1998 Vol. 17, No. 2

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Articles
A numerical prediction model of strong thermocline in the Bohai and the Huanghai Seas
Wang Zongshan, Xu Bochang, Jin Meibing, Zou Emei, Li Fanhua
1998, (2): 141-154.
Abstract:
In this paper, the predecessors' research results of the numerical prediction models of vertical sea temperature structure calculation are reviewed and assessed, whereby a three-dimensional numerical prediction model of a strong thermocline is established by taking into account the absorbed and transmissive radiation at the sea surface, topography, wind stress, current speed, bottom friction and the mixing functions caused by them. As the driving elements of the model are only wind and air-temperature fields, the model has a fairly good practicality, and the results of trial prediction are satisfatory.
A nonlinear model for nonbreaking shoaling random waves
Liu Xin'an Huang Peiji, Chen Xueying, Hu Zejian
1998, (2): 155-165.
Abstract:
In this paper,the spatial evolution of the third-order moment (i.e.,the skewness) of the sea surface elevalion for nonbreaking shoaling random waves versus Hs/d is analyzed by using the data obtained in field and laboratory. Using the empirical relationship given in this paper, the nonlinear model for the sea surlace elevation of nonbreaking shoaling waves in the sernnd-order approximation by expanding the first two terms of Hermitian polynomial is depicted by the parameter Hs/d, and such characteristics as the power spectrum, the bispectrum and the distribution function of sea surface elevation es well have been derived in this paper. The correlation between the skewness and the kurtosis of the sea surface elevation is also discussed.
Numerical sea ice prediction in China
Wu Huiding, Bai Shan, Zhang Zhanhai
1998, (2): 167-185.
Abstract:
A dynamic-thermodynamic ice model with three levels for simulating the ice growth, decay and drift in the Bohai Sea is presented on the basis of review of the climate and ice conditions in the Bohai Sea and the existing sea ice and the existing sea ice models.This model was linked to a numerical weather prediction model for forecasting ice conditions in the Bohai Sea and the northern Huanghai Sea (Yellow Sea) during the winters from 1990 to 1996 at the National Research Center for Marine environmental Forecasts (NRCMEF).The numerical sea ice forecasting products, such es fields of ice thickness, compactness and velocity, ice edge, parameters of ice ridge and local estimate of ice thickness and tracks of ice floes near drilling platforms were produced and sent to the National Marine Forecasting Station of NRCMEF and the Bohai Oil Corporation. Statistical verification has been used for making objective assessment of the model and the forecast system. This study outlines the climate and ire conditions in the Bohai Sea, application of satellite imagery, ice model and its forecasting results and services.
Effects of iron on growth, degree of pigmentization and nitrogen assimilation in Skeletonema costatum
Zheng Airong, Chen Cimei, Zhou Ciyoul, Chen Yuzhou
1998, (2): 187-196.
Abstract:
The effects of iron and the interaction between iron and nitrogen on the growth, degree of pigmentization and nitrogen assimilation of S. costaturn are studied. The results show that with the increase of iron concentration from 3×10-8 to 5×10-6 mol/dm3, nitrogen uptake and assimilation by the alga increased, the degree of cytopigmentization reduced, and content of intracellular amino acid (PAA) and protein raised (Pr).Cell growth rate was the highest at 5×10-6 mol/dm3 Fe Chlorophyll a, thaeo-pigments, PAA and Pr were all related to logarithmic iron concentration. It was also found that the interaction between iron and nitrogen had a marked effect on the growth, degree of pigmentization and nitrogen assimilation at N/P=20:1 (by comparison with N/P=40:1 and 10:1).At given iron concentration, the effects of different specific N source on the rate of transferring PAA to Pr at the N source of lower oxidized state were more marked than at the N source of higher oxidized state.
Studies on seawater self-purification capacity to heavy metals in the Haikou Bay
Chen Chunhua
1998, (2): 197-207.
