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111.
从支配台风中心移动的基本方程出发,着重分析了小地形(地形高度与台风系统的垂直厚度相比为小量)的抬升作用和边界层的摩擦作用对台风移动影响的定性特征。结果表明,较高地势对台风有“吸引”作用;边界层摩擦辐合引起的艾克曼抽吸有利于台风产生沿局地流场引导速度方向的加速度。 相似文献
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Corrected Formula of Bed Resistance Coefficient for Plane Numerical Simulation of Tidal Current 总被引:4,自引:0,他引:4
By means of a logarithm law for the velocity profile,a corrected formula of bed resistancecoefficient,which involves many factors such as gradient of still water depth,variation of surfaceelevation,flow direction,and so on,is derived from the 3D governing equations of tidal current by aver-aging over the whole water depth.Theoretical analysis and application have shown that the 2D plane tidalcurrent numerical model would be more reasonable and could be applied to steep bottom topographywhen the corrected bed resistance coefficient is used,therefore the results of reproduction simulation andengineering calculation would be more scientific and reasonable. 相似文献
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In this paper, we propose a hybrid forecasting model to improve the forecasting accuracy for depth-averaged current velocities (DACVs) of underwater gliders. The hybrid model is based on a discrete wavelet transform (DWT), a deep belief network (DBN), and a least squares support vector machine (LSSVM). The original DACV series are first decomposed into several high- and one low-frequency subseries by DWT. Then, DBN is used for high-frequency component forecasting, and the LSSVM model is adopted for low-frequency subseries. The effectiveness of the proposed model is verified by two groups of DACV data from sea trials in the South China Sea. Based on four general error criteria, the forecast performance of the proposed model is demonstrated. The comparison models include some well-recognized single models and some related hybrid models. The performance of the proposed model outperformed those of the other methods indicated above. 相似文献
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Mark E. Baird Jason D. EverettIain M. Suthers 《Deep Sea Research Part II: Topical Studies in Oceanography》2011,58(5):699-711
The research vessel Warreen obtained 1742 planktonic samples along the continental shelf and slope of southeast Australia from 1938-42, representing the earliest spatially and temporally resolved zooplankton data from Australian marine waters. In this paper, Warreen observations along the southeast Australian seaboard from 28°S to 38°S are interpreted based on synoptic meteorological and oceanographic conditions and ocean climatologies. Meteorological conditions are based on the NOAA-CIRES 20th Century Reanalysis Project; oceanographic conditions use Warreen hydrological observations, and the ocean climatology is the CSIRO Atlas of Regional Seas. The Warreen observations were undertaken in waters on average 0.45 °C cooler than the climatological average, and included the longest duration El Niño of the 20th century. In northern New South Wales (NSW), week time-scale events dominate zooplankton response. In August 1940 an unusual winter upwelling event occurred in northern NSW driven by a stronger than average East Australian Current (EAC) and anomalous northerly winds that resulted in high salp and larvacean abundance. In January 1941 a strong upwelling event between 28° and 33°S resulted in a filament of upwelled water being advected south and alongshore, which was low in zooplankton biovolume. In southern NSW a seasonal cycle in physical and planktonic characteristics is observed. In January 1941 the poleward extension of the EAC was strong, advecting more tropical tunicate species southward. Zooplankton abundance and distribution on the continental shelf and slope are more dependent on weekly to monthly timescales on local oceanographic and meteorological conditions than continental-scale interannual trends. The interpretation of historical zooplankton observations of the waters off southeast Australia for the purpose of quantifying anthropogenic impacts will be improved with the use of regional hindcasts of synoptic ocean and atmospheric weather that can explain some of the physically forced natural variability. 相似文献
120.
Hidekazu Yasuda 《Journal of Oceanography》1998,54(2):151-164
An analytical method for describing horizontal matter dispersion in shear currents is presented using a tensor expression
from the point of view that matter dispersion due to the shear effect should be one of the principal mixing dilution processes.
Although the behavior of horizontal dispersion is considerably more complicated than common longitudinal dispersion, the present
study elucidates the vertical structure of dispersion and the dispersing process from the initial to the stationary stage,
besides the usual depth-averaged dispersion coefficient at the stationary stage. As one of the typical applications of horizontal
dispersion, dispersion due to the pure drift current with an Ekman layer is examined theoretically using the present method.
This examination reveals that the displacement of the centroid and the major axis of dispersion are twisted in the vertical
direction more than the direction of the current vector forming the Ekman spiral; that the variance increases in proportion
to the third power of the elapsed time; and that the dispersion coefficient at the stationary stage remains constant, independent
of the depth normalized by an Ekman layer thickness. Such dependence of the dispersion coefficient in the steady current is
shown to be different from that in the oscillatory current, which is inversely proportional to the depth normalized by a Stokes
layer thickness. This is considered to be induced by the difference of the vertical profiles of the first order moment in
both currents, that is, the shear region of the first order moment is restricted around the floor by the alternation of the
current shear in the oscillatory current while it is diffused in the whole depth in the steady current. 相似文献