The Impact of Recent Frequency in Arctic Haze and Smoke Events on the Radiative Forcing in the Arctic

This research utilizes the experimental and theoretical studies over the impact of absorbing aerosols on the radiative forcing (RF) in the European Arctic with the emphasis put on changes in the occurrence of Arctic haze and biomass burning transport events in the last years and overall values of seasonal RFs.

In previous studies, we coupled aerosol optical and microphysical properties derived from NAAPS and CAMS models as well as measured by in-situ and ground-based remote sensing instruments to build up an AOD climatology and to estimate typical values of the above properties for particular aerosol species. This study, however, aimed to utilize the results from previous research to improve the model of aerosol optical and microphysical properties over the area under study in the MODTRAN (MODerate resolution atmospheric TRANsmission) radiative transfer simulations. We investigated the impact of recent trends in spring-summer aerosol composition on the seasonal values of RFs and performed a sensitivity study of RF response to variability in i.e. surface albedo, solar zenith angle and selected aerosol optical and microphysical properties. We confirmed a slightly negative trend of Arctic Haze AOD (-0.007/10yr), therefore a corresponding decreasing values of spring RFs. The biomass-burning AOD indicated a contrary (slightly positive) trend (0.004/10yr) contributing to an enhancement of summer RFs. While the latter might be a function of increasing frequency of summer wildfires at 50-60 latitudes, the explanation for changes in spring conditions might be of greater difficulty, however, we believe this phenomenon might be remotely connected with the recent spring attenuation of Arctic climatological front as indicated by long-term meteorological studies performed for this area.

Acknowledgements. These results utilized in-situ measurements from spring campaigns conducted in 2014-2017 at Ny-Alesund, Spitsbergen under iAREA (Impact of Absorbing Aerosols in the European Arctic) project.