1992 Vol. 11, No. 4

Display Method:
Dissipation source function and an improvement to LAGFD-WAM model
Yuan Yeli, Hua Feng, Pan Zengdi, Sun Letao
1992, (4): 471-481.
In this paper, a new theoretical expression of dissipation term is presented on the basis of statistical model of breaking wave, which is an improvement to LAGFD-WAM wave model. The computational results in three typical wind fields show a good improvement to LAGFD-WAM model and a better accuracy in comparison with the observed data in the South China Sea.
Preliminary analysis of distribution and variation of perennial monthly mean water masses in the Bohai Sea,the Huanghai Sea and the East China Sea
Liu Shuxun, Shen Xinqiang, Wang Youqin, Han Shixin
1992, (4): 483-498.
On the basis of perennial monthly mean temperature and salinity data, the classification of monthly water masses at the surface and the bottom in the Bohai Sea, the Huanghai Sea and the East China Sea, has been made by using the method of fuzzy cluster from the modified characteristic of water masses in the shallow water area. In this paper, the basic features, growth and decline patterns of water masses in relation to fishing grounds in the whole shelves of the Bohai Sea, the Huanghai Sea and the East China Sea are discussed with emphasis.
A model for the response of wave directions in slowly turning wind fields
Li Luping, Gong Ein
1992, (4): 499-508.
On the basis of the wave energy balance equation, the response model of mean directions of locally wind-generated waves in slowly turning wind fields has been derived. The results show that in a homogeneous field, the time scale of the response is not only related to the rate of wave growth, but also to the directional energy distribution and the angle between the wind direction and the mean wave direction. Furthermore, the law of change in the mean wave direction has been derived. The numerical computations show that the response of wave directions to slowly turning wind directions can be treated as the superposition of the responses of wave directions to a series of sudden small-angle changes of wind directions and the turning rate of the mean wave direction depends on the turning rate and the total turning angles of the wind direction. The response of wave directions is in agreement with the response for a sudden change of wind directions if the change in wind directions is very fast. Based on the normalized rates of wave growth under local winds presented by Wen et al. (1989),a quantitative estimate of the time scale of the response shows that the relationships between the dimensionless time scale and both the dimensionleas total wave energy and the dimensionless peak frequency agree fairly well with the observations in comparison with other models.
Experiments in numerical modelling of the Pacific sea surface temperature anomalies
Zhang Ronghua, Wang Wanqiu
1992, (4): 509-524.
By using the atmosphere-ocean coupled model (CGCM) which is composed of a 2-level global atmospheric general circulation model and a 4-layer Pacific oceanic general circulation model developed in the Institute of Atmospheric Physics of Chinese Academy of Sciences, and two model climatological fields got from the two independent models' numerical integrations respectively, the Pacific sea surface temperature anomalies (SSTA) from 1988 to 1989 are simulated in this paper with observed atmospheric general circulation data and sea surface temperature fields as initial conditions and monthly coupling scheme. In order to remove systematic biases of the model climatological fields, interaction variables between atmosphere and ocean are also corrected simultaneously. The experiments show that the simulation results can be improved effectively if these interaction variables are corrected in spite of the fact that there always exist systematic biases in independent numerical simulations of atmospheric part and oceanic part within CGCM. The basic characteristics of the observed Pacific SSTA in September and October 1988 have been simulated by using the correction scheme, such as the negative SSTA domain in the whole Equatotial Pacific east to 150°E and the positive SSTA domain in the Western Pacific, the northern subVopical Pacific and nearly the whole Southern Pacific. Further numerical simulations show that the model can simulate not only the SSTA in the Pacific and its seasonal variations but also iu interannual changes (for example. La Nino event in the Equatorial Pacific teturinated after May 1989) to a certain degree. Furthermore, some problems existing in experiment processes and what we shoud do in the following stage are also discussed and analysed in this paper.
A preliminary analysis of physical mechanism of transformation process from a landed typhoon into an extratropical cyclone
Zhang Qiuqing, Ding Yihui
1992, (4): 525-535.
A diagnostic study is performed in the paper on the process of typhoon Norris (1980) transforming into an ex-tratropical cyclone after its landing over Southeast China. The main findings are as follows:
The changes of kinetic energy are mainly attributed to the generation due to non-divergent wind. During the early stage of the typhoon landing, there exits only a small quantity of kinetic energy exchanging with the environment. And after it is transformed into an extratropical cyclone, a large amount of kinetic energy is exported from the system toward the environment.
The horizontal and vertical flux-divergence terms of eddy available potenlial energy are the prominent sinks in the budgets of eddy kinetic energy. The generations of eddy kinetic energy due to both the barotropic and baroclinic processes are source terms. The former is remarkable during the initial stage. But after the depression is transformed into an extratropical cyclone, the roles of the generation by the barotropic and baroclinic processes are reversed, i. e.,the latter has become more significant than the former.
Diabatic heating is the most dominant heat source. The terms of vertical heat flux by cumulus and large-scale motion are the major sinks. And the latter is prominent after the system is transformed into an extratropical cyclone.
Atmosphere-ocean interaction and teleconnection in the Northern Pacific during the cold season
Jiang Quanrong, J. M. Wallace
1992, (4): 537-546.
On the basis of the idea in our work (Jiang and Wallace, 1991), the horizontal structure of SST pattern, the atmospheric response to SST change and the atmospheric forcing of the ocean in the Northern Pacific during the cold season are discussed. The results show that PNA pattern is the most prominent normal mode in the atmosphere-ocean interaction in the Northern Pacific during the cold season.
