Simulation of airborne radar observations of precipitating systems at various frequency bands

The choice of the microwave frequency is of considerable importance for precipitating system observations by airborne radar. Currently, these radars operate at X-band (f = 10 GHz), although other frequency bands, may be used jointly or not. Since the measured reflectivity Z_m is f-depending, different physical information about precipitating systems could be obtained. Herein, a comparison of reflectivity fields at different frequency bands is presented. A realistic and flexible model of precipitating systems is presented and simulations of airborne radar observations are performed. Simulated reflectivity fields are degraded as/increases because of Mie effects and microwave attenuation. At S, C and X-bands, attenuation is weak and Mie effects slightly increase the backscattered signal such that they can compensate attenuation at X and K_u bands. The K_a and W-bands suffer from a strong attenuation and significant Mie effects which seriously alter Z_m-fields. For a squall line, the closer convective tower hides the farther ones, which is problematic for a pilot to estimate hazard at long distance. In addition, because hail is the main meteorological hazard for civil aviation, hail-rain discrimination is discussed and clarified for convective systems. It appears that S, C, and X-bands are the best ones, but the significant size of antenna used is prohibitive. Higher frequencies are more difficult to use on civil aviation due to high ambiguities and a too strongly attenuated microwave signal.