一次川东大暴雨过程的中尺度分析

利用观测资料和MM5中尺度非静力模式产生的客观分析资料, 分析了2004年9月3～5日出现在川东地区大暴雨过程的大尺度环流特征和主要的中尺度天气系统及其结构。分析表明:中纬度低压槽的东移与西伸加强的副热带高压在青藏高原北部地区形成了有利于高原切变线和西南低涡生成发展的环流条件;西南低涡东侧的暖式切变线是对流活动最活跃的区域, 强降水主要出现在暖式切变线上;西南低涡是一个主要出现在对流层中低层的涡旋系统, 与大暴雨区相对应的整层强上升运动是低涡切变线南北两侧的正反向垂直环流共同作用的结果。     

Hydrodynamic modelling of mesoscale eddies in the Black Sea

A three dimensional structure of mesoscale circulation in the Black Sea is simulated using the Proudman Oceanographic Laboratory Coastal Ocean Modelling System. A number of sensitivity tests reveal the response of the model to changes in the horizontal resolution, time steps, and diffusion coefficients. Three numerical grids are examined with x-fine (3.2 km), fine (6.7 km) and coarse (25 km) resolution. It is found that the coarse grid significantly overestimates the energy of the currents and is not adequate even for the study of basin-scale circulation. The x-fine grid, on the other hand, does not give significant advantages compared to the fine grid, and the latter is used for the bulk of simulations. The most adequate parameters are chosen from the sensitivity study and used to model both the basin-scale circulation and day-to-day variability of mesoscale currents for the months of May and June of 2000. The model is forced with actual wind data every 6 h and monthly climatic data for evaporation, precipitation, heat fluxes and river run-off. The results of the fine grid model are compared favourably against the satellite imagery. The model adequately reproduces the general circulation and many mesoscale features including cyclonic and anticyclonic eddies, jets and filaments in different parts of the Black Sea. The model gives a realistic geographical distribution and parameters of mesoscale currents, such as size, shape and evolution of the eddies.     

中尺度暴雨模式MRM1对华南暴雨预报试验

利用中尺度暴雨模式MRM1对2001年6、7月华南的暴雨进行数值预报试验．初始场采用T106谱模式的预报场作初估场，海表温度采用1982～2001年的候平均海温。试验结果表明：模式对两个月的1、10、25、50、100mm降水平均TS值分别达到0．629、0．358、0．238、0.160、0．063．两个月中的主要降水过程预报效果较好．特别是7月几次台风暴雨过程。     

中尺度对流系统演变中的一些非平衡动力学问题

深厚湿对流运动发展机制包含湿大气的对称不稳定(MSI和CSI)及锋面环流．它们需要的基本条件是不稳定、水汽和抬升，这些机理在动力学中是有联系和区别的，即虽然都是与基流平衡状态被破坏后引起的中尺度环流有关，但是扰动流非平衡运动是不同的。本文综合概述了有关平衡动力学的研究进展，提出了中尺度对流系统演变中的一些非平衡动力学主要问题，并评述了一些研究的方法及主要结论和尚需进一步探索的方面．以加深对不同机制下深对流运动的认识。     

河流自动综合方法

本文在分析河网结构的基础上,提出了一种基于河流的结构化的河网自动建立方法,建立了两个结构索引即线索树结构索引及层次结构索引,并根据包含以上索引的结构化河网,对河流的自动综合的一系列技术问题进行了初步的探讨。     

中国暴雨中尺度系统发生与发展的诊断分析和数值模拟(Ⅱ)数值模拟

通过改进的MM4中尺度数值模式，对我国三次典型大暴雨过程的模拟，来探讨暴雨中尺度系统发生与发展的问题。主要结果指出:气旋性涡柱在不稳定暖湿气柱内生成和发展，以及与整个涡柱共存的上升运动的持续加强，对暴雨中尺度系统的发展具有重要的作用；地面热通量，凝结潜热释放对暴雨中尺度系统的发展有决定性的作用；各种不同的物理过程和参数化、青藏高原的构形造成的外强迫影响，以及模式空间分辨率等，对暴雨中尺度系统结构与演变以及降雨量的模拟结果均有重要的作用。     

梅雨锋上中尺度对流云团的分析

本文利用每小时红外增强显示（EIR）和红外（IR）云图，6小时降水量及常规气象资料，对1991年6月12—14日和7月6—7日江淮地区大暴雨过程进行分析，给出了梅雨锋上中尺度对流云团活动的特征（包括生成源地、生命史、移向移速及对流云团生成的几种形式）；讨论了中低纬度云系相互作用对暴雨云团发生、发展的重要性；最后概括出中尺度暴雨云团发生、发展的云模型和概念模型。     

1991年6月12-16日江淮特大暴雨中尺度天气过程分析

依据高空、地面常规资料，风、雨量自记资料及卫星、雷达资料分析了１９９１年６月１２－１６日江淮地区一场罕见大暴雨中尺度降水系统的演变过程，揭示了梅雨锋暴雨一些新的观测事实，其中包括中－α系统中对流云核的串状排列、快速向东传播以及中－β系统的若干统计特征等。     

A distributed water-heat coupled model for mountainous watershed of an inland river basin in Northwest China (III) using the outputs from Mesoscale model version 5

The distributed water-heat coupled (DWHC) model is calibrated, with the help of the Mesoscale model version 5 (MM5), by calculating the daily precipitation, the daily average air temperature at the 2.0 m heights and the daily potential evaporation in Heihe mountainous watershed area and its vicinity (96.786°∼102.284°E, 37.328°∼40.601°N, 17 × 10⁴ km²), from February 11 to June 30, 2003. The MM5 model periodically ran every 10 days in 3 km × 3 km grid resolution with an integral time step of 3 s. In the MM5 model, many scheme or options are consulted or adopted, such as the Grell scheme cumulus parameterization method, the Dudhia option, the cloud-radiation scheme, MRF PBL option and the modified Oregon State University Land-surface model (OSULSM). According to the projection transform methods, the MM5 outputs are interpolated to the 1 km × 1 km grid in Alberts projection by using triangle-based cubic interpolation (Cubic) and nearest neighbor interpolation (Nearest) methods, with which the DWHC model shares the same method. The result shows that, when the Nearest method is used, the Nash-Sutcliffe equation value of the daily average runoff is 0.79, the balance error is −0.79% and the goodness of fit R ² value is 0.81. Meanwhile, when the Cubic method is used, the Nash-Sutcliffe equation value, the balance error and the R ² value are 0.79, −0.65% and 0.80, respectively. Though the runoff simulation result is not favorable, it is still better than that using measured data at the meteorological and hydrological stations; the latter has a Nash-Sutcliffe equation value of 0.61. The MM5-DWHC model results also show that runoff mainly occurs on land surfaces and from shallow soil layers. According to model calibration results, certain outputs of MM5 are singular to some extent and the DWHC model is very sensitive to the initial values.     

Chemical perturbations in the planetary boundary layer and their relevance for chemistry transport modelling

The role of perturbations of reactive trace gas concentration distributions in turbulent flows in the planetary boundary layer (PBL) is discussed. The paper focuses on disturbances with larger spatial scales. Sequential nesting of a chemical transport model is applied to assess the effect of neglecting subgrid chemical perturbations on the formation and loss of ozone, NO _x , peroxyacetyl nitrate (PAN) and HNO₃ calculated with a highly complex chemical mechanism. The results point to characteristic differences regarding the process of mixing of chemically reactive species in the PBL and lower troposphere.