access icon openaccess Investigating vertical motion of small insects in atmospheric boundary layer using millimetre-wavelength radar and Doppler LIDAR

It is well known in the meteorological community that millimetre-wavelength cloud radars contain considerable contamination from aerial biota, and much of this comprises small weakly flying insects. Several methods have been explored for removing insect contamination from cloud radar data yet using this data to study the behaviour of insects remains a relatively unexplored area. Here, the authors describe the use of a collocated Ka-band cloud radar and Doppler LIDAR to study the vertical motion of small insects and investigate how this varies depending on the surrounding vertical air motion. We find that in the convective boundary layer, insects are largely concentrated in updrafts. During the daytime, small insects in downdrafts are found to descend at an average rate of 0.25 m s−1, yet insects caught in updrafts showed a descent response that was dependent upon the strength of the updraft in which they were embedded. Although the downward motion of the insects increased with increasing updraft strength, it was insufficient to overcome the rising motion in the updraft, i.e. in updrafts the insects ascend but at a slower speed than the surrounding air. We also report an ongoing efforts to extend this research to the nocturnal stable boundary layer.

Inspec keywords: optical radar; meteorological radar; atmospheric techniques; atmospheric turbulence; atmospheric humidity; clouds; convection; remote sensing by radar; atmospheric boundary layer

Other keywords: insects ascend; millimetre-wavelength cloud radars; weakly flying insects; millimetre-wavelength radar; velocity 0.25 m/s; surrounding vertical air motion; atmospheric boundary layer; Doppler LIDAR; cloud radar data; vertical motion; updraft; collocated Ka-band cloud radar; insect contamination

Subjects: Atmospheric boundary layer structure and processes; Radar equipment, systems and applications; Instrumentation and techniques for geophysical, hydrospheric and lower atmosphere research; Convection, turbulence, and diffusion in the lower atmosphere; Cloud physics; Optical radar; Water in the atmosphere (humidity, clouds, evaporation, precipitation); Atmospheric, ionospheric and magnetospheric techniques and equipment

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