On the Choice of Soil Hydraulic Models in Land-Surface Schemes   总被引：9，自引：0，他引：9  

Yaping Shao  Parviz Irannejad 《Boundary-Layer Meteorology》1999,90(1):83-115

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Autoregressive filtering versus linear detrending in estimation of fluxes by the eddy covariance method   总被引：10，自引：7，他引：3  

Üllar Rannik  Timo Vesala 《Boundary-Layer Meteorology》1999,91(2):259-280

The application of autoregressive running mean filtering (RMF) and linear detrending (LDT) in the estimation of turbulent fluxes by the eddy covariance method is analysed. The systematic, as well as the random, errors of the fluxes arising from filtering and/or limited observation time effects are described. To observe negligible systematic errors in fluxes, the RMF has to be applied with moderately long time constants. However, the obtained flux values are subject to increased random errors during periods of non-stationarity and the method leads to systematic overestimation of variances. These shortcomings are not inherent in the LDT approach, which is recommended for use. But the systematic errors of fluxes due to LDT are not negligible under certain experimental conditions and have to be accounted for. The corrections are important because the relatively small errors in short-period fluxes can translate to significant errors in long-period averages. The corrections depend on the turbulence time scales, which should be preferably estimated as ensemble mean variables for a particular site.  相似文献   

BASIC CLIMATOLOGICAL FEATURES OF AIR-SEA HEAT EXCHANGES IN THE SOUTH CHINA SEA (SCS) REGION AND THEIR RELATIONS WITH THE SCS MONSOONS          下载免费PDF全文

Ren Xuejuan  Qian Yongfu 《Acta Meteorologica Sinica》1999,13(4):426-438

By using the NCEP reanalysis data set in 1979-1995, the fluxes of the latent heat, thesensible heat and the net long-wave radiation in the South China Sea (SCS) are expanded by meansof EOF in order to discuss the basic climatological features in the SCS. The detailed analysis showsthat the air-sea heat exchanges in different SCS regions have different seasonal variations. Themiddle and the north of the SCS are the high value regions of the air-sea heat exchanges during thewinter and the summer monsoon periods, respectively, the seasonal variations of air-sea heatexchanges in the south of the SCS are small. In addition, the proportions of different componentsin the total air-sea heat exchanges have different seasonal variations in different regions. Theresults show that the SCS monsoon and the air-sea heat exchanges in the SCS region are theaccompaniments of each other, the great difference of the sensible heat flux between the IndochinaPeninsula and the SCS before the SCS summer monsoon onset may be one of the triggers of thelatter. There maintains a high value center of the sensible heat flux before the 13th dekad, itsdisappearing time consists with that of the summer monsoon onset. It means that as far as the SCSlocal conditions are concerned, the northwest of the Indochina Peninsula is probably a sensitiveregion to the SCS summer monsoon onset and the land may play a leading role in the SCS summermonsoon onset.  相似文献   

不同下垫面水分与能量传输模式   总被引：16，自引：2，他引：14       下载免费PDF全文

刘和平  刘树华  桑建国 《大气科学》1999,23(4):449-461

首先从简单生物圈模式（Simple Biosphere Model） 的物理模型出发,对其控制方程进行了修改。土壤温度使用求解热传导方程得到,土壤湿度使用了水汽扩散方程、Darcy的水流方程同时求解得到,目的是使简单生物圈模式既能在有植被下垫面使用,又能扩展到考虑水汽运动的沙漠地区使用。为了检验修改后的模式能适用于计算不同下垫面的地气之间水分和能量交换,选择了草原、森林和沙漠三种类型,在4个不同的实验点得到的资料,进行了单点模式（OFF LINE）检验。结果表明,修改后的简单生物圈模式模式可使用于不同下垫面地气之间水分和能量交换,尤其是解决了沙漠地区水热传输的模拟问题。  相似文献   

爆发性气旋发展中斜压强迫与潜热释放作用的数值试验   总被引：2，自引：0，他引：2       下载免费PDF全文

寇正  欧阳子济 《气象科学》1999,19(3):259-269

本文利用一个六层原始方程模式对五例爆发性气旋的发展进行了数值试验,试验结果表明：斜压强迫是气旋爆发性发展的基本因子,而潜热释放的重要性则有较大差异。潜热释放的作用主要集中在两个方面：一是对低层的直接增暖,加强了上升运动;二是对局地斜压性的加强,促进了锋面、槽脊系统的发展,而这两者均有利于气旋的发展。  相似文献   

