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    题名 作者 年代 出处 被引量
1大气和植被生态及土壤系统水文过程相互作用的一些研究显示文摘综述近年来作者对单变量土壤水分演变模式和由作者提出的几种大气和植被生态及土壤系统水文过程相互作用模式 (给定植被冠层的三层相互作用模式、土壤和植被生态水文相互作用的三变量模式和五变量模式 )所作的理论分析和数值模拟的结果 ,鲜明和简洁地显示出这些模式能抓住这个复杂的系统最本质最基本的特征。在给定的大气状态情况下 ,这个复杂系统具有鲜明的多时间尺度现象、对输入响应的频率“红移”现象、多平衡态和极限环、分叉、突变、自组织过程、再生现象、“沙漠化”和混沌现象 ,这些都在实际中得到验证。特别是作者提出的植被 (尤其是枯落物 )“遮蔽机制”的减弱可能是过度放牧导致沙漠化在短期内就显效的主要原因 ,而在很长期间或气候变迁所导致的沙漠化过程中 ,则它和Charney提出的“反照率机制”可能同时起作用 ,建议作进一步的数值模拟加以验证。作者还提出了对响应特征时间尺度第一近似进行修正的方法。曾庆存 曾晓东 王爱慧 Robert E.Dickinson Xubin Zeng Samuel S.P.Shen 2005大气科学2005,29,1:15
2Geochemical characteristics and genetic model of dolomite reservoirs in the eastern margin of the Pre-Caspian Basin显示文摘The widespread Carboniferous KT-I dolomite in the eastern margin of the Pre-Caspian Basin is an important hydrocarbon reservoir. The dolomite lithology is dominated by crystalline dolomite. The δ18O values range from -6.71‰ to 2.45‰, and average 0.063‰, obviously larger than -2.5‰, indicating low-temperature dolomite of evaporation origin. Stable strontium isotope ratios (87Sr/86Sr) range from 0.70829 to 0.70875 and average 0.708365, very consistent with 87Sr/86Sr ratios in Carboniferous seawater. Chemical analysis of Ca and Mg elements shows that the dolomite has 9.1 mole% excess Ca or even higher before stabilization. The degree of order of dolomite is medium-slightly poor, varying in a range of 0.336-0.504 and averaging 0.417. It suggests that the dolomite formed under near-surface conditions. There are two models for the origin of the Carboniferous KT-I dolomite reservoir. These are 1) the evaporation concentration - weathering crust model and 2) the shoal facies - seepage reflux model. The former is mainly developed in restricted platforms - evaporate platforms of restricted marine deposition environments with a representation of dolomite associated with gypsum and mudstone. The latter mainly formed in platform edge shoals and intra-platform shoals and is controlled by dolomitization due to high salinity sea water influx from adjacent restricted sea or evaporate platform.Wang Shuqin Zhao Lun Cheng Xubin Fan Zifei He Ling 2012Petroleum Science2012,9,2:12
3Identification of ferroptosis as a novel mechanism for antitumor activity of natural product derivative a2 in gastric cancer显示文摘Ferroptosis is a type of cell death accompanied by iron-dependent lipid peroxidation,thus stimulating ferroptosis may be a potential strategy for treating gastric cancer,therapeutic agents against which are urgently required.Jiyuan oridonin A(JDA) is a natural compound isolated from Jiyuan Rabdosia rubescens with anti-tumor activity,unclear anti-tumor mechanisms and limited water solubility hamper its clinical application.Here,we showed a2,a new JDA derivative,inhibited the growth of gastric cancer cells.Subsequently,we discovered for the first time that a2 induced ferroptosis.Importantly,compound a2 decreased GPX4 expression and overexpressing GPX4 antagonized the anti-proliferative activity of a2.Furthermore,we demonstrated that a2 caused ferrous iron accumulation through the autophagy pathway,prevention of which rescued a2 induced ferrous iron elevation and cell growth inhibition.Moreover,a2 exhibited more potent anti-cancer activity than 5-fluorouracil in gastric canc er cell line-derived xenograft mice models.Patient-derived tumor xenograft models from different patients displayed varied sensitivity to a2,and GPX4 downregulation indicated the sensitivity of tumors to a2.Finally,a2 exhibited well pharmacokinetic characteristic s.Overall,our data suggest that inducing ferroptosis is the major mechanism mediating anti-tumor activity of a2,and a2 will hopefully serve as a promising compound for gastric cancer treatment.Ying Liu Zan Song Yajie Liu Xubin Ma Wang Wang Yu Ke Yichao Xu Dequan Yu Hongmin Liu 2021Acta Pharmaceutica Sinica B2021,11,6:10
