1. Carpe Diem Kickoff1 CARPE DIEM University of Essex Anthony HoltDavid BebbingtonMartin Fleury Stephan Siemen + …………..

2. Carpe Diem Kickoff2 Work packages WP6 - Anomalous Propagation - implementation of hybrid PEM integrated with LAM WP2 - Doppler Windfields - 3-D wind field synthesis from dual Doppler data. Polarization Review - review of dual polarization techniques in operational weaher radar contexts

3. Carpe Diem Kickoff3 WP2 - Doppler Windfields Dual Doppler Synthesis 3-D windfields may be retrieved using near simultaneously scanned Doppler from two radars in overlap away from baseline. Dual Doppler Synthesis 3-D windfields may be retrieved using near simultaneously scanned Doppler from two radars in overlap away from baseline. co-plane r1 r2 u baseline Divergence condition enables 3-D field to be recovered by integration given boundary conditions Divergence condition enables 3-D field to be recovered by integration given boundary conditions

4. Carpe Diem Kickoff4 Dual Doppler in PADRE Project SMR San Pietro Capofiume CSIM Teolo (PD) 80km

5. Carpe Diem Kickoff5 Dual Doppler Synthesis Dual Doppler windfield slice at 1.5 km using NCAR CEDRIC (R.J. Watson Thesis 1996)

6. Carpe Diem Kickoff6 WP6 - Anomalous Propagation Anomalous propagation can create radar returns from terrain due to partial or total beam bending when strong negative refractive gradients occur. Apparent elevation Actual trajectory M(z) z Strong surface ’reflectivity’ PRECIP or ANAPROP? PRECIP or ANAPROP? 

7. Carpe Diem Kickoff7 ANAPROP event from DARTH Project 100 km Raytrace from HIRLAM model fields predicts RRI and position of ANAPROP

8. Carpe Diem Kickoff8 Parabolic equation methods: PEM ‘Split-step’ parabolic equation methods allow efficient numerical solution of radar wave field in atmosphere with stratified RRI M(T,q) = 10 6 (m-1) Solutions advanced between adjacent coordinate planes. Wavefront sampling must be dense to avoid aliasing: O(100 m) < /2 per sample zz Equation becomes 1st order ODE in Fourier z  p domain: O(1 m)

9. Carpe Diem Kickoff9 Hybrid method: Ray/PEM It can be shown that the methodology for the PEM applies Huyghens’ principle with stationary phase integration. The constructed field closely fulfills Green’s Theorem applied to the Helmholtz equation. It is not necessary to select coordinate planes: any series of surfaces for which stationary phase points can be determined will do. The hybrid method generates surfaces orthogonal to local ray trajectories - surfaces that are very nearly parallel to the wave front. Phase aliasing is avoided, resulting in order of magnitude reduction in wavefront sampling The hybrid method generates surfaces orthogonal to local ray trajectories - surfaces that are very nearly parallel to the wave front. Phase aliasing is avoided, resulting in order of magnitude reduction in wavefront sampling Approximate wavefront