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Reports and presentations:

• Report to NHC describing 2004 SFMR operational performance
  
• Preliminary analysis of operational SFMR performance in 2004
  
• Impact of SFMR surface wind on NHC operations
  
• Summary of SFMR meeting at the Intergovernmental Hurricane Conference 2005
  
• Other presentations at the Intergovernmental Hurricane Conference 2005
  
• Data collected from 1998-2003

The concept for the first experimental SFMR was proposed by C. T. Swift at the University of Massachusetts Microwave Remote Sensing Laboratory (UMASS/MIRSL) and built by NASA's Langley Research Center in 1978. The SFMR design involved a single nadir-viewing antenna and receiver capable of making measurements of radio emission from the sea surface at four selectable frequencies between 4.5 and 7.2 GHz. The "stepping" procedure allowed for estimating the surface wind speed in hurricanes by correcting for rain-induced effects in the measurements, and therefore enabling recovery of the rainrate. The first measurements by the original SFMR were made from the NOAA WC-130 aircraft in Hurricane Allen in 1980. By making assumptions about the vertical structure of the atmosphere together with sea surface temperature (SST) measurements by a downward-looking airborne infrared radiometer, reasonable estimates of the ocean surface brightness temperature (Tb) were made at 4.5, 5.0, 5.6, and 6.6 GHz. Wind speeds were then calculated assuming a linear increase in wind speed with Tb, independent of frequency. Agreement between surface (20 m) winds extrapolated from the 1500 m flight-level and the SFMR estimates for independent flight legs were within +/-10 %. Despite the success in Allen, this instrument was never again flown into a hurricane.

A second SFMR was designed and built in 1982 under the supervision of C. T. Swift. The number of frequencies was expanded to six between 4.6 and 7.2 GHz, and the instrument integration time was reduced to less than one second resulting in improved spatial resolution. A new retrieval algorithm was also implemented. This instrument was flown on board the NOAA WP-3D in 1984, and during 12 flights during the 1985 hurricane season. The SFMR was further modified in 1986 and initially used for studies of sea-ice structure. Using data obtained in Hurricanes Earl (1985), Gilbert (1988), and Hugo (1989), the empirical emissivity/wind speed relationships were refined to include winds over 60 m/s.

With support from the Office of the Federal Coordinator for Meteorology (OFCM) the existing horn antenna was replaced with a dipole array antenna in 1993. The new antenna with a new set of six frequencies was flown in Hurricane Olivia (1994) and retrieved high-quality wind estimates. Further funds were provided by OFCM for an upgrade of the SFMR's receiver, which allowed for increased calibration stability. The reconfigured SFMR was first flown in Hurricane Jerry in 1995. Minor modifications were made to reduce background noise levels after the 1995 season, and since then the SFMR has flown under this configuration. Following component failures in 2000, the NOAA Office of Oceanic and Atmospheric Research (OAR) supported an instrument repair and again the SFMR returned surface winds during the 2001 hurricane season. Since 1980, the SFMR has flown on over 150 flights in 50 tropical cyclones.

Accomplishments:

• Obtain concurrent/collocated surface wind estimates from HRD and AOC SFMRs and GPS dropwindsondes -- Status: completed 16 missions in 3 hurricanes (Frances/Ivan/Jeanne)
• Send report to NHC on performance of SFMR during landfalls of Hurricanes Ivan and Jeanne -- Status: completed Oct. 2004
• Obtain raw measurements for both SFMR systems from AOC -- Status: completed Dec. 2004
• Post-processing of HRD SFMR measurements -- Status: completed Jan. 2005
• Post-processing of AOC SFMR measurements -- Status: completed Feb. 2005
• Presentation of initial results of intercomparison between HRD and AOC SFMR wind measurements at 59th IHC -- Status: completed March 2005
• Updated calibration for AOC SFMR and testing of alternative calibration procedures -- Status: completed April 2005
• Post-processing of GPS sonde surface wind estimates -- Status : completed April 2005

• Indentifying collocated SFMR and GPS surface wind estimates and performing statistical analyses -- Status: Expected completion 3rd Q 2005
• Calibration flights to test results in prepartation for 2005 season -- Status: Expected completion 3rd Q 2005
• Execute 2005 flight missions to collect additional data and test new calibration procedures -- Status: Expected completion 4th Q 2005
• Prepare final report documenting results of evaluation report -- Status: expected completion 4th Q 2005

• Press release

• Magazine article

• Haiyan,J., P.G.Black, E.Zipser, F.D.Marks, and E.W.Uhlhorn, 2005: Validation of rain rate estimeation in hurricanes from the Stepped Frequency Microwave Radiometer : algorithm correction and error analysis, submitted to Jour. of Atmos. Sci.

• Jones, W.L., P.G.Black, V.E.Elnore, 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, pp.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, pp.199-200.

Last modified: 2/23/2005