4Enhancement of CO2 Absorption under Taylor Flow in the Presence of Fine Particles显示文摘The physical absorption of CO2 in water containing different types of particles was studied in a microchannel operated under Taylor flow.The maximum enhancement factors of 1.43 2.15 were measured for activated carbon (AcC) particles.The analysis shows that the enhancement effect can be attributed to the shuttle mechanism.Considering the separate contributions of mass transfer from bubble cap and liquid film,a heterogeneous enhancement model is developed.According to this model,the enhancement factors E Cap,E Film and E Ov are mainly determined by mass transfer coefficient KL (KL,Cap and KL,Film),adsorptive capacity of particles m,and coverage fraction of particles at gas-liquid interface ζ.With both effects of particle-to-interface adhesion and apparent viscosity included,the model predicts the enhancement effect of AcC particles reasonably well.CAI Wangfeng ZHANG Jiao ZHANG Xubin WANG Yan QI Xiangjuan 2013Chinese Journal of Chemical Engineering2013,21,2:9
5Design and experiments of an active isolator for satellite micro-vibration显示文摘In this paper, a soft active isolator(SAI) derived from a voice coil motor is studied to determine its abilities as a micro-vibration isolation device for sensitive satellite payloads. Firstly,the two most important parts of the SAI, the mechanical unit and the low-noise driver, are designed and manufactured. Then, a rigid-flexible coupling dynamic model of the SAI is built, and a dynamic analysis is conducted. Furthermore, a controller with a sky-hook damper is designed. Finally,results from the performance tests of the mechanical/electronic parts and the isolation experiments are presented. The SAI attenuations are found to be more than 20 d B above 5 Hz, and the control effect is stable.Li Weipeng Huang Hai Zhou Xubin Zheng Xintao Bai Yang 2014Chinese Journal of Aeronautics2014,27,6:9
6How Does the Partitioning of Evapotranspiration and Runoff between Different Processes Affect the Variability and Predictability of Soil Moisture and Precipitation?显示文摘Water stored as part of the land surface is lost to evapotranspiration and runoff on different time scales,and the partitioning between these time scales is important for modeling soil water in a climate model.Different time scales are imposed on evapotranspiration primarily because it is derived from differentreservoirs with different storage capacities, from the very rapid evaporation of canopy stores to the slowremoval by transpiration of rooting zone soil moisture. Runoff likewise ranges in time scale from rapidsurface terms to the slower base-flow. The longest time scale losses of water determine the slow variationof soil moisture and hence the longer time scale effects of soil moisture on precipitation. This paper showswith a simple analysis how shifting the partitioning of evapotranspiration between the different reservoirsaffects the variability of soil moisture and precipitation. In particular, it is concluded that a shift toshorter time scale reservoirs shifts the variance of precipitation from that which is potentially predictableto unpredictable.Robert E.Dickinson Guiling WANG Xubin Zeng 曾庆存 2003Advances in Atmospheric Sciences2003,20,3:9
7Decreased b-Cell Function is Associated with Cardiovascular Autonomic Neuropathy in Chinese Patients Newly Diagnosed with Type 2 Diabetes显示文摘The influence of b-cell function on cardiovascular autonomic neuropathy(CAN), an important diabetesrelated complication, is still unclear. In this study, we aimed to investigate the association between residual b-cell function and CAN in patients newly diagnosed with type 2 diabetes. We enrolled 90 newly-diagnosed type 2 diabetic patients and 37 participants with normal glucose tolerance as controls. The patients were divided into a CAN? group(diabetic patients with CAN, n = 20) and a CAN-group(diabetic patients without CAN, n = 70) according to the standard Ewing battery of tests. Fasting and postprandial plasma glucose, insulin, and C-peptide were measured.Homeostasis model assessment-beta cells(HOMA-B) and