Spatially Resolved Latent and Sensible Heat Fluxes of a Cold Air Outbreak Using Wavelet Analysis of Airborne Observations: A CAESAR Case Study

Abstract The representation of turbulent vertical transport of heat and moisture in the marine atmospheric boundary layer (BL) remains a major source of uncertainty in weather and climate models, especially during extreme marine Cold Air Outbreaks (CAOs). This case study of In situ vertical velocity, water vapor, and temperature observations from the Cold‐Air‐outbreak Experiment in the Sub‐Arctic Region airborne campaign's “golden case” demonstrates the unique capability of wavelet analysis to provide spatially‐ and scale‐resolved flight‐level vertical turbulent transport estimates. During the CAO on 16 March 2024, over the Greenland and Norwegian Seas, leg‐averaged latent energy fluxes (LE) reached 170 W m −2 , maintained throughout development into cloud break‐up, whereas near‐ice sensible heat fluxes (SH) reached 250 W m −2 before decreasing to ∼50–75 W m −2 . Averaging over 5 km paths fails to resolve flux variability. Circulatory scales between 200 m and 2 km constituted 56%–72% (47%–73%) of the total upward LE (SH) variance between measured scales 10 m–6.8 km at 150–330 m above sea level, where cloud tops rose from near‐plane to 2.5 km. LE (SH) scales lengthened with fetch and with BL deepening, with >50% of vertical transport occurring at scales less than 0.47 (0.22) km over solid sea ice, and 1.52 (1.65) km 150–500 km from the ice edge. Cloud organization seen in satellite imagery and remotely‐sensed moisture variance spectra similarly increase in scale with fetch. The results mirror eddy covariance estimations and demonstrate the value of representing fine‐scale flux variability and its coupling to the surface and to convectively‐driven circulations.