华南"94·6"特大暴雨的中尺度对流系统及其环境场研究Ⅱ.物理过程、环境场以及地形对中尺度对流系统的作用

在该文第Ⅰ部分中选取1994年6月12日～13日过程进行了较深入的研究,在确定云雨、垂直运动的模拟基本正确以后,利用模式的输出资料对在此期间的β中尺度对流系统的结构和演变进行了分析研究.第Ⅱ部分继续探讨物理过程、初始环境场以及地形对β中尺度对流系统的发生、发展的影响.结果表明:潜热释放对强对流系统发生、发展都有重要的作用.行星边界层过程对对流的发生阶段影响较为明显,而对发展阶段的影响似乎还不大.地面感热和潜热通量对对流系统的强度有影响.对初始场的试验表明,初始湿度场的改变会很明显地影响模拟结果,温度场的影响次之.地形的改变对大尺度的雨带影响不是很大,主要影响强暴雨的强度和落区,地形尤其是喇叭口地形对"94@6"暴雨的增幅作用十分明显.     

2008年初南方雨雪冰冻灾害天气静止锋与层结结构分析

对2008年我国南方持续性雨雪、冰冻灾害天气的影响系统及层结特征做了研究,集中对第3次过程,即1月25～29日期间的天气形势、水汽条件、高原对流系统东移的影响以及地面和大气层结条件进行了分析。研究表明：位于长江或江南地区的准静止锋（或切变线）是雨雪冰冻天气的重要影响系统,锋面西段的逆温层和暖层强,有利于冻雨的形成;水汽在锋前的对流层低层辐合,沿锋面爬升凝结,锋面的东段低层辐合比西段强,造成锋面东段的降水强度大于西段;高原对流系统活跃,且频繁东移影响我国东部,在第3次过程共有3次高原对流的东移过程;最有利于冻雨产生的层结条件应有中层冻结层、暖层、逆温层,且这些层结的强度和厚度要适当;最有利于冻雨出现的地面温度在-1～-3℃,变化非常小,温度、露点差都在1～3℃,接近饱和,风速较弱。最后,提出了适合于我国南方雨雪、冰冻天气的锋面结构与大气层结的物理模型。     

Application of ATOVS microwave radiance assimilation to rainfall prediction in Summer 2004

Experiments are performed in this paper to understand the influence of satellite radiance data on the initial field of a numerical prediction system and rainfall prediction. First, Advanced Microwave Sounder Unit A （AMSU-A） and Unit B （AMSU-B） radiance data are directly used by three-dimensional variational data assimilation to improve the background field of the numerical model. Then, the detailed effect of the radiance data on the background field is analyzed. Secondly, the background field, which is formed by application of Advanced Television and Infrared Observation Satellite Operational Vertical Sounder （ATOVS） microwave radiance assimilation, is employed to simulate some heavy rainfall cases. The experiment results show that the assimilation of AMSU-A （B） microwave radiance data has a certain impact on the geopotential height, temperature, relative humidity and flow fields. And the impacts on the background field are mostly similar in the different months in summer. The heavy rainfall experiments reveal that the application of AMSU-A （B） microwave radiance data can improve the rainfall prediction significantly. In particular, the AMSU-A radiance data can significantly enhance the prediction of rainfall above 10 mm within 48 h, and the AMSU-B radiance data can improve the prediction of rainfall above 50 mm within 24 h. The present study confirms that the direct assimilation of satellite radiance data is an effective way to improve the prediction of heavy rainfall in the summer in China.     

耦合模式在局地辐射雾三维数值模拟研究中的应用

本文利用中尺度数值模式MM5与三维辐射雾模式相耦合,分别对重庆和长沙地区的一次冬季辐射雾过程进行了模拟研究。结果表明,中尺度数值模式与三维辐射雾模式的单向耦合可以较好地模拟出雾的生消演变过程,以及雾的浓度、地理分布特征、形成和维持。由此可以说,利用耦合模式开展雾的预报是可行的。     

Mesoscale Analysis of a Heavy Rainfall Event over Hong Kong During a Pre-rainy Season in South China

