The Optimal Wind Direction for the Occurrence of Wind-Driven Coastal Upwelling Associated with “Aoshio” on the Southeast Shore of Tokyo Bay

2014 ◽  
Vol 641-642 ◽  
pp. 1046-1050
Author(s):  
Zhong Fan Zhu
Keyword(s):  
Coriolis Force ◽  
Wind Direction ◽  
Coastal Upwelling ◽  
Tokyo Bay ◽  
Long Channel ◽  
Layered Fluid

Whether the optimal wind direction for the occurrence of wind-driven coastal upwelling associated with "Aoshio" on the southeast shore of Tokyo Bay exists was not clear. In this study, Tokyo Bay was assumed to be a narrow, infinitely long channel with only the southeast shore and the northwest shore being its two boundaries, and the optimal wind direction for coastal upwelling associated with "Aoshio" on the southeast shore of this idealized channel was discussed. It is found that the optimal wind direction varies with wind duration. If wind duration is very short, the optimal wind direction is almost across the channel while, with the increasing wind duration, the optimal wind direction approaches gradually to be along-channel. This transition is attributed to the increasingly important role that played by the Coriolis force in the motion of the two-layered fluid with the increasing wind duration.

scholarly journals Estimating the Occurrence of Wind-Driven Coastal Upwelling Associated with “Aoshio” on the Northeast Shore of Tokyo Bay, Japan: An Analytical Model

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Zhongfan Zhu ◽  
Jingshan Yu
Keyword(s):  
Surface Water ◽  
Analytical Model ◽  
Analytical Solutions ◽  
Coastal Upwelling ◽  
Tokyo Bay ◽  
Observation Data ◽  
Simple Analytical Model ◽  
Aquatic Animals ◽  
Bottom Oxygen ◽  
Layered Fluid

“Aoshio” in Tokyo Bay is a hydroenvironmental phenomenon in which seawater appears milky blue due to reflection of sunshine off surface water which contains lots of sulfur particles. Its appearance is due to coastal upwelling of bottom oxygen-depleted water, which causes many deaths of shellfish and other aquatic animals around the bay. In this study, we derived some analytical solutions in the context of a two-layered fluid and used them to make a simple analytical model to estimate the occurrence of “Aoshio” phenomenon on the northeast shore of Tokyo Bay. Comparison with observation data suggested that this model was valid to a certain degree.

scholarly journals Applying a Simple Analytical Solution to Modelling Wind-Driven Coastal Upwelling of Two-Layered Fluid at the Head of Tokyo Bay, Japan

Water ◽  
2017 ◽  
Vol 9 (10) ◽  
pp. 744 ◽  
Author(s):  
Zhongfan Zhu ◽  
Xiaomei Bai ◽  
Jie Dou ◽  
Pengfei Hei
Keyword(s):  
Analytical Solution ◽  
Coastal Upwelling ◽  
Tokyo Bay ◽  
Layered Fluid

Qualitative Discussion of Influences of some Factors on the Occurrence of Wind-Driven Coastal Upwelling Associated with “Aoshio” on the Northeast Shore of Tokyo Bay Using the Developed Analytical Model

2014 ◽  
Vol 641-642 ◽  
pp. 1040-1045
Author(s):  
Zhong Fan Zhu
Keyword(s):  
Analytical Model ◽  
Wind Shear ◽  
Coastal Upwelling ◽  
Tokyo Bay ◽  
Interfacial Friction ◽  
Observation Data ◽  
Shear Effect ◽  
Stratification Effect ◽  
Northeasterly Wind ◽  
Qualitative Discussion

An analytical model based on some solutions in the context of a two-layered fluid was developed to estimate the occurrence of northeasterly wind-driven coastal upwelling associated with “Aoshio” on the northeast shore of Tokyo Bay, and its validity was verified by comparing with observation data [1]. In this study, influences of all of the factors incorporated into this analytical model (including densities and thicknesses of the upper and lower layers, the parameter expressing the influences of interfacial friction and bottom friction) on the model are analyzed. The analytical model is found to express the competition between the wind-shear effect and the stratification effect: when the former dominates over the latter, Aoshio will occur on the northeast shore of the bay. The parameter that can be used to characterize the stratification effect can be simply expressed in terms of the product of density contrast and the square of thickness of the upper layer. Using different values of this parameter corresponding to different months in the model can simply estimate in which months it is easy for Aoshio phenomenon to happen on the northeast shore of the bay, and the result is roughly consistent with an observation phenomenon that Aoshio was frequently observed on the northeast shore of the bay in September and May and relatively less observed in June and July during 1978-2010.

scholarly journals Flow patterns of shallow Palic Lake induced by the dominant winds

2012 ◽  
Vol 10 (1) ◽  
pp. 55-67
Author(s):  
Ljubomir Budinski ◽  
Djula Fabian
Keyword(s):  
Numerical Model ◽  
Flow Pattern ◽  
Coriolis Force ◽  
Wind Direction ◽  
Driving Forces ◽  
Open Water ◽  
Flow Patterns ◽  
Two Dimensional ◽  
Lake Model ◽  
Double Gyre

