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A Numerical Study on Effects of Land-Surface Heterogeneity from' Combined Approach' on Atmospheric ProcessPart II: Coupling-Model Simulations 被引量:5
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作者 曾新民 赵鸣 苏炳凯 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2000年第2期241-255,共15页
Two land surface schemes, one the standard Biosphere / Atmosphere Transfer Scheme Version ie (BOZ) and the other B1Z based on B0Z and heterogeneously-treated by' combined approach' , were co 'pled to the m... Two land surface schemes, one the standard Biosphere / Atmosphere Transfer Scheme Version ie (BOZ) and the other B1Z based on B0Z and heterogeneously-treated by' combined approach' , were co 'pled to the meso-scale model MM4, respectively. Through the calculations of equations from the companion paper, parameters representing land surface heterogeneity and suitable for the coupling models were found out. Three cases were simulated for heavy rainfalls during 36 hours, and the sensitivity of short-term weather modeling to the land surface heterogeneity was tested. Through the analysis of the simulations of the three heavy rainfalls, it was demonstrated that BIZ, compared with BOZ, could more realistically reflect the features of the land surface heterogeneity, therefore could more realistically reproduce the circulation and precipitation amount in the heavy rainfall processes of the three cases. This shows that even short-term weather is sensitive to the land surface heterogeneity, which is more obvious with time passing, and whose influence is more pronounced in the lower layer and gradually extends to the middle and upper layer. Through the analysis of these simulations with BlZ, it is suggested that the bulk effect of smaller-scale fluxes (i.e., the momentum, water vapor and sensible heat fluxes) near the s ig nificantly-heterogeneous land surface is to change the larger-scale (i.e., meso-scale) circulation, and then to influence the development of the low-level jets and precipitation. And also, the complexity of the land-atmosphere interaction was shown in these simulations. 展开更多
关键词 Combined approach Land surface heterogeneity Coupling model Numerical experiment
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A Numerical Study on Effects of Land-Surface Heterogeneity from "Combined Approach" on Atmospheric Process Part I: Principle and Method 被引量:3
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作者 曾新民 赵鸣 苏炳凯 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2000年第1期103-120,共18页
A method based on Giorgi (1997a, 1997b) and referred to as ’ combined approach’, which is a combi-nation of mosaic approach and analytical-statistical-dynamical approach, is proposed. Compared with those of other ap... A method based on Giorgi (1997a, 1997b) and referred to as ’ combined approach’, which is a combi-nation of mosaic approach and analytical-statistical-dynamical approach, is proposed. Compared with those of other approaches, the main advantage of the combined approach is that it not only can represent both interpatch and intrapatch variability, but also cost less computational time when the land surface heterogeneity is considered. Because the independent variable of probability density function (PDF) is ex-tended to the single valued function of basic meteorological characteristic quantities, which is much more universal, the analytical expressions of the characteristic quantities (e.g., drag coefficient, snow coverage, leaf surface aerodynamical resistance) affected by roughness length are derived , when the roughness length(and / or the zero plane displacement) heterogeneity has been mainly taken into account with the approach. On the basis of the rule which the PDF parameters should follow, we choose a function y of the roughness length z 0 as the PDF independent variable, and set different values of the two parameters width ratio αn and height ratio γ of PDF (here a linear, symmetric PDF is applied) for sensitivity experiments, from which some conclusions can be drawn, e.g., relevant characteristic terms show different sensitivities to the heterogeneous characteristic (i.e., roughness length), which suggests that we should consider the heterogeneities of the more sensitive terms in our model instead of the heterogeneities of the rest, and which also implies that when the land surface scheme is coupled into the global or regional atmospheric model, sensitivity tests against the distribution of the heterogeneous characteristic are very necessary; when the parameter αn is close to zero, little heterogeneity is represented, and αn differs with cases, which have an upper limit of about 0.6; in the reasonable range of αn, a peak-like distribution of roughness length can be depicted by a small value of γ, etc.. Key words Representation of land surface heterogeneity - “ Combined approach” - Numerical experiment This work was supported by the National Sciences Foundation of China, Grant No.49875005 and the State Key Project (973) G19990434 (03). 展开更多
