1995 Vol. 14, No. 3

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Numerical simulation of the upper ocean currents in South China Sea
Li Rongfeng, Huang Qizhou, Wang Wenzhi
1995, (3): 306-317.
The upper ocean currents in the Pacific Ocean are calculated by using an ocean model with higher honzontal resolution.The large current systems in the Pacific Ocean, such as Kuroshio, Oyashio, NEC, SEC, NECC, California Current and East Australia Current, are well simulated.This paper only gives the numerical simulation recults of the upper ocean currents of the representative months in four seasons in the South China Sea (SCS).It shows that the SCS branch of Kuroshio is the most important current in the northern SCS and it is not only the water resource of the SCS warm current but also a significant part of the overall SCS circulation.There is a relatively strong northeastward flow entering the SCS through the Taiwan Strait throughout the year except for specific months.Some of the numerical results have been confirmed by the observational evidences.
Trend analysis of relative sea level rise or fall of the tide gauge stations in the Pacific
Ma Jirui, Tian Suzhen, Zheng Wenzhen, Chai Xinmin
1995, (3): 319-328.
On the basis of the analytical results of the period components of monthly mean sea level of 236 stations in the Pacific, the period components plus linear trend are used to fit the monthly mean sea level series.The statistical results of linear trend croefficients of these stations indicate that, if the abnormal values of sea-level rise and fall are neglected, the average rise rate of relative sea level in the Pacific is 1.16 mm/a.Affected by nonuniformity of land subsidente and other factors, the regional change of relative sea level rise or faV in the Pacific is greater.In the light of the positive or negative values of linear trend coefficients as well es the geographical position of the sea area, zoning is made of the sea level rise or faV in the Pacific including the coastal areas of China and Southeast Asia to obtain the average rate of rise or fall in each sea area.The rise or fall trends of relative sea level obtained for the entire Pacific Ocean, west coast of North America, the northern and central South America, the greater part of the tropical Pacific and the croastal Islands of Japan are basically in keeping with the other relevant results.The regional average estimated result of the relative sea level in the coast of East Asia is on the rise while the estimated results provided by Barnett tend to drop;the main cause of this nonuniformity is the number of stations selected and the distributional density.
An analytically derived whitecap coverage model
Xu Delun, Liu Wentong
1995, (3): 329-336.
Joint probability function of local surface-particle and phase velocities is derived for a stationary Gaussian wave field with narrow-band spectrum.From the function a model of whitecap coverage is further derived by using tire kinematic condition (including the effect of drift current) for wave breaking.The drift current velocity in the model is then replaced by the friction velocity through an existing empirical formula.A coefficient in the model for relating temporal and spatial scales of wave breaking is determined by using an existing empirical formula of oceanic whitecap coverage and the well-known Pierson-Moskowitz spectrum.The main features of the model agree well with our general knowledge and observational evidence on wave breaking in deep waters.
Modelling of the barotropic processes in the Bohai Sea
Huang Daji, Chen Zongyong, Su Jilan
1995, (3): 337-353.
The barotropic processes of tides, tidal currents, wind-driven currents and the interaction of winds and tides in the Bohai Sea are investigated with a three-dimensional shelf sea model.The tides and tidal currents are well simulated.The main characteristics of tides and tidal currents, such as the types of tides and tidal currents, co-tidal and co-range charts, co-current charts, tidal ellipses, mean tidal currents and tidal residual currents are presented.A pair of cyclonic and anticyclonic headland eddies in the northern Bohai Straits is discovered.The tidal currents have little vertical structure except close to the sea bottom.Driven by strong winds, the currents have a significant three-dimensional structure.In response to coastal geometry and bottom friction, the wind drift in the upper layers is in the direction of the wind or slightly to the right.In depth, considerable compensating currents maintain a circulation balance.The interaction of winds and tides is locally strong.The oscillating tidal currents play a role of dissipating energy.Thus the usual purely wind-driven currents in the area of weak residual tidal currents are often overestimated in the absence of tides.
The concentration and distribution of dimethyl sulfide in the marine atmospheric boundary layer near the equator
Li Xingsheng, Li Zhe, F. Parungo, C. Nagamoto
1995, (3): 355-369.
A one-dimensional photochemical model with parameterized vertical eddy diffusion is used to simulate the dimethyl sulfide (DMS) in the marine atmospheric boundary layer near the equator.The boundary condition of the DMS flux over sea surface is assigned from gas exchange models that depend on sea surface wind speed and DMS concentration in surface water.Photolysis rates at various altitudes are calculated as a function of solar zenith angle, and the radiation calculation includes ozone absorption, surface reflection and molecular scattering.
