Nighttime observation of sheared tropical cyclones using GOES 3.9-mu m data

This note discusses a Geostationary Operational Environmental Satellite pro duct that can reveal the low clouds associated with tropical cyclones at ni ght. It is based on a pixel- by- pixel difference of the longwave (10.8 mum ) and shortwave (3.9 mum) brightness temperature fields. This product is co mpared with daytime visible images from the same satellite and passive micr owave images from the Tropical Rainfall Measuring Mission Microwave Imager and the Defense Meteorological Satellite Program Special Sensor Microwave/ Imager. Implications for weather analysis and forecasting are discussed for weak and shearing systems.