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High resolution 3D wind profiling using an S-band polarimetric FM-CW radar: dealiasing techniques

High resolution 3D wind profiling using an S-band polarimetric FM-CW radar: dealiasing techniques Christine Unal, Herman Russchenberg Delft University of Technology, The Netherlands Dmitri Moisseev Colorado State University, Fort Collins, CO, USA Type of measurement

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High resolution 3D wind profiling using an S-band polarimetric FM-CW radar: dealiasing techniques

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  1. High resolution 3D wind profiling using an S-band polarimetric FM-CW radar: dealiasing techniques Christine Unal, Herman Russchenberg Delft University of Technology, The Netherlands Dmitri Moisseev Colorado State University, Fort Collins, CO, USA Type of measurement First main limitation: small Maximum Unambiguous Doppler velocity Dealiasing techniques (polarimetric and classical) Example of Wind retrieval results

  2. Goal: Dynamics and Microphysics of Precipitation and Clouds Sensor: Doppler polarimetric radar TARA (S-band) High resolution in space (30-3 m) and time (1-10s) Location: Atmospheric profiling site Cabauw (synergy with other sensors)

  3. vertical OB1 MB OB2 MB VV HV HH OB1 OB2 The max. unambiguous Doppler velocity is reduced by a factor 5 time 15o elevation 750 Y X 15o Measurement configuration 3 beams  3 mean Doppler velocities  horizontal wind + vertical wind

  4. Polarimetric de-aliasing Expected differential phase ~ 0 at S-band Measured differential phase: Non simultaneity of VV and HH measurements Maximum unambiguous Doppler speed Measured Doppler speed

  5. Expected differential phase ~ 0 at S-band • Measured differential phase shows different mean values in case of aliasing Main beam: polarimetric dealiasing technique

  6. Main beam: polarimetric dealiasing technique

  7. Main beam: polarimetric dealiasing technique

  8. Classical dealiasing Polarimetric dealiasing Profiles of mean Doppler velocities for the 3 beams

  9. Resulting horizontal wind retrievals

  10. Conclusions High resolution profiling of horizontal wind in precipitation and clouds example with time resolution = 5 s and range resolution = 30 m What has still to be done Improved clutter suppression for non polarimetric beams Separation between fall velocities of hydrometeors and vertical wind Correction for effects of beam divergence (possible limitation for high altitudes clouds) First Objectives Dynamics of the boundary layer. Preparation for study of cloud-aerosol interaction.

  11. Applying the classification in 5 intervals, the Doppler spectra bins of targets with rco smaller than 0.78 are placed in the wrong interval of Doppler velocities Clutter and noise reduction Main beam: polarimetric dealiasing technique

  12. Aliased Doppler spectra Offset beam: classical dealiasing technique Precipitation event slant profile Doppler velocity [m/s]

  13. Resulting spectrograph with dealiasing + noise reduction Search for signal above noise level at Unfolding (using max. spectral reflectivity) Reference: Doppler spectrum of cloud Range continuity check with a cross correlation function Offset beam: classical dealiasing technique

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