Lake Surface Temperature Influence on Atmospheric Circulation and Precipitation Processes in the Great Lakes Region

Abstract:

The Laurentian Great Lakes are a key component of the weather and climate system of the northern and eastern United States through their influences on atmospheric circulation and the availability of moisture. The differences in temperature between the lake surface, land, and atmosphere control a number of small-scale atmospheric circulations in the region. During the spring and early summer months, the lakes are typically colder than the air due to density driven circulations in the lake as well as the high heat capacity of water. This colder water surface helps to generate a stable layer of air, which controls the flow of moisture and momentum over and around the lakes. The stable layer’s strength and location plays a key role in both the placement of precipitation generated downwind of the lakes and the potential suppression of existing convective systems. In this study, precipitation promotion and suppression processes will be explored through a series of high-resolution (< 4 km horizontal grid spacing) Weather Research and Forecasting Model (WRF) simulations with varying lake surface characteristics. Sensitivity of individual events to changes in the lake surface properties is examined, and the results illustrate how the dynamics and intensity of storms may change in a warmer climate.