Effects of winds,tides and storm surges on ocean surface waves in the Sea of Japan

Ocean surface waves are strongly forced by high wind conditions associated with winter storms in the Sea of Japan. They are also modulated by tides and storm surges. The effects of the variability in surface wind forcing, tides and storm surges on the waves are investigated using a wave model, a high-resolution atmospheric mesoscale model and a hydrodynamic ocean circulation model. Five month-long wave model simulations are inducted to examine the sensitivity of ocean waves to various wind forcing fields, tides and storm surges during January 1997. Compared with observed mean wave parameters, results indicate that the high frequency variability in the surface wind filed has very great effect on wave simulation. Tides and storm surges have a significant impact on the waves in nearshores of the Tsushima-kaihyō, but not for other regions in the Sea of Japan. High spatial and temporal resolution and good quality surface wind products will be crucial for the prediction of surface waves in the JES and other marginal seas, especially near the coastal regions.     

Numerical simulation of aerodynamic derivatives and critical wind speed for long-span bridges based on simplified steady wind field

Combining the computational fluid dynamics-based numerical simulation with the forced vibration technique for extraction of aerodynamic derivatives, an approach for calculating the aerodynamic derivatives and the critical flutter wind speed for long-span bridges is presented in this paper. The RNG k-ε turbulent model is introduced to establish the governing equations, including the continuity equation and the Navier-Stokes equations, for solving the wind flow field around a two-dimensional bridge section. To illustrate the effectiveness and accuracy of the proposed approach, a simple application to the Hume Bridge in China is provided, and the numerical results show that the aerodynamic derivatives and the critical flutter wind speed obtained agree well with the wind tunnel test results.     

The Characteristics of Cloud-to-Ground Lightning Activity with Severe Thunderstorm Wind in South and North China

The characteristics of cloud-to-ground（CG） lightning activity with severe thunderstorm wind（STW） in South and North China are analyzed using CG lightning data, radar data, and serious weather reports. The percentage of positive CG（PCG） flashes with STW in North China is larger than that in South China. STW takes place during the period when the total CG and PCG density is increasing fastest. STW also occurs close to the high-value center of CG and PCG density. In North China, the CG and PCG density in the grid of STW maximizes approximately 20 minutes after the STW occurs; while in South China, the PCG density and percentage of PCG in the grid of STW maximizes about 10 minutes before the occurrence of STW. The high-value centers of CG density and PCG density in North China move slightly faster than those in South China, which is opposite to the rate of increasing CG activity.     

风暴过后是丰收？

海洋表面的环境条件可能是非常险恶的，时常会突发冰冷刺骨的暴风和强烈的气旋。然而，在海浪之下幽蓝色的大洋深处，却是另一番世界了。那里极其平静，海洋表面的狂暴波澜变得特别温和，而且水温从未下降到零度以下。     

用曲面拟合法诊断“90．7．6”大暴雨

本文使用一种新的有限区域曲面拟合方法（ＮＭＯＣＳＦ）诊断１９９０年７月６日陕南、陇南的大暴雨过程，发现了在天气图上难以辨别的中尺度低涡，讨论了它对大暴雨的贡献，另外还发现暴雨容易发生在低层能量和水汽通量散度的鞍型场中心点附近等事实。本文试图通过实例分析证明ＮＭＯＣＳＦ作为一种新的客观分析方法和诊断方法在暴雨研究中有广泛的应用前景。     

Estimation of peak relative velocity and peak absolute acceleration of linear SDOF systems

We have found some mistakes in the article by Jianwei Song et al. (2007). The revisions arc given below: 1. "NEHRP 2003" in Figs.8 and 9 should be changed to "BSSC 2003". 2. "Tsopelas" or "Tsopelas method"     

垂直风切变对风暴云影响的数值模拟

本文用一个适合中－β尺度天气系统研究的三维非静力全弹性模式通过对理想环境大气中垂直风切变的不同分布进行数值模拟试验，结果表明：环境风场在风暴的发展演变中具有很大的影响作用，特别是低层风垂直切变值的大小决定了对流风暴的类型和发展演变的主要特征。     

9405号热带风暴分析和预报的评价

1概况9405号热带风暴于7月4日18时30分在我省电白到阳西沿海地区登陆后，经高州市在信宜境内减弱为低气压。中心附近最大风速为23m／s。其路径为：前期稳定向西北偏西方向移动，登陆前后20小时偏北移，减弱为低压后，中心转偏西方向移动（见图1）。本热带风暴的特点是速度快，生命史短（36小时），降雨范围大、强度强，局部地区有特大暴雨，最大田雨量及过程雨量均出现在阳春，分别为331．0、379．8mm。图19405号热带民暴全路径本次过程的降水强度强而广，江河水位急涨；据省三防简报称，殃及10个县区共133个乡镇，受灾人口达356万人，2个县…