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Analysis of a simplification strategy in a nonhydrostatic model for surface and internal wave problems

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Acta Oceanologica Sinica 2023年第2期42卷 29-43页

作者： Jinghua Zhang wensheng jiang Xueqing Zhang Key Laboratory of Marine Environment and Ecology of Ministry of Education Ocean University of ChinaQingdao266100China Tianjin Research Institute for Water Transport Engineering Ministry of TransportTianjin300456China Physical Oceanography Laboratory/Qingdao Collaborative Innovation Center of Marine Science and Technology Ocean University of ChinaQingdao266100China Pilot National Laboratory for Marine Science and Technology(Qingdao) Qingdao266237China

This paper examines the simplification strategy of retaining only the nonhydrostatic effect of local acceleration in a three-dimensional fully nonhydrostatic model regarding the submesoscale wave phenomenon in the *** scale analysis of the vertical component of the Reynold-averaged Navier-Stokes(RANS)equation was performed,confirming the rationalization of this ***,the simplification was implemented in a RANS equation-based nonhydrostatic model NHWAVE(nonhydrostatic WAVE)to make a simplified nonhydrostatic *** examples were taken to test its performance,including surface sinusoidal waves propagating on an idealized East China Sea topography,tidally induced internal lee waves and small-scale solitary *** results show that in a considerably wide range of nonlinear strengths,the simplified nonhydrostatic model can obtain similar results as those in the fully nonhydrostatic model,even for smaller-scale solitary *** influences the applicability of the *** stronger the nonlinearity is,the worse the simplified model describes the nonhydrostatic *** general,the simplified nonhydrostatic model can simulate surface waves better than internal *** of computational efficiency in the simplified nonhydrostatic model is reasonable,reducing the central processing unit time duration in the fully nonhydrostatic model by 16.4%–20.6%.The specially designed algorithm based on the simplified nonhydrostatic equation can remarkably reduce the computational time.

关键词： simplification of nonhydrostatic model submesoscale wave internal lee wave

Spatio-temporal variability of surface chlorophyll a in the Yellow Sea and the East China Sea based on reconstructions of satellite data of 2001-2020

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Journal of Oceanology and Limnology 2024年第2期42卷 390-407页

作者： Weichen XIE Tao WANG wensheng jiang Key Laboratory of Marine Environment and Ecology Ocean University of ChinaQingdao 266100China College of Oceanic and Atmospheric Sciences Ocean University of ChinaQingdao 266100China

Chlorophyll-a(Chl-a)concentration is a primary indicator for marine environmental *** spatio-temporal variations of sea surface Chl-a concentration in the Yellow Sea(YS)and the East China Sea(ECS)in 2001-2020 were investigated by reconstructing the MODIS Level 3 products with the data interpolation empirical orthogonal function(DINEOF)*** reconstructed results by interpolating the combined MODIS daily+8-day datasets were found better than those merely by interpolating daily or 8-day ***-a concentration in the YS and the ECS reached its maximum in spring,with blooms occurring,decreased in summer and autumn,and increased in late autumn and early *** performing empirical orthogonal function(EOF)decomposition of the reconstructed data fields and correlation analysis with several potential environmental factors,we found that the sea surface temperature(SST)plays a significant role in the seasonal variation of Chl a,especially during spring and *** increase of SST in spring and the upper-layer nutrients mixed up during the last winter might favor the occurrence of spring *** high sea surface temperature(SST)throughout the summer would strengthen the vertical stratification and prevent nutrients supply from deep water,resulting in low surface Chl-a *** sea surface Chl-a concentration in the YS was found decreased significantly from 2012 to 2020,which was possibly related to the Pacific Decadal Oscillation(PDO).

关键词： chlorophyll a(Chl a) data interpolation empirical orthogonal function(DINEOF) empirical orthogonal function(EOF)analysis Yellow Sea East China Sea

Improved Numerical Computing Method for the 3D Tidally Induced Lagrangian Residual Current and Its Application in a Model Bay with a Longitudinal Topography

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Journal of Ocean University of China 2019年第6期18卷 1235-1246页

作者： CUI Yanxing jiang wensheng ZHANG Jinghua Laboratory of Marine Environment and Ecology Ocean University of ChinaQingdao 266100China Physical Oceanography Laboratory/CIMST Ocean University of China and Qingdao National Laboratory for Marine Science and TechnologyQingdao 266100China Department of mathematics Changzhi UniversityChangzhi 046000China

An improved method for computing the three-dimensional(3 D)first-order Lagrangian residual velocity(uL)is *** method computes tidal body force using the harmonic constants of the zeroth-order tidal *** with using the tidal-averaging method to compute the tidal body force,the proposed method filters out the clutter other than the single-frequency tidal input from the open boundary and obtains uL that is more consistent with the analytic *** on the new method,uL is calculated for a wide bay with a longitudinal *** strength and pattern of uL are mostly determined by the parts of the tidal body force related to the vertical mixing of the Stokes’drift and the Coriolis effect,with a minor contribution from the advection *** geometrical shape of the bay can influence uL through the topographic *** magnitude of uL increases with the increases in tidal energy input and vertical eddy viscosity and decreases in terms of the bottom friction coefficient.

