程等方  相似文献   

琼江两次洪水过程的水文气象分析     

翟丹华  张亚萍  邱鹏  黎中菊  邓承之  邹华 《气象》2015,41(1):59-67

对2012年7月3—5日和2013年6月30日至7月1日四川盆地东南部四川省和重庆市交界处的琼江流域两次洪水过程的水文气象条件进行了分析。利用数字高程模型DEM提取了琼江流域的河网分布和河道距离出口的分布,结合标准化时间距离方法客观地反映了降水（尤其是强降水）的时空分布情况。SWAN输出的组合反射率因子拼图表明两次琼江流域的强降水均由多段强降水雨带导致,对流系统多在右岸支流源头新生,移向与河流流向一致,在干流产生洪水的叠加效应。由于“6．30”过程中强回波几乎覆盖整个琼江流域长达约16 h,导致严重的洪水叠加效应,洪水漫过原有河道形成大面积滞洪区,洪水行至下游河段回归河槽时,加之河道收窄,造成下游水文站洪峰时间滞后。  相似文献   

西沙西科1井第四系生物礁-碳酸盐岩的岩石学特征   总被引：1，自引：0，他引：1       下载免费PDF全文

孙志鹏  尤丽  李晓  刘立  廖静  刘娜  赵爽  于亚苹 《地球科学》2015,40(4):653-659

从西科1井生物礁-碳酸盐岩的岩心观察和岩石学特征的分析入手, 重点刻画了第四系全新-更新统乐东组生物礁-碳酸盐岩的岩石类型和生物礁类型.543片铸体薄片分析和214.89 m岩心观察表明: 岩石类型主要为粒泥灰岩、泥粒灰岩和骨架灰岩, 其次为粘结灰岩、颗粒灰岩、漂砾灰岩和砾屑灰岩.在纵向上, 埋深0~10 m层段以颗粒灰岩为主, 埋深10~22 m层段为生物碎屑砂分布段, 埋深22.00~214.89 m层段以粒泥灰岩、泥粒灰岩和骨架灰岩为主.生物礁类型以骨架礁为主, 造礁生物为珊瑚和少量珊瑚藻.骨架礁在埋深0~214.89 m均有发育, 丛状和块(段)状礁仅分布于埋深83~98 m.   相似文献   

中国东部深层煤矿床勘查开发技术途径     

张妙逢  贾茜  龙亚平  贾建称  吴艳 《中国煤炭地质》2015,(2):13-16,31

在分析我国煤炭资源分布与供需矛盾的基础上,提出中国东部深层煤矿床勘查开发的主要任务是弄清煤层赋存与分布状态,寻找煤炭资源,精细查明影响矿井生产的各种地质因素和工程技术条件。根据煤炭地质勘查技术发展现状、探测能力与精度,指出深部煤炭资源勘查技术思路是"快速扫面、筛选靶区",勘查方略是"立体综合勘探,精细物探先行、深钻追踪验证",即以精细三维地震和电法勘探为先导,配合其它勘查手段。深层煤矿床勘查工作模式有3个层次,完成深部煤矿床快速精细探测的根本途径是依据煤田(井田)地质背景和勘查地质目标,选取勘查方法和探测技术,实现地质、物探、钻探与地理信息系统、计算机技术的有机结合和多成果相互验证。  相似文献   

Effects of rice straw on the cell viability,photosynthesis, and growth of Microcystis aeruginosa     

苏文  贾育红  卢亚萍  孔繁翔 《中国海洋湖沼学报》2014,32(1):120-129

Rice straw is supposed to be an environment-friendly biomaterial for inhibiting the growth of harmful blooms of the cyanobacterium Microcystis aeruginosa. However, its potential mechanism is not well known. To explore this mechanism, the growth, cell viability （esterase activity, membrane potential, and membrane integrity）, photosynthesis, and cell size ofM. aeruginosa were determined using flow cytometry and Phyto-PAM after exposure to rice straw extracts （RSE）. The results show that doses from 2.0 to 10.0 g/L of RSE efficiently inhibited the alga for 15 days, while the physiologic and morphologic responses of the cyanobacteria were time-dependent. RSE interfered with the cell membrane potential, cell size, and in vivo chlorophyll-a fluorescence on the first day. After 7 days of exposure, RSE was transported into the cytosol, which disrupted enzyme activity and photosynthesis. The cyanobacteria then started to repair its physiology （enzyme activity, photosynthesis） and remained viable, suggesting that rice straw act as an algistatic agent.  相似文献   