关键词 Representation of land surface heterogeneity Combined approach” Numerical experiment
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The penetration depth of atomic radicals in tubes with catalytic surface properties
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作者 Domen PAUL Miran MOZETIC +3 位作者 Rok ZAPLOTNIK Alenka VESEL Gregor PRIMC Denis DONLAGIC 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第7期157-164,共8页
Catalysis of molecular radicals is often performed in interesting experimental configurations.One possible configuration is tubular geometry.The radicals are introduced into the tubes on one side,and stable molecules ... Catalysis of molecular radicals is often performed in interesting experimental configurations.One possible configuration is tubular geometry.The radicals are introduced into the tubes on one side,and stable molecules are exhausted on the other side.The penetration depth of radicals depends on numerous parameters,so it is not always feasible to calculate it.This article presents systematic measurements of the penetration depth of oxygen atoms along tubes made from nickel,cobalt,and copper.The source of O atoms was a surfatron-type microwave plasma.The initial density of O atoms depended on the gas flow and was 0.7×10^(21)m^(-3),2.4×10^(21)m^(-3),and 4.2×10^(21)m^(-3)at the flow rates of 50,300,and 600 sccm,and pressures of 10,35,and 60 Pa,respectively.The gas temperature remained at room temperature throughout the experiments.The dissociation fraction decreased exponentially along the length of the tubes in all cases.The penetration depths for well-oxidized nickel were 1.2,1.7,and 2.4 cm,respectively.For cobalt,they were slightly lower at 1.0,1.3,and 1.6 cm,respectively,while for copper,they were 1.1,1.3,and 1.7 cm,respectively.The results were explained by gas dynamics and heterogeneous surface association.These data are useful in any attempt to estimate the loss of molecular fragments along tubes,which serve as catalysts for the association of various radicals to stable molecules. 展开更多
关键词 oxygen plasma penetration depth CATALYSIS heterogeneous surface recombination atom loss
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The impact of heterogeneity of land surface roughness length on estimation of turbulent flux in model
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作者 Bin Chen XiangDe Xu +1 位作者 YuGuo Ding XiaoHui Shi 《Research in Cold and Arid Regions》 2011年第1期31-40,共10页
Based on preliminary theoretical analysis and numerical experiment, it is found that land surface heterogeneity plays an important role in the models turbulent flux calculation. In nearly neutral atmosphere conditions... Based on preliminary theoretical analysis and numerical experiment, it is found that land surface heterogeneity plays an important role in the models turbulent flux calculation. In nearly neutral atmosphere conditions, variation coefficient of sub-scale roughness length, cell-average roughness, and reference height are main factors affecting the calculation of grid turbulent fluxes. The first factor has a determinant role on calculation deviation. The relative error generated by roughness heterogeneity could be more than 40% in some cases in certain areas (e.g., in vegetation-climate transition belt). Selecting a specific reference height may improve the calculation of turbulent flux. In stable or unstable atmosphere conditions, with sensible heat flux as an example, analysis shows that the discrepancy is correlated to the sub-grid distributions of mean wind velocity, potential temperature gradient between land surface and reference levels, and atmosphere stability near surface layer caused by the heterogeneity of land surface roughness. The calculation of turbulent flux is the most sensitive to stability in the above three factors. The above analysis shows that it is necessary to make a further consideration for the calculation deviation of the turbulent fluxes brought from land surface heterogeneity in the present numerical models. 展开更多
关键词 land surface heterogeneity sub-grid scale grid turbulent flux surface roughness length
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Effects of Heterogeneous Vegetation on the Surface Hydrological Cycle
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作者 周锁铨 陈镜明 +1 位作者 宫鹏 薛根元 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2006年第3期391-404,共14页
