Many global aerosol and climate models, includ-ing the widely used Community Atmosphere Model ver-sion 5 (CAM5), have large biases in predicting aerosols in remote regions such as the upper troposphere and high lat-itudes. In this study, we conduct CAM5 sensitivity simula-tions to understand the role of key processes associated with aerosol transformation and wet removal affecting the vertical and horizontal long-range transport of aerosols to the remote regions. Improvements are made to processes that are cur-rently not well represented in CAM5, which are guided by surface and aircraft measurements together with results from a multi-scale aerosol–climate model that explicitly represents convection and aerosol–cloud interactions at cloud-resolving scales. We pay particular attention to black carbon (BC) due to its importance in the Earth system and the availability of measurements. We introduce into CAM5 a new unified scheme for con-vective transport and aerosol wet removal with explicit aerosol activation above convective cloud base. This new im-plementation reduces the excessive BC aloft to better simu-late observed BC profiles that show decreasing mixing ra-tios in the mid-to upper-troposphere. After implementing this new unified convective scheme, we examine wet re-moval of submicron aerosols that occurs primarily through cloud processes. The wet removal depends strongly on the subgrid-scale liquid cloud fraction and the rate of conver-sion of liquid water to precipitation. These processes lead to very strong wet removal of BC and other aerosols over mid-to high latitudes during winter months. With our im-provements, the Arctic BC burden has a 10-fold (5-fold) in-crease in the winter (summer) months, resulting in a much-better simulation of the BC seasonal cycle as well. Arctic sulphate and other aerosol species also increase but to a lesser extent. An explicit treatment of BC aging with slower ag-ing assumptions produces an additional 30-fold (5-fold) in-crease in the Arctic winter (summer) BC burden. This BC aging treatment, however, has minimal effect on other under-predicted species. Interestingly, our modifications to CAM5 that aim at improving prediction of high-latitude and upper-tropospheric aerosols also produce much-better aerosol op-tical depth (AOD) over various other regions globally when compared to multi-year AERONET retrievals. The improved aerosol distributions have impacts on other aspects of CAM5, improving the simulation of global mean liquid water path and cloud forcing.