1998 Vol. 17, No. 4

Display Method:
An implicit method using contravariant velocity components and its application to calculations in a harbour-channel area
Shi Fengyan, Kong Yazhen, Ding Pingxing
1998, (4): 423-432.
The key problem in the computation of fluid dynamics using fine boundary-fitted grids is how to improve the numerical stability and decrease the calculating quantity.To solve this problem,implicit schemes should be adopted since explicit schemes may bring about a great increase in computation quantity according to the Courant-Fnedrichs-Lewy condition.Whereas the adoption of implicit schemes is difficult to be realized because of the existence of two partial derivatives of surface elevations with respect to variables of alternative detection coordinates in each momentum equation in non-rectangular coordinates.With an aim to design an implicit scheme m non-rectangular coordinates in the present paper,new momentum equations with the contravariant components of velocity vector are derived based on the shallow water dynamic equations in generalized curvilinear coordinates.In each equation,the coefficients before the two derivatives of surface elevations have different orders of magnitude,i.e.,the derivative with the larger coefficient may play a more important role than that with the smaller one.With this advantage,the ADI scheme can then be easily employed to improve the numerical stability and decrease the calculating quantity.The calculation in a harbour and a channel in Macau nearshore area shows that the implicit model is effective in calculating current fields in small size areas.
Calculation of current in the Taiwan Strait during summer Ⅱ.Three-dimensional semidiagnostic and prognostic calculations
Wang Huiqun, Yuan Yaochu
1998, (4): 433-446.
The semidiagnostic and prognostic models are used to compute the current in the Taiwan Strait with wind and hydragraphic data collected during August,1984 and September 1-6,1988.This calculation can be divided into two stages,i.e.(1) the adjustable stage;(2) prognostic calculation.The computed result shows that the density and velocity fields etc.have been adjusted when t=2.5 d,namely the solution of semidiagr(ostic calculation is obtained,and the quasi-steady state solution have been reached after about 40 d.Comparing the results of diagnostic calculation with those of semidiagnostic and prognostic calculations indicates that they agree qualitatively.For example,they all have the foVowing common features:(1) there is a persistent northward flow with a volume transport of 0.8×106m3/s through the Taiwan Strait in summer;(2) the current near the western coast of Taiwan is stronger than that in other regions;(3) the upwelling occurs near the Fujian coast and so on.However,there is a quantitative difference between them as follows.For example,the horimntal velocity near the western coast of Taiwan and the upwelling speed near the Fujian coast both are underestimated in the diagnostic calculation,because the data used in which is smoothed,and they both are intensified in the solutions of semidiagnostic and prognostic calculations.For example,the maximum velocity near the western coast of Taiwan at t=0 d(diagnostic),2.5 d(semidiagnostic) and 300 d(prognostic) is 59.1,62.1 and 62.0 ctn/s,respectively.From the above rnmparison we see it is quite necessary that a semidiagnostic model be used to compute the currents when the data have been smoothed.
Analyses of factors forming offshore SST anomaly(O-SSTA) in China seas
Wang Sizhen, Li Xuhua, Qi Jianhua, Su Yusong
1998, (4): 447-457.
Based on the observations,the location and the strength of warm(cold) anomaly of SST in summer are controlled mainly by the subtropical highs of atmosphere(typhoon track) on the offshore of the China seas.It may be considered from the physical causes that the factors forming O-SSTA include the dynamic response of upper layer ocean on the strong atmospheric forcing and the shallow sea effects.The former consists of the entrainment,the detrainment,the Ekman pumping and the convergence of surface warm water; the later the tidal mixing and higher absorptivity.The parameterized expressions and the significance estimations of each factor are shown.The differences of both forming mechanisms and forming time-scales between the warm anomaly and the cold one are also indicated with different forcing svstemv.
Derivation of sea surface current field from sequential satellite images of the East China Sea
Liu Qingge, Pan Delu, Pan Yuqiu, Lutz Bannehr, Guenter Warnecke
1998, (4): 459-468.
