Processes controlling the vertical aerosol distribution in marine stratocumulus regions – a sensitivity study using the climate model NorESM1-M

Abstract. The vertical distribution of aerosols plays an important role in determining the effective radiative forcing from aerosol–radiation and aerosol–cloud interactions. Here, a number processes controlling aerosol five subtropical marine stratocumulus regions climate model NorESM1-M are investigated, with focus on total extinction. A comparison satellite lidar data (CALIOP, Cloud–Aerosol Lidar Orthogonal Polarization) shows that underestimates extinction throughout troposphere, especially elevated layers two where they seen observations. It is found shape largely determined by emission removal model, primarily through injection height, emitted particle size, wet scavenging. In addition, representation transport related to shallow convection entrainment be important, whereas alterations optical properties cloud microphysics parameterizations have smaller effects distribution. However, none made sufficient for reproducing observed extinction, neither magnitude nor shape. Interpolating levels CALIOP corresponding leads better agreement boundary layer highlights importance resolution.