Vertical air motion and raindrop size distributions in convective systems using a 94 GHz radar

This paper presents a method for the observation of air vertical velocity and raindrop size distribution in convective storms, based on the interpretation of Mie backscattering oscillations seen in the Doppler spectrum observed at vertical incidence with a 94 GHz Doppler radar. The location of the first minimum allows an accurate determination of vertical air motion, which is used to shift the spectrum so that it relates to the raindrops terminal velocity alone. The drop size distribution is then retrieved from the shifted Doppler spectrum. An example of the structure of two-dimensional updrafts and downdrafts observed in the low levels of a convective storm is presented. Drop size distributions can also be estimated and evidence of small drop removal by the updraft is presented.