HOMA-insulin resistance(IR) were calculated. The prevalence of CAN in this population was 22.2%. Compared with the CAN-group, the CAN? group had significantly lower fasting plasma insulin(6.60 ± 4.39 vs 10.45 ± 7.82 l/L, P = 0.029), fasting C-peptide(0.51 ± 0.20 vs0.82 ± 0.51 nmol/L, P = 0.004), and HOMA-B(21.44 ± 17.06 vs 44.17 ± 38.49, P = 0.002). Fasting C-peptide was correlated with the Valsalva ratio(r = 0.24, P = 0.043) and the 30:15 test(r = 0.26,P = 0.023). Further analysis showed that fasting C-peptide(OR: 0.041, 95% CI 0.003–0.501, P = 0.012) and HOMAB(OR: 0.965, 95% CI 0.934–0.996, P = 0.028) were independently associated with cardiovascular autonomic nerve function in this population. The patients with fasting C-peptide values \ 0.67 nmol/L were more likely to have CAN than those with C-peptide levels C0.67 nmol/L(OR:6.00, 95% CI 1.815–19.830, P = 0.003). A high prevalence of CAN was found in patients with newly-diagnosed type 2 diabetes. Decreased b-cell function was closely associated with CAN in this population.Xubin Yang Wen Xu Yanhua Zhu Hongrong Deng Ying Tan Longyi Zeng Jianping Weng 2019Neuroscience Bulletin2019,35,1:7
8Chemical and biological flocculation process to treat municipal sewage and analysis of biological function显示文摘The pilot scale experimental apparatus and the procedure of the chemical and biological flocculation process to verify the feasibility in treating Shanghai municipal sewage were introduced in this paper. In addition, the biological function of the process was discussed. The results of optimal running showed that in the reaction tank, the concentration of mixed liquor suspended solid(MLSS) was 2 g/L, hydraulic retention time(HRT) was 35 min, dosage of liquid polyaluminium chloride(PAC) was 60 mg/L, and the concentration of polyacrylamide(PAM) was 0 5 mg/L. The effluent average concentrations of COD Cr , TP, SS and BOD 5 were 50 mg/L, 0 62 mg/L, 18 mg/L, and 17 mg/L, respectively. These were better than the designed demand. In addition, the existence of biological degradation in this system was proven by several methods. The removal efficiencies of the chemical and biological flocculation process were 20% higher than that of the chemical flocculation process above at the same coagulant dosage. The treatment process under different situations was evaluated on a pilot scale experiment, and the results provided magnificent parameters and optimal condition for future operation of the plant.XIASi-qing YANGDian-hai XUBin ZHAOJian-fu 2005Journal of Environmental Sciences2005,17,1:6
9Radiomic analysis of pulmonary ground-glass opacity nodules for distinction of preinvasive lesions, invasive pulmonary adenocarcinoma and minimally invasive adenocarcinoma based on quantitative texture analysis of CT显示文摘Objective: To identify the differences among preinvasive lesions, minimally invasive adenocarcinomas(MIAs)and invasive pulmonary adenocarcinomas(IPAs) based on radiomic feature analysis with computed tomography(CT).Methods: A total of 109 patients with ground-glass opacity lesions(GGOs) in the lungs determined by CT examinations were enrolled, all of whom had received a pathologic diagnosis. After the manual delineation and segmentation of the GGOs as regions of interest(ROIs), the patients were subdivided into three groups based on pathologic analyses: the preinvasive lesions(including atypical adenomatous hyperplasia and adenocarcinoma in situ) subgroup, the MIA subgroup and the IPA subgroup. Next, we obtained the texture features of the GGOs. The data analysis was aimed at finding both the differences between each pair of the groups and predictors to distinguish any two pathologic subtypes using logistic regression. Finally, a receiver operating characteristic(ROC) curve was applied to accurately evaluate the performances of the regression models.Results: We found that the voxel count feature(P<0.001) could be used as a predictor for distinguishing IPAs from preinvasive lesions. However, the surface area feature(P=0.040) and the extruded surface area feature(P=0.013) could be predictors of IPAs compared with MIAs. In addition, the correlation feature(P=0.046) could distinguish preinvasive lesions from MIAs better.Conclusions: Preinvasive lesions, MIAs and IPAs can be discriminated based on texture features within CT images, although the three diseases could all appear as GGOs on CT images. The diagnoses of these three diseases are very important for clinical surgery.Wei Li Xuexiang Wang Yuwei Zhang Xubin Li Qian Li Zhaoxiang Ye 2018Chinese Journal of Cancer Research2018,30,4:6
