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WP-3D Stepped Frequency Microwave Radiometer (SFMR)

Measurement of the hurricane surface wind field, and in particular the estimation of wind maxima, has long been a requirement of the Tropical Prediction Center/OAR. The NOAA/Hurricane Research Division's Stepped-Frequency Microwave Radiometer (SFMR) is the prototype for a new generation of airborne remote sensing instruments designed for operational surface wind estimation in hurricanes.

The SFMR has a downward pointing antenna which passively reads the microwave radiation coming from the ocean surface. By making assumptions about the vertical structure of the atmosphere together with sea surface temperature measurements by a downward-looking airborne infrared radiometer, reasonable estimates of the ocean surface brightness temperature can be made at six frequencies between 4.6 and 7.2 GHz. Wind speeds are then calculated assuming linear increase in wind speed with these brightness temperatures. Since some of the frequencies are more attenuated by rainfall than others, an estimate of the rainfall rate below the airplane can also be made.

Project page for SFMR development
Report on SFMR in Katrina and Rita 2005


  • Press Release

  • NOAA magazine article

  • Jones, W.L., P.G.Black, V.E.Delnore, and C.T.Swift, 1981: Airborne microwave remote-sensing measurements in Hurricane Allen, Science, 214, pp.274-280

  • Black, P., R. McIntosh, C. Swift, J. Carswell, K. St. Germain, I. Popstefanija, and M. Goodberlet, 1995: Ocean surface wind, stress, and rain rate measurements in tropical cyclones from concurrent airborne microwave scatterometer and radiometer measurements. Reprints of the 27th Conference on Radar Meteorology, Vail, CO, AMS, 623-625

  • Uhlhorn, E. W. and P. G. Black, 2003: Verification of remotely sensed sea surface winds in hurricanes. J. Atmos. Oceanic. Tech. , 20, pp.99-116

  • Black, P. G., E. Uhlhorn, M. D. Powell, J. Carswell, 2000: A new era in hurricane reconnaissance: Real time measurement of surface wind structure and intensity via microwave remote sensing. Proc. 24th Hurr. Trop. Meteor., Ft. Lauderdale, FL, American Meteorological Society, 199-200

Eric Uhlhorn
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Updated February 10, 2005

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