热带气旋北冕暴雨多普勒雷达分析

分析热带气旋北冕在厦门地区造成的暴雨过程中主要降水时段多普勒雷达资料强度场和速度场的特点。分析表明，这次暴雨是多种天气系统相互作用的结果。第三阶段的短时大暴雨是停滞在厦门上空的强单体直接造成的，对应的速度场上有低层东南风和西南风辐合；单体的合并也起了一定的作用，而且单体的分离合并与低空急流的脉动有关。     

华北平原一次秋季大暴雨过程的物理成因分析

20 0 3年 10月 10～ 12日在华北平原南部出现了一次 5 0年同期罕见的大暴雨过程。为了弄清大暴雨形成的物理原因 ,利用常规资料、MM5模拟结果和自动站资料对这次过程进行了初步分析。分析表明 ,源源不断的大中尺度水汽输送及持续较长的时间是这次同期罕见大暴雨的主要原因。而大中尺度急流间的强风向辐合加强了垂直上升运动 ,这是形成华北平原大暴雨的关键所在。     

200 hPa高空急流与宁夏春季沙尘暴过程的特征分析

 利用NCAR/NCEP全球再分析资料，首先分析了1955年到2003年宁夏春季沙尘暴过程与200 hPa急流的关系，发现2月、3月200 hPa的U、V风场与宁夏春季沙尘暴关系密切。然后对1970\_1999年66次宁夏强和特强沙尘暴过程发生前200 hPa急流的演变情况进行了分析，结果表明：宁夏强和特强沙尘暴过程发生前后，高空急流主要表现为3种类型：一是西风急流型;二是副热带急流型;三是西风急流与副热带急流振荡合并型。最后以2001年4月8日宁夏特强沙尘暴天气过程为例，对其发生前后高空急流演变与沙尘暴落区、垂直环流特征及其对沙尘暴的作用进行了分析和探讨，得到了一些新的启示。     

东风低空急流暴雨的中尺度分析

东风低空急流暴雨在湖北比较少见。使用卫星云图、武汉多普勒雷达资料和地面中尺度资料，针对2004年6月4～5日发生在湖北中东部地区的一次东风低空急流暴雨过程进行了中尺度分析，得到：（1）东风低空急流暴雨是在有利的大尺度背景场条件下，在特定的地域触发产生的；（2）东风低空急流在暴雨的形成和发展中起到重要的作用；（3）东风低空急流暴雨是由中尺度回波团和中尺度复合体造成的；（4）东风低空急流暴雨是在多种尺度天气系统相互作用的情况下发生发展的，而中小尺度系统是其产生的最直接的系统。     

2005年江淮流域入梅偏晚的成因分析

2005年是江淮流域入梅偏晚年。利用NCEP／NCAR再分析资料、OLR资料和江苏省气象台提供的2005年逐日降水资料，对2005年江淮流域入梅前的异常环流形势进行分析，探讨了西太平洋副热带高压和低层中高纬冷空气的活动异常与东亚大槽、中西太平洋ITCZ以及东亚副热带高空西风急流等活动异常的关系。结果表明，入梅前，东亚大槽发展强盛，ITCZ偏弱以及东亚副热带高空西风急流强劲少动导致西太平洋副热带高压北抬偏晚。同时，东亚副热带高空西风急流的强劲少动也使南下冷空气势力强劲，中低层副热带锋区偏南，抑制了暖湿的东亚夏季风向江淮流域推进。东亚副热带高空西风急流和西太平洋副热带高压向北突跳偏晚是江淮流域2005年入梅偏晚的主要原因。     

真空动力固结联合扩底旋喷桩在饱和软粘土地基加固中的应用研究

针对饱和软粘土的工程特性,采用了真空动力固结联合扩底旋喷桩加固饱和软粘土地基。结合江苏某软粘土地基加固工程,在探讨其加固机理的基础上,通过对加固过程的方案设计及现场试验结果的分析和讨论,表明该法能够充分发挥强夯、真空降水及旋喷注浆各自的技术优势。该法具有工期短、造价低、预沉降可控、加固效果好等优点。进一步拓宽了饱和软粘土地基的处理方法,为我国沿海地区软粘土地基处理工程提供了新的途径。     

