Remote Measurement of Surface Wind
Microwave Radiometers Installed on Nation’s Hurricane Hunter Fleet
Installation of Stepped Frequency Microwave Radiometer (SFMR) on Hurricane Hunter aircraft will provide better surface wind readings the National Hurricane Center.
NOAA utilizes the services of ten highly modified WC-130J aircraft operated by the Air Force Reserve 53rd Weather Reconnaissance Squadron also known as the Hurricane Hunters. Recently measurement equipment has been installed on these aircraft to provide the National Hurricane Center with real time wind speeds on the ocean surface below the aircraft.
In a statement announcing this technology rollout, NOAA Administrator Vice Admiral Conrad C. Lautenbacher Jr., Ph.D. says, "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. Data from these devices can improve our ability to forecast intensity changes of tropical systems.”
Previously Used Methods of Wind Speed Detection - Measurement of surface wind speed helps hurricane forecasters develop a better picture of storms, providing information on their intensity and the structure of tropical cyclones. Up until now, wind speed was extrapolated from winds experienced aloft at alititude or through the use of GPS enabled dropsondes released from the aircraft.
Wind Speed Measurement Research - Using its own two WP-3D Orions (former Navy submarine patrol aircraft), NOAA began experiments with the use of a radiometer to measure surface wind speed and precipitation during research flights conducted in 2003. The equipment began to be used operationally in 2005.
Stepped Frequency Microwave Radiometer (SFMR) - Known to aircrews as "smurf", the SFMR system bounces microwave emissions off the surface of the ocean and uses the reflected energy it receives to measure the minute levels of radiation produced by sea foam generated by surface winds. The SFMR equipment package is attached directly to the undersurface of the aircraft wing in surface mounted pod.
Basic SFMR Specifications from Lockheed Martin - Use of Hurricane Hunter flights is estimated to improve forecast accuracy by 30 percent. The addition of SFMR technology will likely improve this statistic.
- Radiometer Type - Hatch
- Tuning Bandwidth - 4.6 to 7.2 GHz with a 50 MHz channel bandwidth
- Number of Channels - Up to 8
- Antenna Type - Corrugated horn with a beamwidth of (3 dB) 20-28 deg Polarization Linear
- Measurement Precision - 0.17 Knots at an one second average
- Electronics Power Requirements - 28 Volts DC at maximum of 6 Amperes. Total load of 168 watts
- Environmental Limits - Temperatures of -65°C to +40°C. Humidity of 0 to 100%
- Module Size - 61 x 28 x 33 centimeters (24 x 11 x 13 inches) weighing 18 kilograms (40 pounds)
