THE APPROACH TO REMOTE SENSING OF WATER VAPOR BASED ON GPS AND LINEAR REGRESSION T_m IN EASTERN REGION OF CHINA     

李建国  毛节泰 《Acta Meteorologica Sinica》1998,(4)

The approach to remote sensing of water vapor by using global positioning systems(GPS)isdiscussed.In order to retrieve the vertical integrated water vapor(IWV)or the precipitable water(PW),the weighted“mean temperature”of the atmosphere,T_m would be estimated to the specificarea and season.T_m depends on surface temperature,tropospheric temperature profile,and thevertical distribution of water vapor.The surface temperature dependence is borne out by acomparison of T_m and the values of surface temperature T_s using radiosonde profiles of BeijingStation(No.54511)throughout 1992.The analysis of radiosonde profiles spanning a one-yearinterval(1992)from sites in eastern region of China with a latitude range of 20-50°N and alongitude range of 100-130°E yields the coefficients α and b of a linear regression equation T_m=α bT_s.  相似文献   

C3植物光合作用日变化的模拟   总被引：28，自引：1，他引：27  

于强  任保华  王天铎  孙菽芬 《大气科学》1998,22(6):867-880

对前人光合作用-气孔导度耦合模型进行了修正,建立了光合作用-蒸腾作用-气孔导度的耦合模型,它概括了叶片上各主要物理过程和生理过程之间的相互联系和制约关系。 用数值方法研究了不同环境因子（太阳辐射、温度、湿度和风速等）对光合作用、蒸腾作用和气孔导度的日变化及中午降低（midday depression）的影响。 主要结果是:（1）当边界层导度减小时,光合“午睡”加剧,蒸腾作用减弱,但作为反馈调节,气孔导度增加。 （2）气孔导度的最适温度最低,光合作用次之,蒸腾作用最适温度最高。当光合作用中午受到高温的胁迫时,气孔导度下降的幅度最大,光合作用次之,蒸腾作用的降幅最小。一天中,气孔导度降低的持续时间最长,蒸腾作用降低的持续时间最短。（3）空气绝对湿度越低,气孔导度越低,光合午睡越明显。蒸腾作用则决定于饱和水汽压差(Vpd)和气孔导度两个因素的相反的作用。蒸腾作用随Vpd增加而增大,但Vpd超过一定值后,反而使蒸腾作用下降。 （4）当温度在光合最适温度以上时,太阳辐射的增加使叶温增加,引起光合“午睡”的加剧和气孔导度的降低。（5）ci/cs在中午的降低表明气孔的关闭是光合作用“午睡”现象的原因。  相似文献   

与T63数值预报产品相结合的江苏西南大风的预报方法   总被引：3，自引：2，他引：1  

杜京朝  濮梅娟 《气象科学》1998,18(3):271-277

国家气象中心发送的T63数值预告产品在本台于95年6月份投入业务运行,为尽好、尽快地最大限度地将T63数值产品投入业务使用,以发挥其作用,从而具体体现T63的价值所在、在这方面,我们作了一些探讨与尝试。我们把《江苏大面积西南大风预报工具》与T63数值预告产品进行结合与释用,取得了良好的效果。  相似文献   

Composite suspended sediment particles in river systems: their incidence,dynamics and physical characteristics     

J. C. Woodward  D. E. Walling 《水文研究》2007,21(26):3601-3614

Most of the existing data on the effective particle size characteristics of fluvial suspended sediment derive from instantaneous sampling methods that may not be representative of the overall suspended sediment loads. This presents difficulties when there is a need to incorporate effective particle size data into numerical models of floodplain sedimentation and sediment‐associated contaminant transfer. We have used a field‐based water elutriation apparatus (WEA) to assemble a large (36 flood) database on the time‐integrated nature of the effective and absolute particle size characteristics of suspended sediment in four subcatchments of the River Exe basin of southwest England. These catchments encompass a wide range of terrains and fluvial environments that are broadly representative of much of the UK and temperate, low relief northwest Europe. The WEA provides important data on the physical characteristics of composite particles that are not attainable using other methods. This dataset has allowed, for the first time, detailed interbasin comparisons of the time‐integrated particle size characteristics of suspended sediment and reliable estimates of the contribution of five effective size classes to the mean annual suspended sediment load of the study catchments. The suspended sediment load of each river is dominated by composite rather than primary particles, with, for example, almost 60% (by mass) of the sediment load of the River Exe at Thorverton transported as composite particles > 16 µm in size. All the effective size classes contain significant clay components. A key outcome of this study is the recognition that each catchment has a distinctive time‐integrated effective particle size signature. In addition, the time‐integrated effective particle size characteristics of the suspended loads in each of the catchments display much greater spatial variability than the equivalent absolute particle size distributions. This indicates that the processes producing composite particles vary significantly between these catchments, and this has important implications for our understanding of the dynamics of suspended sediment properties. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

