Status of Dual-Doppler Wind Retrieval Project Carpe Diem 6 th Meeting Helsinki 24 June 2004 by Kheng University of Essex
Recall in Dublin ● What we have done – Shown visualisation examples produced by DARWIn – Converted Polar data -> Cartesian – Successfully constructed 3D wind fields – Shown 2 case studies
Coordinates conversion II
Case I (17 Dec 2002) 1915hr : Dual-Doppler Wind Field
Case Studies - Case I : (17 Dec 2002) 1915hr - Case II : (15 Aug 2003) 1815 hr
Case I (17 Dec 2002) 1915hr : Gattatico Doppler Velocity
Case II (15 Aug 2003) 1815hr : Dual Doppler Wind Field
Remarks from Dublin meeting ● Problems & comments – Limited data sets – How to verify validity of the constructed 3D wind fields. – Triple Doppler retrieval – Comparison with NWP model
New data sets ● 2003 July 13 – 14 – Bologna, Gattatico, scan time (00, 12, 15, 27, 30...) ● 2003 July 31 – Bologna, Gattatico, Teolo ● 2003 September 09 – Bologna, Gattatico ● 2003 November 11 – Bologna, Gattatico, Teolo
Case 1: (2003 Jul 13) 2330 hr 3.2 o PPI – Reflectivity Gattatico Bologna
Case 1: (2003 Jul 13) 2330 hr 3.2 o PPI – Doppler Velocity Bologna Gattatico
Case 1: (2003 Jul 13) 2330 hr 3.2 o Wind Field
How do we know that the wind field is correct?
Numerical procedures ● Iterative method: – horizontal components – vertical component ● Boundary conditions: – zero velocity on ground ● Typical convergent factor
Comparison of reconstructed radial velocity field and radar measurement measurement reconstruction Gattatico Bologna
“along-track” components r1r1 r2r2 r 12 v. (r 12 + r 2 – r 1 ) = 0 = v (cal).r 12 + v r2 (obs) r 2 – v r1 (obs) r 1 Typical relative deviation, /(v.r 12 ) < ±1% v
Case 2: (2003 Jul 31) 1734 hr 3.1 o PPI – Gattatico ZDRReflectivity
Case 2: (2003 Jul 31) 1734 hr 3.1 o PPI – Gattatico ZDR Reflectivity
Case 2: (2003 Jul 31) 1734 hr 3.1 o PPI – Bologna ZDRReflectivity
Case 2: (2003 Jul 31) 1734 hr 3.1 o PPI – Bologna ZDR Reflectivity
Possibility of performing triple- Doppler analysis? we are still trying because of...
Case 2: (2003 Jul 31) 1730 hr 2.5 o PPI – Teolo Doppler velocity Reflectivity
Case 2: (2003 Jul 31) 1730 hr PPI – Doppler Velocity Teolo 2.5 o Gattatico 3.1 o
Case 2: (2003 Jul 31) 1730 hr PPI – Doppler Velocity Teolo 2.5 o Gattatico 3.1 o
Problems with Triple-Doppler ● Teolo – many rays are missing ● Teolo – Doppler radial velocity convention ● Teolo – 470 m asl, lowest elevation 0.9 deg – Minimun height ~ 1400 m (centre) ● Gattatico & Bologna – ? m asl, lowest elevation 0.5 deg – Minimun height ~ 600 m (centre) – Next elevation ~ 1400 m (centre)
Case 3: (2003 Sep 09) 1315 hr 2.3 o PPI – Reflectivity Gattatico Bologna
Case 3: (2003 Sep 09) 1315 hr 2.3 o PPI – Doppler Velocity Gattatico Bologna
measurement reconstruction Case 3: (2003 Sep 09) 1315 hr 2.3 o PPI – Radial Velocity Comparison Gattatico Bologna
Case 3: (2003 Sep 09) 1315 hr 3D wind field
Case 4: (2003 Nov 11) 0349 hr 2.3 o PPI – Reflectivity Gattatico Bologna
Case 4: (2003 Nov 11) 0349 hr 2.3 o PPI – Doppler Velocity (folding problem) Gattatico Bologna
Case 4: (2003 Nov 11) 0349 hr 4.8 o PPI – ZDR (bright band)
Case 4: (2003 Nov 11) 0350 hr 2.5 o PPI – Teolo Doppler velocity Reflectivity
measurement reconstruction Case 4: (2003 Nov 11) 0345 hr 1.4 o PPI – Radial Velocity Comparison Gattatico Bologna
Case 4: (2003 Nov 11) 0345 hr Wind Field
Comparison with NWP model? a CD with radar data has been sent to SMHI and wind field information of several cases have been made available for comparison...
Conclusion ● Analysed a few more new cases. ● All the derived wind fields have been checked by comparing with original measurement and calculating relative deviation of “along-track” component. ● Made initial attempts on triple-Doppler analysis, but need more time to understand Teolo data.