High resolution 3D wind profiling using

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

• Measurement configuration

15o
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

• Main beam polarimetric dealiasing technique

• Expected differential phase 0 at S-band
• Measured differential phase shows different mean
  values in case of aliasing

6

• Main beam polarimetric dealiasing technique

7

• Main beam polarimetric dealiasing technique

8

• Profiles of mean Doppler velocities for the 3
  beams

Classical dealiasing
Polarimetric dealiasing
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

• Main beam polarimetric dealiasing technique

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
12

• Offset beam classical dealiasing technique

Aliased Doppler spectra
Precipitation event slant profile
Doppler velocity m/s
13

• Offset beam classical dealiasing technique

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