Towards Closing the Surface Energy Budget of a Mid-latitude Grassland   总被引：4，自引：1，他引：3  

Adrie F. G. Jacobs  Bert G. Heusinkveld  Albert A. M. Holtslag 《Boundary-Layer Meteorology》2008,126(1):125-136

Observations for May and August, 2005, from a long-term grassland meteorological station situated in central Netherlands were used to evaluate the closure of the surface energy budget. We compute all possible enthalpy changes, such as the grass cover heat storage, dew water heat storage, air mass heat storage and the photosynthesis energy flux, over an averaging time interval. In addition, the soil heat flux was estimated using a harmonic analysis technique to obtain a more accurate assessment of the surface soil heat flux. By doing so, a closure of 96% was obtained. The harmonic analysis technique appears to improve closure by 9%, the photosynthesis for 3% and the rest of the storage terms for a 3% improvement of the energy budget closure. For calm nights (friction velocity u _* < 0.1 m s⁻¹) when the eddy covariance technique is unreliable for measurement of the vertical turbulent fluxes, the inclusion of a scheme that calculates dew fluxes improves the energy budget closure significantly.  相似文献   

山地复杂下垫面湍流特征观测分析   总被引：1，自引：0，他引：1  

杨胜朋  吕世华  陈玉春  奥银焕  蒋熹 《高原气象》2008,27(2):272-278

利用谱方法和能量闭合度分析等方法,对兰州市皋兰山2006年夏季和2005年冬季涡度相关系统测定的湍流数据质量进行了分析,结果表明:4个观测点测定的三维风速、空气温度的功率谱在惯性副区都符合"-2/3"定律,垂直风速和温度的协谱在惯性副区也基本符合"-4/3"定律.4个观测点都存在能量平衡不闭合现象,夏季观测点绿化地和裸地能量平衡比率(EBR)分别为66%和94%,冬季绿化地和裸地的EBR分别为62%和84%;裸地观测点的闭合程度明显好于绿化地.本文还讨论了能量闭合度的日变化特征及各个观测点的地表能量收支状况.  相似文献   

Water quality assessment for Ulansuhai Lake using fuzzy clustering and pattern recognition   总被引：1，自引：0，他引：1  

任春涛  李畅游  贾克力  张生  李卫平  曹有玲 《中国海洋湖沼学报》2008,26(3):339-344

Water quality assessment of lakes is important to determine functional zones of water use. Considering the fuzziness during the partitioning process for lake water quality in an arid area, a multiplex model of fuzzy clustering with pattern recognition was developed by integrating transitive closure method, ISODATA algorithm in fuzzy clustering and fuzzy pattern recognition. The model was applied to partition the Ulansuhai Lake, a typical shallow lake in arid climate zone in the west part of Inner Mongolia, China and grade the condition of water quality divisions. The results showed that the partition well matched the real conditions of the lake, and the method has been proved accurate in the application.  相似文献   

隆升幅度及隆升速率研究方法综述   总被引：5，自引：2，他引：5  

王国灿 《地质科技情报》1995,14(2):17-22

对有关隆升幅度和速率定量研究的古生物、古气候法、古地球法、地质压力计法、热年代学方法及变质作用ｐ－Ｔ－ｔ轨迹法作了概括，重点阐述了近年来热年代学方法在隆升幅度和速率量研究中的应用。此外，对这些方法应用的前提和条件作了评述。  相似文献   

应用随机辐射传输模型反演云南松林分郁闭度   总被引：1，自引：0，他引：1  

李骁尧  黄华国 《遥感学报》2020,24(6):752-765

随机辐射传输模型可用于模拟水平分布不均一森林的辐射传输过程。本文以云南松林分为研究对象，提出一种应用随机辐射传输模型的郁闭度反演方法。该方法以随机辐射传输模型中参数与林分郁闭度的定量关系为基础，提出了针对云南松的冠型等效模型，构建了郁闭度和卫星反射率（GF-1和Landsat 8卫星影像）的查找表，并实施了反演。基于野外实测的30个样地进行了郁闭度数据验证，并和基于NDVI回归模型的反演方法进行对比。结果表明，反演结果能够较准确反映云南松林分郁闭状况（R²=0.8345，RMSE=0.0688），通过冠型修正能够降低反演误差，冠型等效模型是合理的。反演方法机理清晰且适用范围广，研究成果可为大面积森林郁闭度反演提供模型和方法支持。  相似文献   

