1 WP6: Anaprop Modelling U. Essex

2 Anaprop model components Refractivity { height, range, azimuth} from NWP data –NWP data: temp, humidity { pressure, cartesian grid coords of polar stereographic map} Parabolic Equation Method propagation model –Simulated path loss { height, range } at each azimuth Terrain backscatter (dBZ) extraction –Function of incident intensity and wavefront angle with terrain slope PPI display of anaprop model and observed radar reflectivities –Simultaneous display using colour and contour plots on terrain background

3 Regions of high negative modified refractive gradient Modified refractivity, M (r, z) Puig Bernat Radar, Catalunya 03.00,19/07/2003 Azimuth = 250 degrees Colour palette units: Modified refractivity (ppm)

4 High negative modified refractive gradient Low path loss at terrain level at ranges of km and km PEM simulated path loss Radar elevation: 0.7 degrees Radar height: 30 metres Beam bandwidth: ~ 1 degree Frequency: 6 GHz Puig Bernat Radar, Catalunya 03.00,19/07/2003 Azimuth = 250 degrees Colour palette units: One way path loss (dB)

5 PEM simulation Azimuth = 250 o Regions of high reflectivity at ranges of km and km are in good agreement with PEM simulation Observed radar reflectivity

6 Terrain backscatter (dBZ) extraction Terrain backscatter (dBZ) { incident intensity, wavefront angle with terrain slope} –Extract incident field from (incident + reflected) by filtering in elevation angle domain relative to terrain slope at each range step –i.e. via Fourier transform of field amplitude { height} –Derive intensity and angle with terrain slope at terrain level –Apply model of radar backscattering cross section per unit area Function of grazing angle and surface roughness for bare soil model –Express terrain backscatter in dBZ by equating received radar power to that expected from raindrops in absence of anaprop

7 Radar elevation: 0.7 degrees Radar height: 30 metres Beam bandwidth: ~ 1 degree Frequency: 6 GHz Puig Bernat Radar, Catalunya 03.00,19/07/2003 Azimuth = 250 degrees Modelled radar reflectivity

8 Radar elevation: 0.7 degrees Radar height: 30 metres Beam bandwidth: ~ 1 degree Frequency: 6 GHz Puig Bernat Radar, Catalunya 03.00,19/07/2003 Max radar range: 250 km (20km/div) Reflectivity display range: -10 to 70 dBZ

9 Observed radar reflectivity

10 Modelled terrain coast Puig Bernat Radar, Catalunya 03.00,19/07/2003 Max radar range: 250 km (20km/div)