Estimation of Winds over the Great Lakes

Past efforts to estimate wind speeds over a large lake have met with very limited success. The purpose of this study is to demonstrate that, with a combined theoretical-empirical approach, winds over a lake can be obtained from transformed wind speeds at nearby land stations. The theoretical results provide a basis for comparison of many empirical data sets and establish a rational means of analyzing the expected differences between winds over land and those over a marine surface. This in turn affords a means of examining systematic variations in the ratio of wind speeds over a lake to wind speed over land. The good agreement between theory and observation indicates that wind estimates over the lake can be made for a wide range of synoptic conditions with an rms error of 5 knots. The theoretical curve for the lake wind/land wind ratio provides an estimate of lake winds well beyond wind speeds for which there are good empirical data.