10Analysis of high-frequency local coupling instability induced by multi- transmitting formula - P-SV wave simulation in a 2D waveguide显示文摘Local coupling instability will occur when the numerical scheme of absorbing boundary condition and that of the field wave equation allow energies to spontaneously enter into the computational domain.That is, the two schemes support common wave solutions with group velocity pointed into the computation domain.The key to eliminate local coupling instability is to avoid such wave solutions.For lumped-mass finite element simulation of P-SV wave motion in a 2D waveguide, an approach for stable implementation of high order multi-transmitting formula is provided.With a uniform rectangular mesh, it is proven and validated that high-frequency local coupling instability can be eliminated by setting the ratio of the element size equal to or greater than 2^(1/2) times the ratio of the P wave velocity to the S wave velocity.These results can be valuable for dealing instability problems induced by other absorbing boundary conditions.Xie Zhinan Zhang Xubin 2017Earthquake Engineering and Engineering Vibration2017,16,1:6
11Insulin requirement profiles and related factors of insulin pump therapy in patients with type 2 diabetes显示文摘Continuous subcutaneous insulin infusion(CSII)is an effective therapy to control hyperglycemia in both patients with type 1 diabetes and type 2 diabetes.However,there is little data investigating the insulin dose setting during CSII therapy in type 2 diabetes to achieve optimal glycemic control and avoid the risk of hypoglycemia.Thus,this study is aimed to assess the dose characteristics of insulin requirement and explore the related clinical factors in patients with type 2 diabetes who were treated with CSII.A total of 327 patients(195 males)aged 52.9±12.5 years old were included in this study.Patients were treated with CSII to achieve the target fasting capillary blood glucose(4.4-7.0 mmol L^(-1))and 2-h postprandial capillary blood glucose(4.4-10.0 mmol L^(-1))by adjusting insulin infusion according to the seven-point capillary blood glucose profiles.Total daily insulin dose(TDD),total daily insulin dose per kilogram(TDD kg-1)and the ratio of total basal insulin dose(TBD)to TDD(%TBa)were calculated after patients achieved the glucose targets for at least 3 days via 1-2 weeks of CSII treatment.And insulin dose,insulin dosing patterns and the relevant clinical factors were analyzed.The mean ratio of basal/bolus insulin distribution of all patients was 40%:60%.Patients with central obesity needed more TDD(51.3±17.1 U versus 43.5±14.0 U,P<0.05)and TDD kg^(-1)(0.8±0.3 U kg^(-1)versus 0.7±0.2 U kg^(-1),P<0.05)than those without central obesity.Pearson's correlation analysis demonstrated that TDD was positively correlated with body mass index(BMI),waist circumference(WC),baseline fasting plasma glucose(FPG),fasting C-peptide level,2 h-postprandial C-peptide level and time to achieve glycemic target(all P<0.05);TDD kg^(-1)was positively correlated with waist-to-hip ratio(WHR),baseline FPG,glycosylated hemoglobin Ale(HbAlc),fasting C-peptide level and time to achieve glycemic target,and negatively correlated with BMI(all P<0.05).Multiple linear regression analyses revealed that BMI(β=1.796,P<0.01),WC(β=0.109,P<0.01),baseline FPG(β=1.459,P<0.01)and HbAlc(β=0.930,P=0.021)were independently related to TDD.Gender(β=-0.107,P=0.003),WC(β=0.005,P=0.029),baseline FPG(β=0.025,P<0.01)and HbAlc(β=0.016,β=0.007)were independently associated with TDD kg^(-1).Gender(β=-0.015,P=0.048)and disease duration(β=0.134,P=0.029)were independently associated with%TBa.