Approximation of the infra-red radiation flux in an atmosphere with cloud     

M. J. Manton 《Pure and Applied Geophysics》1978,116(6):1049-1062

Summary A three-stream infra-red radiation scheme for use particularly in boundary layer models is described. Local uniformity of the atmosphere (i.e. a generalization of the cooling to space approximation in clear air) is assumed, and the radiation equation is solved by simple collocation rather than by the full discrete ordinate method. In clear air the scheme corresponds to the usual approximation, which incorporates the Elsasser factor in the transmission function to account for diffuse radiation. The band models of Goody for water vapour and Elsasser for carbon dioxide are used for the band averaging of the transmission functions. Consistent with this, the band averaging of the radiation flux in cloud is undertaken by replacing the rapidly varying absorption coefficients for the gases by the actual band-averaged values of those coefficients. The band averaging is precise in the limits of strong and weak gaseous absorption.  相似文献   

On the scavenging of SO2 by cloud and raindrops: I. A theoretical study of SO2 absorption and desorption for water drops in air     

C. J. Walcek  H. R. Pruppacher 《Journal of Atmospheric Chemistry》1983,1(3):269-289

An extention of our previous theory for trace gas absorption into freely-falling cloud and raindrops is presented. This theory describes the convective diffusion of a trace gas through air and into a water drop with internal circulation, the drop falling at its terminal velocity. Using flow fields for the circulating water inside and for the moving air outside the drop, obtained by numerical solutions to the Navier—Stokes equation of motion, we numerically solved the convective diffusion equation to determine the uptake of SO₂ by water drops of various sizes, time exposure to the gas phase, and concentration of SO₂ in the gas phase. It was found that for drops of radius larger than 1 mm and relatively low gas concentrations (10 ppb (v)), resistance to gas diffusion lies mainly in the gas phase; while for drops of radius less than 500 m and gas concentrations larger than those found in the atmosphere (1% (v)), the resistance to diffusion lies primarily in the liquid phase. With drop sizes and gas concentrations between these limits, the rate of SO₂ uptake is controlled by a coupled resistance to diffusion inside and outside the drop. In addition to our general model, a simplified version was formulated which allows considerable savings in computer time for evaluation and improved ease of handling without significant loss of accuracy. A comparison between our simplified model and that of Barrie (1978) shows that the boundary-layer approach of Barrie may be a useful alternate approach to estimating trace gas absorption by water drops, provided appropriate values are chosen for the thickness of the boundary layers involved.  相似文献   

Seismic waves in a layered half-space from an arbitrary buried source     

MENG Fanshun  WANG Zaishan  LI JianjunCollege of Marine Geosdence  Ocean University of China  Qingdao  P.R.ChinaNo. Petrolum-mining Plant  Da Qing Petroleum Administration  Daqing  P.R.China 《中国海洋大学学报(英文版)》2003,2(2):201-206

In this paper, a transfer matrix and a three-dimensional dynamic response of a layered half-space to an arbitrary buried source are derived with the aid of a technique which combines the Laplace and two-dimensional Fourier transforms in a rectangular coordinate system. This method is clear in concept, and the corresponding formulas given in the paper are simple and convenient for marine seismic prospecting and other fields' applications. An example is presented and the calculated results are in good agreement with those of the finite element method (FEM).  相似文献   

'Cultures of GM': discourses of risk and labelling of GMOs in the UK and EU   总被引：1，自引：0，他引：1  

Clare B Herrick 《Area》2005,37(3):286-294

The debate over genetically modified foods has become one of the defining environmental and social issues of the past decade. As the public naturalize biotechnology within existing cultural systems, this produces what I term 'cultures of GM'. This paper examines how these 'cultures' are legitimized and sustained through an appraisal of divergent North American and European conceptions of risk and their translation into food labelling policies. It is argued that the dialectical relationship between risk perception and its cultural context offers an instructive vantage point for critical reflection by geographers.  相似文献   

