Summer circulation and exchange in the Saginaw Bay-Lake Huron system

Abstract

We use a three-dimensional, unstructured grid hydrodynamic model to examine circulation and exchange in the Saginaw Bay-Lake Huron system during the summer months for three consecutive years (2009)(2010)(2011). The model was tested against ADCP observations of currents, data from a Lagrangian drifter experiment in the Saginaw Bay, and temperature data from the National Data Buoy Center stations. Mean circulation was predominantly cyclonic in the main basin of Lake Huron with current speeds in the surface layer being highest in August. Circulation in the Saginaw Bay was characterized by the presence of an anticyclonic gyre at the mouth of the outer bay and two recirculating cells within the inner bay. New estimates are provided for the mean flushing times (computed as the volume of the bay divided by the rate of inflow) and residence times (computed as e-folding flushing times based on dye concentration modeling treating the bay as a continuously stirred tank reactor) for Saginaw Bay. The average flushing time (over the 3 months of summer and for all 3 years) was 23.0 days for the inner bay and 9.9 days for the entire bay. The mean e-folding flushing time was 62 days (2 months) for the inner bay and 115 days (3.7 months) for the entire bay for the summer conditions examined in this work. To characterize the behavior of river plumes in the inner Saginaw Bay, trajectory data from GPS-enabled Lagrangian drifters were used to compute the absolute diffusivity values in the alongshore and cross-shore directions.

Wind speed and direction estimation using manifold approximation

“…The figure validates the manifold assumption, which can be considered as linear locally, but with an overall complicated topology. Table 1.In particular, the proposed manifold-based estimation approach gives better results than the state-ofthe-art method proposed in [3], as well as some well-known interpolation methods, while the computational complexity is comparable. Computations are performed using MAT-LAB, on an Intel Core E7500 2.93Hhz platform.…”

“…The raw dataset of wind speed and direction is converted into two coordinates in the Cartesian coordinate system, named x and y directions, which is consistent with prior works [3]. We exploited a nonlinear dimensional reduction to convert high-dimensional data into two-dimensional Euclidean space [4].…”

Estimation of Residence Time and Transport Trajectory in Tieshangang Bay, China

“…Therefore, water exchange has been increasingly investigated in estuarine and coastal water quality studies in recent years [3][4][5][6][7]. As a concept related to water exchange, transport time scales such as water age, flushing time, residence time, and transient time are often used as parameters for representing the time scale of the physical transport processes [5,[8][9][10][11][12]. These time scales can describe how some water quality parameters (e.g., eutrophication, red tides, and chlorophyll-a concentration, etc.)…”

Investigation of Residence and Travel Times in a Large Floodplain Lake with Complex Lake-River Interactions: Poyang Lake (China)

“…One important physical attribute of lakes is the transport time scale (e.g., residence time, water age, flushing time, and travel time) that describes the lake's ability to renew the water contained within it via water level regime dynamics [3,4]. Although the time scale concept was designed to characterize the transport processes of lakes, this scale does not have a universally accepted definition.…”

“…The terms 'residence time' and 'travel time' are most commonly used to represent the time scale of the physical transport processes and to elucidate associated water quality problems in lakes and other hydrological systems [5]. In the literature, a widely used concept for quantifying the residence times for lakes is known as the e-folding time [2,4,5]. The e-folding time corresponds to the time when the average concentration of contaminants in the lake is reduced to 1/e or 37% of the initial concentration [6][7][8].…”