台湾岛附近海洋对0908号台风“莫拉克”的响应特征   总被引：1，自引：1，他引：0  

赖巧珍  马雷鸣  黄伟  吴立广 《海洋学报》2013,35(3):65-77

在模拟2009年登陆我国东部沿海的台风"莫拉克"的基础上,利用AVHRR/AMSR和SODA再分析数据和模拟结果,初步评估了GRAPES-ECOM海-气耦合模式(上海台风研究所基于GRAPES-TCM区域台风模式和ECOM海洋模式开发而成)模拟台风期间海洋响应的能力,并分析了台风期间台湾岛周围海域的海温、上升流、中尺度冷涡等的变化特点。分析结果表明,GRAPES-ECOM耦合模式较好地模拟了表层海温对台风的响应,与深水海洋响应比较,揭示了近海对台风响应的一些新特征:(1)在台湾以东海域,台风活动改变了黑潮海域海水的垂直运动,诱导黑潮南部沿岸上升流,而北部先于台风存在的上升流减弱,导致不同水深海温的最大降温位置都出现在路径左侧,与深海偏向路径右侧不同;(2)位于台湾岛东北面的彭佳屿冷涡因其形成与大陆架和黑潮有关,当台风在台湾以东洋面活动时,冷涡位于台风右前方,黑潮表层海水辐合流向大陆架,冷涡中心温度上升,强度减弱,当台风转折北上,冷涡位于台风东南侧,表层海水辐散,加强底层冷水上涌,从而增强了该冷涡的强度;(3)台风不仅加深了台湾海峡的混合层深度,还使得海水的垂直热力结构改变,并使整层海温趋于一致。  相似文献   

改进的移动粒子半隐式法模拟楔形体入水砰击   总被引：1，自引：0，他引：1  

余谦  张怀新 《海洋工程》2013,31(6):9-15

移动粒子半隐式法(Moving-Particle Semi-Implicit Method,MPS)是一种新的基于拉格朗日(Lagrange)理念的无网格方法,适用于模拟自由液面的大变形和水流的喷射现象。用基于大涡模拟的改进MPS法首先模拟了矩形体的入水砰击,砰击压力的计算结果证明了这种方法的正确性,然后模拟了楔形体的匀速入水砰击,并与实验结果进行了对比,验证了大涡模拟改进MPS法在砰击问题中的适用性。  相似文献   

Air-sea carbon-dioxide flux estimated by eddy covariance method from a buoy observation   总被引：1，自引：0，他引：1  

HUANG Yansong  SONG Jinbao  WANG Juanjuan  FAN Conghui 《海洋学报(英文版)》2012,31(6):66-71

Precise measurements of the CO2 gas transfer across the air-sea interface provide a better understanding of the global carbon cycle.The air-sea CO2 fluxes are obtained by the eddy covariance method and the bulk method from a buoy observation in the northern Huanghai sea.The effects of buoy motion on flux calculated by the eddy covariance method are demonstrated.The research shows that a motion correction can improve the correlation coefficient between the CO2 fluxes estimated from two different levels.Without the CO2-H2 O cross-correlation correction which is termed as PKT correction,the air-sea CO2 fluxes estimated by eddy covariance method using the motion corrected data are nearly an order of magnitude larger than those estimated by the bulk method.After the CO2-H2 O cross-correlation correction,some eddy covariance CO2 fluxes indeed become closer to the bulk CO2 flux,whereas some are overcorrected which are in response to small water vapor flux.  相似文献   

