Lagrangian calculations of raindrop growth in shallow convective clouds based on kinematic fields obtained through dual-Doppler data syntheses

A research is carried out to examine the effects of cloud-scale flow on drop growth and investigate if accretion alone can produce raindrops of sizes similar to those observed by the aircraft. A simple lagrangian collection model is used to produce drop-growth trajectory analyses using temporally evolving dual-Doppler-derived wind fields, interpolated to a three-dimensional grid. Radial velocity measurements are first synthesized on a Cartesian grid every 2.5 to 5 minutes. Drop trajectories are initialized at various positions in the lower part of the cloud. A range of initial droplet sizes between 30 and 100 mm diameter are used. The gridded velocity are interpolated to the position of the particle using a four-dimensional interpolating scheme. The interpolated values are then used in a first-order-accurate forward-in-time integration scheme to calculate drop-growth trajectories.