Using the three-layer variable infiltration capacity (VIC-3L) hydrological model and the successive interpolation approach (SIA) of climate factors, the authors studied the effect of different land cover types on ... Using the three-layer variable infiltration capacity (VIC-3L) hydrological model and the successive interpolation approach (SIA) of climate factors, the authors studied the effect of different land cover types on the surface hydrological cycle. Daily climate data from 1992 to 2001 and remotely-sensed leaf area index (LAI) are used in the model. The model is applied to the Baohe River basin, a subbasin of the Yangtze River basin, China, with an area of 2500 km^2. The vegetation cover types in the Baohe River basin consist mostly of the mixed forest type (-85%). Comparison of the modeled results with the observed discharge data suggests that: (1) Daily discharges over the period of 1992-2001 simulated with inputs of remotely-sensed land cover data and LAI data can generally produce observed discharge variations, and the modeled annual total discharge agrees with observations with a mean difference of 1.4%. The use of remote sensing images also makes the modeled spatial distributions of evapotranspiration physically meaningful. (2) The relative computing error (RCE) of the annual average discharge is -24.8% when the homogeneous broadleaf deciduous forestry cover is assumed for the watershed. The error is 21.8% when a homogeneous cropland cover is assumed and -14.32% when an REDC (Resource and Environment Database of China) land cover map is used. The error is reduced to 1.4% when a remotely-sensed land cover at 1000-m resolution is used. 展开更多
关键词 surface heterogeneity landcover hydrological cycle remote sensing
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The Characteristics and Parameterization of Aerodynamic Roughness Length over Heterogeneous Surfaces 被引量:11
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作者 卢俐 刘绍民 +4 位作者 徐自为 阳坤 蔡旭辉 贾立 王介民 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2009年第1期180-190,共11页
Aerodynamic roughness length (Z0m) is a key factor in surface flux estimations with remote sensing algorithms and/or land surface models. This paper calculates ZOrn over several land surfaces, with 3 years of experi... Aerodynamic roughness length (Z0m) is a key factor in surface flux estimations with remote sensing algorithms and/or land surface models. This paper calculates ZOrn over several land surfaces, with 3 years of experimental data from Xiaotangshan. The results show that Z0m is direction-dependent, mainly due to the heterogeneity of the size and spatial distribution of the roughness elements inside the source area along different wind directions. Furthermore, a heuristic parameterization of the aerodynamic roughness length for heterogeneous surfaces is proposed. Individual Z0m over each surface component (patch) is calculated firstly with the characteristic parameters of the roughness elements (vegetation height, leaf area index, etc.), then Z0m over the whole experimental field is aggregated, using the footprint weighting method. 展开更多
关键词 aerodynamic roughness length heterogeneous surfaces FOOTPRINT
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Heat Flux Apportionment to Heterogeneous Surfaces Using Flux Footprint Analysis
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作者 彭谷亮 蔡旭晖 +3 位作者 张宏升 李爱国 胡非 Monique Y.LECLERC 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2008年第1期107-116,共10页
Heat flux data collected from the Baiyangdian Heterogeneous Field Experiment were analyzed using the footprint method. High resolution (25 m) Landsat-5 satellite imaging was used to determine the land cover as one o... Heat flux data collected from the Baiyangdian Heterogeneous Field Experiment were analyzed using the footprint method. High resolution (25 m) Landsat-5 satellite imaging was used to determine the land cover as one of four surface types: farmland, lake, wetland, or village. Data from two observation sites in September 2005 were used. One site (Wangjiazhai) was characterized by highly heterogeneous surfaces in the central area of the Baiyangdian: lake/wetland. The other site (Xiongxian) was on land with more uniform surface cover. An improved Eulerian analytical flux footprint model was used to determine “source areas” of the heat fluxes measured at towers located at each site from surrounding landscapes of mixed surface types. In relative terms results show that wetland and lake areas generally contributed most to the observed heat flux at Wangjiazhai, while farmland contributed most at Xiongxian. Given the areal distribution of surface type contributions, calculations were made to obtain the magnitudes of the heat flux from lake, wetland and farmland to the total observed flux and apportioned contributions of each surface type to the sensible and latent heat fluxes. Results show that on average the sensible heat flux from wetland and farmland were comparable over the diurnal cycle, while the latent heat flux from farmland was somewhat larger by about 30-50 W m-2 during daytime. The latent and sensible fluxes from the lake source in daytime were about 50 W m-2 and 100 W m-2 less, respectively, than from wetland and farmland. The results are judged reasonable and serve to demonstrate the potential for flux apportionment over heterogeneous surfaces. 展开更多
关键词 Eulerian analytical model flux footprint heat flux heterogeneous surface
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The Influence of Convergence Movement on Turbulent Transportation in the Atmospheric Boundary Layer 被引量:15
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作者 胡隐樵 左洪超 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2003年第5期794-798,共5页
