Abstract.A simple model to determine a turbulence effect in formation of the Antarctic Circumpolar Current (ACC) is suggested. The model is founded on the theory of rotationally anisotropic turbulence and is set up as a generalization of the geostrophic description of the Antarctic Circumpolar Current (ACC). It predicts the turbulence effect as an additive correction to the flow velocity predicted by the geostrophic balance. The correction, calculated from the optimally analyzed hydrographic data in the Southern Ocean, results in an increased ACC total baroclinic volume transport and in a shift in the current velocity maximum to the south, if compared with the pure geostrophic estimate.
SUMMARYSpatial correlations of temperature, salinity and nutrient concentrations in the Gulf of Finland are estimated for winter, spring, summer and fall. The correlation estimates are based on the results of observations in the Gulf of Finland for the period 1972-1991. The time and space resolution of the correlation model are determined by averaging the original data in time over each month and in space over the cells with horizontal dimensions equal to 10' in the east-west and 20' in the south-north direction and to the standard sampling depth intervals in the vertical direction. The fluctuations of the averaged data are defined as deviations of the month and cell average data values from the seasonal 20-year overall mean values. The model of spatial correlation is based on the assumption that the fluctuations of the month-and-cell average data form a random sample out of a spatially homogeneous, horizontally isotropic and temporally stationary field. Most of the estimated correlations are positive, except for the vertical correlation component of salinity in summer, which shows considerable negative values at the distance lags exceeding 30 m. As an example of assimilation of the estimated correlations, the statistical (optimal) linear interpolation approach was applied for estimation of the optimal location of a measurement site, additional to the three currently used international monitoring stations, commonly known as LL12, LL7 and LL3A, in the Gulf of Finland. The optimal location of the additional fourth measurement site, which leads to the least average interpolation error, was found to be within the vertical column of cells with co-ordinates 60" 00' N 28" 10' E for salinity and 60" 00' N 28" 20' E for total phosphorus concentration measurements. The same average error cannot be achieved by increasing the sampling frequency at the three present international monitoring stations.
A model to calculate the vertical distribution of the average velocity in the oscillating turbulent boundary layer forced by the overlaying oscillating free flow is discussed. The model is founded on the Rotationally Anisotropic Turbulence theory. The oscillating boundary layer is treated within the approximation of average velocity depending on the time and vertical coordinate only. The description results in an analytical expression for the flow velocity analogous to the expression for the flow velocity in the boundary layer of oscillating pipe flow. The resulting expressions for the vertical velocity profile are compared with respective laboratory data obtained in two tests of an oscillatory water tunnel experiment. It is shown that similar to the description of oscillating flow in tubes, the outcome of the suggested model with the appropriate values of the model parameters matches the measured velocity data reasonably well. RÉSUMÉUn modèle est traité ici pour calculer la distribution verticale de la vitesse moyenne dans la couche limite turbulente mise en oscillation forcée par l'oscillation libre d'une couche supérieure. Le modèle est fondé sur la théorie de la turbulence anisotrope rotationnelle. La couche limite en oscillation est traitée avec une approximation de la vitesse moyenne dépendant seulement du temps et de la coordonnée verticale. Il en résulte une expression analytique de la vitesse analogue à celle de la vitesse de la couche limite oscillante dans un tuyau. Les expressions résultantes pour le profil vertical de vitesse sont comparées aux données obtenues respectivement dans deux tests expérimentaux de tunnel en eau oscillant. On montre que, comme la description de l'écoulement oscillant dans les tubes, les résultats du modèle suggéré, avec les valeurs appropriées des paramètres, concordent raisonnablement avec les données de vitesses mesurées.
A quasi-stationary model of vertical distribution of concentration of suspended particular matter in the bottom layer of 1D open channel with a sloped bottom and varying free surface slope is discussed. The model proceeds from the balance between the turbulent diffusion and settling with the buoyancy flux effects on the medium turbulence neglected. The model outcome is formulated in the form of an analytic formula for the vertical distribution of concentration. It is shown that the derived formula embraces two basic types of vertical distribution of concentration, one with a monotonic decrease of concentration gradient and the other with a gradient maximum (lutocline) located at some distance from the bottom. The first distribution type realizes for a relatively large settling velocity or low intensity of turbulence and the second type for a small settling velocity or high intensity of turbulence. The skill of the model to mimic realistic situations is demonstrated on data measured in the Jiaojiang Estuary (China).
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