Numerical simulation of the tropical Pacific response to equatorial wind stress anomalies
Hua Ming, Ni Yunqi
1992, (4): 547-557.
The results of the tropical Pacific response to the sudden onset of the equatorial wind stress anomalies are discussed. The ocean model is a barotropic, non-linearized one that includes reduced-gravity and an equation for the temperature of the ocean mixed-layer. The experiments are based on a state of equilibrium reached through a long running under the action of annual mean wind stress. There are two kinds of westward wind intensity regions: the whole tropical Pacific and the western tropical Pacific, which are all between latitude 6. 8°N and 6. 8°S.
In these cases, the results show that the positive sea surface temperature (SST) anomalies in the Eastern Pacific and the negative SST anomalies in the Western Pacific are produced, and the positive SST anomalies propagate eastward, just as those observed during the actual El Nino phenomena. The propagations of the Kelvin waves and Rossby waves in the ocean are discussed.
Another experiment is also carried out in simulating the process of the decay of El Nino phenomena. The propagations of the Kelvin waves and Rossby waves in the ocean are discussed. Mother experiment is also carried out in simulating the process of the decay of El Nino event after the weakened Equatorial Pacific eastern winds returned to normal. The results are similar to the observations, too.
A numerical study of the impact of SST anomaly in the warm pool area on atmospheric circulation in winter
Dong Min, Chen Longxun, Liao Hong
1992, (4): 559-572.
In this paper the impacts of the anomalous SST in the warm pool area of the Western Equatorial Pacific on the winter time circulation and the East Asian monsoon are studied by using the NCAR CCM. It is found that the abnormal heating in the warm pool area will change the strength and the position of the Walker Cell in the Equatorial Pacific and the anti-Walker Cell in the equatorial Indian Ocean. Both the Walker and anti-Walker Cells are strengthened. The local Hadley Cells over two hemispheres near the warm pool are also strengthened. The subtropical highs in two hemispheres become stronger and move poleward slightly. The westerly jets in the extratropical regions have similar changes as the subtropical highs. The winter monsoon in South-East Asia is weakened by the abnormal heating in the warm pool. The experiment also show that there are wave trains emanating from surrounding areas of the warm pool to the high latitudes, causing various changes in circulations and local weather.
Paleomagnetism and paleoclimate change in the South China Sea since the late Pleistocene
Xidong Chen, Douglas F. Williams, Yuan Youren, Wang Baogui, Tang Xianzan, Fan Shiqing, Liu Zongyang
1992, (4): 573-581.
Signal processing techniques of cross-correlation, power spectral analysis and cross-power spectral analysis are used to determine the relationships between paleomagnetic properties and the oxygen isotope record of the South China Sea during the late Pleistocene. On the basis of correlation tests between the δ18O time series of cores V3 and A15 with the paleomagnetic properties of core SCS01, five events of susceptibility and intensity of natural remanent magnetization are identified as glacial events corresponding to δ18O positive events. The magnetic properties of the sediments which are independent of the geomagnetic field are sensitive climatic indicators which have frequencies corresponding to the Milankovitch orbital parameters.
The ultrastructural study of the spermatid differentiation in Cyclina sinensis
Zeng Zhinan, Li Fuxue
1992, (4): 583-592.
The authors have observed submicroscopically the transformation of spermatid and the sperm structure in the spermatogenesis process of Cyclma sinensis. The results show during the spermatid differentiation the nuclear morphology transforms from the elliptical into the cylindrical shape. The morphological transformation of the nuclear chromatin experiences from the small masses of fine granule aggregation to granular substructures with a granular diameter of 20-41 nm (containing a few masses), then to large coarsely granules with a diameter of 36.8-52.6 nm and at last to the homogenate with high electron density. The proacrosomal granules secreted by Golgi complex aggregate to form a large spherical granule which moves gradually to the anterior pole of the nucleus to join the acrosomal formation. The fusion of some mitochondria and the disintegration of a few ones result in the mitochondrial number decrease and volume enlargement. Finally, the mitochondrial ring which consists of five mitochondria and locates at the posterior pole of the nucleus, surrounds the proximal and distal tentrioles to form the main structure of the middle section of sperm. The spermatozoon of Cyclina sinensis is of the primitive type and consists of head, middle section and tail flagellum. In addition, it is of interest to note that a special spherical structure in the subacrosomal area is observed.
The study of fluorescence characteristics and biochemical composition of a marine diatom Thalassiosira pseudonana 3H in light and dark cycles Ⅰ. The effects of nutrients
Zhu Mingyuan, Yang Xiaolong, J. J. Cullen
1992, (4): 593-602.
The effects of nutrients on the fluorescence characteristics and biochemical composition of marine diatom Thalassiosira pseudonana 3H in light and dark cycles were investigated with continuous culture. The results show that with the increase of nutrient deficiency, the ratio of enhanced fluorescence to fluorescence (Fd/F), cellular chloropyll-a and protein content of the algae decline, but the fluorescence yield (F/Chl), DCMU enhanced fluorescence yield (Fd/Chl), cellular carbohydrate content, carbohydrate/Chl, protein/Chl, carbohydrate/protein increase. The changing amplitude of each parameter is different at different nutrition status, sampling time and different light intensity.
Vertical membrane floating breakwater
William G. McDougal, Liu Wentong, Charles K. Solllt
1992, (4): 603-610.
The mechanism of retinomotor movements in the retina of banded grouper (Epinephelus awoara)
He Daren, Zhang Houquan
1992, (4): 611-615.
Phytoplankton ecology in the adjacent waters of the Daya Bay Nuclear Power Station in Guangdong in spring
Yang Qingliang, Lin Jinmei
1992, (4): 617-624.