Abstract:
By combining hydrological exchange with chemical self-purification, the seawater self-purification capacity to heavy metals was studied, and the calculated results show that the hydrological exchange ratio during spring tide is 32.0%, and is 5.4% during ebb tide; the self-purification capacities to Cu, Pb, Zn and Cd in one cycle are respectively 1.04 t, 7.64 t, 15.22 t and 0.78 t; the hydrological exchange period is 10 d; the self-purification capacity to Cu measured is 42 t/d in the Haikou Bay.
Tidal bedforms in eastern part of the Bohai Sea
Liu Zhenxia, S. Berne, Wang Kuiyang, T. Marsset, Xia Dongxing, Tang Yuxiang, J. F. Bourillet
1998, (2): 209-231.
Abstract:
A system of tidal bedforms has developed in the part of the Bohai Sea. It consists of the Laotieshan Channel, the Liaodong Shoal and the Shoal. The first of these is a tidal current scour region and the other two are tidal current depositional regions. The morphology of the sea floor has a close relation with tidal current vekxity. The maximum tidal current velocity is up to 5 knots in the Laotieshan Channel where strong erosion occurs. The maximum tidal current velocity is 1.3-2.3 knots and the absolute value of M2 tidal current ellipticity is less than 0.4 in the Liaodong Shoal, indicating that the reciprocating tidal current is strong enough to form tidal sand ridges. The maximum tidal velocity is 1.2-1.6 knots and the absolute value of M2 tidal current ellipticity is larger than 0.4 in the Bozhong Shoal, indicating that rotation of tidal currents increases so as to form tidal sand sheet. The small-scale bedforms surveyed in detail in the area and shown in the side scan sonar mosaic are subaqueous dunes, sand ribbons, comet-tail marks and scour furrows, which indicate that the sand ridges and sand sheet are still under the action of tidal current processes at the present time. Based on the interpretation of tidal currents, bedforms, and sedi ment thickness, it is inferred that the general direction of sediment transport within the study area is from the Laotieshan Channel to the Liaodong and Bozhong Shoals. The small scale bedforms in the detailed survey area indicate that the net sediment transport direction is from south to north.
Propagation and growth of Ponnotheres pholadis living in mantle cavity of Hiatula acuta
Yang Yaocong, Li Fuxuel, Cai Lizhe
1998, (2): 233-241.
Abstract:
This paper presents the study of the propagation and alternation of generations of Pinnotheres pholadis by observing yearly development and measuring carapace breadth of P.pholadis living in mantle cavity of Hiatula acuta. The reproductive period of P.pholadis was from March to October, and two breeding peaks were respectively from the last ten-day period of April to the first ten-day period of June, and from the last ten-day period of September to the first ten-day period of October. The alternation of generations of P.pholadis was as follows:Individuals hatching in spring matured next year and two breeding periods and died after the second breeding period. Their olds were one and half year. Individuals hatching in the autumn had one breeding period next year, and another breeding period in the third year, their olds were two years. P.pholadis got into mantle cavity of Hiatula acuta when the carapace of P.pholadis was 3.2 mm wide. Before that,they had been free-living.
Study on diel rhythm of chlorophyll a and photosynthesis in nearshore waters of Qingdao
Mao Xinghua, Zhu Mingyuan, Yang Xiaolong, Hao Yawei, John Cullen
1998, (2): 243-254.
Abstract:
A study was made on the dial rhythm and variation of Chl a and photosynthesis in the nearshore of qingdao. Both Chl a and photosynthesis show obvious dial rhythm; the peak value of surface Chl a appeared in the afternoon,while bottom Chl a around noon;the maximum value of photosynthetic rate appeared in the morning, noon and afternoon. The scope of the diet rhythm of Chl a and photosynthesis and the time for the appearance of the peak value varied in different months. Moreover, the mechanism of the formation of this diet rhythm is also discussed in this paper.
Notes
Effects of advection, turbulence and radiation on formation of seafog——A theoretical analysis
Hu Ruijin, Zhou Faxiu, Liu Qi
1998, (2): 255-265.
Abstract:
Earthquake-induced hydrodynamic pressure of cylindrical structure in extreme shallow water
Li Changsheng, Tang Yougang, Xiang Zhongquan
1998, (2): 267-276.
Abstract: