Synthetic Aperture Radar Observations of the Surface Signatures of Cold-Season Bands over the Great Lakes

Abstract

An important aspect of operational meteorology in and around the Great Lakes region of the United States and Canada in the winter months is the forecasting of lake-effect precipitation. While the synoptic- and mesoscale processes that govern the development of lake-effect precipitation have been well understood for many years, problems observing these bands remain because of the limited boundary layer coverage provided by the Weather Surveillance Radar-1988 Doppler (WSR-88D) network. While traditional visible and infrared satellite imagery helps alleviate these coverage limitations, overcast conditions often negate this advantage. Here, a new method for observing lake-effect bands by using synthetic aperture radar (SAR) to identify and characterize their surface signatures is presented. SAR is a remote sensing tool that images surface roughness. Over water, this roughness is related to the surface wind stress and, hence, surface wind field. Here, three cases are documented where the SAR aboard the Canadian Radar Satellite-1 imaged the footprints of precipitating bands over the Great Lakes: one case with multiple snowbands west of one main band over Lake Superior, and two cases with shore-parallel bands over each of Lakes Ontario and Michigan. These cases are first documented using traditional observing methods: infrared satellite imagery, WSR-88D, and surface observations. Then, each SAR image is interpreted based upon the traditional observations. The ultimate goal is to demonstrate that SAR is capable of detecting the surface signatures associated with Great Lakes precipitation bands that could be of value to forecasters when data from traditional observation platforms are unavailable.