Classical turbulent K closure theory of the atmospheric boundary layer assumes that the vertical turbulent transport flux of any macroscopic quantity is equivalent to that quantity's vertical gradient transport fl... Classical turbulent K closure theory of the atmospheric boundary layer assumes that the vertical turbulent transport flux of any macroscopic quantity is equivalent to that quantity's vertical gradient transport flux. But a cross coupling between the thermodynamic processes and the dynamic processes in the atmospheric system is demonstrated based on the Curier-Prigogine principle of cross coupling of linear thermodynamics. The vertical turbulent transportation of energy and substance in the atmospheric boundary layer is related not only to their macroscopic gradient but also to the convergence and the divergence movement. The transportation of the convergence or divergence movement is important for the atmospheric boundary layer of the heterogeneous underlying surface and the convection boundary layer. Based on this, the turbulent transportation in the atmospheric boundary layer, the energy budget of the heterogeneous underlying surface and the convection boundary layer, and the boundary layer parameterization of land surface processes over the heterogeneous underlying surface are studied. This research offers clues not only for establishing the atmospheric boundary layer theory about the heterogeneous underlying surface, but also for overcoming the difficulties encountered recently in the application of the atmospheric boundary layer theory. 展开更多
关键词 linear thermodynamics turbulent transportation cross coupling atmospheric boundary layer heterogeneous underlying surface
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Estimation of Turbulent Sensible Heat and Momentum Fluxes over a Heterogeneous Urban Area Using a Large Aperture Scintillometer 被引量:2
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作者 Sang-Hyun LEE Jun-Ho LEE Bo-Young KIM 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2015年第8期1092-1105,共14页
The accurate determination of surface-layer turbulent fluxes over urban areas is critical to understanding urban boundary layer (UBL) evolution. In this study, a remote-sensing technique using a large aperture scint... The accurate determination of surface-layer turbulent fluxes over urban areas is critical to understanding urban boundary layer (UBL) evolution. In this study, a remote-sensing technique using a large aperture scintillometer (LAS) was investigated to estimate surface-layer turbulent fluxes over a highly heterogeneous urban area. The LAS system, with an optical path length of 2.1 km, was deployed in an urban area characterized by a complicated land-use mix (residential houses, water body, bare ground, etc.). The turbulent sensible heat (QH) and momentum fluxes (z) were estimated from the scintillation measurements obtained from the LAS system during the cold season. Three-dimensional LAS footprint modeling was introduced to identify the source areas ("footprint") of the estimated turbulent fluxes. The analysis results showed that the LAS-derived turbulent fluxes for the highly heterogeneous urban area revealed reasonable temporal variation during daytime on clear days, in comparison to the land-surface process-resolving numerical modeling. A series of sensitivity tests indicated that the overall uncertainty in the LAS-derived daytime QH was within 20%-30% in terms of the influence of input parameters and the non- dimensional similarity function for the temperature structure function parameter, while the estimation errors in z were less sensitive to the factors of influence, except aerodynamic roughness length. The 3D LAS footprint modeling characterized the source areas of the LAS-derived turbulent fluxes in the heterogeneous urban area, revealing that the representative spatial scales of the LAS system deployed with the 2.1 km optical path distance ranged from 0.2 to 2 km2 (a "micro-a scale"), depending on local meteorological conditions. 展开更多
关键词 heterogeneous surface large aperture scintillometer mesoscale modeling surface energy balance turbulentexchange
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Injectable self-healing nanocellulose hydrogels crosslinked by aluminum:Cellulose nanocrystals vs.cellulose nanofibrils
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作者 Zhongxin Lin Renliang Huang +4 位作者 Jiangjiexing Wu Anastasia Penkova Wei Qi Zhimin He Rongxin Su 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2022年第10期389-397,共9页
