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WP6: Anaprop Modelling

This model utilizes NWP data to calculate refractivity, simulate path loss, and extract terrain backscatter. It provides a PPI display of anaprop model and observed radar reflectivities, allowing for simultaneous analysis.

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WP6: Anaprop Modelling

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  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) Colour palette units: Modified refractivity (ppm) Puig Bernat Radar, Catalunya 03.00,19/07/2003 Azimuth = 250 degrees

  4. Low path loss at terrain level at ranges of 87-91 km and 136-138 km High negative modified refractive gradient PEM simulated path loss Colour palette units: One way path loss (dB) 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

  5. Regions of high reflectivity at ranges of 87-91 km and 136-138 km are in good agreement with PEM simulation PEM simulation Azimuth = 250o 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. Modelled radar reflectivity Puig Bernat Radar, Catalunya 03.00,19/07/2003 Radar elevation: 0.7 degrees Radar height: 30 metres Beam bandwidth: ~ 1 degree Frequency: 6 GHz Azimuth = 250 degrees

  8. Modelled radar reflectivity Max radar range: 250 km (20km/div) Reflectivity display range: -10 to 70 dBZ 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

  9. Observed radar reflectivity

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

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