T_(63)L_(16)谱模式水汽初始场的处理和试验

在T63L1 6谱模式中 ,初始输入的水汽场 ,经展谱后 ,垂直各层一般出现 2 %～8%的负水汽点。为了克服这一负水汽现象 ,我们采用了“逐步循环订正法”对初值进行了一些特别处理。经实例计算表明 ,其效果明显 ,不仅负水汽现象得以克服 ,而且各层水汽场的水平分布不会带来明显的变化     

A New Approach for Parameter Optimization in Land Surface Model

In this study,a new parameter optimization method was used to investigate the expansion of conditional nonlinear optimal perturbation (CNOP) in a land surface model (LSM) using long-term enhanced field observations at Tongyu station in Jilin Province,China,combined with a sophisticated LSM (common land model,CoLM).Tongyu station is a reference site of the international Coordinated Energy and Water Cycle Observations Project (CEOP) that has studied semiarid regions that have undergone desertification,salination,and degradation since late 1960s.In this study,three key land-surface parameters,namely,soil color,proportion of sand or clay in soil,and leaf-area index were chosen as parameters to be optimized.Our study comprised three experiments:First,a single-parameter optimization was performed,while the second and third experiments performed triple-and six-parameter optimizations,respectively.Notable improvements in simulating sensible heat flux (SH),latent heat flux (LH),soil temperature (TS),and moisture (MS) at shallow layers were achieved using the optimized parameters.The multiple-parameter optimization experiments performed better than the single-parameter experminent.All results demonstrate that the CNOP method can be used to optimize expanded parameters in an LSM.Moreover,clear mathematical meaning,simple design structure,and rapid computability give this method great potential for further application to parameter optimization in LSMs.     

Perturbation of regional ocean tides due to coastal dikes

The tidal regime modeling system for ocean tides in the seas bordering the Korean Peninsula is designed to cover an area that is broad in scope and size, yet provide a high degree of resolution in coastal development areas, including the Saemangeum area in the eastern Yellow Sea and the Ariake Sea in Japan, where serious environmental problems have occurred after the completion of interior tidal dikes. With this simulation system, we have estimated the changes in tidal regime due to barriers at Saemangeum and Isahaya Bay in the Ariake Sea. Some results in terms of perturbations in tidal elevations due to the construction of coastal dikes are presented and discussed.     

增长模叠加方式及其对集合预报初始扰动的影响

用增长模繁殖法(BGM)有效地构造集合预报初始扰动的一个前提是, 任两个扰动之间应尽可能的发散.本文从增长模发展和饱和的角度分析了增长模叠加方式与集合预报初始扰动"取样性"的关系, 无论是从扰动形势演变得出的定性结论还是定量计算的结果都显示: 在相同初始模的情况下, 通过改变扰动叠加方式分别构造多个扰动样本的做法是近似等效的.用这种方法增加的集合样本从"取样性"的角度来看是没有多大意义的, 更多的是在浪费有限的计算资源.构造多个初值的有效方法应该是从不同初始模出发进行增长模的繁殖.     

一种新型的中尺度暴雨集合预报初值扰动方法研究

提出一种针对对流不稳定构造具有中尺度运动特征的集合预报扰动初值的新方法--异物理模态法, 介绍了异物理模态法产生初值扰动区域和扰动振幅的数学处理方案, 即由不同对流参数化方案预报离差获得集合预报初值扰动区域、扰动结构和扰动振幅的数学处理过程. 利用美国PSU/NCAR的MM5中尺度模式, 对一次典型暴雨进行异物理模态法初值扰动集合预报试验, 详细分析了扰动初值的结构和集合预报结果. 结果表明, 该方法产生的初值扰动场具有合理的中尺度环流结构, 可以反映对流敏感区域的对流不稳定的预报不确定性, 集合预报结果可以明显改善控制预报.     

顺层边坡稳定性及可靠度的随机有限元分析法

阐述了基于摄动法的随机有限元基本原理,采用以均值为中心的2阶摄动随机有限元,运用局部平均的空间离散方法,对顺层边坡的应力场进行了2阶统计均值、协方差和方差的分析,并结合顺层边坡沿软弱夹层滑动的破坏特征,推导了基于Mohr-Coulomb准则的顺层边坡整体稳定的安全系数和可靠度的计算表达式。结合典型顺层岩质路堑边坡工程实例,采用摄动随机有限元法进行了边坡稳定性和可靠度的分析计算。结果表明,文中介绍的摄动随机有限元法可以考虑多种随机变量对边坡系统的影响,可同时采用安全系数和可靠度作为边坡稳定性的评价指标,判定结果更为准确和全面。     

Ar同位素地质的若干问题

本文主要讨论作者在工作中所遇到的一些问题，作者认为一定要重视岩石、矿物中36Ar对定年的影响，只有较好的解决K-Ar定年系统的初始比，才能较好的提高定年的准确性。油气田Ar同位素分馏及He、Ar在瓦斯突出的预报方面值得重视。     

区域初始分析误差对梅雨锋中尺度低压数值预报的影响

以梅雨锋中尺度低压个例为研究对象,根据目标观测的思想,采用NCEP和T106再分析资料分析了区域初始分析误差对梅雨锋中尺度低压数值预报误差的影响。结果表明:区域初始分析误差对数值预报误差有重要影响,改善某些特定区域初始场质量有可能改善随后数值预报的效果。但是,区域初始分析误差对数值预报误差的影响较为复杂,它与天气类型、不同个例和区域间误差相互作用等因素密切相关。对梅雨锋中尺度低压短期数值预报有较大影响的初始分析误差与梅雨锋锋区及其附近地区的要素场关系密切,相比较而言,风场似乎更加重要一些。如果对梅雨锋带中低层风切变区及相伴低空急流区有更好的描述,这将对梅雨锋中尺度低压系统数值预报效果的改善有着积极的作用。在此基础上,就相关的目标观测设计问题作了简要讨论。     

Impacts of Initial Conditions on Cloud-Resolving Model Simulations

Impacts of initial conditions on cloud-resolving model simulations are investigated using a series of sensitivity experiments. Five experiments with perturbed initial temperature, moisture, and cloud conditions are conducted and compared to the control experiment. The model is forced by the large-scale vertical velocity and zonal wind observed and derived from NCEP/Global Data Assimilation System （GDAS）. The results indicate that model predictions of rainfall are much more sensitive to the initial conditions than those of temperature and moisture. Further analyses of the surface rainfall equation and the moisture and cloud hydrometeor budgets reveal that the calculations of vapor condensation and deposition rates in the model account for the large sensitivities in rainfall simulations.     

青海西金乌兰湖地区移山湖晚泥盆世辉绿岩墙群——西金乌兰洋初始裂解的重要证据

在青海西金乌兰湖地区移山湖和倒流沟一带发现的辉绿岩墙,侵入于泥盆系拉竹龙组变质石英砂岩、长石石英砂岩和元古宇宁多群灰白色白云母石英片岩、黑云母石英片岩中,岩石类型为辉绿岩、辉长辉绿岩,结合同位素测年及古生物证据分析其地质时代为晚泥盆世,可能与古特提斯北部河卡山东段克觉杂尔根基性岩墙群一样,反映了可可西里地区壳幔演变过程,是古陆块裂解、西金乌兰洋初始形成的证据。