With excellent biocompatibility and unique physiochemical properties,nanocelluloses including cellulose nanocrystals(CNCs)and cellulose nanofibrils(CNFs)are promising candidates for preparing biomedical hydrogels.CNCs... With excellent biocompatibility and unique physiochemical properties,nanocelluloses including cellulose nanocrystals(CNCs)and cellulose nanofibrils(CNFs)are promising candidates for preparing biomedical hydrogels.CNCs and CNFs are different in morphology and surface charges.Herein,CNCs and two CNFs(CNFs-C,Carboxylated CNFs;CNFs-P,Phosphorylated CNFs)were synthesized and applied to fabricate hydrogels through metal crosslinking.Aluminum crosslinking was found to be the best choice for enhancing the strength.This study systematically compared the morphologies,storage modulus,loss factor,continuous shear ramp,self-healing,swelling,in vitro degradation and injectable properties of the fabricated hydrogels,Further,a radar chart is summarized as guidelines to direct the rational selection to meet the specific requirements of further biomedical applications.At the same nanocellulose concentration and after Al^(3+)crosslinking,CNCs hydrogels had strong water holding capacity twice as much as that of CNFs hydrogels.While CNFs hydrogels showed higher hardness and stronger resistance to degradation than that of CNCs.These results provide detailed insights into nanocellulose hydrogels,making it possible to use these guidelines to select hydrogels for desired performance. 展开更多
关键词 Cellulose nanocrystals Cellulose nanofibrils surface heterogeneities GELS Fabrication Mechanical properties
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A Parameterization Scheme for Regional Average Runoff over Heterogeneous Land Surface Under Climatic Rainfall Forcing 被引量:1
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作者 刘晶淼 丁裕国 +1 位作者 周秀骥 李云 《Acta meteorologica Sinica》 SCIE 2010年第1期116-122,共7页
The mean instantaneous runoff rate over a mesoscale region is considered to be the residue between the areal mean precipitation and the amount of water infiltrated into surface soil layer.A rainfall probability densit... The mean instantaneous runoff rate over a mesoscale region is considered to be the residue between the areal mean precipitation and the amount of water infiltrated into surface soil layer.A rainfall probability density function(PDF) derived from rainfall data in 1996 is used,in conjunction with the mathematic description and empirical expression of rain water infiltration physics,in order to accurately estimate the soil infiltration rate and distribution.A statistical-dynamic scheme of regional mean surface runoff is constructed.The runoff rate can be viewed as the difference between mean precipitation and infiltration on a regional basis,and the averaged infiltration can be treated independently over saturated and unsaturated areas.For the physics of land surface water cycle,infiltration is caused by a source of water supply associated with the properties of underlying surface.After rainfall,with part of the water transported into the soil surface layer,runoff occurs just due to the surplus from the water trapped by vegetation cover and soil infiltration.Hence,the key in calculating surface runoff lies dominantly in the estimation of water amount required for surface-layer soil.Thus,the expression for soil water flux is utilized to derive a formula for the infiltration.Similarly,from the PDF for soil moisture and precipitation,a formula of sub-grid regional mean runoff rate is obtained by considering heterogeneous soil water content and climatic rainfall forcing in 1996 as well as precipitation and soil data over the Yangtze delta region.Sensitivity experiments are also done to indentify affecting factors.Evidence suggests that the proposed scheme gives the runoff rates highly close to those from the Mosaic method,thereby demonstrating the high reliability and feasibility of the statistical-dynamic parameterization scheme. 展开更多
关键词 regional mean runoff surface heterogeneity probability density function atmospheric rainfall forcing
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Shifting from homogeneous to heterogeneous surfaces in estimating terrestrial evapotranspiration: Review and perspectives 被引量:4
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作者 Yuanbo LIU Guoyu QIU +11 位作者 Hongsheng ZHANG Yonghui YANG Yinsheng ZHANG Quan WANG Wenzhi ZHAO Li JIA Xibin JI Yujiu XIONG Chunhua YAN Ning MA Shumin HAN Yifan CUI 《Science China Earth Sciences》 SCIE EI CSCD 2022年第2期197-214,共18页
Terrestrial evapotranspiration(ET)is a crucial link between Earth’s water cycle and the surface energy budget.Accurate measurement and estimation remain a major challenge in geophysical,biological,and environmental s... Terrestrial evapotranspiration(ET)is a crucial link between Earth’s water cycle and the surface energy budget.Accurate measurement and estimation remain a major challenge in geophysical,biological,and environmental studies.Pioneering work,represented by Dalton and Penman,and the development of theories and experiments on turbulent exchange in the atmospheric boundary layer(ABL),laid the foundation for mainstream methodologies in ET estimation.Since the 1990s,eddy covariance(EC)systems and satellite remote sensing have been widely applied from cold to tropical and from arid to humid regions.They cover water surfaces,wetlands,forests,croplands,grasslands,barelands,and urban areas,offering an exceptional number of reports on diverse ET processes.Surface nocturnal ET,hysteresis between ET and environmental forces,turbulence intermittency,island effects on heterogeneous surfaces,and phase transition between underlying surfaces are examples of reported new