%TBa is around 40%in Chinese patients with type 2 diabetes treated with CSII when glycemic control is achieved.In addition to body weight or BMI,WC and glucose levels before CSII should be considered to set TDD.Patients with central obesity or poor glycemic control might need more TDD.Higher%TBa should be considered in female patients or patients with longer disease duration.Xubin Yang Hongrong Deng Xiuzhen Zhang Daizhi Yang Jinhua Yan Bin Yao Jianping Weng Wen Xu 2019Science China(Life Sciences)2019,62,11:6
12Three-dimensional simulations of strong ground motion in the Shidian basin based upon the spectral-element method显示文摘The strong motion of a small long and narrow basin caused by a moderate scenario earthquake is simulated by using the spectral-element method and the parallel computing technique.A total of five different geometrical profiles within the basin are used to analyze the generation and propagation of surface waves and their relation to the basin structures in both the time and frequency domain.The amplification effects are analyzed by the distribution of peak ground velocity(PGV)and cumulative kinetic energy(Ek) in the basin.The results show that in the 3D basin,the excitation of the fundamental and higher surface wave modes are similar to that of the 2D model.Small bowls in the basin have great influence on the amplification and distribution of strong ground motion,due to their lateral resonances when the wavelengths of the lateral surface waves are comparable to the size of the bowls.Obvious basin edge effects can be seen at the basin edge closer to the source for constructive interference between direct body waves and the basin-induced surface waves.The Ek distribution maps show very large values in small bowls and some corners in the basin due to the interference of waves propagating in different directions.A high impedance contrast model can excite more surface wave modes,resulting in longer shaking durations as well as more complex seismograms and PGV and Ek distributions.Liu Qifang Yu Yanyan Zhang Xubin 2015Earthquake Engineering and Engineering Vibration2015,14,3:6
13Fe–Mn/MCM-41: Preparation,Characterization,and Catalytic Activity for Methyl Orange in the Process of Heterogeneous Fenton Reaction显示文摘Active Fe-and Mn-loaded MCM-41(Fe–Mn/MCM-41),which was synthesized via a hydrothermal reaction followed by impregnation,is used in the heterogeneous Fenton reaction to degrade methyl orange(MO) in aqueous solution. The synthesized samples were characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,N_2 adsorption–desorption isotherm analysis,Fourier transform infrared spectroscopy,and X-ray photoelectron spectroscopy. Compared with Fe/MCM-41 and Mn/MCM-41,Fe–Mn/MCM-41 showed higher activity for MO degradation and mineralization. Effects of various operating parameters,such as pH,Mn content,and H_2O_2 dosage,on the degradation process were subsequently investigated. Results of experiments on the effect of radical scavengers revealed that the degradation of MO could be attributed to oxidation by HO_·. The synergy of Fe and Mn species in the Fenton oxidation process was also explained.Xubin Zhang Jianxin Dong Zhencheng Hao Wangfeng Cai Fumin Wang 2018Transactions of Tianjin University2018,24,4:6
14北极夏季冰面上近地层特征及热量收支问题显示文摘应用1999年8月19~24日我国第1次北极考察资料对北极夏季近地层气象要素梯度特征和冰面热量收支问题进行了讨论.北极夏季近地层相对于冰面的相对湿度很大,经常接近于饱和状态,冰温具有明显的日变化,夜间冰面附近冰温梯度较大,白天很小.在冰温垂直分布中20cm冰层温度有时可出现极大值.冰面热量收支计算表明,夜间冰面辐射冷却损失热量主要由冰层向冰面热量输送来补偿.白天冰层的热量主要来源于穿透短波辐射,冰面和以下冰层间的热量交换很低.白天冰面冰雪融化热量是不可忽视的.周明煜 李诗明 陈陟 张占海 Xubin Zeng 2006地球物理学报2006,49,2:4