2009-2010年冬季南海东北部中尺度过程观测   总被引：2，自引：1，他引：1  

刘长建  庄伟  夏华永  杜岩 《海洋学报》2012,34(1):8-16

根据南海北部陆架陆坡海域2009-2010年冬季航次的CTD调查资料,发现西北太平洋水在上层通过吕宋海峡入侵南海,其对南海东北部上层水体温盐性质的影响自东向西呈减弱趋势,影响范围可达114°E附近。入侵过程中受东北部海域反 气旋式涡旋(观测期间,其中心位于20.75°N,118°E附近) 的影响,海水的垂向和水平结构发生了很大变化,特别是涡旋中心区域,上层暖水深厚,混合层和盐度极大值层显著深于周边海域。该暖涡在地转流场、航载ADCP观测海流及卫星高度计资料中均得到了证实。暖涡的存在还显著影响了海水化学要素的空间分布,暖涡引起的海水辐聚将上层溶解氧含量较高的水体向下输运,使次表层的暖涡中心呈现高溶解氧的分布特征。  相似文献   

Observations of submesoscale eddies using high-frequency radar-derived kinematic and dynamic quantities     

Sung Yong Kim 《Continental Shelf Research》2010

The spatio-temporal variability of submesoscale eddies off southern San Diego is investigated with two-year observations of subinertial surface currents [O(1) m depth] derived from shore-based high-frequency radars. The kinematic and dynamic quantities — velocity potential, stream function, divergence, vorticity, and deformation rates — are directly estimated from radial velocity maps using optimal interpolation. For eddy detection, the winding-angle approach based on flow geometry is applied to the calculated stream function. A cluster of nearly enclosed streamlines with persistent vorticity in time is identified as an eddy. About 700 eddies were detected for each rotation (clockwise and counter-clockwise). The two rotations show similar statistics with diameters in the range of 5–25 km and Rossby number of 0.2–2. They persist for 1–7 days with weak seasonality and migrate with a translation speed of 4–15 cm s⁻¹ advected by background currents. The horizontal structure of eddies exhibits nearly symmetric tangential velocity with a maximum at the defined radius of the eddy, non-zero radial velocity due to background flows, and Gaussian vorticity with the highest value at the center. In contrast divergence has no consistent spatial shape. Two episodic events are presented with other in situ data (subsurface current and temperature profiles, and local winds) as an example of frontal-scale secondary circulation associated with drifting submesoscale eddies.  相似文献   

Meso-scale circulation at the intermediate-depth east of Mindanao observed by Argo profiling floats   总被引：1，自引：0，他引：1  

ZHOU Hui  YUAN DongLiang  GUO PeiFang  SHI MaoChong & ZHANG QiLong Key Laboratory of Ocean Circulation  Wave Studies  Chinese Academy of Sciences  Qingdao  China  Physical Oceanography Laboratory  Ocean University of China  Qingdao 《中国科学:地球科学(英文版)》2010,(3)

The meso-scale circulation at the intermediate depth east of Mindanao is studied using Argo profiling floats observations. The trajectories and the parking-depth velocities of Argo floats show that the intermediate-depth circulation east of Mindanao contains significant meso-scale features that are highly variable both in space and in time. Both cyclonic and anticyclonic eddies at the intermediate depth (1000–2000 m) are indicated by the trajectories east of Mindanao. The mean tangential velocities of these eddies are about 10 cm/s at 2000 m and over 20 cm/s at 1000 m, which indicates that the geostrophic calculation may contain large errors due to the vigorous eddy activity at the reference levels. The analyses also suggest that these eddies might play an important role in mass and vorticity balances of the intermediate-depth circulation east of Mindanao.  相似文献   

Construction and progress of Chinese terrestrial ecosystem carbon,nitrogen and water fluxes coordinated observation   总被引：1，自引：0，他引：1  

Guirui Yu  Wei Ren  Zhi Chen  Leiming Zhang  Qiufeng Wang  Xuefa Wen  Nianpeng He  Li Zhang  Huajun Fang  Xianjin Zhu  Yang Gao  Xiaomin Sun 《地理学报(英文版)》2016,26(7):803-826