phenomena,posing theoretical and practical challenges to mainstream ET methodologies.Additionally,based on non-conventional theories,new methods have emerged,such as maximum entropy production and nonparametric approaches.Furthermore,high-frequency on-site observation and aerospace remote sensing technology in combination form multi-scale observations across plant stomata,leaves,plants,canopies,landscapes,and basins.This promotes an insightful understanding of diverse ET processes and synthesizes the common mechanisms of the processes between and across spatial and temporal scales.All the recent achievements in conception,model,and technology serve as the basis for breaking through the known difficulties in ET estimation.We expect that they will provide a rigorous,reliable scientific basis and experimental support to address theoretical arguments of global significance,such as the water-heat-carbon cycle,and solve practical needs of national importance,including agricultural irrigation and food security,precise management of water resources and eco-environmental protection,and regulation of the urban thermal environment and climate change adaptation. 展开更多
关键词 EVAPOTRANSPIRATION Atmospheric boundary layer Heterogeneous surface Uncertainty
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Characteristics of Secondary Circulations in the Convective Boundary Layer over Two-Dimensional Heterogeneous Surfaces 被引量:2
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作者 SHEN Lidu SUN Jianning and LIU Peng 《Journal of Meteorological Research》 SCIE CSCD 2016年第6期944-960,共17页
Large-eddy simulations are conducted to investigate the impacts of the scale of chessboard-like heteroge- neous surface heating and the background wind on secondary circulations (SCs) in the convective boundary lay... Large-eddy simulations are conducted to investigate the impacts of the scale of chessboard-like heteroge- neous surface heating and the background wind on secondary circulations (SCs) in the convective boundary layer (CBL). When the wind blows along the diagonal of the chessboard pattern, the cases with different heterogeneity length scales (λ = 1.2, 2.4, and 4.8 km) and weak background wind (U = 2.5 m s-1) suggest that there exists a threshold for the roll-like SCs, which is satisfied when the heterogeneity length scale is 1.6 times the boundary layer height (λ = 1.6zi). During the CBL development, the SC intensity increases before this threshold is met, whereas it decreases thereafter. The cases with different background wind speeds (U = 2.5, 5.0, and 10.0 m s-1) and relatively large heterogeneity length scale (λ = 4.8 km) show that the SCs are strengthened by larger wind speeds when the heterogeneity length scale is so large that the threshold cannot be met during the CBL development. Another case with wind direction along neither the diagonal nor the side of the chessboard pattern shows that the roll-like SCs can still be triggered, but the roll axes are orientated along the diagonal of the chessboard pattern rather than along the wind direction. 展开更多
关键词 background wind convective boundary layer heterogeneous surface large-eddy simulation secondary circulation TURBULENCE
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An improved algorithm to estimate the surface soil heat flux over a heterogeneous surface: A case study in the Heihe River Basin 被引量:1
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作者 LI NaNa JIA Li LU Jing 《Science China Earth Sciences》 SCIE EI CAS CSCD 2015年第7期1169-1181,共13页
Surface soil heat flux(G0) is an indispensable component of the surface energy balance and plays an important role in the estimation of surface evapotranspiration(ET). This study calculated G0 in the Heihe River Basin... Surface soil heat flux(G0) is an indispensable component of the surface energy balance and plays an important role in the estimation of surface evapotranspiration(ET). This study calculated G0 in the Heihe River Basin based on the thermal diffusion equation, using the observed soil temperature and moisture profiles, with the aim to analyze the spatial-temporal variations of G0 over the heterogeneous area(with alpine grassland, farmland, and forest). The soil ice content was estimated by the difference in liquid soil water content before and after the melting of the frozen soil and its impact on the calculation of G0 was further analyzed. The results show that:(1) the diurnal variation of G0 is obvious under different underlying surfaces in the Heihe River Basin, and the time when the daily maximum value of G0 occurs is a few minutes to several hours earlier than that of the net radiation flux, which is related to the soil texture, soil moisture, soil thermal properties, and the vegetation coverage;(2) the net radiation flux varies with season and reaches the maximum in summer and the minimum in winter, whereas G0 reaches the maximum in spring rather than in summer, because more vegetation in summer hinders energy transfer into the soil;(3) the proportions of G0 to the net radiation flux are different with seasons and surface types, and the mean values in January are 25.6% at the Arou site, 22.9% at the Yingke site and 4.3% at the Guantan site, whereas the values in July are 2.3%, 1.6% and 0.3%, respectively; and(4) G0 increases when the soil ice content is included in thermal diffusion equation, which improves the surface energy balance closure by 4.3%. 展开更多