A series of NOAH AVHRR data over the East China Sea were collected from the ground station of the Institute of Oceanography,Hangzhou,China.Three methods,including a functional analytic method FAM),a maximum cross correlation(MCC)' method and a correlation relaxation(C-R) method,are applied to derive the sea surface current field from sequential satellite images in the area of the East China Sea.Several preprocessing steps,such as geometric correction,SST determination,image projection,image navigation and grey value normalization as well as land and cloud mask are performed.The results from the three methods reflect the general current system in this area reasonably.
Classification of highly turbid Jiaojiang Estuary
Dong Lixian
1998, (4): 469-482.
The Jiaojiang Estuary is shallow,macro-tidal dominated and extremely turbid,with a larger variation of the freshwater discharge.The estuarine stratification and classification are analysed by using a set of field data observed in wet season.
In spring tide,the depth-mean peak tidal currents can reach 2 m/s.During flood tide the water column is vertitally homogeneous,but the horizontal salinity gradient is large and there is a fresh water front.A 1 m thick fluid mud layer capped by lutocline is formed when the tidal current is less than 0.3 m/s.As the low-salinity trapped in the fluid mud layer,underlying saltier water enhances vertical mixing when the fluid mud layer is eroded and the water column is only slightly stratified during ebb tide.
Dynamics of DOC of euphotic layer in the Taiwan Strait——Diurnal variation of large range
Peng Xingyue, Hong Huasheng, Shang Shaoling
1998, (4): 483-493.
Three oceanographic investigations from 1994 to 1995 in the Taiwan Strait show that the dissolved organic carbon in the euphoric layer has.large-scale diurnal variation[2-4 mg/dm3],and its amplitude range has spatial and seasonal changes.Generally,the DOC in the euphotic layer is higher at day than that at night.According to the diurnal variations,DOC can be divided into two parts:new DOC and old DOC.The content of new DOC varies rapidly every day but the content of old does not.Though there is still not a good explanation for this diurnal variation of DOC,it may call attention to the study of organic carbon dynamics,especially the DOC primary production of phytoplankton,the DOC utilization of bacteria,and the flux of DOC in coastal sea water.
Study on purification and ultrastructure of a baculovirus in Penaeus chinensis
Shi Tuo, Kong Jie, Bao Zhenmin, Liang Xingming, Liu Ping, Wang Chongming
1998, (4): 495-502.
A kind of baculovirus was isolated from the cephalothorax homogenate of sick or morbid Penaeus chinensis by differential centrifugation and density gradient centrifugation.Electron microscopic examination of ultrathin section of the gills,stomach and mid-gut tissues also revealed the presence of rod-shaped baculoviral particles with the same size in the affected cell nuclei,where most of the virions arranging in cluster assembled and caused a series of cytopathic changes.The virion covered with bilaminal envelope was 320-400 nm×100-130 nm in size,whereas the nucleocapsid ranged in size of 250-300 nm in length and 70-100 nm in breadth respectively.No nuclear polyhedron or granulin occlusion bodies have been found in cells.According to the principle of viral classification,this newly found virus could probably belong to the non-occluded subgroup oI insect baculoviridae,i.e.,C subgroup baculovirus.
Fate of particle-reactive pollutants in the Xiamen Bay
Chen Min, Huang Yipu
1998, (4): 503-508.
A simple model is established to describe the fate of particle-reactive pollutants in the Xiamen Bay.Based on the conditional distribution coefficients(Ka)of chemicals and residence times of particle and waters,the model can be used to predict the fractions of pollutants which would be scavenged to sediments and would escape from the system.The model is calibrated using scavenging data derived from 234Th-238U disequilibrium.The fate of a potential pollutant which will be scavenged is a function of the properties of the chemical,of the particle dynamics,and of the waters dynamics in the environment.It is inappropriate to overlook any factor.
Late Quaternary diatom and sea level changes in estuarine plain of the Jiulong River
Chen Wenrui, Lan Dongzhao, Chen Chenghui
1998, (4): 509-518.
Four units and twenty-four zones of diatom have been discerned in the Borehole ZKS in the estuarine plain of the)iulong River,Fujian Province.Comprehensive analysis of these,together with microbiological assemblages and age determinations in some other boreholes,shows that during the Late Wiirm Glacial,sea level of the study area rose and fell frequently,but had principally been in the environments of estuary-bay.This mainly resulted from the tectonic subduction.In this period 3 low sea levels occurred,at 18,16 and 12 kaBP respectively.During Hokx"ene,sea water intruded massively and the sea level over the transgression maximum had been 5-10 m higher than that of the present.
