Lagrangian single-column modeling of Arctic airmass transformation during HALO-(𝒜𝒞)³

Abstract. In Arctic warm-air intrusions (WAIs), airmasses undergo a series of radiative, turbulent, cloud and precipitation processes, the sum of which constitutes the airmass transformation. During the Arctic airmass transformation, heat and moisture is transferred from the airmass to the Arctic environment, melting the sea-ice and potentially reinforcing feedback mechanisms responsible for the amplified Arctic warming. We tackle this complex, poorly understood phenomenon from a Lagrangian perspective, using the WAI event on 12–14 March captured by the 2022 HALO-(𝒜𝒞)³ campaign. Our trajectory analysis of the event suggests that the intruding airmass can be treated as an undistorted air column, therefore justifying the use of a single-column model. In this study, we test this hypothesis using the Atmosphere-Ocean Single-Column Model (AOSCM). The rates of heat and moisture depletion vary along the advection path due to the changing surface properties and large-scale vertical motion. The ability of the Lagrangian AOSCM framework to emulate elements of the airmass transformation seen in aircraft observations, ERA5 reanalysis and operational forecast data, makes it an attractive tool for future model analysis and diagnostics development. Our findings can benefit the understanding of the timescales and driving mechanisms of Arctic airmass transformation and help determine the contribution of WAIs in Arctic Amplification.