Detection of Turbulence with Airborne Weather Radars using Space-Time Filtering

Detection of hazardous atmospheric zones with a high level of turbulence is a crucial problem for airborne weather radars. Usually it is solved via estimation of the spectrum width of weather echoes. Unfortunately atmospheric turbulence is not the only phenomenon that increases the spectrum width in airborne weather radars. Spectrum spreading of the same kind is introduced by the finite value of the antenna beamwidth because each scatterer within a resolution volume has its own Doppler shift even if it is not involved in turbulent motion. Implementation of space-time (2D) filtering in airborne weather radars to discriminate these two phenomena is considered in the correspondence. A dual channel (monopulse) antenna system is proposed for the realization of the 2D filter. It is shown that the filter can suppress reflections from weather targets with a low level of atmospheric turbulence and its output can be used to detect the presence of a pronounced turbulence via a simple threshold test.