Possible Detection of insects in an urban environment as detected by a frequency modulated-continuous wave radar

Frequency modulated-continuous wave (FM/CW) radars have been used for a number of years to investigate the evolution of the convective boundary layer. Typically the radars were positioned in rural environments as part of larger experiments. During the summer of 2003 the West Desert Test Center deployed a 2.9 GHz FM/CW radar just north of the central business district of Oklahoma City, OK in support of the Joint Urban 2003 urban dispersion experiment. We found that in this urban region insect behavior exhibit a strong diurnal cycle; insects are typically dormant during the day and active at night. On nights where the radar return signal was not contaminated by precipitation or clouds, the insects emerged several hours before sunset and reached a peak concentration near midnight. The insect density decreased gradually until most of the insects had either returned to the ground or moved to another location by sunrise. Other features suggest a high concentration of insects at altitudes of 3 km. The imagery suggests that the insects are either migrating or are trapped by elevated inversions above the convective boundary layer.