Study of a model for correcting the effects of horizontal advection on surface fluxes measurement based on remote sensing     

Tian  Jing  Zhang  Renhua  Sun  Xiaomin  Zhu  Zhilin  Zhou  Yanlian 《中国科学:地球科学(英文版)》2006,49(2):273-280

As well known, the methods of remote sensing and Bowen Ratio for retrieving surface flux are based on energy balance closure; however, in most cases, surface energy observed in experiment is lack of closure. There are two main causes for this: one is from the errors of the observation devices and the differences of their observational scale; the other lies in the effect of horizontal advection on the surface flux measurement. Therefore, it is very important to estimate the effects of horizontal advection quantitatively. Based on the local advection theory and the surface experiment, a model has been proposed for correcting the effect of horizontal advection on surface flux measurement, in which the relationship between the fetch of the measurement and pixel size for remote sensed data was considered. By means of numerical simulations, the sensitivities of the main parameters in the model and the scaling problems of horizontal advection were analyzed. At last, by using the observational data acquired in agricultural field with relatively homogeneous surface, the model was validated.

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ANALYSIS OF DRIVING FORCES ON THE CHANGE OF HISTORICAL FARMLAND USE IN SHANDONG PROVINCE DURING THE QING DYNASTY （1644-1911）     

ZHANGXue-qin GEQuan-sheng ZHENGJing-yun 《中国地理科学(英文版)》2003,13(3):207-215

How land-cover has been changed by human use over the last 300 years is one of the five overarching questions guiding the Land-use/Cover Change (LUCC) Science/Research Plan. China has variety of historical docu-ments providing unique data superiority. So the characteristics of farmland area in Shandong Province during the Qing Dynasty (1644-1911) are summarized firstly: 1) the rising trend of farmland area was striking; 2) farmland area had re-markable fluctuation; 3) farmland area per capita decreased dramatically; 4) wasteland reclamation index increased rapidly. Then, the driving forces of farmland area change are analyzed. It is concluded that natural and human factors are jointly influential. Among the driving forces, human dimensions are the main factors of farmland area change,which direct the general tendency of the changes mentioned above. And the natural factors influence the stability of farmland area as well. Variation of the natural factors would act as the major contributory factor to farmland area change during years or periods of abrupt climatic changes, or during the intensive occurring periods of natural hazards.Besides, the passive aspects of human factors, such as war chaos also influenced the fluctuation of the farmland area.This research indicates that it is feasible to study the land-use/cover change by Chinese historical literatures, which has huge potential to provide a comprehensive picture of the growing dominance of human land-use and land-cover pat-terns that can be used in many global change research oroiects.  相似文献   

SIMULATION AND PREDICTION OF DEBRIS FLOW USING ARTIFICIAL NEURAL NETWORK     

WANGXie-kang HUANGEr CUIPeng 《中国地理科学(英文版)》2003,13(3):262-266

Debris flow is one of the most destructive phenomena of natural hazards. Recently, major natural haz-ard, claiming human lives and assets, is due to debris flow in the world. Several practical methods for forecasting de-bris flow have been proposed, however, the accuracy of these methods is not high enough for practical use because of the stochastic and non-linear characteristics of debris flow. Artificial neural network has proven to be feasible and use-fill in developing models for nonlinear systems. On the other hand, predicting the future behavior based on a time se-ries of collected historical data is also an important tool in many scientific applications. In this study we present a three-layer feed-forward neural network model to forecast surge of debris flow according to the time series data collect-ed in the Jiangjia Ravine, situated in north part of Yunnan Province of China. The simulation and prediction of debris flow using the proposed approach shows this model is feasible, however, further studies are needed.  相似文献   

Characters of the Pco2 and CO2 Flux in the East China Sea in Autumn     

纪雷  崔鹤  辛淑平  王军  张龙军  陆贤昆 《中国海洋湖沼学报》2003,21(2):180-186

Pco2 of air and seawater samples from the East China Sea(ECS) were measured in situ in autumn, 1994,Ocean currents,terrestrial fluviation,biological activities,etc.,Pco2 char-acters in air and seawater were investigated,CO2 flux and its character in the East China Sea are discussed on the basis of the Pco2 profiles of air and seawater,It was clear that the nearshore was the source of CO2;and tht the oulter sea area was the sink of CO2; and that the shelf area of the EXS is a net sink for atmospheric CO2 in autumn.  相似文献   

