波浪的非线性显式弥散关系     

王亮  李瑞杰  Dong-Young LEE 《海洋湖沼通报》2002,1(3):9-18

波浪的非线性弥散关系在应用于求解波浪的变形问题时很不方便，需要与含非线性效应的缓坡方程一起进行迭代运算，往往导致数值计算的计算量太大，计算过于复杂。采用显式形式表达非线性弥散关系，可以克服上述缺点，大为简化波浪变形数值计算的计算量。本文通过将现有的非线性弥散关系进行分析比较，给出了一个更为一般的非线性弥散关系及其显式表达式，经比较可知，该显式弥散关系与相对应非线性弥散关系吻合的很好。本文最后用该显式结合含弱非线性效应的缓坡方程，对复式浅滩地形上的波浪折射绕射进行了计算。结果表明，考虑弱非线性可以得出与实验数据更为相符的结果，而采用显式弥散关系可以有效提高计算效率,在波浪的非线性计算中不失为一种切实有效的方法。  相似文献   

Offshore Structural Control Considering Fluid Structure Interaction     

Ju Myung KIM Dong Hyawn KIM Gyu Won LEE 《中国海洋工程》2006,20(2):259-268

1.IntroductionAmong various control devices,Tuned Mass Damper(TMD)has been mostfrequently usedtothecontrol of structural vibration induced by oscillating loads such as earthquakes,winds,and waves.This is due to the fact that it operates without external e…  相似文献   

Stable carbon isotopic evidence for climate change across the late Pleistocene to early Holocene from Lesotho,southern Africa     

P. ROBERTS  J. A. LEE‐THORP  P. J. MITCHELL  C. ARTHUR 《第四纪科学杂志》2013,28(4):360-369

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Analysis of Determinants for an Enhanced and Long-lasting Coastal Convective System by Means of a Case Study(26 July 2011)     

Jung-Tae LEE  Dong-In LEE  Shingo SHIMIZU  Cheol-Hwan YOU 《大气科学进展》2019,36(12):1327-1339

A precipitation system developed continuously along the western coastline of the Korean Peninsula and created considerable precipitation both along the coast and inland on 26 July 2011. In this study, the causes for this nearshore convective system are investigated from observations and the results of model experiments. Three-dimensional radar fields clearly show that a change of wind at the surface border played an important role in the development of the nearshore convection system. The simulation results, which are very similar to the observations, show that the surface border generated and maintained the convergence zone. The roughness change enhanced the convergence, and the interaction between the deepening cold pool and downward flow maintained the convergence zone. The surface mechanical discontinuity affected by the roughness change between sea and land formed the convergence (gradient of wind stress),which induced momentum transfer to the upper layer. The cold pool created a steep gradient of potential temperature and provided the reason for the propagated convergence zone with the downward flow. The maximum value of the surface change factor, which comprises the influencing factors for the long-lasting convective system, reflects the enhancement of the system at the coast.  相似文献   

Recent Progress in Dual-Polarization Radar Research and Applications in China     

Kun ZHAO  Hao HUANG  Mingjun WANG  Wen-Chau LEE  Gang CHEN  Long WEN  Jing WEN  Guifu ZHANG  Ming XUE  Zhengwei YANG  Liping LIU  Chong WU  Zhiqun HU  Sheng CHEN 《大气科学进展》2019,36(9):961-974

Dual-polarization(dual-pol)radar can measure additional parameters that provide more microphysical information of precipitation systems than those provided by conventional Doppler radar.The dual-pol parameters have been successfully utilized to investigate precipitation microphysics and improve radar quantitative precipitation estimation(QPE).The recent progress in dual-pol radar research and applications in China is summarized in four aspects.Firstly,the characteristics of several representative dual-pol radars are reviewed.Various approaches have been developed for radar data quality control,including calibration,attenuation correction,calculation of specific differential phase shift,and identification and removal of non-meteorological echoes.Using dual-pol radar measurements,the microphysical characteristics derived from raindrop size distribution retrieval,hydrometeor classification,and QPE is better understood in China.The limited number of studies in China that have sought to use dual-pol radar data to validate the microphysical parameterization and initialization of numerical models and assimilate dual-pol data into numerical models are summarized.The challenges of applying dual-pol data in numerical models and emerging technologies that may make significant impacts on the field of radar meteorology are discussed.  相似文献   

Behavior of air particles associated with atmospheric recirculation over complex coastal area     

Soon-Hwan Lee  Geon-Young Park  Lim-Seok Chang  Chang-Keun Song 《Asia-Pacific Journal of Atmospheric Sciences》2015,51(4):311-322

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Chemical Characteristics of Carbonaceous Aerosols During Dust Storms over Xi'an in China   总被引：1，自引：0，他引：1  

LI Xuxiang  CAO Junji  Judith CHOW  HAN Yongming  Shuncheng LEE  John WATSON 《大气科学进展》2008,25(5):847-855

