Joint Distribution of Wave Heights and Wavelengths and Distribution of Wave Steepness   总被引：1，自引：0，他引：1  

ZHENG Guizhen LIU Xuehai XU Delun Ph. D. Candidate  Physical Oceanography Laboratory  Ocean University of Qingdao  Qingdao  P. R. China. Graduate Student  Physical Oceanography Laboratory  Ocean University of Qingdao  Qingdao  P. R. China. Professor  Physical Oceanography Laboratory  Ocean University of Qingdao  Qingdao  P. R. China. 《中国海洋工程》1999,(2)

-A joint probability density is derived for wavelengths and wave heights.It is asymmetric anddepends only on the spectral bandwidthεdefined by Cartwright and Longuet-Higgins(1956).After that atheoretical probability density for wave steepness is obtained.It tends to Rayleigh distribution asε→0.Acomparison between theorethal steepness distribution and laboratory experiment result shows good agree-ment.  相似文献   

On the Bandwidth Parameter of Wind-Wave Spectra   总被引：1，自引：1，他引：0  

LIU Xuehai ZHENG Guizhen XU Delun Graduate Student  Physical Oceanography Laboratory  Ocean University of Qingdao  Qingdao  P. R. China Ph. D. Candidate  Physical Oceanography Laboratory  Ocean University of Qingdao  Qingdao  P. R. China Professor  Physical Oceanography Laboratory  Ocean University of Qingdao  Qingdao  P. R. China 《中国海洋工程》1999,(4)

In light of the analysis of the physical implication and underlying assumption of the bandwidthparameterεof wave spectrum,a time-averaging method is used to evaluateεof the JONSWAP spectrum fordifferent sea states.The resulting values ofε,which vary from 0.44 to 0.53 depending on the dimensionlessfetch,are physically meaningful and reasonable.The same method is also used to computeεfrom wind-waverecords measured in a flume under different wind speeds at different fetches.The computed values ofε,which vary with wind fetches and speeds too,are compared with those evaluated for the JONSWAP spec-trum.  相似文献   

Optimum Environmental Load Design Criterion for Marine Structures Based on Investment and Benefit Analysis     

ZHANG Shuhua  YU Yifa  LI Benxia Associate Professor  Ocean University of Qingdao  Qingdao  P. R. China. Master  Ocean University of Qingdao  Qingdao  P. R. China. 《中国海洋工程》1998,(2)

Marine structures operating in natural ocean environment are subjected to various stochasticloads.For design of the marine structures,the most important task is to determine environmental load de-sign criterion.This paper presents a method to determine the optimum environmental load design criteri-on for marine structures.This method is based on the investment and benefit analysis and it can reach thedesign purpose of decreasing total costs during the service life of the structures and increasing economicbenefits.  相似文献   

A Whitecap Coverage Model Based on the Surface Slope For Criterion of Wave Breaking   总被引：3，自引：2，他引：1  

Xu Delun  Yu Dingyong  Lu Hongmin Professor  Physical Oceanography Laboratory  Ocean University of Qindao  Qingdao Associate Professor  Engineering School  Ocean University of Qindao  Qingdao Senior Engineer  Physical Oceanography Laboratory  Ocean University of Qingdao  Qingdao 《中国海洋工程》1998,(1)

Using the limit surface slope as a criterion of wave breaking,a simple model for estimatingthe spatial fraction of breaking surface of sea at an instant,which is regarded as the whitecap coverge inthis paper,is analytically derived from the probability density of surface slope based on Gaussianstatistics.The resulting fraction is found depending on the fourth moment of wave spectum,m_4,as well asthe critical threshold of surface slope.By expressing the fourth moment in terms of the Neumannspectrum,a formula linking the fraction and wind speed for fully developed sea states is obtianed.Anotherformula relating the fraction to both wind speed and fetch(or duration)is achieved by expressing m_4 interms of the Krylov spectrum and applying the empirical relationships used in the SMB ocean wave pre-dicting technique.A comparison between these results and the field data of whitecap coverage collected byMonahan and O＇Muircheartuigh shows an encouraging agreement.  相似文献   

Size-Dependent Growth Rate of Nitzschia closterium at Different Concentrations of Petroleum Hydrocarbon     

YANG Rujun  TANG Hongjie  XIN Yu    WANG XiulinCollege of Chemistry  Chemical Engineering  Ocean University of China  Qingdao  P. R. China 《中国海洋大学学报(英文版)》2009,8(1)

  相似文献   

CHARACTERISTICS OF INTRASEASONAL VARIATIONS IN THE MIXED LAYER OF "WARM POOL" AREAS     

孙即霖  刘秦玉 《中国海洋湖沼学报》1996,(4)

