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Library > Fact Sheets > Stepped-Frequency Microwave Radiometer

STEPPED-FREQUENCY MICROWAVE RADIOMETER

Posted 1/28/2009 Printable Fact Sheet
 
Photos 
SFMR Ready for 2007
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)
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PURPOSE:

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. The SFMR, affectionately known as "smurf,"  is installed on the WC-130J within a pod attached to the aircraft's wing. 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. Currently, winds are extrapolated from the winds at the aircraft's altitude or from a dropsonde released from the aircraft, however, the SFMR directly measures the surface winds and is not confined to a single point like the dropsonde. This constant measurement of surface winds gives the National Hurricane Center in Miami a more complete picture of the storm.

The SFMR can also determine rainfall rates within a storm system. This, in addition to wind speeds at flight level, provides structural detail of the storm.

The final Hurricane Hunter aircraft equipped with the SFMR was delivered Feb. 15, 2008 completing the fleet of 10 WC-130J aircraft outfitted with the smurf pod.

The Hurricane Hunters improve the accuracy of the NHC forecast by 30 percent, a number likely to rise with the use of the SFMR.

SPECIFICATIONS:

Radiometer Type                                                            Hatch
Tuning bandwidth                                                          4.6 -7.2 GHz
Number of channels                                                      Up to 8
Receiver Channel Bandwidth                                      50 MHz
Antenna Type                                                                   Corrugated horn
Antenna Beamwidth                                                       (3 dB) 20-28 deg Polarization                                                                       Linear
Measurement precision                                                 0.17 K (1second averaging)
Electronics Power Requirements                                28VDC, 2A
Thermal Control Power Requirements                       28VDC, 4A (max)
Power                                                                                 168 W
Operating Temperature                                                  -65°C to +40°C
Humidity                                                                              0 to 100%
Size                                                                                      (L x W x H) 24" x 11" x 13"
Weight                                                                                  40 lbs.







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