关键词： Lagrangian residual current tidal body force numerical method dynamics

Analytical Solution for 3D Tidal Flow with Vertically Varying Eddy Viscosity

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Journal of Ocean University of China 2019年第4期18卷 771-783页

作者： CHEN Yang jiang wensheng FENG Shizuo Physical Oceanography Laboratory/CIMST Ocean University of China and Qingdao National Laboratory for Marine Science and Technology Qingdao 266100 China Laboratory of Marine Environment and Ecology Ocean University of China Qingdao 266100 China

In this study, a 3D idealized model of tidal flow, in which the tidal elevation and velocities are solved analytically, is developed. The horizontal eddy viscosity is neglected, and the vertical eddy viscosity used in the study is assumed to be independent of time and only varies as a parabolic function in the vertical direction. The analytical solution is obtained in a narrow rectangular bay, with the topography varying only across the bay. The model results are compared with the field observations in the Xiangshan Bay. The results show that the influence of varying vertical eddy viscosity mainly has two aspects. On one hand, it amplifies the magni- tude of the tidal elevation, particularly the amplitude near the head of the bay. On the other hand, it adjusts the axial velocity profile, resulting in an obvious frictional effect. Furthermore, the tidal elevation and velocities are more sensitive to the magnitude of the eddy viscosity near the bottom than the structure in the upper water layer.

关键词： vertically varying eddy viscosity tidal flow analytical solution three dimensional

A Lagrangian mean theory on coastal sea circulation with inter-tidal transports ***

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Acta Oceanologica Sinica 2008年第6期27卷 1-16页

作者： FENG Shizuo JULian jiang wensheng Key Laboratory of Physical Oceanography of Ministry of Education Institute of Physical Oceanography Ocean University ofChina Qingdao 266100 China

A brief review is made on the theory of the Lagrangian residual circulation and inter-tidal transports in a convectively weakly nonlinear system. In the review the emphasis is put on the systematical development of the theory and its weakness of convectively weakly nonlinear approximation. The fundamentals of a Lagrangian tidally-averaged theory on circulation with inter-tidal transport processes have been proposed for a general nonlinear coastal/estuarine system. The Lagrangian residual velocity is strictly de- fined, and it has been verified to be able to embody the velocity field of circulation. A new concept of the concentration for inter- tidal transport processes is presented. The concentration describing the inter-tidal transport processes should be a ＂Lagrangian inter-tidal concentration＂ defined and named, but not the Eulcrian tidally-averaged concentration used traditionally. The circulation described here contains a set of infinite temporal-spatial fields of velocity/concentration, each of which corresponds to a specific value of tidal phases varying continuously over one tidal cycle. When the convectively weakly nonlinear condition（ with a smaller order of eddy diffusion and sources） is approximately satisfied, a set of infinite temporal-spatial fields of velocity/concentration can be reduced to a single one.. the mass transport velocity/the Eulerian tidally averaged concentration as exhibited traditionally.

关键词： nonlinear shallow waters tide-dominating system coastal water circulation Lagrangian residual velocity Lagrangian inter-tidal concentration

A Numerical Study of the Effects of Coastal Geometry in the Bohai Sea on Storm Surges Induced by Cold-Air Outbreaks

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Journal of Ocean University of China 2011年第1期10卷 9-15页

作者： ZHAOPeng jiang wensheng Physical Oceanography Laboratory Ocean University of China Qingdao 266100 P. R. China

Strom surges are not only determined by the atmospheric forcing,but also influenced by the coastal geometry and *** Bohai Sea,as one of China’s marginal seas,is seriously harmed by storm surges,especially those caused by cold-air *** the coastline of the Bohai Sea has changed evidently these years,storm surges may have new characteristics due to the changes in the local *** paper aims to find out these new characteristics by primarily investigating the influence of the changes in the local geometry on storm surges with numerical methods.20 scenarios were constructed based on the track and inten-sity of the cold-air outbreaks to describe the actual *** analyzing the model results of the control scenarios,it is found that the main changes of the maximum surge elevation occur in the Bohai Bay and the Laizhou *** the top of the Bohai Bay,the maximum surge elevation is obviously decreased,while in the Laizhou Bay,it is enhanced by the growing Yellow River ***,however,does not suggest that the storm surges in the Laizhou Bay become more serious.A comparison of the risk assessment of storm surges in the Tanggu,Huanghua and Yangjiaogou regions shows that the risk of storm surges in these coastal areas is lightened by the evolvement of the coastal *** near Yangjiaogou,though the maximum surge elevation becomes higher to subject more areas to risk,the risk is still reduced by the evolvement of the Yellow River Delta.