Paleoceanographic events of the southern Okinawa Trough during last 20 000 years
Li Baohua, Zhao Quanhong, Wang Yongji, Jian Zhimin, Chen Ronghua
1998, (4): 519-530.
Two high resolution down-mres(92-255,92-170) are used to study the paleoceanographic events of the southern Okinawa Trough during the last 20 000 years.Planktonic foraminifera are quantitatively analyzed and three paleoceanographic events are recognized.Glacial/post-glacial variations in sea surface temperature(SST),water masses,and upper water mlumn structure are the most important environmental changes recorded by planktonic foramirtifera.There is also an abrupt climatic event(about 10 710-9 170 a BP) during the Termination Ⅰ,planktonic foraminifera(PF) δ18O and SST have a same return pattern,but benthic foraminifera(BF) δ18O doesn't have.Discrepancy between PF δ18O and BF δ18O may reflect that the sea surface water is more sensitive to abrupt,short term envirorunental change than the sea bottom water.High-resolution strata also suggest a middle-Holocene Pulleniatina obliquiloculata minimum event.
Studies on pathogen of explosive epidemic disease of shrimp Ⅱ.Purification of pathogen
Wang Jinxing, Liu Changbin, Zhang Hongwei, Zhao Shuangyi, Zhang Yanjun, Zhao Jing
1998, (4): 531-536.
The pathogen of explosive epidemio disease of farmed Chinese shrimp(Penaeus chinensis)was isolated and purified from the cephalothorax and hepatopancreas of diseased shrimps by means of different speeds of centrifugation and sucrose gradient ultracentrifugation.The results showed that same virus isolated from the diseased shrimps in various regions of China was a kind of baculovirus covered with envelope,which was 95-125 nm in diameter and 360-410 nm in length.The size of the capsid was 80-90 nm×330-350 nm.The nucleic acid of the virus was demonstrated as DNA.The result of artificial infection demonstrated that the virus was the pathogen of explosive epidemic disease of farmed Chinese shrimp.
Multivariate analysis for ordination and comparison of size of Artemia cysts
Tang Senming
1998, (4): 537-544.
It is known that the biometrics of brine shrimp cysts is of strain inherent.The analysis and comparison of the cyst characters for the identification of unknown cysts from different geographical origin become possible.In this paper,multivariate methods,mainly Principle Component Analysis(PCA) and Nonmetric Multi-dimensional Scaling(MDS),are used for the purpose.Good results are gained with the analysis of the published data and some row data from cyst size.It shows that multivariate methods can cluster the similar characteristics of batch cysts and make out impure or mingled cysts of different origin.Among others,MDS,with row data from the cyst measurement,can be easily used for the analysis of cyst ordination and comparison.The result demonstrates that the cysts of Chinese parthenogenetic brine shrimp are well discriminated by their geographic locations along the coastal China with larger size distributing in the south.
Occurrence and distribution of vibrios in fishes and shellfishes in coastal waters of Hong Kong
Xu Huaishu, Li Jun, Phyllis Brayton, Norman Y. S. Woo, David Swartz, Zhang Shuting, Rita R. Colwell
1998, (4): 545-553.
The summer occurrence and distribution of vibrios in the fishes and shellfishes in the coastal waters of Hong Kong were investigated.A total of 69 strains of vibrios were isolated from all samples examined.The strains,along with 10 reference strains were classified with the technique of numerical taxonomy based on 54 characters and 62 of the 69 strains fell into 5 major phena,identified as V.flaraheamolyticus(30 strains),V.alginolyticus(23 strains),V.choloerae(3 strains),V.harveyi(2 strains) and V.fluvialis(4 strains).Among them.V.pnraheamolyticus and V.alginolyticus were the predominant species in the fishes,shellfishes and the coastal waters of Hong Kong and comprised 43.5% and 33.3% of the total Vibrio spp.isolates respectively.Meanwhile,3 strains of non-Ol V.cholerae were isolated from oyster and it was the first time to record V.cholerae non-Ol in seawater or from shellfishes in Hong Kong.These results highlighted the potential risks of food poisoning associated with raw or undercooked seafood.