滑动平均差检测法的提出及验证   总被引：1，自引：1，他引：0  

包为民  沈丹丹  倪鹏  周俊伟  孙逸群 《地理学报》2018,73(11):2075-2085

时间序列突变点的检测研究是当前气候变化问题的关键环节,其方法和成果也较多,传统的检测方法因统计量结构不合理、假设条件不符合实际以及受主观因素影响等,结果常常缺乏可信度。本文提出一种新的时间序列突变点的检测方法——滑动平均差检测法,将该方法分别用理想时间序列和实际观测序列进行应用检验,并与现有常用的4种突变检验方法比较,发现滑动平均差法具有：① 结构简单、物理意义明确;② 检测突变点更精确;③ 能同时检测出所有突变点的突变位置和其突变强度3个明显的优势。综合利用滑动平均差检测法和传统的4种方法,对黄河流域几个重点水文控制站实测输沙量资料进行突变分析,结果表明：黄河上游输沙量在1986年发生突变,黄河中游输沙量在1979年和1996年发生突变,华县站和潼关站输沙量在1979年、1996年和2003年发生突变,造成输沙量突变的主要因素为水利工程建设和大规模水土保持措施等人类活动。  相似文献   

Seasonal variability of the Antarctic Coastal Current and its driving mechanisms in the Weddell Sea   总被引：2，自引：0，他引：2  

Ismael Núez-Riboni  Eberhard Fahrbach 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(11):1927-1941

Insight into the dynamics of the Antarctic Coastal Current (ACoC) is achieved by quantifying the contributions of its driving mechanisms to the seasonal variability of its barotropic and baroclinic components. These mechanisms are sought out in the local wind, the sea-ice concentration, wind curl of the Weddell Gyre (Sverdrup transport) and the thermohaline forcing related to warming/cooling and ice melting and freezing. These driving mechanisms induce most of the seasonal variability of both the barotropic and baroclinic components of the ACoC by deepening the pycnocline towards the coast and sharpening the baroclinic profile following thermal wind balance. The resulting coastal current has mainly a barotropic transport (82%) and a major annual cycle, which explains 37% of this component's variability (tides and other high-frequency events generate 40%). The wind contributes with 58% of the seasonal variability of the barotropic component and 23% of the baroclinic; the sea-ice concentration contributes with 8% and 18%, respectively; Sverdrup transport with 4% and 30% and the thermohaline forcing with 30% and 29%. The results of this study are obtained with analysis of fifteen CTD sections (potential density and geostrophic velocities) of RV-Polarstern obtained between 1992 and 2005, as well as composite, spectral and harmonic analyses of 9 years of time series from moored instruments (current speed and temperature), wind speed, atmospheric pressure and sea-ice concentration of satellite imagery.  相似文献   

自然金—银类质同象系列矿物晶胞参数变化规律及其表述方程     

姜跌先 《地球科学与环境学报》1991,(3)

本文提出了自然金—银类质同象系列矿物晶胞参数与金、银原子数百分比成二次函数关系,并推导出了表示二者之间函数关系的方程式。利用该方程式,可以用金原子数百分比计算出晶胞参数,反之亦然。并首次将其应用在自然金—银类质同象系列矿物的研究中。  相似文献   

五维波动问题的一种解法     

谭阳  柯红路 《广东海洋大学学报》2006,26(3):71-73

介绍解五维波动问题的微分算子级数法,首先引进数性算子概念及微分算子级数法;其次,推导出了求解公式;最后通过求解公式求解了一些五维波动方程的例题,得出任何维数(n≥5)的波动方程柯西问题都可以用微分算子级数法求其解。  相似文献   

Snow water content estimation from measured snow temperature     

李志军  赵海清  冯恩民  程斌  卢鹏 《极地研究(英文版)》2007,18(1):1-7

The vertical temperature profiles of snow and sea ice have been measured in the Arctic during the 2nd Chinese National Arctic Research Expedition in 2003(CHINARE2003).The high-resolution temperature profile in snow is solved by one-dimensional heat transfer equation.The effective heat diffusivity,internal heat sources are identified.The internal heat source refers to the penetrated solar radiation which usually warms the lower part of the snow layer in summer.By temperature gradient analysis,the zero level can be clarified quantitatively as the boundary of the dry and wet snow.According to the in situ time series of vertical temperature profile,the time series of water content in snow is obtained based on an evaluation method of snow water content associated with the snow and ice physical parameters.The relationship of snow water content and snow temperature and temporal-spatial distribution of snow water content are presented  相似文献   