15FGFR/RACK1 interacts with MDM2, promotes P53 degradation, and inhibits cell senescence in lung squamous cell carcinoma显示文摘Objective:FGFR is considered an important driver gene of lung squamous cell carcinoma(LSCC).Thus,identification of the biological events downstream of FGFR is important for the treatment of this malignancy.Our previous study has shown that the FGFR/RACK1 complex interacts with PKM2 and consequently promotes glycolysis in LSCC cells.However,the biological functions of the FGFR/RACK1 complex remain poorly understood.Methods:Anchorage-independent assays and in vivo tumorigenesis assays were performed to evaluate cancer cell malignancy.Distant seeding assays were performed to evaluate cancer cell metastasis.β-gal staining was used to examine cell senescence,and immunoprecipitation assays were performed to examine the interactions among FGFR,RACK1,and MDM2.Results:FGFR/RACK1 was found to regulate the senescence of LSCC cells.Treatment with PD166866,an inhibitor of FGFR,or knockdown of RACK1 induced senescence in LSCC cells(P<0.01).A molecular mechanistic study showed that FGFR/RACK1/MDM2 form a complex that promotes the degradation of p53 and thus inhibits cell senescence.PD166866 and RG7112,an MDM2/p53 inhibitor,cooperatively inhibited the colony formation and distal seeding of LSCC cells(P<0.01),and upregulated the expression of p53 and p21.Conclusions:Together,our findings revealed the regulatory roles and mechanisms of FGFR/RACK1 in cell senescence.This understanding should be important in the treatment of LSCC.Tao Chen Fei Wang Shupei Wei Yingjie Nie Xiaotao Zheng Yu Deng Xubin Zhu Yuezhen Deng Nanshan Zhong Chengzhi Zhou 2021Cancer Biology & Medicine2021,18,3:3
16Effect of Metallic Film in Diamond Growth from an Fe—Ni—C System at High Temperature and High Pressure显示文摘The metallic film surrounding a diamond single crystal,which plays an important role the diamond growth from and Fe-Ni-C system,has been successfully investigated by using transmission-electron microscopy(TEM),Raman layer(near diamond)of the film by TEM and Raman spectroscopy,but a parallel relationship exists between the(111) plane of γ-(Fe,Ni) and the (100) plane of (Fe2Ni)3C in this region.Compared with that of the film has an increase of 0.9V.According to the microstructures on the film obtained by the TEM.Raman spectra,and XPS,the catalytic mechanism of the film may be assumed as follows.In the surface layer of the film,iron and nickel atoms in the γ-(Fe,Ni) lattice can absorb carbon atoms in the (Fe,Ni)3C lattice and make them transform to an sp^3-like state.Then carbon atoms with the sp^3-like structure are separated from the (Fe,Ni)3C and stack on the growing diamond crystal.This study provides a direct evidence for the diamond growth from a metallic catlayst-graphite system under high temperature and high pressure.XUBin LIMu-Sen YINALong-Wei CUIJian-Jun GONGJian-Hong 2003Chinese Physics Letters2003,20,5:3
17Analysis of liquid bridge between spherical particles显示文摘A pair of central moving spherical particles connected by a pendular liquid bridge with interstitial Newtonian fluid is often encountered in particulate coalescence process. In this paper, by assuming perfect-wet condition, the effects of liquid volume and separation distance on static liquid bridge are analyzed, and the relation between rupture energy and liquid bridge volume is also studied. These points would be of significance in industrial processes related to adhesive particles.Fusheng Mu Xubin Su 2007China Particuology2007,5,6:3
18Microstructure evolution,texture and mechanical properties of a Mg-Gd-Y-Zn-Zr alloy fabricated by cyclic expansion extrusion with an asymmetrical extrusion cavity:The influence of passes and processing route显示文摘In the present work,two processing routes(A and B)with 3 CEE-AEC passes are performed on Mg-13 Gd-4 Y-2 Zn-0.4 Zr alloys,and the resultant microstructure evolution,texture analysis and mechanical properties are investigated systematically.The core difference between the two processing routes is the orientation between the expansion and extrusion steps,i.e.,they are parallel to each other for on route A and perpendicular to each