Delft University of Technology 1 Do eddy dissipation rate retrievals work for precipitation...

DelftUniversity ofTechnology 1

Do eddy dissipation rate retrievals work for precipitation profilingDoppler radar?, CESAR Science Day, June 18th, 2014

Do eddy dissipation rate retrievals work for precipitation profiling

Doppler radar?A.C.P. Oude Nijhuis, C.M.H. Unal, O.A. Krasnov, H.W.J. Russchenberg and A.

Yarovoy



Introduction & Motivation



We all want a safe flight...

EXCLUSIVE: 'WAKE TURBULENCE' & PILOT ERROR COULD HAVE CAUSED SFO ASIANA CRASH (7 Jul 2013)



We all want a safe flight...



Air planes can crash because of a WV when:* They hit a wake vortex* They experience a roll moment* They are close to the ground* They have little time to correct



Solution to increase capacity???* Montoring WVs



Solution

- New radars and lidars have higher sensitivities.- They can scan the glide slope and detect the WVs and weather hazards.



Solution

WVs and weather hazards can be monitored under all weather conditions by using scanning radars and lidars!

???????!!!!???????

Solution to mitigate weather hazards and increase airport capacity:



WV monitoring along the glide slope

Touch - Down Area

Runway 3000 m / 60 m (typically)

Wind Final Approach Fix (FAF)

ILS Interception Area

Altitude between 2000 and 6000 ft (typically)

H = 400 ft

400 m 2500 m

25 000 m

ILS Glide Slope

5 500 m

Final Approach

Landing

Mode-S Downlink

Radar/Lidar Sensors



We would like to improve turbulence retrievals and improve wake vortex monitoring. How to do this?

WV and turbulence monitoring

Imrpove turbulenceretrievals

ImproveWV monitoring

Improve wind retrievals

Improve WV detection and retrievals

Measurement analysis:Use CESAR.

Simulations



We would like to improve turbulence retrievals and improve wake vortex monitoring. How to do this?

• Use the Cabauw research site and apply EDR retrievals to the available radars.

• Try to answer the question how radars and lidars can be used to retrieve turbulence.

• Make a validation with other instruments to conclude whether the results are reliable.

WV and turbulence monitoring



Do eddy dissipation rate retrievals work for preciptation profiling

Doppler radar?methods



Cabauw research site

TARA (S-band RADAR) measures the vertical Doppler verlocities at Cabauw.

330 m

Tower with sonic anemometer at 180 m. (and other levels)Atmospheric

Profilingbetween 180 m and ~ 15 km.



Methods

The eddy dissipation rate (EDR) is based on the assumption of homogenous isotropic frozen turbulence. In the inertial sub-range the dissipation goes with a -5/3 power.

Figure from O'Connor (2010).



Methods

Several retrieval methods are possible:• Use the Doppler spectral width. • Use a sequence of Doppler velocities. Several methods exist

for analysis: 1. variance, 2. power spectrum, 3. structure functions.

The eddy dissipation rate (EDR) is based on the assumption of homogenous isotropic frozen turbulence. In the inertial sub-range the dissipation goes with a -5/3 power.



Do eddy dissipation rate retrievals work for preciptation profiling

Doppler radar?Results



Application to sonic anemometers

Measurements from the sonic anemometers on June 21st 2012.•10 Hz vertical speeds are converted into EDR values with different methods.•Time domain is used, and average horizontal wind speed is used.•10 minutes of data are used.



Application to TARA

Measurements from the TARA on June 21st 2012.•Vertical speeds (terminal fall speed subtracted) are converted into EDR values with different methods.•Time domain is used, and average horizontal wind speed is used.•10 minutes of data are used.



Application to TARA

Measurements from the TARA on June 21st 2012.•Doppler spectral width are converted into EDR values.•Eq. Refl. is used to estimate the drop size distribution.



Problem!

One storm event is not giving any conclusive analysis…

… solution: use one year of TARA and CESAR data for analysis.



Solution

Apply edr retrievals to one year of TARA data and sonic anemometer data.

Make scatter density plots of all variables against all variables to understand what is gonig on.

Parameters•BSRN site (radiation parameters)•IDRA reflectivity•Nubiscope cloud cover•Sonic wind speed, wind direction, EDR•TARA reflectivity, wind speed, wind direction, EDR•Tower temperature, humidity, etc.



First results

• Different EDR methods applied to the sonic anemometer look ok.

• Different EDR methods applied to TARA look ok.• Comparison of wind direction between TARA and sonic

goes well.• Comparison of EDR form TARA against sonic

anemometer does not go well.• Variance in differential reflectivity can be an interesting

parameter for the estimation of EDR.

http://homepage.tudelft.nl/4n06h/cesar_scatterplots/test.html



Outlook

• Check for bugs and/or errors.• Use angular statistics for comparison of direction.• Use 10 min. average for comparison of wind speed and

wind direction.• Do the analysis for different rain intensities

• Simulations for better understanding• Develope advanced algorithms



Outlook

fall speed Spectral fall speed width

Delft University of Technology 1 Do eddy dissipation rate retrievals work for precipitation...

Documents

Transcript of Delft University of Technology 1 Do eddy dissipation rate retrievals work for precipitation...