利用GPS基准站数据浅析我国地壳垂直运动   总被引：1，自引：0，他引：1  

荣敏  孙付平  贾小林  周巍  刘光明 《测绘工程》2009,18(4):7-9

应用国内GPS基准站1999-2005年共？年的垂直位移时间序列数据，浅析我国的地壳垂直运动。粗略地分析GPS基准站的垂向位移分量时间序列，表明地壳垂直运动受到多种因素的影响。  相似文献   

Stream nitrate levels in a small catchment in south west England over a period of 35 years (1970–2005)     

Tim P. Burt  Fred Worrall 《水文研究》2009,23(14):2056-2068

This study considers a 35‐year record of streamwater nitrate concentration in a small agricultural catchment in south west England (Slapton Wood). The study revisits earlier work to assess whether upward trends have been maintained and how the controls upon streamwater concentration have been altered. The study has shown that (1) the catchment has reached a new position of equilibrium and increases in nitrate concentration have lessened; (2) the occurrence of severe drought in the record means that records of less than a decade are misleading and only long‐term records can illustrate changes of state; (3) the change of state observed in the catchment is illustrated in the switching of long‐term memory effects from a negative to a positive annual memory and (4) several significant long‐term impulsivity relationships with rainfall that become insignificant over the course of the study period. The study shows the importance of long‐term records in understanding changes in state in catchments and understanding the time constants of a range of driving processes. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Neural network time series prediction of environmental variables in a small upland headwater in NE Scotland     

M. J. Aitkenhead  R. J. Cooper 《水文研究》2008,22(16):3091-3101

Short‐term prediction of environmental variables such as stream flow rate is useful to members of the general public and environmental scientists alike, providing the ability to predict environmental disasters or scientifically interesting events. Here, a neural‐network based method is presented, which is capable of providing advance flood warnings or the prediction of high stream flow events for research purposes in a small upland headwater in NE Scotland. This method relies on training from past time series data acquired in the field, and provides the ability to predict a range of hydrological and meteorological variables up to 24 h ahead using feedback of predicted values at time t as new inputs for the next time step t + 1. The system is rapid and effective, relies on standard neural network training methods, and has the potential to be implemented in a web‐based monitoring and prediction package. The model design could be implemented at any study site where time series data has been gathered, and is sufficiently flexible to accept whatever data is available. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

黔北牛蹄塘组的地球化学特征及形成环境   总被引：7，自引：5，他引：7  

袁宏  肖加飞  何熙琦  白平 《贵州地质》2007,24(1):55-59,63

贵州北部早寒武世的黑色岩系-牛蹄塘组。主要为黑色页岩,含浮游生物,其中产钼、钒等矿床。其具有独特的元素地球化学特征:K、Ti元素在黑色页岩中的含量高于底部硅质岩,而P元素的含量却相反,硅质岩中的含量显著高于其上覆的黑色页岩;岩孔和菜园两地的共同特点是V、Ba、U的含量明显偏高,富集系数在3以上,显著的差别是Ta元素,其在岩孔是亏损的,而在菜园却明显富集;西部岩孔的稀土总量高于东部菜园,稀土配分曲线形态近于水平或略向左倾,具弱的负Eu异常或不显异常。硅质岩较页岩的负Ce异常程度高。地层特征、元素地球化学特征及特征元素和比值,所反映的是下寒武统牛蹄塘组形成于缺氧的还原环境。  相似文献   

条带状铁建造(BIFs)研究的几个问题   总被引：8，自引：0，他引：8  

李碧乐  霍亮  李永胜 《矿物学报》2007,27(2):205-210

前寒武纪条带状铁建造(BIFs)中拥有全球最重要的铁矿资源,BIFs中以及包括BIFs在内的含铁岩系还含有丰富的金、铜、锌、钴、铂族等有用元素。本论文主要针对BIFs形成过程中与成矿有关的几个关键问题进行评述和探讨,包括BIFs的成矿系列,地幔柱与BIFs的关系,微生物在BIFs形成中的作用等。认为BIFs内部以及包括BIFs在内的含铁岩系均构成贱、贵金属成矿系列;地幔柱与BIFs之间存在密切的时、空和成因联系;在早前寒武纪缺氧的环境下,厌氧的细菌类生物通过光合作用为BIFs中铁质沉淀提供了氧。希望该研究对包括BIFs的成矿作用在内的前寒武纪地质研究以及拓展找矿思路有所启示。  相似文献