一次暴雨过程预报的多模式NWP产品与物理参数的综合分析应用

对照常规天气图实况资料,检验几种常用NWP产品对2008年7月5日山东一次强降水过程的形势场预报和降水预报,并对其物理量场进行诊断分析.结果表明,暴雨落区与诸多物理量场的配置紧密相关;暴雨区出现在低层水汽辐合中心移动路径上,位于与水汽通量散度强辐合中心和强上升运动中心接近处;暴雨区移动方向与水汽通量大值中心、△θse(500-850)负值中心长轴方向一致,水汽通量散度低层辐合、高层辐散两者均满足时有利于强降水发生;200 hPa高空辐散的抽吸作用远比仅有低层辐合更有利于上升运动发展;地面强降水区出现在200 hPa强辐散中心所在处.     

Influence of leaf water potential on diurnal changes in CO2 and water vapour fluxes

Mass and energy fluxes between the atmosphere and vegetation are driven by meteorological variables, and controlled by plant water status, which may change more markedly diurnally than soil water. We tested the hypothesis that integration of dynamic changes in leaf water potential may improve the simulation of CO₂ and water fluxes over a wheat canopy. Simulation of leaf water potential was integrated into a comprehensive model (the ChinaAgrosys) of heat, water and CO₂ fluxes and crop growth. Photosynthesis from individual leaves was integrated to the canopy by taking into consideration the attenuation of radiation when penetrating the canopy. Transpiration was calculated with the Shuttleworth-Wallace model in which canopy resistance was taken as a link between energy balance and physiological regulation. A revised version of the Ball-Woodrow-Berry stomatal model was applied to produce a new canopy resistance model, which was validated against measured CO₂ and water vapour fluxes over winter wheat fields in Yucheng (36°57′ N, 116°36′ E, 28 m above sea level) in the North China Plain during 1997, 2001 and 2004. Leaf water potential played an important role in causing stomatal conductance to fall at midday, which caused diurnal changes in photosynthesis and transpiration. Changes in soil water potential were less important. Inclusion of the dynamics of leaf water potential can improve the precision of the simulation of CO₂ and water vapour fluxes, especially in the afternoon under water stress conditions.     

Comparison of manual and automatic methods for measurement of methane emission from rice paddy fields

The methane emission flux from rice paddies was simultaneously measured with automatic and manual methods in the suburban of Suzhou. Both methods were based on the static chamber/ GC-FID techniques. Detail analysis of the experimental results indicates: a) The data of methane emission measured with the automatic method is reliable. b) About 11 or 19 o’clock of local time is recommended as the optimum sampling time for the manual spot measurement of methane emission from rice paddies. The methane emission fluxes measured by manual sampling at local time other than the optimum time have to be corrected. The correction coefficient may be determined by automatic and continuous measurement. c) In order to get a more accurate result, an empirical correction factor, such as 18%, is recommended to correct the seasonally total amount of measured methane emission by enlarging the au-tomatically measured data or reducing the manually measured ones.     

近45 a黑龙江省春季风速变化的区域特征分析

用方差极大正交旋转REOF方法,将经过均一性检验、分布较均匀的黑龙江省1961～2005年25个测站春季风速变化分为5个区,并对各区风速变化特征进行了分析,最后探讨了人类活动对风速变化的可能影响.结果表明:近45 a来,黑龙江省各个区域风速均呈减小趋势,人类活动可能是导致春季风速减小的一个原因.     

Robustness of Precipitation Projections in China:Comparison between CMIP5 and CMIP3 Models

Three sources of uncertainty in model projections of precipitation change in China for the 21st century were separated and quantified: internal variability,inter-model variability,and scenario uncertainty.Simulations from models involved in the third phase and the fifth phase of the Coupled Model Intercomparison Project(CMIP3 and CMIP5) were compared to identify improvements in the robustness of projections from the latest generation of models.No significant differences were found between CMIP3 and CMIP5 in terms of future precipitation projections over China,with the two datasets both showing future increases.The uncertainty can be attributed firstly to internal variability,and then to both inter-model and internal variability.Quantification analysis revealed that the uncertainty in CMIP5 models has increased by about 10%–60% with respect to CMIP3,despite significant improvements in the latest generation of models.The increase is mainly due to the increase of internal variability in the initial decades,and then mainly due to the increase of inter-model variability thereafter,especially by the end of this century.The change in scenario uncertainty shows no major role,but makes a negative contribution to begin with,and then an increase later.     