关键词： storm surge cold-air outbreak Bohai Sea Caofeidian: Yellow River Delta

Numerieal Prediction of Storm Surge in the Qingdao Area Under the Impact of Climate Change

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Journal of Ocean University of China 2014年第4期13卷 539-551页

作者： FENG Jianlong jiang wensheng BIAN Changwei Physical Oceanography Laboratory Ocean University of China Laboratory of Marine Environment and Ecology Ocean University of China

A typhoon-induced storm surge simulation system was developed for the Qingdao area, including a typhoon diagnostic model for the generation of wind and pressure fields and a 2D Advanced Circulation(ADCIRC) model for simulating the associated storm surge with a 200 m resolution along the Qingdao coastline. The system was validated by an extreme surge event Typhoon Mamie(8509) and the parameters of Typhoon Mamie were used to investigate the sensitivity of typhoon paths to Qingdao storm surges with four selected paths: the paths of Typhoons Mamie(8509), Opal, 3921 and 2413, the selection being made according to their relative position to Qingdao. Experiments based on the Typhoon Mamie(8509) storm surge were also conducted to study the possible influences of future climate changes, including the sea level rise and sea surface temperature(SST) rise, on storm surges along the Qingdao coast. Storm surge conditions under both present day and future(the end of the 21 st century) climate scenarios associated with the four selected paths were simulated. The results show that with the same intensity, when typhoons follow the paths of 3921 and 2413, they would lead to the most serious disasters in different areas of Qingdao. Sea level and SST affect storm surges in different ways: sea level rise affects storm surge mainly through its influence on the tide amplitude, while the increased SST has direct impact on the intensity of the surges. The possible maximum risk of storm surges in 2100 in the Qingdao area caused by typhoons like Mamie(8509) was also estimated in this study.

关键词： storm surge typhoon path climate change Qingdao

3D Modal Solution for Tidally Induced Lagrangian Residual Velocity with Variations in Eddy Viscosity and Bathymetry in a Narrow Model Bay

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Journal of Ocean University of China 2019年第1期18卷 69-79页

作者： DENG Fangjing jiang wensheng VALLE-LEVINSON Arnoldo FENG Shizuo Physical Oceanography Laboratory/CIMST Ocean University of China and Qingdao National Laboratory for Marine Science and Technology Laboratory of Marine Environment and Ecology Ocean University of China Department of Civil and Coastal Engineering University of Florida

In this study, we examine the results obtained by the Finite-volume Coastal Ocean Circulation Model(FVCOM) regarding the effects of eddy viscosity and bathymetry on the three-dimensional(3 D) Lagrangian residual velocity(LRV) in a narrow bay. The results are cast in terms of two nondimensional numbers: the ratio of friction to local acceleration(δ) and the ratio of the minimum depth over shoals to the maximum depth in the channel(ε). The ratio δ depends on the eddy viscosity and mean depth. For a given eddy viscosity, when ε > 0.5, the along-estuary LRV tends to be vertically sheared and when ε < 0.5, the exchange is laterally sheared. When ε << 1, the structure of the 3 D, depth-integrated, and breadth-averaged LRV changes only slightly as δ increases. For ε values between 0.33 and 0.5, the structure of the 3 D LRV is mainly laterally sheared. In the same ε range, the 3 D and depth-integrated LRV exhibit reversed structures from high to low δ values. In addition, the breadth-averaged LRV weakens the typical twolayered circulation when δ decreases. When ε is 1, the two-layered vertical structure reverses direction, and a three-layered vertical structure develops in the outer bay as δ decreases.

关键词： eddy viscosity bathymetric effects Lagrangian residual velocity 3D narrow bay

Study on the Seasonal Variation of the Suspended Sediment Distribution and Transportation in the East China Seas Based on SeaWiFS Data

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Journal of Ocean University of China 2008年第4期7卷 385-392页

作者： WANG Wenjuan jiang wensheng Physical Oceanography Laboratory Ministry of Education Ocean University of China Qingdao 266100 P. R. China

The monthly mean suspended sediment concentration in the upper layer of the East China Seas was derived from the retrieval of the monthly binned SeaWiFS Level 3 data during 1998 to 2006. The seasonal variation and spatial distribution of the suspended sediment concentration in the study area were investigated. It was found that the suspended sediment distribution presents apparent spatial characteristics and seasonal variations, which are mainly affected by the resuspension and transportation of the suspended sediment in the study area. The concentration of suspended sediment is high inshore and low offshore, and river mouths are generally high concentration areas. The suspended sediment covers a much wider area in winter than in summer, and for the same site the concentration is generally higher in winter. In the Yellow and East China Seas the suspended sediment spreads farther to the open sea in winter than in summer, and May and October are the transitional periods of the extension. Winds, waves, currents, thermocline, halocline, pycnocline as well as bottom sediment feature and distribution in the study area are important influencing factors for the distribution pattern. If the 10rag L^-1 contour line is taken as an indicator, it appears that the transportation of suspended sediment can hardly reach 124^o00＇E in summer or 126^o00＇E in winter, which is due to the obstruction of the Taiwan Warm Current and the Kuroshio Current in the southern Yellow Sea and the East China Sea.

关键词： suspended sediment seasonal variation SeaWiFS East China Seas