农田尺度土壤水分的监测   总被引：7，自引：1，他引：7       下载免费PDF全文

杨诗秀  雷志栋 《水科学进展》1996,7(1):14-19

根据田间试验实测资料分析了田间土壤水分的空间变化特征和时间动态变化,探索了监测农田水分变化时如何确定其合理的取样数目,讨论了农田尺度的土壤水分应如何监测,为节水灌溉,提高田间用水管理水平提供科学依据。  相似文献   

冀东地区油气微渗漏地植物的遥感基础研究     

黄秀华  张磊 《遥感学报》1992,(2)

本文通过已知含油区及背景区地植物及地表土壤多种微量金属元素和吸附烃的综合分析,并利用遥感资料与物探资料作复合评价,讨论了冀东油气微渗漏地区的遥感植物地球化学标志。  相似文献   

多级SPOT立体影像匹配     

陶闯  林宗坚 《遥感学报》1992,(2)

立体影像匹配是自动提取SPOT影像高程信息的关键技术。本文根据SPOT影像在几何构像关系和影像质量上的特点,提出了多级匹配的结构策略。实际像对匹配实验表明,多级匹配法具有较好的可靠性和精度水平,而且运算速度快,在快速生成DEM数据辅助遥感信息分析方面,有重要的应用价值。  相似文献   

基于计算机视觉的专题图读取系统     

林宗坚  卢健  邸凯昌 《武汉大学学报(信息科学版)》1992,(2)

本文提出了一种基于计算机视觉的专题图读取系统方案。该系统用CCD相机获取专题图影象,通过线划跟踪、弧段矢量化、拓扑结构形成、数据压缩、几何纠正与拼接等步骤,实现专题图的自动读取,继而进行各种几何量算和统计,建立专题信息库  相似文献   

Monthly summaries of merchant ship surface marine observations and implications for climate variability studies     

Réjean Michaud  Charles A Lin 《Climate Dynamics》1992,7(1):45-55

We compute the interannual fluctuations of the surface heat budget of the North Atlantic using the trimmed monthly summaries of the Comprehensive Ocean-Atmosphere DataSet (COADS) for the period 1950–1979. The presence of long-period trends in the heat budget imply large variations of the northward cross-equatorial heat transport over the years. To assess the reliability of these variations, we compare the COADS climate signal to that derived from the ocean weather stations (OWSs) of the North Atlantic. The sea surface temperature, air temperature and sea level pressure show good correlation between the anomaly time series derived from the merchant ship monthly summaries of COADS, and those derived from OWS monthly summaries, except for northernmost locations during winter. In contrast, the sensible and latent heat parameters, which require simultaneous measurements of various variables, have merchant ships and ocean weather stations anomaly time series that are poorly correlated. Only in heavily travelled latitudes and during winter, when the air-sea heat exchange anomalies are large, are the merchant ship measurements able to reproduce the interannual fluctuations of the heat fluxes. The long-period trends in the surface heat budget of North Atlantic equatorward of 40° N implied by COADS thus appear unrepresentative of true climate trends. The COADS trends result from a gradual increase in the magnitude of the reported winds over the years due probably to variations in the ratio of measured to estimated winds, as well as from long period fluctuations in the near surface vertical temperature and humidity gradients. Offprint requests to: R Michaud  相似文献   

青海可可西里无人区夏季温度分布特征   总被引：1，自引：0，他引：1  

张琳 《高原气象》1992,11(2):203-207

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Numerical study on dry deposition processes in canopy layer     

Lei Xiaoen  Julius S. Chang 《大气科学进展》1992,9(4):491-500

A coupling model between the canopy layer (CL) and atmospheric boundary layer (ABL) for the study of dry deposition velocity is developed. The model consists of six parts: chemical species conservation equation including absorptive factor; the species uptake action including detailed vertical variation of absorptive element in CL; momen-tum exchange in CL which is represented by a first-order closure momentum equation with an additional larger-scale diffusive term; momentum exchange in ABL which is described by a complete set of the ABL turbulent statistic parameters; absorptivity (or solubility or reflection) at the surface including effects of the physical and chemi-cal characters of the species, land type, seasonal and diurnal variations of the meteorological variables; and deposition velocity derived by distributions of the species with height in CL. Variational rules of the concentration and deposi-tion velocity with both height and time are simulated with the model for both corn and forest canopies. Results pre-dicted with the bulk deposition velocity derived in the paper consist well with experimental data.  相似文献   

用物质线的轨迹积分方法研究阻塞     

张绍晴  陈久康 《南京气象学院学报》1992,15(3):315-322

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长期预报的相空间近邻等距法   总被引：6，自引：0，他引：6  

林振山 《大气科学》1992,16(5):530-537

考虑到确定性系统的外在随机因素和内在随机性(浑沌)所造成的长期预报的不准确性,本义将有关浑沌的理论和数理统计理论结合起来,提出了d维相空间距平符号传播的“正、反规则”假说和近邻等距模式.实例检验表明,经调试后距平符号的报准率一般为66％—80％,而相对误差一般不大于8％.  相似文献   

Precambrian Geochronology, Chronotectonic Framework and Model of Chronocrustal Structure of the Zhongtiao Mountains   总被引：8，自引：0，他引：8  

Sun Dazhong  Li Huimin  Lin Yuanxian  Zhou Huifang  Zhao Fengqing  Tang Min 《《地质学报》英文版》1992,66(1):23-37

The Zhongtiao Mountains, a typical exposure area of Precambrian rocks, are a concentration area of vari-ous types of copper deposit. The rocks were dated using several dating methods. Based on the age data ob-tained by means of three methods, several aspects are dealt with: (1) the dating results obtained by differentmethods and their geological implications have been compared; (2) a chronotectonic framework has been con-structed by means of these reliable ages, which indicates that the ages of the rocks of the Proterozoic mobilebelt fall in a time span of 2400 to 2000 Ma during which global magmatic records are lacking and reflects theages of important events in the mobile belt; (3) according to the ages of inherited zircons, neodymium modelage of the depleted mantle sources (T_(DM)) and geochemical and geological data, a model of Precambrianchronocrustal structure has been constructed, representing a typical for the North China craton.  相似文献