Shear heating in continental strike-slip shear zones:model and field examples   总被引：5，自引：0，他引：5  

Philippe Hervé Leloup  Yannick Ricard  Jean Battaglia  & Robin Lacassin 《Geophysical Journal International》1999,136(1):19-40

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供水管网在地震时的可靠性评估方法   总被引：2，自引：0，他引：2  

张宏伟  吴海欣 《地震工程与工程振动》1999,19(2):100-103

本文提出了一种供水管网系统在地震作用时间的可靠性分析方法,开发出相应计算机应用软件并通过实例计算验证了该方法的可靠性和实用性。  相似文献   

The thermal structure and thickness of continental roots   总被引：19，自引：0，他引：19  

C. Jaupart  J. C. Mareschal 《Lithos》1999,48(1-4):93-114

We compare heat flow data from the Precambrian shields in North America and in South Africa. We also review data available in other less well-sampled Shield regions. Variations in crustal heat production account for most of the variability of the heat flow. Because of this variability, it is difficult to define a single average crustal model representative of a whole tectonic province. The average heat flow values of different Archean provinces in Canada, South Africa, Australia and India differ by significant amounts. This is also true for Proterozoic provinces. For example, the heat flow is significantly higher in the Proterozoic Namaqua–Natal Belt of South Africa than in the Grenville Province of the Canadian Shield (61 vs. 41 mW m⁻² on average). These observations indicate that it is not possible to define single value of the average heat flow for all provinces of the same crustal age. Large amplitude short wavelength variations of the heat flow suggest that most of the difference between Proterozoic and Archean heat flow is of crustal origin. In eastern Canada, there is no good correlation between the local values of heat flow and heat production. In the Archean, Proterozoic and Paleozoic provinces of eastern Canada, heat flow values through rocks with the same heat production are not significantly different. There is therefore no evidence for variations of the mantle heat flow beneath these different provinces. After removing the local crustal heat production from the surface heat flow, the mantle (Moho) heat flow was estimated to be between 10–15 mW m⁻² in the Archean, Proterozoic and Paleozoic provinces of eastern Canada. Estimates of the mantle heat flow in the Kaapvaal craton of South Africa may be slightly higher (≈17 mW m⁻²). Large-scale variations of bulk crustal heat production are well-documented in Canada and imply significant differences of deep lithospheric thermal structure. In thick lithosphere, surficial heat flow measurements record a time average of heat production in the lithospheric mantle and are not in equilibrium with the instantaneous heat production. The low mantle heat flow and current estimates of heat production in the lithospheric mantle do not support a mechanical (conductive) lithosphere thinner than 200 km and thicker than 330 km. Temperature anomalies with surrounding oceanic mantle extend to the convective boundary layer below the conductive layer, and hence to depths greater than these estimates. Mechanical and thermal stability of the lithosphere require the mantle part of the lithosphere to be chemically buoyant and depleted in radiogenic elements. Both characteristics are achieved simultaneously by partial melting and melt extraction.  相似文献   

早前寒武纪古地热状态的构造环境意义   总被引：2，自引：0，他引：2  

白瑾 《地学前缘》1999,6(4):323-330

区域变质作用是在造山运动中地热流和动力联合作用的体现。在早前寒武纪的造山带中,随着地壳的缩短,古地热流向构造边界聚敛,形成由高温到低温的区域变质相带序列,它既指示古地热流运移的方向,又是构造边界的指向。古地热流值的高低同构造环境的性质有关,如陆内裂陷带的区域变质仅达绿片岩相,而陆缘活动带的则可高达角闪岩相。古地热流从活动带的边界向中心运移,具有向心性,随着构造层的深埋,构成地热槽,它的片段则表现为地热斜。识别这些古地热状态,可为构造环境属性的鉴定提供有力的依据  相似文献   

胜利油气区东营凹陷现今地温场研究   总被引：13，自引：0，他引：13  

熊振  王良书 《高校地质学报》1999,5(3):312-321

文中利用热导率分散模型,根据地层中砂质含量数据计算东营凹陷第三系各沉积地层单元的原地热导率,再利用热阻率法根据东营凹陷１７０口测温井中测温资料计算出第三系各地层界面上和特征深度处温度,进而研究东营凹陷现今地下温度。计算结果表明,第三系各地介面上地温分布特征主要受各界面埋藏深度控制,而地下各特征深度上地温分布特征主要受热流平面分布特征控制。  相似文献