The simulated results of the DMS diurnal cycle are in good agreement with the observations.Sensitivity tests of the model indicate that the concentration of the DMS in the marine surface layer appears to be affected by a combination of chemical processes and meteorological conditions.In addition, photochemical processes are rather important.The reaction of the DMS with.OH radical, the heterogeneous conversion of SO2 and the deposition of NSS-SO4- and the methanesulfonic acid (MSA) are critical factors of controlling the DMS, SO2, NSS-SO4- and the MSA concentrations and distributions in the atmosphere.The DMS concentration in air is directly proportional to surface wind speed, but it is inversely proportional to boundary layer height in the convective boundary layer.The distributions of the DMS concentrations in sir are strongly influenced by atmospheric stratification in stable conditions.
Characteristic analysis on oxygen isotopic tracer in the East China Sea and waters to east of the Ryūkyū-guntō
Hong Ashi, Yuan Yaochu
1995, (3): 371-381.
Samples of O isotopic tracer were mlleMed at Sections P3, P25, PcM-t/2-E and PCM-1/2.w in both the Fast China Sea and the area to the east of the Ryūkyū-guntō during October-November, 1991.
Analytical results of the δ18O are as follows: (1) In the Kuroshio area, the δ18O isolines are almost parallel to the 200 m isobath.The value of δ18O is negative and reaches minimum mt the main axis of the Kuroshio, and increases on both sides. (2) In the Taiwan Warm Current (TWC) area there is a high δ18O tongue extending to the northeast. (3) In the area near the coast, the distribution of δ18O isoline shows that the Changjiang River runoff diffuses seaward and the land-ocean isotopic effect from the nearshore to the offshore. (4) The values of δ18O are from -1.0×10-3 to -0.5×10-3 in the shelf. (5) There is a low mre of δ18O value (<-1.6×10-3) at the 600 m layer in the Kuroshio area, which is quite in accord with the existence of a low salinity mre (S G 34.30) between the 600 and 800 m layers in the same area.Finally, the mrrelations of the δ18O with the salinity and temperature, the upwelling and so on are discussed.
Chemical characteristics and estimation on the vertical flux of N, P, Si in upwelling area of Taiwan Strait
Chen Shuitu, Ruan Wuqi
1995, (3): 383-392.
Based on the data obtained from oceanographic surveys at the central and northern parts of the Taiwan Straft during the pgriod from 1983 to 1988, it is showed that the nutrient content in the coastal and bottom waters is relatively high with an upward and offward decrease, and that the upwelling in the Fujian coastal area controls the distribution of nutrients in summer.The upwelling water is characterized by 2.29 μmol/dm3 of nitrate; 2.83 μmol/dm3 of silicate; 0.20 μmol/dm3 of dissolved inorganic phosphate, respectively.Significant rnrreJation between nutrients and dissolved oxygen content and its degree of saturation, temperature, and salinity, respectively are found in the upwelling area.Average of N/P ratio in the area (15.9) approaches to Redfield ratio.Their vertical flux is estimated to be 23.6 mg/ (m2·d) for PQ43-P, 223 mg/ (m2·d) for NO3-N, 302 mg/ (m2·d) for SiO32--Si, respectively, which is the main source of nutients in the areas in summer.The mean of the flux of PO43--P and NO3--N is about 86% and 73% necessary for phytoplankton in the euphotic zone.
Analysis of the dynamic characteristics and stochastic simulation on variations of beach volumes
Chen Zishen
1995, (3): 393-403.
This paper analyzes the dynamic characteristics of the variations of the beach volumes for three level zones of the Yanjing Beach in the Shuidong Bay of the western Guangdong Province by using the methods of dynamic system analysis end the multi-dimensional spectral estimation.The results show that the variations of the beach volume are characterized by the multiband oscillations with a dominant semimonth period.Upwards the low tide level, the beach tends to be stable.The estimates of the partial mherences and the partial phases indicate that the variations of the beach volumes are mainly the results of the direct actions of the waves which are influenced by the tidal level changes and driven by the wind stress.The simulation results of the beach volume series for different beach height zones by threshold mixed regressive models indicate that the influence of the tide on the variations of the beach volumes is weakened and the direct actions of the wave energy and the wind stress are apparently enhanced with the increase of the beach height.
Chemical forms of copper and zinc in the surficial sediments of Borollos Lake, Egypt
M. S. El-Deek
1995, (3): 405-412.