Observational data obtained during the TOGA-COARE IOP in the "warm pool" area of the West-ern Tropical Pacific were used to analyze some characteristics of the intraseasonal variations in the mixedlayer. The influence of westerly burst and rainfall on SST, salinity. and mixed layer depth are discussed.There are two pairs of counteracting processes in the "warm pool" mixed layer: (1) The increase of mixedlayer depth caused by local westerly bursts and the decrease of mixed layer depth caused by larger scaleeasterly relaxation;(2) the vertical mixing by local wind and the strong stratification due to rainfall in themixed layer. Some possible mechanisms through the interactions between the intraseasonal time scale varia-tions of the oceanic mixed layer and atmospheric low frequency oscillations are revealed.  相似文献   

Meridional Variation of the 1955-2003 Sea Level Anomalies in the Tropical Pacific Ocean Associated with El Nio Events     

FANG Mingqiang)  )  and QU Liqin)  )) Ocean Remote Sensing Institute  Ocean University of China  Qingdao  P. R. China ) The Key Laboratory of Ocean Remote Sensing  Ministry of Education  P. R. China 《中国海洋大学学报(英文版)》2007,(4)

The Sea Level Anomaly-Torque (SLAT, relative to a reference location in the Pacific Ocean), which means the total torque of the gravity forces of sea waters with depths equal to the Sea Level Anomaly (SLA) in the tropical Pacific Ocean, is defined in this study. The time series of the SLAT from merged altimeter data (1993-2003) had a great meridional variation during the 1997-1998 El Nio event. By using historical upper layer temperature data (1955-2003) for the tropical Pacific Ocean, the tempera- ture-based SLAT is also calculated and the meridional variation can be found in the historical El Nio events (1955-2003), which suggests that the meridional shifts of the sea level anomaly are also intrinsic oscillating modes of the El Nio cycles like the zonal shifts.  相似文献   

大直径潜孔锤气力反循环流体速度与压力模型     

黄勇  殷琨  朱丽红  博坤 《吉林大学学报(地球科学版)》2011,(Z1):232-236

为解决大直径潜孔锤反循环钻进技术中气体携带岩屑不彻底和地面供气压力难以控制问题,必须开展循环气体流动参数即速度压力分布研究。根据反循环钻进中流体通道特点对流场分区,采用"倒算法"按循环系统流动的反方向推导各分区流场的气体速度和压力公式,建立流体参数数学模型,并对所得模型进行实例验算。以直径1.2 m、孔深40 m硬岩钻孔为例,钻孔出口流速为40 m/s时,钻头喷嘴气体流速为456 m/s,喷嘴截面积为0.002 4 m2,孔口气体注入压力为1.2 MPa,循环系统压力降约为0.9 MPa。计算结果表明,该模型可为地面气源参数调节和优化喷嘴结构提供依据。  相似文献   

高阶有限差分法管波传播数值模拟     

孟庆生  樊玉清  张珂  张盟 《吉林大学学报(地球科学版)》2011,41(1):292-298

为正确认识流体充填钻孔中管波的传播规律,首先给出均匀各向同性介质中包含流体充填钻孔条件下的弹性波动力学方程和二阶速度-应力公式及差分格式的稳定性条件和边界条件;然后利用高阶交错网格有限差分法,结合典型模型,模拟了不同时刻管波的传播快照和复杂层状介质中管波的合成地震记录,并与实际管波地震记录进行了对比。结果表明:在地层分界面、溶洞的边界等波阻抗差异界面处,管波都会产生反射;反射管波的振幅、频率特征受界面两侧的岩石物理性质差异的影响;在理论合成记录中,反射管波与直达管波同相轴的交点与理论模型中地层分界面或异常体的边界一致。  相似文献   

ENSO循环的非对称性及其机制初步探讨   总被引：1，自引：0，他引：1  

于毅  孟祥凤  张磊  赵杰臣 《热带海洋学报》2011,(4)

利用SODA(Simple Ocean Data Assimilation)资料,以Nino3.4区SSTA(sea surface temperature anomaly)指数为标准,选取典型El Nio和La Nia事件进行合成分析,观察ENSO的非对称性。通过分析ENSO事件发生过程中温跃层深度异常和斜压能量转化率的变化,研究其对ENSO循环非对称性的影响。由于与ENSO相关的海洋异常信号在南、北太平洋的传播主要是以Rossby波的形式,Rossby波可以通过不稳定机制获得能量成长和传播,斜压能量转化率越强,携带ENSO相关海洋异常信号的Rossby波就可能获得更多的能量成长,这种信号传播至赤道区域可以更快地导致ENSO事件的爆发。研究表明,在El Nio事件达到顶峰时,北太平洋ENSO相关的Rossby波传播区斜压不稳定能量很强(可使Rossby波增幅)、温跃层加深(可使Rossby波加速),有利于El Nio相关的暖信号传出,这很好地解释了El Nio事件总是比La Nia事件振幅大以及El Nio事件向La Nia事件转化比La Nia事件向El Nio事件转化快很多的现象。因...  相似文献