Overview of Purdue's Mobile Disdrometer Operations in PERiLS 2022

The Propagation, Evolution and Rotation in Linear Storms (PERiLS) field program was conceived to fill a major gap in our understanding of and ability to predict tornadoes that form primarily from quasi-linear convective systems (QLCSs) as contrasted with their more extensively studied supercellular counterparts. The program is a natural evolution of the VORTEX-SE field program (2016-2018) and focuses on the southeast-U.S., owing to the juxtaposition of meteorological and societal factors that make this region particularly vulnerable to QLCS tornadoes.

A major science objective of PERiLS is to uncover links between QLCS microphysics, cold pool strength, gust front structure, and tornado potential on time horizons of minutes to hours. Microphysical processes that are potentially linked to tornadogenesis potential include 1) cooling from rain evaporation and hail melting that modulates cold pool strength and gust front dynamics, and 2) size sorting of hydrometeors by low-level storm-relative inflow winds that are strongly coupled to low-level updraft rotation. These processes may be detectable as changes in rain DSDs as measured by disdrometers and inferred from polarimetric radar observations. These two platforms combine a wealth of information about changes in cold pool structure and near-storm inflow kinematics relevant to tornado potential that would otherwise be difficult to obtain with either platform alone.

The first season of PERiLS took place March-April 2022, comprising four IOPs, each of which observed tornadic QLCSs. Our Purdue-based team's role was to deploy the Portable In Situ Precipitation Stations (PIPS) in a line-parallel array ahead of an approaching QLCS. The PIPS are six instrumented packages jointly owned and operated by Purdue, OU, and NSSL. Each contains a Parsivel2 disdrometer along with standard meteorological instruments (temperature, relative humidity, pressure, and wind speed and direction). Here, we provide an overview of our operations in IOP1 (03/22/2022), IOP2 (03/30/2022), and IOP3 (04/05/2022). These cases feature a tornadic supercell merging with a QLCS, a parallel stratiform tornadic QLCS, and a mid-morning tornadic QLCS with extensive antecedent precipitation, respectively. We also present preliminary analyses of the DSD and polarimetric radar observations.