Blending Extrapolated Radar Reflectivity with Model Simulated Reflectivity for a Seamless Significant Convection Nowcast in support of Meteorological Services for the Terminal Area

Significant convection is vital information for pilots and air traffic controllers in inclement weather situations. The performance of conventional nowcasting system normally drops rapidly beyond 2 hours or so due to the limitation in the simple extrapolation scheme. To improve that, blending with high resolution non-hydrostatic numerical weather prediction model is one of the promising approaches as model can provide system evolution information and thus address a major limitation of simple extrapolation scheme, namely storm growth and decay. We have enhanced a high resolution non-hydrostatic NWP model to generate simulated radar reflectivity data from prognostic variables of different water species. These simulated radar parameters, after calibration, are blended with the radar-based nowcasting system to generate a seamless product on significant convection within the FIR for the next 0-6 hours.

This paper presents an experimental blending algorithm that merges the extrapolated and model simulated radar reflectivity. The algorithm extracts the time evolution information of the convection systems as predicted by the NWP model and integrates them with the extrapolated radar reflectivity. Preliminary performance of this blending method will also be highlighted in this paper.

The seamless significant convection nowcast would be useful for generating the trajectory-based convection forecast and for estimating the impact of the significant convection on the planned flight path in support of the ASBU Block 1 and 3 of the Global Air Navigation Plan development which has been adopted by ICAO for the next generation of civil aviation initiative in the next 15 or more years.