棉铃虫发生发展与气候条件的关系研究进展     

黄健  健 《沙漠与绿洲气象(新疆气象)》2024,18(1):1-11

棉铃虫Helicoverpa armigera 属鳞翅目夜蛾科，是一种世界性的重大害虫，在世界各地均有分布。因其具有远距离迁飞，繁殖力强等特点，条件适宜时常大面积暴发成灾，给农业生产带来较大损失。摸清棉铃虫生活习性、种群变化规律是棉铃虫防治的前提条件。由于棉铃虫是变温昆虫，气候条件对其生长发育、成灾机制等产生极大影响。因此，本文系统综述了气候变暖对棉铃虫影响的研究进展，包括棉铃虫生长发育、体色变化、繁殖、滞育、飞行、越冬、与作物的互作关系等方面，并对未来研究重点进行了展望。以期对棉铃虫的综合治理提供理论依据。  相似文献   

基于惯导/天文高精度定姿方法     

杨生  孙付平  陈坡  秦士琨 《测绘学院学报》2009,(2)

研究了利用惯性导航系统与天文导航系统进行组合定姿的方法;构造了惯导/天文组合导航系统的状态方程和量测方程;采用卡尔曼滤波技术设计了惯导/天文组合定姿算法。设计飞行器的典型飞行轨迹,通过数学仿真对该算法的有效性进行了验证。结果表明,天文导航能够有效地补偿惯性导航因陀螺漂移带来的误差,非常适用于飞行器的高精度定姿。  相似文献   

Impacts of maintenance channel dredging in a northern Adriatic coastal lagoon. I: Effects on sediment properties,contamination and toxicity     

Roberta Guerra  Andrea PasterisMassimo Ponti 《Estuarine, Coastal and Shelf Science》2009

Conservation and management of coastal lagoons envisage direct human intervention. To prevent siltation and to preserve the hydrodynamics features of the lagoon system, the inner channels undergo regular maintenance dredging.  相似文献   

三维城市模型的研究与实践(英文)   总被引：3，自引：0，他引：3  

朱庆  胡明远  张叶廷  杜志强 《地球空间信息科学学报》2009,12(1):18-24

The way we interact with spatial data has been changed from 2D map to 3D Virtual Geographic Environment (VGE). Three-dimensional representations of geographic information on a computer are known as VGE, and in particular 3D city models provide an efficient way to integrate massive, heterogenous geospatial information and georeferenced information in urban areas. 3D city modeling (3DCM) is an active research and practice topic in distinct application areas. This paper introduces different modeling paradigms employed in 3D GIS, virtual environment, and AEC/FM. Up-to-date 3DCM technologies are evolving into a data integration and collaborative approach to represent the full spatial coverage of a city, to model both aboveground and underground, outdoor and indoor environments including man-made objects and natural features with 3D geometry, appearance, topology and semantics. Supported by the National Natural Science Foundation of China ( No. 40871212, No. 40671158), the Leading Academic Discipline Project of Shanghai Educational Committee( No.J50104).  相似文献   

宁南县城后山泥石流综合治理工程财务管理     

徐素琼 《山地学报》1990,(4)

宁南县城后山泥石流综合治理工程总预算为159.00万元,实际拨款129.01万元。为用好这笔资金,严格了财务管理制度,采取了专项资金专人管理措施,加强对用工、材料、资金和施工等的管理,使工程不但超计划数量完成,而且未追加投资,做到了费省效宏,较好地发挥了投资效益。  相似文献   

排水管网多尺度几何语义建模     

蓝贵文  唐宇龙  杜永良  潘柱光  莫栩琪 《测绘通报》2021,(3):123-127

针对排水管网管理业务的不同需求,研究排水管网的多尺度几何语义表达方法,本文提出了包含“源—网—厂—汇”的排水管网多尺度几何语义模型。通过对排水管网组成要素及其相互间的关系进行系统地分析,并参考CityGML规范,提出了排水管网多细节层次模型;根据不同排水管网要素的特点,采用符号化及BIM等建模方式分别构建了不同细节层次的排水管网要素模型,支持排水管网多尺度可视化分析。并以某区域的排水管网数据为例,对本文提出的建模方法进行验证。  相似文献