Classifying Bird and Insect Radar Echoes at S Band

Current Hydrometeor Classification Algorithm (HCA) of the WSR-88D radars features a class “Biological” for radar echoes from birds and insects. The HCA is not capable of separating echoes from birds from echoes from insects. Such a separation is important for meteorology, aviation, agriculture, and ecology. Birds are active fliers; they bias the radar estimation of the wind significantly. Insects are good wind tracers therefore the selection of radar echoes from insects can be used for better estimation of the wind which is one of the major meteorological parameters. Flying birds are a hazard for aviation. In 2015, 13,795 collisions of birds with aircrafts and helicopters were recorded by FAA with an annual loss of $229 million. Insects are not dangerous for aviation but produce similar echoes to birds. The detection of birds by radar would be beneficial for the air traffic management.

A fuzzy logic algorithm for separating of bird echoes from insect echoes using the dual polarization Next Generation Radar (NEXRAD) WSR-88D and considering range effects has been developed. September is a peak migrating season for birds. Radar data was analyzed from all clear air days in September 2017 to verify the composition of clear air echoes. The membership functions are derived directly from the distributions of radar variables and weighted in an objective manner. The algorithm has been tested on three cases. Two cases with known Monarch butterfly abundance, confirmed by the US Department of Agriculture (USDA) are correctly identified as being insect dominated. One classification for a 24-hour period further confirms that birds (insects) are responsible for most night (day) time radar echoes.