Impact of Interannual Variation of Synoptic Disturbances on the Tracks and Landfalls of Tropical Cyclones over the Western North Pacific

This study investigates the tropical cyclone (TC) activity associated with the two leading modes of interannual variability in synoptic disturbances. Both leading modes are found to be related to a dipole pattern of TC occurrence between the subtropical western North Pacific and the South China Sea. Therefore, in this study we performed composite analyses on TC tracks and landfalls, based on the cases of combined modes, to highlight the differences. The composite results indicate that these cases are characterized by distinct features of TC tracks and landfalls: more TCs tend to take recurving tracks and attack eastern China, Korea and Japan, or more TCs exhibit straight-moving tracks and hit the Philippines, Vietnam and southern China. Further analyses suggest that these distinctions in the TC prevailing tracks and landfalls can be attributed to the differences in large-scale steering flow and TC genesis location.     

Impact of the Spring SST Gradient between the Tropical Indian Ocean and Western Pacific on Landfalling Tropical Cyclone Frequency in China

The present study identifies a significant influence of the sea surface temperature gradient(SSTG) between the tropical Indian Ocean(TIO; 15°S-15°N, 40°-90°E) and the western Pacific warm pool(WWP; 0°-15°N, 125°-155°E) in boreal spring on tropical cyclone(TC) landfall frequency in mainland China in boreal summer. During the period 1979-2015, a positive spring SSTG induces a zonal inter-basin circulation anomaly with lower-level convergence, mid-tropospheric ascendance and upper-level divergence over the west-central TIO, and the opposite situation over the WWP, which produces lower-level anomalous easterlies and upper-level anomalous westerlies between the TIO and WWP. This zonal circulation anomaly further warms the west-central TIO by driving warm water westward and cools the WWP by inducing local upwelling, which facilitates the persistence of the anomaly until the summer. Consequently, lower-level negative vorticity, strong vertical wind shear and lower-level anticyclonic anomalies prevail over most of the western North Pacific(WNP), which decreases the TC genesis frequency. Meanwhile, there is an anomalous mid-tropospheric anticyclone over the main WNP TC genesis region,meaning a westerly anomaly dominates over coastal regions of mainland China, which is unfavorable for steering TCs to make landfall in mainland China during summer. This implies that the spring SSTG may act as a potential indicator for TC landfall frequency in mainland China.     

超强台风“天鹅”（2015）路径突变过程机理研究

本文采用中国气象局的最佳台风路径数据和美国国家环境预报中心1°×1°每6 h再分析资料作为研究工作的基本场,运用了分部位涡反演方法探讨影响2015年第15号超强台风“天鹅”路径突变的物理机制,得到以下结论:（1）就天气系统而言,“天鹅”整个移动过程中都受到周围环境场及引导气流的影响,主要的影响系统包括西北太平洋副热带高压、季风涡旋、邻近台风“艾莎尼”及台风外围反气旋;（2）定量分析了与各影响系统扰动位涡相关的引导气流矢量,发现整个过程中超强台风“天鹅”的移动始终受西北太平洋副热带高压的影响,其次是来自季风涡旋及台风外围反气旋的贡献,而当“天鹅”有向北转向趋势时,与外围反气旋相关的东北向引导气流导致了台风的路径北折;（3）进一步定量分析了总扰动位涡在不同高度层上相关引导气流的贡献,结果表明在垂直方向上对流层中层系统的引导气流矢量与“天鹅”的移动最为吻合,而形成于低层系统的偏南风气流与“天鹅”向北突然转向有着密切的联系,并在转向后逐渐向中高层发展增强。     

