Wind observation in boundary layer by W-band radar using non-hydrometeor echo

A W-band cloud radar has high sensitivity enough to observe non-precipitating cloud. It normally aims to observe various clouds, rain or snow, but it frequently receive non-hydrometer echoes near the surface. It is thought that non-hydrometeor echoes are caused by small insects or bits of vegetation. They are usually removed from data set to use meteorological study. However, if those insects are floating in the air and blowing with wind, they can be used as wind tracers.

National Institute of Information and Communications Technology is operating a W-band (95.04GHz) cloud profiling radar called “SPIDER”. In 2003 and 2004, vertically pointing observations of SPIDER from the ground are made at Tokyo, Japan. Non-hydrometer echoes were frequently observed from the surface to the altitude of 1.2 km in summer and 0.5 km in winter. The height ranges of the echoes show diurnal change: maximum in the noon and minimum in night. Their Doppler speeds show large variability in daytime and small variability in night, which seems to indicate convective activity in boundary layer. Availability of non-hydrometeor echoes for boundary layer study will be discussed in the presentation.