关键词 surface soil heat flux soil ice content surface energy balance heterogeneous surfaces
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Application of response surface methodology for optimization of Orange Ⅱ removal by heterogeneous Fenton-like process using Fe_3O_4nanoparticles 被引量:6
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作者 Kun Chen Guang-Hua Wang +3 位作者 Wen-Bing Li Dong Wan Qin Hu Lu-Lu Lu 《Chinese Chemical Letters》 SCIE CAS CSCD 2014年第11期1455-1460,共6页
In this study, Fe3O4nanoparticles(Fe3O4NPs) were successfully prepared via oxidation–precipitation method and characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD) and Fourier transform inf... In this study, Fe3O4nanoparticles(Fe3O4NPs) were successfully prepared via oxidation–precipitation method and characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD) and Fourier transform infrared spectroscopy(FT-IR). The characterization results indicated that Fe3O4 NPs with regular crystal structure and a narrow of diameters had been synthesized successfully and had high purity. A series of experiments were carried out to investigate the degradation of Orange II by the obtained heterogeneous Fe3O4 catalysts in the presence of H2O2. The response surface methodology(RSM) based on Box–Behnken design(BBD) was employed to design and optimize individual and interactive effects of the four main independent parameters(catalyst loading, initial p H, reaction temperature and H2O2concentration) on decolorization efficiency of Orange II. A significant quadratic model(p-value 〈0.0001, R2= 0.9369) was derived using analysis of variance(ANOVA). Optimum conditions were catalyst loading of 1.5 g/L, initial p H of 2.7, reaction temperature of 42 8C and H2O2 concentration of 22 mmol/L, respectively. The predicted decolorization rate under the optimum conditions as determined by the proposed model was 99.55%. Confirmatory tests were carried out and the decolorization rate of 99.49% was observed under the optimum conditions, which agreed well with the model prediction. 展开更多
关键词 Fe3O4 nanoparticles Heterogeneous Fenton-like Orange II Response surface methodology
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Suppression of seismic surface waves based on adaptive weighted super-virtual interferometry 被引量:1
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作者 AN ShengPei HU TianYue 《Science China Earth Sciences》 SCIE EI CAS CSCD 2016年第11期2179-2188,共10页
For land seismic surveys, the surface waves are the dominant noises that mask the effective signals on seismograms.The conventional methods isolate surface waves from the effective signals by the differences in freque... For land seismic surveys, the surface waves are the dominant noises that mask the effective signals on seismograms.The conventional methods isolate surface waves from the effective signals by the differences in frequencies or apparent velocities,but may not perform well when these differences are not obvious. Since the original seismic interferometry can only predict inter-receiver surface waves, we propose the use of super-virtual interferometry(SVI), which is a totally data-driven method, to predict shot-to-receiver surface waves, since this method relieves the limitation that a real shot should collocate with one of the receivers for adaptive subtraction. We further develop the adaptive weighted SVI(AWSVI) to improve the prediction of dispersive surface waves, which may be generated from heterogeneous media at the near surface. Numerical examples demonstrate the effectiveness of AWSVI to predict dispersive surface waves and its applicability to the complex near surface. The application of AWSVI on the field data from a land survey in the east of China improves the suppression of the residual surface waves compared to the conventional methods. 展开更多
关键词 Heterogeneous media Near surface Dispersive surface waves Interferometry Correlation coefficient
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Effect of Mesoscale Land Use Change on Characteristics of Convective Boundary Layer:Semi-Idealized Large Eddy Simulations over Northwest China 被引量:4
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作者 Bangjun CAO Shuwen ZHANG +3 位作者 Deqin LI Yanlin LI Linfan ZHOU Jiemin WANG 《Journal of Meteorological Research》 SCIE CSCD 2018年第3期421-432,共12页