During the Heavy Rainfall Experiment in South China （HUAMEX） of 1998, a record heavy rainfall event occurred in the delta of the Pearl River during the 24 hours from 1200 UTC 8 June to 1200 UTC 9 June, 1998, and a 24-hour precipitation maximum of 574 mm was reported in Hong Kong. In this paper, some mesoscale characteristics of this heavy rainfall event are studied using data from satellites, Doppler radar, wind profilers, and automatic meteorological stations collected during HUAMEX. The following conclusions are drawn： （1） During this heavy rainfall event, there existed a favorable large-scale environment, that included a front with weak baroclinity in the heavy rain area and with an upward motion branch ahead of the front. （2） Unlike most extratropical or subtropical systems, the closed low in the geopotential height field does not exited. The obvious feature was that a southerly branch trough in the westerlies existed and Hong Kong was located ahead of the trough. （3） The rainfall areas were located in the warm sector ahead of the front, rather than in the frontal zone, which is one of the characteristics of heavy rainfalls during the pre-rainy season of South China. A southerly warm and moist current contributed to the heavy rainfall formation, including the transportation of rich water vapor and the creation of strong horizontal wind convergence. （4） The observations show that the heavy rainfall in Hong Kong was directly caused by a series of meso β systems rather than a mesoscale convective complex （MCC）. These meso β systems moved with the steering current in the lower-mid troposphere, their life cycles were 3-6 hours, and their horizontal sizes were 10-100 km. （5） The disturbances in the lower and mid troposphere, especially that in the planetary boundary layer （PBL） were very shallow. However, they are a possible trigger mechanism for the occurrence and development of the mesoscale convective systems and related heavy rainfalls. Finally, a conceptual model of the heav     

2014年11月上旬西北太平洋一次极端强度爆发气旋的数值模拟和分片位涡反演分析

基于NCEP 6 h一次,0.5°（纬度）×0.5°（经度）水平分辨率的GFS（Global Forecasting System）再分析数据,利用数值模式WRF（Weather Research and Forecasting）,对2014年11月上旬西北太平洋一次极端强度的爆发气旋事件进行了模拟。在成功复制爆发气旋主要特征的基础上,较详细的分析了本次爆发气旋快速发展的有利环境条件,并利用分片位涡反演的方法,对此次爆发气旋的快速发展过程进行了研究,主要结论如下:（1）本次爆发气旋的爆发性发展阶段维持了约27 h,其最大加深率约为3.98 Bergeron（气旋加深率单位）,最低中心气压约为919.2 hPa。（2）爆发气旋的快速发展与对流层高层高空急流对热量的输送,对流层中层西风带短波槽槽前暖平流和正涡度平流的有利准地转强迫,以及对流层低层暖锋伴随的暖平流过程密切相关。（3）分片位涡反演的结果表明,对流层顶皱褶对应的平流层大值位涡下传和降水凝结潜热过程造成的正位涡异常是本次爆发气旋快速发展的主导因子,而对流层低层的斜压过程贡献相对较小。在气旋爆发期的前期和强盛期,降水凝结潜热释放是爆发气旋发展的最重要因子,而在爆发期后期,随着降水的减弱和爆发气旋的东北向移动,对流层顶皱褶作用所造成的正位涡异常成为维持气旋快速发展的最有利因子。     

初值水汽场对华南春季一次强飑线触发和维持影响的数值试验

在对观测资料分析的基础上,采用WRF模式探讨初始场水汽分布对华南2014年3月30—31日产生雷暴大风、强降水的飑线过程触发和维持的影响。研究基于ERA-interim和NCEP-FNL再分析资料在华南地区水汽分布的差异性,设计了四组将两类资料水汽按比例融合作为初始场的数值试验,水汽场从NCEP-FNL越靠近ERA-interim水汽,模拟的飑线演变越趋近实况,试验结果表明更准确的水汽初始场有利于提高飑线等强对流系统的预报准确率。在对流初生阶段,区域内水汽含量增多,最大有效位能增大,对流越容易触发;对流发展中后期,充沛的水汽有利于飑线组织形态和强度的维持。      

地质特深孔绳索取心钻杆机械性能研究

地质特深孔绳索取心钻杆结构区别于API石油钻杆,其机械性能计算不可直接引用API石油钻杆的相关理论公式。针对这一理论依据与计算方法缺失,本文对地质特深孔双台肩钻杆接头进行了受力分析,开展了钻杆接头拉伸载荷与扭转载荷计算理论研究,构建了绳索取心钻杆机械性能计算的理论方法。同时,通过有限元分析和台架试验,确定了H-5000规格双台肩绳索取心钻杆的机械性能,验证了计算方法的准确性,并提出了钻杆结构改进建议与下一步研究方向,为高性能薄壁绳索取心钻杆“服役”于5000 m地质岩心钻探工程提供了技术支撑。     

特深钻探钻柱组合优化设计研究

钻杆柱作为地球深部探测中深地与深水钻探技术的核心与关键,单一规格钻柱许用深度有限,难以满足大陆万米特深孔科学钻探及大洋深水深孔钻探工程的设计要求。本文通过减轻下部钻柱重力及提高上部钻柱强度方案,对其组合设计开展优化研究。以拉伸条件下的强度计算为主,加之一定的设计安全系数和拉伸余量来满足动载荷以及其他复杂情况对钻柱强度的需求,并开发了钻柱组合设计与安全系数计算的软件,可实现不同孔深设计和钻杆结构要求下的钻柱组合设计与安全系数计算。     

积极采用先进技术，提高地矿部门钻探生产水平

针对当前地矿部门地质岩心钻探生产技术水平现状，经过分析对比，为进一步提高地矿部门地质岩心钻探生产水平，提出了推广３项主要先进技术的建议。