Characterization of carbonaceous aerosols including CC （carbonate carbon）, OC （organic carbon）, and EC （elemental carbon） were investigated at Xi＇an, China, near Asian dust source regions in spring 2002. OC varied between 8.2 and 63.7μgm^- 3, while EC ranged between 2.4 and 17.2 μ m^-3 during the observation period. OC variations followed a similar pattern to EC and the correlation coefficient between OC and EC is 0.89 （n=31）. The average percentage of total carbon （TC, sum of CC, OC, and EC） in PM2.5 during dust storm （DS） events was 13.6%, which is lower than that during non-dust storm （NDS） periods （22.7%）. CC, OC, and EC accounted for 12.9%, 70.7%, and 16.4% of TC during DS events, respectively. The average ratio of OC/EC was 5.0 in DS events and 3.3 in NDS periods. The OC-EC correlation （R^2=0.76, n=6） was good in DS events, while it was stronger （R^2=0.90, n=25） in NDS periods. The percentage of watersoluble OC （WSOC） in TC accounted for 15.7%, and varied between 13.3% and 22.3% during DS events. The distribution of eight carbon fractions indicated that local emissions such as motor vehicle exhaust were the dominant contributors to carbonaceous particles. During DS events, soil dust dominated the chemical composition, contributing 69% to the PM2.5 mass, followed by organic matter （12.8%）, sulfate （4%）, EC （2.2%）, and chloride （1.6%）. Consequently, CC was mainly entrained by Asian dust. However, even in the atmosphere near Asian dust source regions, OC and EC in atmospheric dust were controlled by local emission rather titan the transport of Asian dust.  相似文献   

Evaluation of wind resource using numerically optimized data in the southwestern Korean Peninsula     

Dong-Hyuk Kim  Hwa-Woon Lee  Soon-Hwan Lee 《Asia-Pacific Journal of Atmospheric Sciences》2010,46(4):393-403

The wind distribution over the Korean Peninsula was analyzed using numerically optimized wind data to reduce the uncertainties in estimating the wind resources. The simulated data were validated by a comparison with surface wind observations and three statistical indexes. According to the simulated surface winds, mesoscale circulation, such as land-sea breeze and mountain-valley winds affect the wind characteristics of the hub height at coastal and inland regions. However, the prevailing winds are strongly associated with the synoptic forcing at the island and mountainous regions, not the regional circulation. On the other hand, the atmospheric stability definitely affects the strength of the daytime and nocturnal wind speed at a hub height. Overall, there was a significant difference between the numerical and logarithmic method to estimate the wind energy at hub height. Moreover, the discrepancy in the wind density estimated using the two methods becomes clear over inland and mountainous areas.  相似文献   

Modification of nocturnal drainage flow due to urban surface heat flux     

Soon-Hwan Lee  Hae-Dong Kim 《Asia-Pacific Journal of Atmospheric Sciences》2010,46(4):453-465

Dense observations and numerical experiments were carried out to estimate the modification of mesoscale circulation, particularly cold drainage wind. It was confirmed that nocturnal drainage flow can develop on clear calm summer day and change due to orographical forcing and the heterogeneity of heat flux induced by the discontinuity of land-use. The temperature of nocturnal drainage flow at Sungji Valley, Busan Korea, tended to increase as it passed over the urban surface due to anthropogenic heat. The increase in temperature reached 2.9 K at night. The roughness associated with the exchange of momentum flux alone and the pass of nocturnal drainage flow is important for modifying the characteristics of flow Numerical simulations carried out under various surface conditions showed good agreement with the observations. Urban heat fluxes from the surface during the day are fundamental causes of the changes in the urban mesoscale circulation. In addition, the impact of a discontinuity of surface heat flux on mesoscale flow modification tends to be greater at night than during the day because the direction of urban surface heat fluxes at night is different from that in rural areas. In addition, the criterion to estimate the increase in temperature nocturnal drainage flow was also proposed, and provided results that generally agreed with the numerical results.  相似文献   

Observational and numerical analysis of the characteristics of MCS development associated with trigger effect of isolated islands     

Soon-Hwan Lee  Soo-Jin Hwang  Chan-Su Ryu 《Asia-Pacific Journal of Atmospheric Sciences》2010,46(3):355-367

In order to clarify the characteristics of Mesoscale Convective System (MCS) development and understand the impact of the trigger effect of isolated islands, observational and numerical analysis of the heavy rainfall were carried out over the southwestern part of the Korean Peninsula on July 14, 2004. Satellite based remote sensing data and numerical model MM5 with observational data adjustment were used in this study. The MCS development, in this case, was accompanied not by directional wind shear, but by speed shear which was strongly associated with development of the updraft cloud. An inversion layer at a 750 hPa level is one of the fundamental factors in increasing instability. Effective separation of the upper and lower level atmospheric structure due to an inversion layer at a 750 hPa level creates a suitable condition to develop a MCS. According to numerical analysis it has been found that isolated islands located off the southwestern part of the Korean Peninsula are not a principal factor in causing the heavy rainfall due to the evolution of MCS in this case. Transferable topographic forcing of the downwind side can often induce the variation of MCS intensity, while associated with the precipitation amount over the lee side of the isolated islands at a mature stage of MCS development.  相似文献