西昆仑落石沟一带铅锌矿成矿规律与找矿前景

西昆仑落石沟矿带是新疆西南部重要的成矿区带,落石沟矿带已发现铁、铜、铅锌矿(床)点13处,成矿潜力巨大。文章在综合前人工作成果的基础上,就区域内铅锌矿的分布规律、成矿地质背景、矿床地质特征、区域物化探异常特征、成矿模式、控矿因素等方面进行了介绍,重点以宝塔山、多宝山铅锌矿作为典型矿床对其成矿特征进行了分析和对比,指出西昆仑落石沟一带为寻找MVT型(碳酸盐岩容矿型)铅锌矿的有利地区,初步总结了该成矿带铅锌矿的控矿规律,确定了区域预测要素,提出了找矿有利地区。     

金川铜镍硫化物样品中锇同位素比值的高精度分析

采用两种独立的190Os稀释剂、4个不同的化学流程,用等离子体质谱仪、TRITON热表面电离质谱仪和MAT-262固体质谱仪3种质谱仪器,在4个实验室分别对采自金川铜镍硫化物样品的187Os/188Os同位素比值进行分析,样品分析数量达到56个。4个实验室获得的结果分别为0.3356±0.0018(n=12,2s)、0.3363±0.0008(n=6,2s)、0.3363±0.0010(n=18,2s)和0.3353±0.0034(n=20,2s)。采用ISOPLOT软件对所得56个数据进行加权平均计算,得到187Os/188Os同位素比值为0.33602±0.00022(置信度95%)。两台TRITON热表面电离质谱仪测量的结果几乎完全一致,且精度高于MAT-262固体质谱仪和等离子体质谱仪。比较了碱熔和Carius管两种溶样方法,结果表明,对于所研究的样品,用Carius管溶矿方式可以将含锇矿物完全溶解。     

碳化对加填料氯氧镁胶凝材料力学性能的影响

以添加不同掺量填料的氯氧镁水泥(MOC)试件为基体,在空气和碳化箱中分别养护至规定龄期,研究碳化对掺加填料MOC力学性能的影响,并与空气环境进行对比,运用XRD和SEM分析碳化后水化产物和微观结构的变化规律。结果表明,28 d龄期内,随着填料掺量的增加MOC试件碳化后的抗折强度均有所增加,碳化后的抗压强度均有提升,碳化过程反应生成了MgCO_3,不同碳化龄期的主要物相均为5Mg(OH)_2·MgCl_2·8H_2O(5相),而掺加填料不影响MOC的水化产物的组成。     

顾及小波变换的土地利用变化与经济因子的多尺度相关性分析

以武汉市为研究区域,借助小波分析工具,揭示了土地利用变化的特征尺度。通过小波方差-尺度图可以辨别出,样区中64m尺度域上的小波方差为极值点,能较好地反映土地利用变化的空间格局。在特征尺度分析的基础上进行土地利用变化与经济影响因子多尺度相关性分析,结果表明,各经济影响因子的对土地利用变化的制约性随尺度的增大不断增强,小尺度上经济因子与土地利用变化的相关性较小;在特征尺度上,一般经济因子的相关系数较大,原因在于特征尺度上土地利用的空间结构信息丰富,能较好地反映经济因子与土地利用变化的相关性;大尺度上随着信息的不断合并,多数经济因子相关系数增长缓慢并逐渐趋于稳定;多尺度相关性分析反映了经济影响因子作为宏观制约因素影响样区土地利用的变化,也验证了特征尺度分析的有效性。