Borollos Lake is situated in the northern part of Nile Delta along the Mediterranean coast of Egypt between 31°21'-31°35'N and 30°31'-31°10'E.This work reveals that more than 82% of the total nipper occurs in the residual fraction.Only 4.6%, 7.3% and 6.1% of the total nipper occurs in the fractions bound to carbonate, oxides and organic matters, respectively.The exchangeable-Cu is in trace amounts and the other fractions were relatively low in comparison with zinc fractions.The residual fraction of zinc reaches between 66% and 88%.The carbonate-Zn, organic-Zn and oxides fractions range from 1.3% to 7.9%, 2.8% to 11.6% and 2.8% to 13.2%, respecticely.There is no pollution by Cu and Zn metals in comparison with the results previously reported for other poVuted Egyptian aquatic environments such as Mariut.
Halophilic Vibrios in the waters of Xiamen Harbor and Daya Bay
Ni Chunzhi, Ye Dezan, Lin Yanshun, Zhou Zongcheng, Yao Ruimei, Gu Jingyu
1995, (3): 413-420.
The distribution features, species composition end seasonal variation of halophilic Vibrios in 7 stations of Xiamen Harbor and 9 stations of the Daya Bay were studied.The counts of Vibrios were analyzed with the most probable number (MPN) technique.The media TCBS was used to isolate Vibrios, and API20E system employed to identify the Vibrios.The results reveals that the density of Vibrios in the Daya Bay ranged from 30.0×105 to 2.4×105 cell·dm-3 and the average density was 6.61×103 cell·dm-3, and that in Xiamen Harbor was 2.3×102-2.4×105 cell·dm-3 and 7.8×103 cell·dm-3 on the average.The number of Vibrios varied seasonally with the water temperature, and was higher in the summer than in the autumn.The Vibrio species in the two bays mainly included Vibrio alginolyticus, V.parahaemolyticus, V.fluvialis, V.tralnificus, V.mimicus and V.metshnikovii and V.alginolyticus was the predominant species.
Sea water environment copper requirement of egg hatching and naupliar metamorphosis of Peaneus chinensis
Yuan Youxian, Qu Keming, Liu Libo, Gao Chengnian, Zhang Duxi
1995, (3): 421-428.
Anew method was used to rerttove heavy metals in sea water.The requirement of nipper in sea water of egg hatching and naupliar metamorphosis of Penaeus chinenris was investigated.A certain amount of nipper ion and chelator nitrilotriacetic acid (NTA) were added in the de-heavy-metal-ionized sea water and then the cupric ion accvity was calculated.The effects of nipper ion on egg hatching and naupliar metamorphosis were observed.It was first found by experiments that trace ionic copper (10-10.08-10-8.80 mol/dm3) was essential to the growth and development of egg and nauplii of penaeid shrimp and chelated nipper had no actions for these living processes, but in high wncentrations (>10-7.00 mol/dm3) ionic nipper was toxic.The naupliii were more sensitive to necessity and toxicity of ionic copper than eggs.
Nonlinear effect on inertia component of wave forces on a cylinder
Li Yanbao, Song Reng
1995, (3): 429-437.
A series of experiments on wave forces on a cylinder have been carried out when inertia component is dominant for a small size cylinder.The influence of nonlinear effect on the inertia component of wave forces on a cylinder is analyzed.The applicable range of nonlinear wave theories, such as Stokes and cnoidal wave theories, in calculating wave forces on a cylinder is discus9ed.A correction method is suggested for linear wave theory in calculating wave forces on a cylinder under the nonlinear condition.
Uncertainty and joint probability of sea ice loads
Liu Defu, Yang Yongchun, Wang Chao, Li Tongkui
1995, (3): 439-445.
Ice load is one of the most important factors for design of marine structures in mld sea area.The design criteria of ice Loads for marine structures consist of two parts., level ire thickness and crushing strength.Due to the strong randomness of the affecting factors on ice thickness and crushing strength, such as ice temperature, air temper-store, water temperature, salinity, wind field, numerical simulation method cen not produce satisfactory results.This paper proposes a method of uncertainty analysis and joint probabilistic prediction of level ice thickness and crushing strength instead of traditional ice load criteria for marine structures.
Notes Ecological study of macrobenthos in Fuqing Bay
Li Rongguan, Jiang Jinxiang, Cai Erxi, Xu Huizhou
1995, (3): 447-453.
Use of a new clone of Artemia parthenogenetica (OP1) to increase genetic variation
Gao Mingjun, Cai Yaneng
1995, (3): 455-460.