The Role of Coherent Structures in the Atmospheric Surface Layer Accelerating/Decelerating the Aerosols Flux Surface Deposition

Accelerations in the boundary-layer flows over ice- and snow-covered surfaces in the high latitude winters generate coherent structures which locally enhance updrafts and downdrafts, forcing rapid exchanges of energy and matter. We report observations of the turbulent flow in the Atmospheric Surface Layer during IGAC-ALPACA winter 2022 in Fairbanks, Alaska. We used two collocated eddy-covariance towers at ~ 3 m and ~ 11 m above the ground synchronized to a condensation particle counter and an optical particle sizer at 11 m height to determine high sampling frequency aerosols size distribution and concentration.

Multiresolution continuous wavelet analysis is applied to the turbulent time series to detect the presence of coherent structures. Spectral analysis and identification methods are applied to detect the coherent structures (i.e., sweeps and ejections). Intervals of wave-like occurrences are also identified. Based on that information and the 30 min eddy-covariance fluxes we determined the fraction of aerosols exchange aimed by coherent structures. Aerosols flux and deposition of polar ecosystems is further discussed.