Ice number concentration retrievals from scanning cloud radar measurements for studying secondary ice production

Poster PDF

Description

A fundamental understanding of secondary ice production is critical for better prediction of ice number concentration, and thus of precipitation production and cloud radiative forcing. In the past, our understanding has mainly relied on laboratory experiments and airborne in-situ observations. Such observations are limited and transient, making it difficult to capture the full lifecycle of secondary ice production events at sufficient spatiotemporal resolution and to document the local atmospheric environments. Consequently, the frequency and evolution of these events largely remains a mystery. Here, we develop a novel method for retrieving ice number concentration in a Lagrangian reference frame, providing a necessary component for bridging the gap between theory and observations of secondary ice production. The retrieval method overcomes the outstanding challenge of separating pristine ice crystals from snow aggregates by exploiting a variety of polarimetric observables from Scanning ARM Cloud Radars. We will present examples from the Biogenic Aerosols - Effects on Clouds and Climate field campaign in Hyytiälä, Finland. These new retrievals show great potential for shedding light on the trigger requirements and dominant mechanisms of secondary ice production.