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Polarimetric Radiometer and Scatterometer Measurements

Polarimetric Radiometer and Scatterometer Measurements. Simon H. Yueh Jet Propulsion Laboratory Operational SVW Requirement Workshop, Miami 7 June 2006. Outline. Introduction Coastal Winds off Southern California Active and Passive Measurements for Hurricane Erika in 1997

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Polarimetric Radiometer and Scatterometer Measurements

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  1. Polarimetric Radiometer and Scatterometer Measurements Simon H. Yueh Jet Propulsion Laboratory Operational SVW Requirement Workshop, Miami 7 June 2006

  2. Outline • Introduction • Coastal Winds off Southern California • Active and Passive Measurements for Hurricane Erika in 1997 • Combined Polarimetric Measurements in Monterey Bay in 2000 • WindSat Signals for High winds • Summary

  3. Coastal Wind off Southern California from POLSCAT/DC-8 on 17 Feb 2002 10km

  4. Coastal Wind off Southern California from POLSCAT on 17 Feb 2002 After about 4 hours, wind speed increased by about 4-5 m/s

  5. Polarimetric Radiometry • Microwave emission from sea surfaces is polarized and varies with ocean surface wind speed and direction • Stokes vector describes the full polarization properties of polarized radiation • Measurement techniques • Coherent Correlation measurements • Incoherent power measurements

  6. Symmetry Properties of Polarimetric Radiometer Signals • Tv and Th are symmetric with respect to wind direction. • U and V are odd functions of wind direction

  7. Radar V H f Wind Ocean Surface POLARIMETRIC SCATTEROMETRY • Polarimetric Scattering Matrix VV VH HV HH • Polarimetric Correlation • Theoretical Predictions of Polarimetric Signature of Wind Direction • svv, shh, svh and rhhvv are cosine functions of wind direction • rhhhv and rvvhv are sine functions

  8. Significance of Polarimetry and Combined Active/Passive • Measurements • Inversion • From c2, we get φ, -φ, φ+180 and 180-φ • From s, we get two solutions, φ and 180-φ • Polarimetry will reduce the number of directional solutions • Will enhance the identification of circulation

  9. NUSCAT/WINDRAD Data at 35 m/s Wind Speed in September 1997 NASA P-3 FLIGHT OVER HURRICANE ERIKA IN SEPTEMBER 1997 (AVHRR INFRARED) • Simultaneous 13 GHz radar and multi-frequency radiometer observations • Radar and polarimetric radiometer data showed consistent wind direction.

  10. POLSCAT/WINDRAD ON NCAR C-130 • OCEAN FLIGHTS NEAR MONTEREY, CA IN AUGUST 2000 AND JULY 2002 • STAR FLIGHT PATTERNS OVER MBARI MOORINGS Mooring POLSCAT PALS WINDRAD WINDRAD

  11. POLSCAT DATA FROM ONE STAR FLIGHT PATTERN Over MBARI M2 Mooring on August 16, 2000 • Clear Wind Direction Signals in All Polarimetric Channles at 10 M/S Wind Speed • sVV, sHH, sVH, sHV, and rVVHH are cosine functions • rVVHV, rVVVH, rHHHV, rHHVH are sine functions Upwind

  12. Polarimetric Scatterometer and Radiometer Measurements at 11 m/s on Aug 16, 2000 Crosswind Upwind

  13. QuikSCAT and WindSat MatchupHurricane Isabel

  14. WindSat 10 GHz Data for Hurricane Isabel Rev 3510 • U data show circulation around eye

  15. WindSat Tb Tb(W,f) HOLLAND’S TC MODEL WIND 5 m/s and 20 degree bins Location Velocity of forward motion Central and ambient pressure Radius of maximum wind speed Angle of the maximum wind GMF FOR VERY HIGH WIND • The Approach is based on Young’s technique (JGR 1993) for the estimate of Geosat Altimeter wind speed algorithm • The same technique applied to the QuikSCAT data to develop the model function for very high winds

  16. Holland Model Direction Versus QuikSCAT Wind Direction for Isabel (QuikScat Rev 22012)

  17. WindSat U and V Signals Versus Holland’s Directional Model for Rev 3510 The data from other revs have similar directional features.

  18. Polarimetric WindSat Data Show Response to Hurricane Wind direction • WindSat 10, 18 and 37 GHz data from hurricane Isabel respond to hurricane wind direction • 10 GHz U1 data show strong response at 50 m/s or higher wind speed

  19. WindSat U Model Function and Comparison with Aircraft K-band Data • WindSat U data agree well with aircraft data • Observable passive directional signals for above 30 m/s

  20. Summary • Airborne scattermeter data frequently showed features with a few Km scale • Scatterometer and polarimetric radiometer data show consistent directional signals for 20-35 m/s • Polarimetric scatterometer signals complement the directional characteristics of VV, HH and HV NRCS • WindSat 10-GHz U data showed directional response to ocean wind direction for 50-60 m/s winds. • There were anomalous directional features in V data near eye

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