2011/2012年夏季南极半岛北端周边海域的水团与水交换

通过分析中国第28次南极考察队于2011年12月至2012年1月在南极半岛北端周边海域获得的5条断面CTD观测温盐剖面数据, 进一步认识了该海域的水团组成和水交换情况。观测区域南部的鲍威尔海盆及周边深海区, 可以观测到保持了较显著高温核心的威德尔深层水、密度大于28.27 kg·m^-3的威德尔海深层水以及温度低于－0.7 ℃的威德尔海底层水。周边陆坡上的威德尔海深层水则表现出因与周围水体发生混合而核心性质减弱的特征。在菲利普海岭、埃斯佩里兹海槽等复杂地形处, 观测到的对应于威德尔海深层水深度的混合与热盐入侵过程更为显著。威德尔海深层水能够到达南设得兰群岛以北的象岛东北面海域, 但是高盐核心加深至1 500 db, 并上覆温度基本不变但盐度随深度显著增大的较暖水体, 表明威德尔海深层水经历了不同的路径和变性过程。布兰斯菲尔德海峡中没有绕极深层水大规模侵入的迹象, 但是乔治王岛周边陆架上可能存在涡旋等中尺度过程, 会影响德雷克海峡与布兰斯菲尔德海峡之间的水交换。     

Determination of the effect of initial inner-core structure on tropical cyclone intensification and track on a beta plane

The sensitivity of TC intensification and track to the initial inner-core structure on a β plane is investigated using a numerical model. The results show that the vortex with large inner-core winds(CVEX-EXP) experiences an earlier intensification than that with small inner-core winds(CCAVE-EXP), but they have nearly the same intensification rate after spin-up. In the early stage, the convective cells associated with surface heat flux are mainly confined within the inner-core region in CVEXEXP, whereas the vortex in CCAVE-EXP exhibits a considerably asymmetric structure with most of the convective vortices being initiated to the northeast in the outer-core region due to the β effect. The large inner-core inertial stability in CVEX-EXP can prompt a high efficiency in the conversion from convective heating to kinetic energy. In addition, much stronger straining deformation and PBL imbalance in the inner-core region outside the primary eyewall ensue during the initial development stage in CVEX-EXP than in CCAVE-EXP, which is conducive to the rapid axisymmetrization and early intensification in CVEX-EXP. The TC track in CVEX-EXP sustains a northwestward displacement throughout the integration, whereas the TC in CCAVE-EXP undergoes a northeastward recurvature when the asymmetric structure is dominant. Due to the enhanced asymmetric convection to the northeast of the TC center in CCAVE-EXP, a pair of secondary gyres embedded within the large-scale primary β gyres forms, which modulates the ventilation flow and thus steers the TC to move northeastward.     

论水库工程之管运洪水

鉴于水库工程管理运用的重要性,提出管运洪水的新概念,并和设计洪水做了全面对比,指出二者异同。在此基础上提出了评判管运洪水是否合理的两个通用准则:条件合乎要求和防洪安全达标。将推求管运洪水的方法分为两大类:一类以分期内洪水最大值为依据,另一类以年最大值为依据。这两类方法本质不同,使用时各有优缺点。第一类方法的结果不完全符合现行标准的要求,而第二类方法的结果符合要求,但对资料条件要求较高。     

9012号热带气旋登陆后维持不消的动力机制

分析了影响南海的几类台风路径所对的２００ｈＰａ辐散风场和速度热场的特征,发现２００ｈＰａ辐散风场对台风路径有一定的制约作用。主要体现在：（１）２００ｈＰａ辐散风场表征的季风环流结构的差异决定着台风路径扣期趋势;（２）西太平洋副高所对应的辐散风次级辐台线的走向和西伸程度指示着信风特征,影响台风未来的路径;（３）台风一般向辐散中心以外的次级辐散线西侧２个经距的位置移动,用辐散风环流的物理意义和台风受环     

国内城市地下空间开发利用现状与发展趋势

我国城镇化水平不断提高的过程中,各类“城市病”是多数城市必须面对的难题,城市地下空间的开发利用成为各个城市解决这一问题的有效途径。在这样的背景下,我国城市地下空间开发利用从21世纪起进入快速发展阶段,十几年来地下空间利用增长迅猛,成就斐然。文章总结了当前我国城市地下空间各功能开发现状,并分等级叙述了我国几类城市地下空间开发利用现状。最后文章提出我国城市地下空间开发利用的趋势是向地质调查先行,网络化与分层化规划,协同化利用,内部环境生态化和人性化,管理数字化和智能化方向发展;不同城市将根据其社会经济需求和地质环境特点差异化重点开发,科学利用城市地下空间资源,发挥其社会、经济效益,让城市更美好。