© 2003 University of Essex

Progress of Dual Doppler Radar

Visualisation SoftwareDARWIn

( Doppler Analysis and Retrieval of Wind Information )

Yong Kheng Gohkygoh@essex.ac.uk

http://prswww.essex.ac.uk15-16 December 2003

© 2003 University of Essex

Contents

Part I :

- Status of DARWIn

Part II :

- Case studies

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Status of Software

- Reading SMR data (Bologna & Gattatico)

- Graphics generation: 2-D Visualisation: PPI, RHI, VAD 3-D Visualisation: Velocity vectors

- Data Conversion: polar -> Cartesian

- Construction of wind velocity vectors

- Saving retrieved wind vectors in ASCII file

© 2003 University of Essex

Reading SMR data sets

- Available data set:15 Aug 2003 (1400 - 1857)

17 Dec 2002 (1800 - 2357)

- Data Quality:Weak Z in region of interest

SPC Radar Scan problems (Aug 2003 case)

GAT Radar Time problems (both cases)

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Visualisation I

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Visualisation II

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Visualisation III

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Visualisation IV

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Visualisation V

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Visualisation VI

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Coordinates conversion I

- Grid resolution:0.5 km x 0.5 km (x ~1 km)

- Ray resolution:Spacing 0.25 km

beam width 0.9 deg

approx. 1 km width

- Algorithm:

trap and average

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Coordinates conversion II

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Wind Extraction : Algorithm

- Horizontal componentsdata: radial velocity from 2 radarsVr = u sin(az) cos(el) + v cos(az) cos(el) + W sin(el)W = Wt + w, Wt = 2.6 Z0.107

- Vertical componentMass continuity equation Boundary conditions

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Wind Extraction : boundary conditions

- Currently using V = 0, on ground

- What boundary condition do we want to use?

- Any other information available? Wind vector at 10 m

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Wind Field Data Structure

- Header lines:location of grid center

date/time

data files name

- Data:6 columns

x, y, z, Vx, Vy, Vz

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Case Studies

- Case I : (17 Dec 2002) 1915hr

- Case II : (15 Aug 2003) 1815 hr

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Case I (17 Dec 2002) 1915hr : Gattatico Reflectivity

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Case I (17 Dec 2002) 1915hr :Bologna Reflectivity

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Case I (17 Dec 2002) 1915hr : Gattatico Doppler Velocity

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Case I (17 Dec 2002) 1915hr : Dual-Doppler Wind Field

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Case I (17 Dec 2002) 1915hr : RHI along Radar-to-Radar line

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Case I (17 Dec 2002) 1915hr : Dual-Doppler Wind vs. VAD

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Case II (15 Aug 2003) 1815hr :Bologna Reflectivity

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Case II (15 Aug 2003) 1815hr :Bologna Reflectivity

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Case II (15 Aug 03) 1815hr : Gattatico Reflectivity

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Case II (15 Aug 2003) 1815hr :Bologna Doppler Velocity

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Case II (15 Aug 2003) 1815hr :Dual Doppler Wind Field

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What next ... ?

- More data for analysis

- Extracting vertical wind component

- Testing + verifying DARWIn (Cedric)

- Extraction of clear- air wind

- Comparison with NWP

- Triple Doppler?

© 2003 University of Essex

Summary

●DD-VAD Analysis -- RHIs show Bologna Radar can have problems.

●Conversion -- demonstrates the quality of the polar->cartesian conversion.

●3-D wind field -- examples of retrieved data and problems with boundary conditions.

●Verifying results -- any other info available?