γ射线暴研究概况   总被引：1，自引：0，他引：1  

黎卓  戴子高  陆埮 《天文学进展》2003,21(4):334-369

γ射线暴(简称γ暴)的研究自1997年以来由于余辉的发现而有了很大的突破。在此，对γ暴的观测作了简要的概述，而对γ暴的理论进展和存在问题进行了较为全面的评述，内容包括γ暴本身、余辉、能源机制、寄主星系、暴周环境、高能粒子和引力波辐射、宇宙学意义等。  相似文献   

类太阳色球活动星εEri磁场的观测研究     

刘学富  曹雪勇 《天文学报》1996,37(3):227-234

本文给出１９９３—１９９４年期间，用云南天文台１米望远镜折轴摄谱仪观测获得类太阳色球活动星。εＥｒｉ的５个波段高分辨、高信噪比光谱，运用两种不同方法：谱线轮廓塞曼致宽分析和多重线统计分析法成功地测定了εＥｒｉ的表面磁场强度和磁场的覆盖因子，并对这两种磁场测定方法作了简单的讨论．  相似文献   

γ射线暴的研究进展（Ⅳ：特强γ射线暴和软γ重复暴   总被引：2，自引：0，他引：2  

陆建隆  潘善龙  陆埮 《天文学进展》1996,14(4):302-314

最近CGRO上的仪器观测到了两个迄今为止发现的最强的λ暴GB930131和GB940217,其光子最高能量均达GeV量级;GB930131的峰值计数率达2×10~6个光子s~(-1);而GB940217的持续时间竟长达90min。另外沉寂了多年的软重复暴源SGR1900 14和SGR1806-20的再次爆发也由BATSE发现。一系列的观测还发现这些软重复暴均与X射线源对应且与超新星遗迹成协。文中对特强暴和软重暴(SGR)的性质及研究进展作了较为详细的评述。  相似文献   

广西小平阳岩溶区地裂缝形成因素分析     

张骏  卢玉东  孙建中  范文 《地球科学与环境学报》1996,(4)

８０年代以来，广西小平阳岩溶区出现了大量的地裂缝。通过调查研究．这些地裂缝的形成是受多种因素控制的．其中包括构造、土体性质、水的作用、地形地貌、气候及植被等因素。在上述因素中．构造是主导因素，上体性质是基础因素．其它则为诱发因素，也是因地质环境要素变化所引起的因素。主导因素是通过诱发因素起作用的．并最终通过土体性质因素导致产土地裂缝。  相似文献   

西南极纳尔逊岛Stansbury半岛火山岩地质特征初论          下载免费PDF全文

郑祥身 《极地研究》1990,2(4):28-35

纳尔逊岛Stansbury半岛被玄武质、玄武安山质熔岩和火山碎屑岩以及沉积火山碎屑岩所覆盖。区域火山岩地层对比证明其是在形成长城站地区火山岩的同一火山作用下发育起来的。据地质接触关系和岩石组合特点,初步认为该半岛火山岩地层可以进一步划分为三个岩性段,分别形成于两期火山作用。该半岛的主要构造线方向平行于菲尔德斯海峡,这在地貌特征及次火山岩的分布上得到了证实。  相似文献   

The FAST/SKA site selection in Guizhou province   总被引：1，自引：0，他引：1  

B. Zhu  Y. Nie  R. Nan  B. Peng 《Astrophysics and Space Science》2001,278(1-2):213-218

Many karst depressions with diameters of 300 m to 500 m, suitable for constructing Arecibo-style radio telescopes, were identified in the south of Guizhou Province by Remote Sensing (RS) and Geographic Information System (GIS) technologies together with field investigations. Fundamental topography and landform databases were established for 391candidate depressions, and using GIS the3-dimensional images of depressions, at a scale of 1:10000, were then simulated to fit a spherical antenna. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献