固底管桩单桩承载力的研究

通过现场对预应力管桩底部采用高压旋喷法进行加固这一新的施工工艺试验,探讨预应力管桩桩端为水泥土情况下的受力机理及提高管桩端阻力和单桩极限承载力的效果,并探讨其在天津地区的适用性。     

Nocturnal Low-Level Jet Characteristics Over Kansas During Cases-99

Characteristics and evolution of the low-level jet (LLJ)over southeastern Kansas were investigated during the 1999 Cooperative Surface-AtmosphereExchange Study (CASES–99) field campaign with an instrument complement consisting of ahigh-resolution Doppler lidar (HRDL), a 60 m instrumented tower, and a triangle of Dopplermini-sodar/profiler combinations. Using this collection of instrumentation we determined thespeed U_X, height Z_X and direction D_X of the LLJ. We investigate here the frequencyof occurrence, the spatial distribution, and the evolution through the night, of these LLJcharacteristics. The jet of interest in this study was that which generates the shear and turbulencebelow the jet and near the surface. This was represented by the lowest wind maximum.We found that this wind maximum, which was most often between 7 and 10 m s¹,was often at or just below 100 m above ground level as measured by HRDL at the CASEScentral site. Over the 60 km profiler–sodararray, the topography varied by 100 m. The wind speed anddirection were relatively constant over this distance (with some tendency for strongerwinds at the highest site), but Z_X was more variable. Z_X was occasionally about equal at allthree sites, indicating that the jet was following the terrain, but more often it seemed to berelatively level, i.e., at about the same height above sea level. Z_X was also more variable thanU_X in the behaviour of the LLJ with time through the night, and on some nights $U_X wasremarkably steady. Examples of two nights with strong turbulence below jet level were furtherinvestigated using the 60 m tower at the main CASES–99 site. Evidence of TKE increasing withheight and downward turbulent transport of TKE indicates that turbulence was primarilygenerated aloft and mixed downward, supporting the upside–down boundary layer notion in thestable boundary layer.     

Small-Scale Variability in the Coastal Atmospheric Boundary Layer

The influence of the main large-scale wind directions on thermally driven mesoscale circulations at the Baltic southwest coast, southeast of Sweden, is examined. The aim of the study is to highlight small-scale alterations in the coastal atmospheric boundary layer. A numerical three-dimensional mesoscale model is used in this study, which is focused on an overall behaviour of the coastal jets, drainage flows, sea breezes, and a low-level eddy-type flow in particular. It is shown that synoptic conditions, together with the moderate terrain of the southeast of Sweden (max. height h₀ 206 m), governs the coastal mesoscale dynamics triggered by the land-sea temperature difference T. The subtle nature of coastal low-level jets and sea breezes is revealed; their patterns are dictated by the interplay between synoptic airflow, coastline orientation, and T.The simulations show that coastal jets typically occur during nighttime and vary in height, intensity and position with respect to the coast; they interact with downslope flows and the background wind. For the assigned land surface temperature (varying ±8 K from the sea temperature) and the opposing constant geostrophic wind 8 m s^-1, the drainage flow is more robust to the opposing ambient flow than the sea breeze later on. Depending on the part of the coast under consideration, and the prevailing ambient wind, the sea breeze can be suppressed or enhanced, stationary at the coast or rapidly penetrating inland, locked up in phase with another dynamic system or almost independently self-evolving. A low-level eddy structure is analyzed. It is governed by tilting, divergence and horizontal advection terms. The horizontal extent of the coastal effects agrees roughly with the Rossby radius of deformation.     

钻孔后压浆灌注桩承载力试验研究

介绍了钻孔后压浆灌注桩施工工艺和加固机理,并根据原位测试结果分析了钻孔后压浆灌注桩荷载传递规律和大面积堆载试验对承载力的影响。