Studies of lake currents have highlighted that in case of stagnant waters winds are the dominant driving forces. This study is dealing with the influence of dominant winds on the flow pattern of Palic Lake. Action of steady winds of different directions has been tested on the lake by means of a two dimensional numerical model, while in addition to winds all other permanent factors like actual bathymetry, inflow and outflow as well the Coriolis force have been accounted for. The experiments have revealed that winds of different directions created corresponding characteristic flow patterns (in base plot), which were similar in cases of winds having opposite directions. However, in such cases the direction of flow was opposite. Moreover, the Palic Lake model produced the well known double-gyre flow pattern: in the coastal strip the direction of the current corresponded to the wind direction, while it was opposite in the domain of open water.

The Relationships among Wind, Horizontal Pressure Gradient, and Turbulent Momentum Transport during CASES-99

2013 ◽  
Vol 70 (11) ◽  
pp. 3397-3414 ◽  
Author(s):  
Jielun Sun ◽  
Donald H. Lenschow ◽  
Larry Mahrt ◽  
Carmen Nappo
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Pressure Gradient ◽  
Coriolis Force ◽  
Wind Direction ◽  
Momentum Flux ◽  
Momentum Transport ◽  
Horizontal Pressure Gradient ◽  
Horizontal Pressure ◽  
Turbulent Momentum

Abstract Relationships among the horizontal pressure gradient, the Coriolis force, and the vertical momentum transport by turbulent fluxes are investigated using data collected from the 1999 Cooperative Atmosphere–Surface Exchange Study (CASES-99). Wind toward higher pressure (WTHP) adjacent to the ground occurred about 50% of the time. For wind speed at 5 m above the ground stronger than 5 m s−1, WTHP occurred about 20% of the time. Focusing on these moderate to strong wind cases only, relationships among horizontal pressure gradients, Coriolis force, and vertical turbulent transport in the momentum balance are investigated. The magnitude of the downward turbulent momentum flux consistently increases with height under moderate to strong winds, which results in the vertical convergence of the momentum flux and thus provides a momentum source and allows WTHP. In the along-wind direction, the horizontal pressure gradient is observed to be well correlated with the quadratic wind speed, which is demonstrated to be an approximate balance between the horizontal pressure gradient and the vertical convergence of the turbulent momentum flux. That is, antitriptic balance occurs in the along-wind direction when the wind is toward higher pressure. In the crosswind direction, the pressure gradient varies approximately linearly with wind speed and opposes the Coriolis force, suggesting the importance of the Coriolis force and approximate geotriptic balance of the airflow. A simple one-dimensional planetary boundary layer eddy diffusivity model demonstrates the possibility of wind directed toward higher pressure for a baroclinic boundary layer and the contribution of the vertical turbulent momentum flux to this phenomenon.

Production of asari (Manila) clams, Ruditapes philippinarum, during the period of harvest decrease in the 2000s in the Banzu tidal area, Tokyo Bay

2020 ◽  
Vol 33 ◽  
pp. 14
Author(s):  
Mitsuharu Toba ◽  
Jun Kakino ◽  
Kazuo Tada ◽  
Yutaka Kobayashi ◽  
Hideharu Tsuchie
Keyword(s):  
Field Investigation ◽  
Ruditapes Philippinarum ◽  
Management Style ◽  
Seed Stock ◽  
Tokyo Bay ◽  
Yearly Variation ◽  
Culture Area ◽  
Stock Biomass ◽  
Tidal Area ◽  
High Level

In Tokyo Bay, the harvestable quantity of asari (Manila) clams Ruditapes philippinarum has been decreasing since the late 1990s. We conducted a field investigation on clam density in the Banzu culture area from April 1988 to December 2014 and collected records spanning January 1986 to September 2017 from relevant fisheries cooperative associations to clarify the relationship between the temporal variation in stock abundance and the production activities of fishermen. The yearly variation in clam abundance over the study period was marked by larger decreases in the numbers of larger clams. A large quantity of juvenile clams, beyond the biological productivity of the culture area, may have been introduced as seed stock in the late 1980s despite the high level of harvestable stock. The declines in harvested quantity began in the late 1990s and may have been caused by decreases in harvestable stock despite the continuous addition of seed stock clams. The harvested quantity is likely to be significantly dependent upon the wild clam population, even within the culture area, as the harvestable quantity was not correlated with the quantity of seed stock introduced during the study period. These declines in harvested quantity may have resulted from a decreasing number of operating harvesters due to the low level of harvestable stock and consequently reduced profitability. Two findings were emphasized. A certain management style, based on predictions of the contributions of wild and introduced clams to future stock biomass, is essential for economically-feasible culturing. In areas with less harvestable stock, actions should be taken to maintain the incomes of harvesters while avoiding overexploitation, even if the total harvest quantity decreases.

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