The Stepped-Frequency Microwave Radiometer is a state-of-the-art instrument designed to continuously and accurately measure the winds at the ocean's surface directly below the aircraft. As the plane flies through a storm, the SFMR senses microwave radiation naturally emitted from foam created on the sea by winds at the surface. Computers then determine wind speeds based on the levels of microwave radiation detected. The SFMR can also determine rainfall rates within a storm system. This, in addition to wind speeds at flight level, provide structural detail of the storm. (Photo Courtesy of Lockheed Martin)