A Simple Parameterisation for Flux Footprint Predictions   总被引：9，自引：6，他引：9  

N. Kljun  P. Calanca  M. W. Rotach  H. P. Schmid 《Boundary-Layer Meteorology》2004,112(3):503-523

Flux footprint functions estimate the location and relative importance of passive scalar sources influencing flux measurements at a given receptor height. These footprint estimates strongly vary in size, depending on receptor height, atmospheric stability, and surface roughness. Reliable footprint calculations from, e.g., Lagrangian stochastic models or large-eddy simulations are computationally expensive and cannot readily be computed for long-term observational programs. To facilitate more accessible footprint estimates, a scaling procedure is introduced for flux footprint functions over a range of stratifications from convective to stable, and receptor heights ranging from near the surface to the middle of the boundary layer. It is shown that, when applying this scaling procedure, footprint estimates collapse to an ensemble of similar curves. A simple parameterisation for the scaled footprint estimates is presented. This parameterisation accounts for the influence of the roughness length on the footprint and allows for a quick but precise algebraic footprint estimation.  相似文献   

Numerical Studies with a Regional Atmospheric Climate Model Based on Changes in the Roughness Length for Momentum and Heat Over Antarctica     

C. H. Reijmer  E. Van Meijgaard  M. R. Van Den Broeke 《Boundary-Layer Meteorology》2004,111(2):313-337

A regional atmospheric climate model is used toexamine the effect of changes in the roughnesslengths of momentum (_z0m) and heat (_z0h)on the structure of the lower atmosphere and on thesurface energy fluxes over Antarctica. Fourexperiments were carried out in which _z0mand/or _z0h were altered with respect to acontrol experiment. The changes consisted of (1) alowering of _z0m from a field aggregated froma vegetation map with an orographic correction basedon the European Centre for Medium-Range WeatherForecasts _z0m field, to a constant value of10^-3 m; and (2) a lowering of _z0h from a valueequal to _z0m to a constant value of 10^-3 mor a value dependent on the wind speed via a surfacerenewal model. A reduction of _z0m results in theexpected increase in near-surface wind speed. It alsoresults in an increase in the depth of the layer in whichsouth-easterly near-surface winds prevail, and in adecrease in the strength of the large-scale flow overthe continent, in particular in summer. In theescarpment region a decrease of _z0m is foundto result in too high wind speeds. Surface temperatureson average decrease while atmospheric temperaturesincrease, resulting in an increase of near-surfacestatic stability. Changes in roughness lengths donot significantly change the temperature profiles.The surface fluxes, on average found reduced, aremodelled best by using the _z0h based on thesurface renewal method.  相似文献   

Kinetics of the Gas-Phase Reactions of OH Radicals, NO3 Radicals and O3 with Three C7-Carbonyls Formed From The Atmospheric Reactions of Myrcene, Ocimene and Terpinolene     

Jillian Baker  Janet Arey  Roger Atkinson 《Journal of Atmospheric Chemistry》2004,48(3):241-260

Rate constants for the gas-phase reactions of OH radicals, NO₃ radicals and O₃ with the C₇-carbonyl compounds 4-methylenehex-5-enal [CH₂=CHC(=CH₂)CH₂CH₂CHO], (3Z)- and (3E)-4-methylhexa-3,5-dienal [CH₂=CHC(CH₃)=CHCH₂CHO] and 4-methylcyclohex-3-en-1-one, which are products of the atmospheric degradations of myrcene, Z- and E-ocimene and terpinolene, respectively, have been measured at 296 ± 2 K and atmospheric pressure of air using relative rate methods. The rate constants obtained (in cm³ molecule^–1 s^–1 units) were: for 4-methylenehex-5-enal, (1.55 ± 0.15) × 10^–10, (4.75 ± 0.35) × 10^–13 and (1.46 ± 0.12) × 10^–17 for the OH radical, NO₃ radical and O₃ reactions, respectively; for (3Z)-4-methylhexa-3,5-dienal: (1.61 ± 0.35) × 10^–10, (2.17 ± 0.30) × 10^–12, and (4.13 ± 0.81) × 10^–17 for the OH radical, NO₃ radical and O₃ reactions, respectively; for (3E)-4-methylhexa-3,5-dienal: (2.52 ± 0.65) × 10^–10, (1.75 ± 0.27) × 10^–12, and (5.36 ± 0.28) × 10^–17 for the OH radical, NO₃ radical and O₃ reactions, respectively; and for 4-methylcyclohex-3-en-1-one: (1.10 ± 0.19) × 10^–10, (1.81 ± 0.35) × 10^–12, and (6.98 ± 0.40) × 10^–17 for the OH radical, NO₃ radical and O₃ reactions, respectively. These carbonyl compounds are all reactive in the troposphere, with daytime reaction with the OH radical and nighttime reaction with the NO₃ radical being predicted to dominate as loss processes and with estimated lifetimes of about an hour or less.  相似文献   

土水特征曲线的通用数学模型研究   总被引：13，自引：3，他引：13  

戚国庆  黄润秋 《工程地质学报》2004,12(2):182-186

土水特征曲线对于研究非饱和土的物理力学特性至关重要。根据土水特征曲线可以确定非饱和土的强度、体应变和渗透系数 ,甚至可以确定地下水面以上水份分布。由于土体物理力学特性的差异 ,导致描述其土水特征曲线的数学模型也各不相同。因此 ,建立土水特征曲线的通用数学表达式 ,显得尤为必要。本文对土水特征曲线数学模型进行了研究 ,依据这些模型的数学表达式形式 ,将其划分为 4种类型。分别由这 4种类型的数学模型推导出具有统一表达式形式的土水特征曲线通用数学模型 ,并运用陕北高原黄土土水特征曲线试验数据对通用数学模型进行了研究  相似文献   

