Arctic spring and summertime aerosol optical depth baseline from long-term observations and model reanalyses – Part 1: Climatology and trend

Abstract. We present an Arctic aerosol optical depth (AOD) climatology and trend analysis for 2003–2019 spring summertime periods derived from a combination of multi-agency reanalyses, remote-sensing retrievals, ground observations. This includes the U.S. Navy Aerosol Analysis Prediction System ReAnalysis version 1 (NAAPS-RA v1), NASA Modern-Era Retrospective Research Applications, 2 (MERRA-2), Copernicus Atmosphere Monitoring Service (CAMSRA). Spaceborne retrievals AOD are considered Moderate Resolution Imaging Spectroradiometer (MODIS), Multi-angle SpectroRadiometer (MISR), Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). Ground-based data include sun photometer AErosol RObotic NETwork (AERONET) sites oceanic Maritime Network (MAN) measurements. reanalysis AODs spaceborne show consistent climatological spatial patterns trends both summer seasons over lower (60–70? N). Consistent also found high (north 70? N) reanalyses. The reanalyses yield more results than climate models, can be verified well AERONET, corroborate complementary analysis. Speciated variable total among three little so March–May (MAM) June–August (JJA). Black carbon (BC) in comes predominantly biomass burning (BB) sources MAM JJA, BB overwhelms anthropogenic JJA study period. exhibits multi-year negative positive during 2003–2019, due to overall decrease sulfate/anthropogenic pollution significant increase smoke. Interannual variability is significantly large, driven by fine-mode and, specifically, smoke, smoke contribution interannual variation larger MAM. It recommended that models should account emissions variabilities change studies.