Spatial and seasonal variations of black carbon over the Arctic in a regional climate model

Black Carbon (BC) absorbs the radiation and alters snow/ice albedo, which influences the Earth-Atmosphere radiation balance over the Arctic region. BC masses are estimated using Weather Research and Forecasting with Chemistry (WRF-CHEM) model over the Arctic region during the boreal winter and summer seasons of 2018. The meteorological parameters such as near surface temperature and relative humidity in WRF-CHEM are found to agree well with the observations. BC masses are found between 5-20 ng m(-3) during boreal winter over most parts of the Arctic, while BC values are double in summer. Siberian and Canadian regions exhibit higher BC concentrations (> 30 ng m(-3)) owing to the fire activities. BC produced by fires in the Alaska and Canadian regions of Arctic have lesser spread than BC form Siberian fires as the winds are mostly from east to west in winter. The model simulated BC is lower and higher than the observed BC during winter and summer respectively over Ny-Alesund. However, the day to day variations can be captured by the model. The vertical profile of BC shows two peaks in winter, one at 1 km and the other strong peak at higher altitude of 12.5 km associated with long-range transport from mid-latitude and tropical regions, while in summer one peak at lower altitude is found. BC has large spatial variations in the Arctic which can significantly impact the Arctic as well as global climate.