Wind Variability over a Small and Sheltered Lake: Trout Lake Field Study

Abstract

Wind is one of the most important, highly uncertain, and least investigated drivers of lake processes. In lake modeling, the wind over a lake is often estimated from point measurements at a remote weather station. Whether the surrogate wind data is representative of a lake’s wind field depends on distance from the weather station as well as sheltering of the lake by trees and topography. To better understand the actual wind field over a small wind-sheltered lake we deployed five anemometers in different locations on Trout Lake, MN, for four months. We compared wind speeds and directions recorded on Trout Lake to Grand Marais Airport, 16 kilometers away. The effect of wind sheltering on the lake was quantified by a wind sheltering coefficient estimated using measured wind speeds and also an empirical model, adjusted for varying fetch and canopy cover depending on wind direction. Our long-term goal is to identify the data and analysis required to reduce uncertainty in lake water quality and fish habitat models.