Capital's Utopia: Vandergrift,Pennsylvania, 1855–1916     

《The Professional geographer》2005,57(1):146-148

  相似文献   

广东交通建设占用耕地的特征及其趋势预测     

梁志娇  丘世均 《云南地理环境研究》2005,17(1):50-54

1990～2000年是广东省交通建设大发展时期和耕地减少的高峰期。通过对这一时段的分析,发现交通建设占用耕地已成为广东省非农建设占用耕地的主要成分和耕地减少的一大因素。在空间分布特征上,利用土地扩展集中指数和扩展强度两个指标进行计算分析,结果是广东省交通占用耕地分布区域不均匀,扩展区域主要集中于清远、广州等市;而占用最为严重的地区是深圳和汕头两市。根据广东交通发展的需要,预测到2030年,全省由于交通建设还需占用土地118295.26hm2。  相似文献   

多通道时间传递接收机NTSCGPS-1的研制与测试   总被引：2，自引：0，他引：2  

高玉平  漆溢  王正明 《全球定位系统》2004,29(2):16-20

近20年来，GPS共视(GPS CV)技术作为一种主要技术被用于TAI时间比对。GPS时间传递接收机是进行GPSCV时间比对的主要设备。介绍了中科院国家授时中心采用Motorola VP Oncore GPS OEM板、GT200计数器研发的高精度、多通道GIPS时间传递接收机NTscGPS-1的原理和特点。并通过实际观测数据分析，认为NTSCGPS-1的观测噪声水平与其它时间传递接收机相当，并有较好的兼客性。  相似文献   

GPS共视接收机短期观测资料处理算法研究   总被引：1，自引：0，他引：1  

杨旭海  卢晓春  胡永辉  李志刚 《武汉大学学报(信息科学版)》2004,29(3):205-209

提出了一种新的基于总体最小二乘数据拟合的短期观测资料处理算法 ,同时考虑测量时刻和时差测量值的不确定性 ,可提高共视接收机输出的单站数据精度。超短基线单通道共视测量数据表明 ,使用新算法后 ,可以提高原始共视数据短期稳定度  相似文献   

农情遥感信息与其他农情信息的对比分析   总被引：11，自引：0，他引：11  

黄进良  徐新刚  吴炳方 《遥感学报》2004,8(6):655-663

农情信息多种多样 ,来源不同 ,分散于各个部门或单位 ,缺乏相互交换与验证 ,综合分析与集成不够 ,特别是遥感信息为经济领域决策服务的渠道不通畅。为更好地应用各种信息 ,必须加强信息综合分析。对耕地面积、作物面积、作物单产、作物长势、粮食产量等几种农情信息中不同来源的信息进行了初步对比分析 ,肯定了遥感监测农情信息在客观性、时空连续性、可对比与可预测、低成本等几个方面的优势 ,同时也分析了遥感信息的不足和局限。认为遥感信息与其他信息不是互相替代的关系 ,而是互相补充、互相验证的关系。只有通过多源农情信息的综合分析和集成 ,才能更全面准确地反映农情。  相似文献   

Synrift stratigraphic geometry in a transfer zone coarse-grained delta complex, Miocene Pohang Basin, SE Korea   总被引：2，自引：0，他引：2  

Young Kwan Sohn  Moon Son† 《Sedimentology》2004,51(6):1387-1408

The Gojusan fan delta is a coarse‐grained delta complex on the western margin of the Miocene Pohang Basin, SE Korea. The deposits consist of five facies associations (FA): alluvial‐fan conglomerates (FA I), shallow‐marine mouth‐bar sandstones (FA II), fluvial and mouth‐bar conglomerates (FA III), Gilbert‐type foreset conglomerates (FA IV) and hemipelagic mudstones (FA V). Different facies associations characterize the northern, central and southern parts of the delta complex. To the north, FA IV is laterally juxtaposed with FA I or the basement, with scarp‐derived breccias along the contact. Centrally, and to the south, FA I is laterally juxtaposed with FA II, with an abrupt facies change and local inliers of basement rocks along the contact. Early alluvial fan and mouth‐bar deposits are overlain by the topset (FA III) and truncated by the foreset (FA IV) of a Gilbert‐type delta in the central part of the fan delta complex, whereas FA II passes transitionally upward into FA III in the south, with the latter extending basinward into a gently inclined shoal water delta front. Gilbert‐type and shoal‐water geometries are therefore developed in the same delta complex. The composite delta geometry is interpreted as reflecting (1) its development near an extensional transfer zone where the hangingwall relief was variable over short distances along strike, and (2) the operation of intrabasinal faults. This interpretation contrasts with previous studies that viewed the delta complex as having formed along a pull‐apart basin margin.  相似文献