Abstract
Abstract. We compare ground-based measurements of aerosol optical depth and Ångström parameter at six Arctic stations in the period 2001–2006 with the results from two global aerosol dynamics and transport models, ECHAM-HAM and TM5. Satellite measurements from MODIS and the MACC reanalysis product are used to examine the spatial distribution and the seasonality of these parameters and to compare them with model results. We find that both models provide a good reproduction of the Ångström parameter but significantly underestimate the observed AOD values. We also explore the effects of changes in emissions, model resolution and the parametrization of wet scavenging.
Highlights
The Arctic is extremely vulnerable to past and future climate change, through complex interactions which can lead to severe regional impacts on the local hydrology, cryosphere and ecosystems, and to feedbacks on the global climate system (IPCC AR4, 2007)
Satellite observations of AOD and Angstrom parameter are provided by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra and Aqua satellites
While ACCMIP includes data from the Global Fire Emission Database 2 (GFED2), we explore ACCMIP emissions using the more recent Global Fire Emissions Database version 3 (GFED3) monthly biomass burning emission database and we allow these emissions to vary annually instead of using a climatological mean
Summary
The Arctic is extremely vulnerable to past and future climate change, through complex interactions which can lead to severe regional impacts on the local hydrology, cryosphere and ecosystems, and to feedbacks on the global climate system (IPCC AR4, 2007). Global atmospheric and aerosol models are important tools for studying climatic feedbacks and for estimating their impact on the climate system They provide boundary conditions for higher resolution regional models. In both cases, a reasonable representation of the concentration and optical properties of aerosols over the Arctic is required. Aerosol concentration measurements in the Arctic are sparse, and the main source of data for model verification is provided by measurements of atmospheric optical properties collected by a network of a small number of measuring stations and by satellite observations. We explore the sensitivity of modeled Arctic aerosol optical depths to different emission datasets and model resolutions, considering a simple change in the parametrization of wet scavenging for HAM which has been recently suggested (Bourgeois and Bey, 2011).
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