Direct measurements of particle and black carbon dry deposition in the low Arctic
Abstract
Particle removal through dry deposition has a direct impact on short- and long-range transport of aerosols, concentrations of cloud condensation nuclei, and aerosol impacts on cloud albedo and lifetime. Direct observations of dry deposition in the Arctic are scarce which makes constraining current models difficult. We present new measurements of total particle and black carbon (BC) deposition as well as size-resolved particle dry deposition from the low Arctic in Utqiagvik, AK, USA, in September and October 2021. Median total particle and BC deposition were 0.13 cm s-1 and 0.85 cm s-1 respectively and were strongly dependent on the measured friction velocity. Size-dependent velocities showed a minimum around 0.13 µm. We compare these measurements to previous observations of dry deposition in the Arctic and highlight the large range of observed deposition velocities over snow and ice surfaces. Using size-resolved deposition models we show that current resistance models of dry deposition are unable to capture our observations and vastly under predict deposition rates. Removing the assumption of a flat surface by incorporating an interception term results in an ~53% increase in modeled deposition rate and substantial improvements in model measurement agreement in this work. We hypothesize that the discrepancy with current models is due to the misclassification of a snow-covered tundra as a flat surface, which leads to an overestimation of particle lifetime and impacts. These observations are further contextualized using GEOS-Chem.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.A43G..07B