1. Advanced Signal Processing for Airborne Data in Severe Weather
D. Emmitt, K. Godwin and S. Greco
WG-SBLW
2-4 February 2010

2. Issues related to severe weather airborne DWL investigations
Platform motion
Seldom straight and level
Strong horizontal wind gradients
Need to get VADs complete rapidly
Trade sensitivity for rapid revisit
Surface layer returns over water are “messy”
Much information that is difficult to extract automatically

3. Focus on Layer Adjacent to the Surface (LAS)
Potential information from DWL
Wind speed (removing surface contribution)
Wave motion(wave lengths)
Presence of foam
Presence of sprays
TKE

4. What we have to work with
50 meter range resolution (Gausian pulse ~ 70 meters FWHM)
10 cm beam diameter
Spectral domain
Frequency
Spectral feature width
Frequency discrimination of multiple LOS motions

5. Processing tools Threading Sliding range gates Movies (contextual)
Filtering

6. LAS
Water
Spectrum for range gate 20 associated with data taken at
33 degrees off nadir. The data has not been fully corrected
for the aircraft forward motion

7. Monitor Pulse Amplitude Versus Frequency
Amplitude: Black Dots
Frequency:
Open Squares

8. Shift from Aerosol to Ground Peak in Amplitude

9. DWL over swell with small wind waves (~ 22 knots)
Water

11. DWL over very disturbed water surface (~60 knots)
Water Hagupit

12. Example of the ocean surface
C: \DWL_labs\P3DWL_soft