Eddy Covariance technique (EC) achieves the direct measurement on ecosystem carbon, nitrogen and water fluxes, and it provides scientific data for accurately assessing ecosystem functions in mitigating global climate change. This paper briefly reviewed the construction and development of Chinese terrestrial ecosystem flux observation and research network (ChinaFLUX), and systematically introduced the design principle and technology of the terrestrial ecosystem carbon, nitrogen and water fluxes coordinated observation system of ChinaFLUX. In addition, this paper summarized the main progress of ChinaFLUX in the ecosystem carbon, nitrogen and water exchange and environmental controlling mechanisms, the spatial pattern of carbon, nitrogen and water fluxes and biogeographical mechanisms, and the regional terrestrial ecosystem carbon budget assessment. Finally, the prospects and emphases of the terrestrial ecosystem carbon, nitrogen and water fluxes coordinated observation of ChinaFLUX are put forward to provide theoretical references for the development of flux observation and research in China.  相似文献   

A numerical study of detached shear layers in a rotating sliced cylinder     

M. A. Page 《地球物理与天体物理流体动力学》2013,107(1-2):51-69

Abstract

The low Rossby number flow in a rotating cylinder with an inclined bottom, of small slope, is examined when part of the lid of the container is rotating at a slightly different rate. The resulting flow is calculated numerically by solving the governing equations for the two-dimensional geostrophic motion which approximates the flow in most of the fluid including the inertially-modified E ^¼ -layers. The presence of ageostrophic regions, on the container walls and beneath the velocity discontinuity on the lid, is accounted for in the governing equations and their boundary conditions. This study supplements previous work on this configuration, in which the zero Rossby number flow was calculated and experimental results were presented, by enabling a direct comparison to be made between the results of the low Rossby number theory and the experiments. The numerical results for a range of Rossby and Ekman numbers compare well with those from the experiments despite a severe limitation on the size of the Rossby number arising from the analysis in the ageostrophic part of the detached shear layer.  相似文献   

Large-eddy simulations of convection-driven dynamos using a dynamic scale-similarity model     

Hiroaki Matsui  Bruce A. Buffett 《地球物理与天体物理流体动力学》2013,107(3):250-276

Dynamo simulations require sub-grid scale (SGS) models for the momentum and heat flux, the Lorentz force, and the magnetic induction. Previous large eddy simulations (LES) using the scale similarity model have represented many aspects of the SGS motion. However, discrepancies are observed due to interchanging the order of filtering operation and spatial differentiation. In this study, we implement a correction term for this commutation error specifically for the scale-similarity model. Furthermore, we implement a dynamic scheme to evaluate time-dependent coefficients for the SGS models. We perform dynamo simulations in a rotating plane layer with different spatial resolutions, and compare results for the time dependence of the large-scale magnetic field. Simulations are performed at two different Rayleigh numbers, using constant values for the other dimensionless numbers (Ekman, Prandtl, and magnetic Prandtl numbers). Both cases show that the dynamic LES can accurately represent the large-scale magnetic field, whereas the dynamo failed in the direct simulations without the SGS terms at the same spatial resolutions. We conclude that the dynamic versions of the SGS and commutation error correction are essential for successful dynamos on coarser grids.  相似文献   

A model of secondary upwelling over the shelf break     

Hezi Gildor  Erick Fredj  Alex Kostinski 《地球物理与天体物理流体动力学》2013,107(4):301-308

Motivated by our puzzling high-resolution radar observations of surface vortices in the nearly rectangular Gulf of Eilat/Aqaba, northern Red Sea, we propose and explore the driven cavity approach to this geophysical phenomenon. While the lid-driven cavity has long been considered a benchmark problem in computational fluid dynamics, its oceanographic context has not been considered. Despite the additional effects of rotation and stratification, our modeling demonstrates that when the fluid within a cavity geometrically similar to the Gulf of Eilat is driven by the external current, an interior vortex can develop as in our observations. Furthermore, the Eilat vortices appear only under relatively calm conditions, adding evidence to the intriguing possibility of their simple shear-driven origin.  相似文献