Specialized surface wind instruments fly onboard nation’s hurricane hunter fleet

NOAA: For the first time, America’s entire fleet of aircraft that fly through hurricanes now have instruments that measure surface winds, giving forecasters at NOAA’s National Hurricane Center a better view of the intensity and the size of these powerful storm systems.

The instrument, known as a stepped frequency microwave radiometer, attached to the wing of each aircraft detects radiation that is naturally emitted from foam created on the sea by winds at the surface. Computers onboard the aircraft then determine surface wind speeds based on the levels of microwave radiation detected.

"When a hurricane threatens our coasts, key on the minds of forecasters and emergency managers is the strength of the surface winds. With this equipment we’ll have that information in real time,” said retired Navy Vice Admiral Conrad C. Lautenbacher Jr., Ph.D., under secretary of commerce for oceans and atmosphere and NOAA administrator. “Data from these devices can improve our ability to forecast intensity changes of tropical systems.”

In the past, aircrews extrapolated wind speeds from the aircraft's altitude or from a GPS dropsonde released from the aircraft. The stepped frequency microwave radiometer provides a continuous measurement of surface winds giving NOAA’s National Hurricane Center forecasters a more complete picture of the storm. The instrument can also determine rainfall rates within a storm system. This, in addition to wind speeds at flight level, provides structural detail of the tropical cyclone.

The current generation of this radiometer was first used on NOAA’s two WP-3D Orion aircraft in 2003 for research flights and then used operationally in 2005. Installation on the ten WC-130J hurricane hunter aircraft flown by the Air Force Reserve 53rd Weather Reconnaissance Squadron began in 2006 and was just completed.

The National Oceanic and Atmospheric Administration, an agency of the U.S. Commerce Department, is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and information service delivery for transportation, and by providing environmental stewardship of our nation's coastal and marine resources. Through the emerging Global Earth Observation System of Systems (GEOSS), NOAA is working with its federal partners, more than 70 countries and the European Commission to develop a global monitoring network that is as integrated as the planet it observes, predicts and protects.

The Stepped-Frequency Microwave Radiometer continuously and accurately measures the winds at the ocean's surface directly below this WC-130J aircraft (photo from Lockheed Martin).