other for route B.The results show that a remarkable grain refinement is achieved via both processing routes due to dynamic recrystallization(DRX).Fine equiaxed grains are observed in the samples processed with route B with a final size of 3.6±0.4μm compared to the grain size of 4.5±0.5μm with route A.With an increasing number of CEE-AEC passes,the overall texture intensity decreases,and the basal texture gradually changes to the mixed texture components.The shear deformation introduced by the asymmetrical extrusion cavity promotes a broad angular distribution of the basal planes on routes A and B,leading to an obvious increase in the Schmid factor for the activation of the basal a slip system.The tensile test at ambient temperature reveals that the comprehensive mechanical properties are improved,and the conventional mechanical anisotropy of as-received alloys is alleviated by successive CEE-AEC processing,which is mainly derived from the competitive balance relation between the grain refinement and texture modification.Zhaoming Yan Xubin Li Jie Zheng Zhimin Zhang Qiang Wang Kaihua Xu Hongzhi Fan Guanshi Zhang Jiaxuan Zhu Yong Xue 2021Journal of Magnesium and Alloys2021,9,3:2
19Snow Albedo's Dependence on Solar Zenith Angle from In Situ and MODIS Data显示文摘Since snow cover is one of the fastest modifications to the land surface albedo, the treatment of snow-covered surface albedo is important for the simulation of land processes in weather and climate models. A simple formulation is developed here to represent the solar zenith angle (SZA) dependence of albedo under maximum snow cover condition on the basis of Moderate Resolution Imaging Spectroradiometer (MODIS) Bidirectional Reflectance Distribution Function (BRDF) algorithm. The SZA dependence of black-sky (or direct) albedo is weaker under snow condition than that under snow-free condition, and it does not differ much among different vegetation types. The blue-sky albedo (or combined albedo from direct and diffuse radiations) based on the above formulation and in situ diffuse ratio of solar radiation is consistent with in situ data from two Canadian sites (grassland and evergreen needleleaf forest) and one U.S. grassland site. In particular, the SZA dependence of bluesky snow albedo is almost always weak because of high diffuse ratios for high SZA in winter. With the snow albedo formulation from this study and snow-free albedo formulations from the authors' previous studies, albedos with partial snow cover can be obtained as the snow frac- tion-weighted average of snow and snow-free albedos.Zhuo Wang Xubin Zeng 2008Atmospheric and Oceanic Science Letters2008,1,1:2
20Improving the Treatment of the Vertical Snow Burial Fraction over Short Vegetation in the NCAR CLM3显示文摘One deficiency of the NCAR Community Land Model (CLM3) is the disappearance of the simulated snow even in the middle of winter over a boreal grassland site due to unrealistically modeled high downward turbulent fluxes. This is caused by the inappropriate treatment of the vertical snow burial fraction for short vegetation. A new snow burial fraction formulation for short vegetation is then proposed and validated using in situ observations. This modification in the CLM3 largely removes the unrealistic surface turbulent fluxes, leading to a more reasonable snowmelt process, and improves the snow water equivalent (SWE) simulation. Moreover, global offline simulations show that the proposed formulation decreases sensible and latent heat fluxes as well as the ground temperature during the snowmelt season over short vegetation dominant regions. Correspondingly, the SWE is enhanced, leading to the increase in snowmelt-induced runoff during the same period. Furthermore, sensitivity tests indicate that these improvements are insensitive to the exact functional form or parameter values in the proposed formulation.王爱慧 Xubin ZENG 2009Advances in Atmospheric Sciences2009,26,5:2
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