A SIMPLE PROGNOSTIC CLOSURE ASSUMPTION TO DEEP CONVECTIVE PARAMETERIZATION:Ⅱ          下载免费PDF全文

Chen Dehui  Philippe Bougeault 《Acta Meteorologica Sinica》1993,7(2):212-223

A series of 3D predictions,dealing with the development of a heavy storm observed during the OSCAR experiment,were carried out by utilizing the PERIDOT model,and introducing alternatively the cumulus parameterization scheme of Bougeault (1985) and the prognostic one (Chen,1989;Chen and Bougeault,1993),with three different grid sizes:160 km,80 km,40 km.The feasibility of the new prognostic scheme and its improvement on the problem of dependency of the predicted rainfall upon the grid size of the numerical model were verified by comparison of the rainfall observed and those predicted.The results demonstrate that,in general,the predicted rainfall increases when the grid size decreases for both diagnostic and prognostic schemes.However,with the new prognostic scheme,the numerical model is capable,on the one hand,for the larger grid sizes,to increase the rainfall,which is under-estimated with the scheme of Bougeault (1985);on the another hand,for the smaller grid sizes,to reduce the rainfall,which is usually over-estimated.In other word,there is an obvious improvement on the problem under study.  相似文献   

细网格非静力二维高阶闭合模式对山体流场特征的模拟分析     

刘红年  蒋维楣 《高原气象》1994,(4)

本文采用二阶矩湍流闭合方案，分别就非静力和准静力两种条件建立ＰＢＬ数值模式，并模拟了二维山脊流场的结构，计算了二维山体对气流平均场和湍流场的影响。计算结果表明，无论是平均场还是湍流场，采用准静力假设都会造成模拟结果的较大偏差，且对平均场的影响比对湍流场的影响更为显著。两种模式计算结果的差别还随地形坡度和背景风增大而增大。  相似文献   

Intra-arc opening and closure of a marginal sea: The case of the Guerrero Terrane (SW Mexico)     

Olivier  Monod  Michel  Faure  Juan-Carlos  Salinas 《Island Arc》1994,3(1):25-34

Abstract The pre-Oligocene structure of southwest Mexico, south of the trans-Mexico volcanic axis, is investigated from Taxco (Guerrero state, abbreviation: Gro) to the Pacific coast. Three volcano-sedimentary units are recognized; from east to west the calc-alkaline Teloloapan, tholeiitic Arcelia and calc-alkaline Zihuatanejo suites. Structural and stratigraphic data show that the Teloloapan volcanic arc, active during ?Late Jurassic and early Cretaceous, was built upon continental basement. The Teloloapan lavas are overlain by the Albian–Cenomanian Morelos platform carbonates and followed by the Upper Cretaceous Mexcala flysch. In contrast, the Arcelia pillow lavas are associated with sandstones and cherts of Albian-?Cenomanian age. The Zihuatanejo arc was also installed upon continental basement and its magmatic activity was in part coeval with Arcelia magmatism. Unlike the almost undeformed Zihuatanejo volcanic rocks, all the other volcanic units are involved in east-vergent thrusting and recumbent folding associated with ductile tectonics, as well as the Late Cretaceous Mexcala flysch overlying the Morelos platform carbonates. Contrasting with previous views, the present results do not support a major mid-Cretaceous thrusting event in the study area. The new geodynamic interpretation proposed here considers that the Arcelia rocks were formed in a marginal basin situated east of the Zihuatanejo arc. Closure of this basin in Paleocene times is responsible for the east vergent thrust tectonics in SW Mexico.  相似文献   

大兴安岭北段塔河辉长岩的岩石学特征及其构造意义   总被引：9，自引：2，他引：9  

周长勇  葛文春  吴福元 《吉林大学学报(地球科学版)》2005,35(2):143-149

塔河辉长岩是大兴安岭北段塔河地区最具代表性的辉长岩体.该岩体主要由橄榄辉长岩、浅色橄榄辉长岩、淡色辉长岩(斜长岩)、橄长岩及辉长岩组成,以橄榄辉长岩和橄长岩为主.其主要造岩矿物由斜长石、橄榄石、单斜辉石及少量角闪石组成,具反应边结构和包含嵌晶结构.电子探针分析结果表明,其橄榄石Fo平均为77,属贵橄榄石.单斜辉石全部落入透辉石区.斜长石An平均为85,为倍长石.岩相学特征表明,该岩体为典型的堆晶辉长岩体.根据An-Fo及AlZ -TiO2 图解可以判别该岩体形成于活动大陆边缘/岛弧的构造环境中,属于I型弧堆晶辉长岩,其形成可能与古亚洲洋闭合过程中板块俯冲-流体交代作用有关,是研究古亚洲洋闭合历史的一个重要岩石学标志.  相似文献   

博格达裂谷闭合和区域隆起的同位素年代学证据及地质意义   总被引：8，自引：0，他引：8  

王银喜  顾连兴  张遵忠  张开均  李惠民  吴昌志  杨杰东 《地球学报》2005,26(Z1):102-104

博格达造山带位于准噶尔和吐鲁番-哈密两个前寒武纪地块之间，是晚古生代的大陆裂谷。经研究，博格达大石头-色皮口地区的流纹岩Rb-Sr同位素年龄为307.1±1.3 Ma，表明博格达地区火山活动由早石炭世持续到晚石炭世。该年龄可视为博格达裂谷闭合和区域隆什之后造山阶段产物的形成年龄。该区流纹岩其源区物质主要来自于亏损地幔或是由玄武岩浆演化经分离结晶作用形成的流纹岩这一特征是十分罕见的。  相似文献