Lateral dispersion of dye and drifters in the center of a very large lake

Abstract

To better understand lateral dispersion of buoyant and nonbuoyant pollutants within the surface waters of large lakes, two lateral dispersion experiments were carried out in Lake Michigan during the stratified period: (1) a dye tracking experiment lasting 1 d; and (2) a drifter tracking experiment lasting 24 d. Both the dye patch and drifters were surface‐released at the center of Lake Michigan's southern basin. Near‐surface shear induced by near‐inertial Poincaré waves partially explains elevated dye dispersion rates (1.5–4.2 m2 s−1). During the largely windless first 5 d of the drifter release, the drifters exhibited nearly scale‐independent dispersion ( K ∼ L0.2), with an average dispersion coefficient of 0.14 m2 s−1. Scale‐dependent drifter dispersion ensued after 5 d, with K ∼ L1.09 and corresponding dispersion coefficients of 0.3–2.0 m2 s−1 for length scales L = 1500–8000 m. The largest drifter dispersion rates were found to be associated with lateral shear‐induced spreading along a thermal front. Comparisons with other systems show a wide range of spreading rates for large lakes, and larger rates in both the ocean and the Gulf of Mexico, which may be caused by the relative absence of submesoscale processes in offshore Lake Michigan.

Predicting larval alewife transport in Lake Michigan using hydrodynamic and Lagrangian particle dispersion models

“…By including random walk turbulence simulations in the model, this reality was represented by a patch of possible drifter initial positions. We used two scenarios of K H (13 and 188 m 2 s À1 ), representative of the 0.2-2 km resolution of our unstructured model grid (Thupaki et al 2013), although diffusion values vary even when forcing and background conditions are similar (Choi et al 2020). In addition to the real stochastic nature of turbulent flow, there are also inaccuracies in the model currents (Figs.…”

Near-Surface Dispersion and Current Observations Using Dye, Drifters, and HF Radar in Coastal Waters

“…A study has illuminated that dispersion in coastal regions is anisotropic, showcasing marked differences between the dispersion patterns of dyes and drifters, particularly concerning the orientation of wind and surface currents [52]. Additional research on lateral dispersion in a large lake has highlighted that near-surface shear can lead to varying dispersion rates for buoyant versus nonbuoyant pollutants, thus reflecting the distinct behaviors of dyes and drifters [10]. Importantly, vertical shear, propelled by wind forces, has a pronounced impact on the dispersion of dyes and drifters, with dyes, due to their susceptibility to depth-dependent currents, tending to display wider and more segmented dispersion patterns [27].…”

“…Drifters, passive devices tracked by satellite, provide direct measurements of surface currents, reflecting the movements of water parcels at the ocean's surface within a Lagrangian reference frame. Consequently, they have been instrumental in monitoring ocean circulations across various water bodies, from lakes and coastal areas to open oceans, moving passively with the surface current [8][9][10][11][12]. This platform has been proven to be an effective means of quantifying horizontal dispersion [13,14] and validating ocean models [15,16].…”

An Economical Open-Source Lagrangian Drifter Design to Measure Deep Currents in Lakes

“…Currents have historically been investigated in marine settings using a variety of robust and capable sampling equipment, though often expensive and difficult to deploy (Edwards et al, 2006, and references therein). Currents in the Laurentian Great Lakes of North America and similar large lakes (Choi et al, 2020;Edwards et al 2006), in the coastal zone (Sabet and Barani, 2011), and in estuaries (Spencer et al, 2014;Suara et al, 2018;Déjeans et al, 2021) have also been investigated, yet smaller and medium-sized lakes (~50-500 km 2 ) have received less attention than perhaps they should have, despite improvements in technology including the availability of small GPS units as tracking devices (McCormick et al, 2006;Manley, 2010). New technology and low-cost, high-performance materials are therefore unlocking opportunities to measure currents in a wider range of water body sizes, including smaller inland lakes.…”