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 a nd raindrop size distribution in convective storms, based on the interpreta tion of Mie backscattering oscillations seen in the Doppler spectrum observ ed at vertical incidence with a 94 GHz Doppler radar. The location of the f irst 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 shif ted Doppler spectrum. An example of the structure of two-dimensional updraf ts and downdrafts observed in the low levels of a convective storm is prese nted. Drop size distributions can also be estimated and evidence of small d rop removal by the updraft is presented.