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Ground-based and Space-based Radar Precipitation Imaging V.Chandrasekar Colorado state University

Ground-based and Space-based Radar Precipitation Imaging V.Chandrasekar Colorado state University January 28, 2008. Introduction CSU-CHILL radar - PPI (Plan Position Indicator) scan - RHI (Range Height Indicator) scan Tropical Rainfall Measurement Mission (TRMM)

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Ground-based and Space-based Radar Precipitation Imaging V.Chandrasekar Colorado state University

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  1. Ground-based and Space-based Radar Precipitation Imaging V.Chandrasekar Colorado state University January 28, 2008 Symposium on Imaging

  2. Introduction • CSU-CHILL radar • - PPI (Plan Position Indicator) scan • - RHI (Range Height Indicator) scan • Tropical Rainfall Measurement Mission (TRMM) • - Precipitation Radar (PR) Symposium on Imaging

  3. CSU-CHILL radar : New antenna installation Symposium on Imaging

  4. Example of PPI scan Symposium on Imaging

  5. Example of RHI scan Symposium on Imaging

  6. The received signal corresponds to resolution volume determined by the transmit pulse width & beam width • Backscattered signal in weather radars is from distributed target • Cross range resolution is dependent on the antenna beam width and range Symposium on Imaging

  7. Symposium on Imaging

  8. Symposium on Imaging

  9. - + + - + - - + + - + - + - + - + - + - Waveform Coding at CSU-CHILL radar • Intrinsic backscattering properties of hydrometeor in a linear polarization basis enables the measurements such as size, shape and spatial orientation • Intrinsic backscattering properties of hydrometeor is described by the backscattering covariance matrix Symposium on Imaging

  10. Ev Eh Waveform Coding at CSU-CHILL radar Backscattered signal from horizontal polarization Backscattered signal from vertical polarization • Backscattering covariance matrix is given by Symposium on Imaging

  11. H- Receiver Dual Channel Digital Waveform Generator H-Transmitter H Duplexer STALO V-Transmitter V V- Receiver REF OSCILLATOR Waveform Coding at CSU-CHILL radar • The received signal in the two polarization channels can be written as • The covariance matrix of the received signal is given by Symposium on Imaging

  12. Waveform Coding at CSU-CHILL radar Reflectivity from (a) Alternate mode (20:34:00 UTC) (b) Walsh coded simultaneous mode (20:28:51 UTC). Data collected by CSU-CHILL on May 29, 2007 LDR estimated from (a) Alternate mode (20:34:00 UTC) (b) Walsh coded simultaneous mode (20:28:51 UTC). Data collected by CSU-CHILL on May 29, 2007 Symposium on Imaging

  13. Networked System Processing KCYR KSAO KRSP KLWE Symposium on Imaging

  14. Networked System Processing Tornadic circulation feature; wind speeds greater than 40 m/s (90 mph) UNFILTERED FILTERED Symposium on Imaging

  15. Networked System Processing Measurement at each radar node Networked retrieval Symposium on Imaging

  16. Reflectivity retrieval in a networked radar environment: Demonstration from IP-1 radar network Symposium on Imaging

  17. Before After KTLX May 7, 2007 CSE Symposium on Imaging

  18. Before After KTLX May 8, 2007 CSE Symposium on Imaging

  19. TRMM-PR : orbital and observatory characteristics • TRMM : Tropical Rainfall Measurement Mission - Joint mission between NASA and JAXA - Observing precipitation over tropical regions between 37oS and 37oN - Satellite was lunched in 1997 • PR : Precipitation Radar (installed on TRMM) • - 13.8 GHz Ku-band radar • - Horizontal resolution at nadir : 4.3 km. • ( 5 km. postboost) • - Range resolution : 250 m. • - Swath width : 215 km. ( 245 km postboost) • - Altitude : 350 km. ( 402.5 km postboost) • Note : TRMM was boosted in altitude in August 2001 A hurricane in TRMM-PR track 215 km. Symposium on Imaging (Adopted from TRMM data user handbook, 2001)

  20. Ground and Space-based radar volume matching • Performance and system cross validation Symposium on Imaging

  21. Geometry of pulse volume and resolution degradation effect of space-based radar measurement. Effective vertical resolution = xr + xb = h*cosθ + r θB sin θ Effective horizontal resolution = hr + hb = h*sinθ + r θB cos θ to surface Symposium on Imaging

  22. Geometric distortion in the space-base radar image caused by platform motion Symposium on Imaging

  23. Difference in resolution between space and ground-based radar images • A couple example from simultaneous observations between NEXRAD and TRMM TRMM-PR NEXRAD : KAMX Miami, FL Symposium on Imaging

  24. TRMM-PR NEXRAD : KEVX , Red Bay/Eglin, FL Symposium on Imaging

  25. 3-D volume matching and shifting based on GR and SR resolution volumes Symposium on Imaging

  26. Matched and Aligned images between SR and GR GR SR Symposium on Imaging

  27. Matched images of a tropical storm in Bay of Bengal GR (SHAR, India) SR (TRMM-PR) Symposium on Imaging

  28. Summary • The Radar research group works on a variety of problems all the way from • Design and development of imaging sensors • Analysis of images for interpretation and • Cross validation of images from multiple platforms • Developing hardware, theory algorithms and and novel applications Symposium on Imaging

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