A BALLOON-BORNE PARTICLE SIZE, IMAGING, AND VELOCITY PROBE FOR IN SITU MICROPHYSICAL MEASUREMENTS

Abstract

A balloon-borne instrument known as the PArticle Size, Image, and Velocity (PASIV) probe has been developed at the National Severe Storms Laboratory to provide in situ microphysical measurements in storms. These observations represent a critical need of microphysical observations for use in lightning studies, cloud microphysics simulations, and dual-polarization radar validation. The instrument weighs approximately 2.72 kg and consists of an HD video camera, a camera viewing chamber, and a modified Parsivel laser disdrometer mounted above the camera viewing chamber. Precipitation particles fall through the Parsivel sampling area and then into the camera viewing chamber, effectively allowing both devices to sample the same particle stream. The data are collected onboard for analysis after retrieval. Taken together, these two instruments are capable of providing a vertical profile of the size, shape, velocity, orientation, and composition of particles along the balloon path within severe weather. The PASIV probe has been deployed across several types of weather environments including thunderstorms, supercells, and winter storms. Initial results from two cases in the Deep Convective Clouds and Chemistry Experiment are shown that demonstrate the ability of the instrument to obtain high temporal and spatial resolution observations of the particle size distributions (PSD) within convection. The ability to resolve the PSD into different particle habits and compare to observed radar and model analysis values is also demonstrated.