A diagnostic study of two heavy rainfall events in South China     

Liji Wu  Yaping Shao  Andrew Y. S. Cheng 《Meteorology and Atmospheric Physics》2011,111(1-2):13-25

South China is prone to heavy rainfall which may occur both in the pre-monsoon and the monsoon season. The responsible synoptic systems and the water-vapor sources, however, can be substantially different for different seasons. In this study, we aim to develop conceptual models for typical heavy rainfall events in South China through diagnostic case studies. A number of events have been analyzed using the NCEP/NCAR data, but the discussions here are focused on two representative events, one for the pre-monsoon season and the other for the monsoon season. Both events are found to be associated with extensive moist convective instability in the lower part of the troposphere. For the pre-monsoon case the instability was much weaker and the uplift of the warm moist air was provided by the cold air intrusion related to a weak cold front. The moist potential vorticity theory can be used to explain the increase of vorticity and vertical velocity in the lower part of the troposphere. For the monsoon event, the lower troposphere was extensively and strongly unstable and the upward motion was provided by the shear of a southwesterly low-level jet (LLJ) which appeared to be driven, at least partially driven, by the upper-level jet. In both events, LLJ played a major role in not only providing the dynamic conditions but also the supply of water vapor for heavy rainfall in South China. The diagnostic results presented in this study provide a useful guidance for future numerical simulations.  相似文献   

净全辐射异常值的审核处理     

秦榕  井立红  何亚平  玛依努尔·阿不拉  侯玲红  黄海云  杨霰 《气象》2011,37(5):645-648

针对近年来在省级质量控制数据R文件时净全辐射出现的问题,利用<地面自动站观测资料三级质量控制软件--省级软件>对净全辐射质量控制时数据异常原因进行举例分析,并采用人机交互方法对经质量控制后系统自动生成的疑误信息进行综合分析判断,同时结合有关规定和问题解答提出相应的处理方法,以确保净全辐射观测数据的真实、准确、可靠,进而为业务科研工作提供科学的、准确的数据.  相似文献   

Atmospheric pollution indicated by trace elements in snow from the northern slope of Cho Oyu range,Himalayas     

Yaping Liu  Shugui Hou  Sungmin Hong  Soon-Do Hur  Khanghyun Lee  Yetang Wang 《Environmental Earth Sciences》2011,63(2):311-320

Samples collected from a 0.87 m snow pit at a high altitude site in the Cho Oyu range, Himalayas were measured for V, Cr, Mn, Co, Ni, Cu, Zn, As, Rb, Sr, Cd, Sn, Sb, Ba, Tl, Pb, Bi, Th, and U using inductively coupled plasma mass spectrometry. In addition, major ions, oxygen stable isotopes, and microparticles were also measured to assist the interpretation of seasonal variation of trace elements. The trace elements show a distinct seasonality, i.e., higher concentrations during the non-monsoon season than those during the monsoon season. Significant correlation is observed between Ba and the other trace elements. Crustal enrichment factor (EF_c) analysis indicates that V, Mn, Co, Ni, Rb, Sr, and Th originate mainly from crustal dust, while anthropogenic inputs make an important contribution to the other trace elements (i.e., Cu, Zn, As, Cd, Sn, Sb, Ti, Pb, Bi, and U). Evidence from air mass back trajectories suggests that atmospheric trace element pollution reaching the studied area is transported dominantly by Indian summer monsoon during the monsoon season, while it is transported mainly by the westerlies during the non-monsoon season.  相似文献