Aircraft Observations of Ice Nucleating Particles in the Arctic and Sub-Arctic Boundary Layer and Free Troposphere

RUSSELL PERKINS, Ryan Patnaude, Camille Mavis, Kevin R. Barry, Paul DeMott, Sonia Kreidenweis, Paquita Zuidema, Bart Geerts, Greg McFarquhar, Sebastian Schmidt, Colorado State University

     Abstract Number: 338
     Working Group: Aerosols, Clouds and Climate

Abstract
Ice Nucleating Particles (INPs) are responsible for primary cloud glaciation warmer than -38 °C, and a critical control on secondary ice production processes. Mixed-phase clouds fall into this temperature range and are common in the spring and autumn transition seasons in the Arctic, and during wintertime cold-air outbreak (CAO) events, where cold airmasses over the Arctic ice flow southward over North Atlantic open water. Two recent campaigns, across three deployments, have targeted these cloud types with an extensive suite of instrumentation, but we will focus on INP measurements here. The Cold-Air outbreak Experiment in the Sub-Arctic Region (CAESAR) occurred in Feb-April of 2024, targeting CAO events over the Norwegian Sea and Greenland Sea. Several strong and weak CAO events were captured, including events with evidence of long-range transported terrestrial aerosol from Europe, Asia, and Africa. Evidence of elevated INP concentrations is found over the marginal ice zone, potentially related to increased biological production. The Arctic Radiation-Cloud-Aerosol-Surface-Interaction eXperiment (ARCSIX) will occur with two deployments, one in May-June and another in July-August of 2024, targeting different sea ice and cloud systems in the Lincoln Sea and surrounding areas. This presentation will discuss preliminary findings from both campaigns, with a special focus on local arctic sources and long-range transported aerosol and the roles of INPs sourced from above and below clouds.