WE3.L09 - RAIN EFFECT ON POLARIMETRIC SAR OBSERVATION

RAIN EFFECT ON POLARIMETRIC SAR OBSERVATION Hiroaki Yasuma and Hajime Fukuchi Tokyo Metropolitan University Dept. of Aerospace Engineering July 28, 2010

INTRODUCTION (1) Distortions in the SAR observational data come from various factors. Absorption by the atmosphere （ oxygen, water vapor, and so on. ） Scattering by the weather particle （ Rain, snow, fog, and hail, etc. ） It is essential to know the radio propagation characteristics. Faraday Rotation (FR) （ Phenomenon of polarization rotation ） Observation Frequency Example of SAR Meteorological Particle FR X-Band TerraSAR-X (9.65 GHz) Important Negligible Negligible Important C-Band RADARSAT-2 (5.405GHz) L-Band PALSAR (1.27GHz)

INTRODUCTION (2) ,[object Object],[object Object],[object Object],[object Object],[object Object],TerraSAR-X. © EADS Astrium

IN CASE OF TerraSAR-X ,[object Object]

[object Object],PURPOSE OF RESEARCH Evaluate the effects of rain quantitatively ・ Observation frequency ・ Rainfall rate ・ Incident angle ・ Canting angle of rain drops ・ Rain area length

POLSAR OBSERVATION MODEL The scattering matrix S sequentially receives turbulence in the propagation route. Ice Layer P: Ice Distortion Matrix Ionosphere F: Faraday Rotation Receive Antenna R Transmit Antenna T Rainfall Q: Rain Distortion Matrix Land Surface S: Scattering Matrix When rainfall is the only error source If Q is computable with already known S , M can be obtained

THE RAIN EFFECT AREA ,[object Object],SAR Rainfall Area A Rain drops Rainfall SAR Area B ,[object Object]

THE MAJOR THREE EFFECTS BY RAIN ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

ATTENUATION RATIO ,[object Object],[object Object],Incident waves Attenuated waves H passes through the rain drop more than V. Rain drop

DEPOLARIZATION ,[object Object],[object Object],Canting angle Incident wave Attenuated wave

ESTIMATE THE RAIN DISTORTION MATRIX (Q) ,[object Object],Derivation of Q : Oguchi’s method* Rain Shape: Pruppacher-and-Pitter Drop Size Distribution: Marshall-and-Palmer Rain Area Length: 5 km Incident Angle: 40° Canting Angle: 0 ° or 45 ° Scattering Matrix : (Plate or Trihedral) * Tomohiro Oguchi, “Scattering properties of Pruppacher-and-Pitter form rain drops and cross polarization due to rain: Calculation at 11, 13, 19.3 and 34.8GHz,” Radio Science , vol. 12, no. 1, pp. 41-51, 1977.       1 0 0 1

ESTIMATION RESULTS: RAIN-INDUCED ATTENUATION ,[object Object],Canting angle: 0° Rain Attenuation [dB/km]

ESTIMATION RESULTS: ATTENUATION RATIO Canting angle: 0° ,[object Object]

ESTIMATION RESULTS: DEPOLARIZATION Canting angle: 45° ,[object Object]

ESTIMATION RESULTS: POLARIZATION SIGNATURE ,[object Object],Rain rate: 50 [mm/h] Canting Angle: 22.5° Derivation of Q : Oguchi’s method Rain Shape: Pruppacher-and-Pitter Drop Size Distribution: Marshall-and-Palmer Rain Area Length: 5 km Incident Angle: 40° Scattering Matrix : (Plate or Trihedral)       1 0 0 1

Trihedral (or Plate) Reflector: S= Co-pol. Cross pol. Ideal

Trihedral (or Plate) Reflector: S= 5.405 [GHz] Co-pol. Cross pol.

Trihedral (or Plate) Reflector: S= Co-pol. Cross pol. 9.65 [GHz]

Trihedral (or Plate) Reflector: S= Co-pol. Cross pol. 13.9 [GHz]

CONCLUSIONS ,[object Object],[object Object]

REFERENCES ,[object Object],[object Object],[object Object]

WE3.L09 - RAIN EFFECT ON POLARIMETRIC SAR OBSERVATION

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