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Model investigation of the origins of wintertime Arctic aerosols over northern Alaska

Abstract : The Arctic is influenced by long-range transport of aerosols from mid-latitude emissions, especially in winter and spring, leading to formation of Arctic Haze. Natural aerosols, such as sea-salt, also contribute to wintertime Arctic aerosol loadings. Local sources of aerosols are highlighted as being important, but many uncertainties remain about the relative contributions of natural and anthropogenic sources and aerosol processes. In particular, models have difficulties reproducing observed aerosol distributions and composition. In this study, the Weather Research Forecasting Model with chemistry (WRF-Chem) is used to investigate origins of wintertime aerosols over northern Alaska focusing on the influence of local versus remote sources and examining the role of meteorology, in particular, stable boundary layers that can trap aerosols near the surface. The model was run first in hemispheric mode using AMAP-ECLIPSEv6 anthropogenic emissions and a dynamical (WRF) setup for improved simulation of cold, stable meteorological conditions over wintertime Alaska. Model results are evaluated against available surface data and, in particular, data collected at Utqiaġvik during January-February 2014. A variety of air masses were sampled including air masses originating from the Arctic Ocean and from the North Slope of Alaska oil and gas extraction emissions to the east on the northern coast of Alaska. We investigate the ability of the model to reproduce observed natural aerosols, especially local and transported sea-salt and marine organic aerosols. The sensitivity of modelled aerosols and natural emissions to, for example, sea-ice fraction, surface winds, and relative humidity, are examined, as well as model treatments of marine organic aerosols. We also investigate the ability of the model to reproduce anthropogenic aerosols originating from remote sources and runs including local emissions are used to assess the influence of aerosols originating from the North Slope of Alaska oil fields. Simulations at higher resolutions over northern Alaska are also used to examine the effect of increasing model resolution on simulated meteorology and boundary layer aerosols. The results are used to estimate the relative contributions of local and remote natural and anthropogenic aerosols to wintertime aerosols over northern Alaska.
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Submitted on : Saturday, April 10, 2021 - 6:02:49 PM
Last modification on : Friday, July 2, 2021 - 3:14:04 AM

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  • HAL Id : insu-03195197, version 1

Citation

Eleftherios Ioannidis, Kathy S. Law, Jean-Christophe Raut, Tatsuo Onishi, Rachel Kirpes, et al.. Model investigation of the origins of wintertime Arctic aerosols over northern Alaska. AGU Fall Meeting, Dec 2020, Online Meeting, United States. pp.C045-0005. ⟨insu-03195197⟩

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