天山乌鲁木齐河源一号冰川探地雷达测厚及其数据分析     

何茂兵 孙波杨亚新  焦克勤 《华东地质学院学报》2004,27(3):235-239

探地雷达是一种利用电磁波的反射原理探测地下介质分布特征的地球物理勘探技术，在冰川研究中发挥了重要作用。在天山一号冰川上用探地雷达进行了探测，获得了能够清晰地分辨冰一岩界面的雷达剖面。根据这些雷达剖面读出冰厚值，再结合最新的冰川地形图，作出了天山一号冰川的冰厚等值线图和冰下地形图；并由天山一号冰川最新的表面积数据推算了冰储量。  相似文献   

Environmental Properties of Minerals and Contaminants Purified by the Mineralogical Method   总被引：2，自引：0，他引：2  

LU Anhuai School of Earth  Space Sciences  Peking University  Beijing 《《地质学报》英文版》2004,78(1):191-202

The investigation of the environmental properties of minerals, i.e., environmental mineralogy, is a branch of science dealing with interactions between natural minerals and spheres of the Earth surface as well as a reflection of global change, prevention of ecological destruction, participation in biomineralogy, and remediation of environmental pollution. Pollutant treatment by natural minerals is based on the natural law and reflects natural self-purification functions in the inorganic world, similar to that of the organic world - a biological treatment. A series of case studies related to natural self-purification, which were mostly completed by our group, are discussed in this paper. In natural cryptomelane there is a larger pseudotetragonal tunnel than that formed by [MnO6] octahedral double chains, with an aperture of 0.462-0.466 nm2, filled with K cations. Cryptomelane might be a real naturally-occurring mineral of the active octahedral molecular sieve (OMS-2). CrⅥ-bearing wastewater can be treate  相似文献   

城市应急管理模型之设计   总被引：2，自引：0，他引：2  

危福泉  黄宏生 《福建地震》2004,(2)

随着城市建设的快速发展 ,各类危及国家和人民群众生命财产安全的突发性事故灾害时有发生 ,尽管各有关部门的抢救队伍在实施抢险救援中发挥了积极作用 ,但各抢险救援力量专业单一、分散行动 ,形成不了合力 ,难以及时有效处置重大或特大突发性、综合性、大面积的城市事故灾害 ,特别是像地震以及的美国的 9 1 1那样突发性事故。我们目前开展的震害预测与灾害快速评估系统只是针对地震的 ,而地震是小概率事件。因此要应对城市各种重大突发事件 ,城市有必要建立一种应急机制或综合的应急管理信息系统。根据“数字城市”的思想 ,通过一个通信系统与信息系统集成的平台 ,统一协调公安、消防、急救、交警、公共事业、民防、地震等政府部门 ,为市民提供快速、及时的各种救助和相应的服务。统一报警、统一指挥、快速反应、联合行动 ,从而有效地减少损失。  相似文献   

SMBR中污染物处理效率随污泥浓度变化的数学模型     

陈兆波  任南琪  呼冬雪  王爱杰 《地球科学进展》2004,(Z1)

以一体式膜生物反应器(SMBR)对生活污水进行处理,研究不同水力停留时间(HRT)条件下污泥浓度对有机物去除率的影响,并对所得试验数据进行曲线拟合,建立有机物去除率与污泥浓度的数学模型。试验结果表明:在溶解氧(DO)浓度为2.0～3.0mg/L的条件下,HRT为3h、2h和1h时,有机物去除率(η)随着污泥浓度的增大而增大,但当污泥浓度增大到6000mg/L时,η增大趋势逐渐减小,并趋于稳定。有机物去除率与污泥浓度的数学模型表明:有机物去除率(η)与水力停留时间(τ)、进水COD浓度(S_o)和污泥负荷率(N_s)等主要运行参数有关,并可以通过调节运行参数τ、S_o和N_s来达到所需要的COD去除率。  相似文献   

Composition and Assemblage Characteristics of Magnetic Minerals in Layer S_(5-1) of Xifeng and Duanjiapo Sections     

贾蓉芬  彭先芝  周正  刘德汉  王冠鑫  王德强 《中国地球化学学报》2004,23(3)

Magneticmineralsintheloess paleosolseriesaccountforabout 1 % -2 %ofthetotal (LiuTungshengandZhangZhonghu ,1 962 ) .Duetotheiraerolianorigin ,themagneticmineralsarecomplicatedincomposition ,largeingrainsizerange ,andsignificantlydifferentincrystallinity .Asaresult,researchonthesemagneticmineralswouldbesetwithalotofdifficulties.Previousre searchersemployedopticalmicroscopic ,X raydiffractionandM ssbauerspectrometrictechniquestostudythemagneticmineralsintheloess paleosolseries,andchieflyontheb…  相似文献   

Simulation Experiments of Land Surface Physical Processes and Ecological Effect over Different Underlying Surface     

LIU Shu-hua~ 《地球科学进展》2004,(Z1)

Based on the existing Land Surface Physical Process Models(Deardorff, Dickinson, LIU, Noilhan, Seller, ZHAO), a Comprehensive Land Surface Physical Process Model (CLSPPM) is developed by considering the different physical processes of the earth‘s surface-vegetation-atmosphere system more completely. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feas...  相似文献