Although large-scale topography and land use have been properly considered in weather and climate models, the effect of mesoscale and microscale heterogeneous land use on convective boundary layer(CBL) has not been fu... Although large-scale topography and land use have been properly considered in weather and climate models, the effect of mesoscale and microscale heterogeneous land use on convective boundary layer(CBL) has not been fully understood yet. In this study, the influence of semi-idealized strip-like patches of oases and deserts, which resemble irrigated land use in Northwest China, on the CBL characteristics, is investigated based on the Weather Research and Forecasting(WRF)-large eddy simulation(LES) driven by observed land surface data. The influences of soil water content in oases on aloft CBL flow structure, stability, turbulent kinetic energy(TKE), and vertical fluxes are carefully examined through a group of sensitivity experiments. The results show that secondary circulation(SC)/turbulent organized structures(TOS) is the strongest/weakest when soil water content in oases is close to saturation(e.g.,when the oases are irrigated). With the decrease of soil water content in oases(i.e., after irrigation), SC(TOS) becomes weak(strong) in the lower and middle CBL, the flux induced by SC and TOS becomes small(large), which has a dramatic impact on point measurement of eddy covariance(EC) fluxes. The flux induced by SC and TOS has little influence on EC sensible heat flux, but great influence on EC latent heat flux. Under this circumstance, the area averaged heat flux cannot be represented by point measurement of flux by the EC method, especially just after irrigation in oases. Comparison of imbalance ratio(i.e., contribution of SC and TOS to the total flux) reveals that increased soil moisture in oases leads to a larger imbalance ratio as well as enhanced surface heterogeneity. Moreover,we found that the soil layer configuration at different depths has a negligible impact on the CBL flux properties. 展开更多
关键词 oasis and desert land surface heterogeneity large eddy simulation soil water content secondary circulation turbulent organized structure
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Temporal decay of the catalytic oxidation of methane over palladium supported on silica
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作者 CORTS Joaquín VALENCIA Eliana +1 位作者 PINEDA Marcelo ARAYA Paulo 《Science China Chemistry》 SCIE EI CAS 2013年第11期1601-1607,共7页
The temporal decay of the oxidation of methane(CH4-O2reaction)over palladium supported on silica is determined experimentally at different temperatures,comparing the results with those of various classical models whic... The temporal decay of the oxidation of methane(CH4-O2reaction)over palladium supported on silica is determined experimentally at different temperatures,comparing the results with those of various classical models which show the behavior of the adsorbed phase as the cause of the phenomenon.This effect is visualized through Monte Carlo simulations of the CH4-O2reaction on a mixed lattice whose partial poisoning,due to the configuration of the OH groups on the surface of the adsorbate,is translated into a gradual decay of the reaction’s activity. 展开更多
关键词 catalytic CH4-O2 reaction surface heterogeneity in superficial reaction Monte Carlo simulation superficial catalyticreaction CH4-O2 reaction over palladium
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Variations in soil moisture over the ‘Huang-Huai-Hai Plain' in China due to temperature change using the CNOP-P method and outputs from CMIP5 被引量:1
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作者 SUN GuoDong PENG Fei MU Mu 《Science China Earth Sciences》 SCIE EI CAS CSCD 2017年第10期1838-1853,共16页
In this study, the variations in surface soil liquid water(SSLW) due to future climate change are explored in the‘Huang-Huai-Hai Plain'(‘3H') region in China with the Common Land Model(CoLM). To evaluate the... In this study, the variations in surface soil liquid water(SSLW) due to future climate change are explored in the‘Huang-Huai-Hai Plain'(‘3H') region in China with the Common Land Model(CoLM). To evaluate the possible maximum response of SSLW to climate change, the combination of the conditional nonlinear optimal perturbation related to the parameter(CNOP-P) approach and projections from 10 general circulation models(GCMs) of the Coupled Model Intercomparison Project5(CMIP5) are used. The CNOP-P-type temperature change scenario, a new type of temperature change scenario, is determined by using the CNOP-P method and constrained by the temperature change projections from the 10 GCMs under a high-emission scenario(the Representative Concentration Pathway 8.5 scenario). Numerical results have shown that the response of SSLW to the CNOP-P-type temperature scenario is stronger than those to the 11 temperature scenarios derived from the 10 GCMs and from their ensemble average in the entire ‘3H' region. In the northern region, SSLW under the CNOP-P-type scenario increases to0.1773 m^3 m^(-3); however, SSLW in the scenarios from the GCMs fluctuates from 0.1671 to 0.1748 m^3 m^(-3). In the southern region,SSLW decreases, and its variation(–0.0070 m^3 m^(-3)) due to the CNOP-P-type scenario is higher than each of the variations(–0.0051 to –0.0026 m^3 m^(-3)) due to the scenarios from the GCMs. 展开更多
关键词 CNOP-P surface soil liquid water CMIP5 Climate change Seasonal and regional heterogeneity
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