An Overview of the Cold-Air outbrEaks over the Sub-Arctic Region (CAESAR) campaign

In the spring of 2024, the US National Science Foundation sponsored the Cold-Air outbrEaks in the Sub-Arctic Region (CAESAR) aircraft campaign, with the simple goal of characterizing cold-air outbreak (CAO) clouds coming off of the Arctic sea ice as comprehensively as possible. A strength of the CAESAR strategy is a comprehensive aerosol, cloud and remote sensing instrumentation suite and early development of a close connection to modeling spanning a range of scales, in part by building on prior DOE-sponsored activity through the Cold-Air Outbreaks in the Marine Boundary Layer (COMBLE) campaign. The higher-level motivation for CAESAR is to better understand how clouds participate and feedback upon the changing Arctic. New technologies, improved data integration and modeling frameworks that are increasingly comparable to the observations hold promise that both the numerical weather prediction and  global modeling of the super-cooled liquid, mixed-phase and ice clouds can be improved through the focus provided by the field campaign. In this presentation we provide an overview of the NCAR C-130 aircraft campaign, and its approach to the problem of improving understanding of the cold-air outbreak cloud evolution, microphysical processes including their relationship to aerosol, and cloud mesoscale organization including the development of CAO clouds into polar lows. Initial highlights will be included.