Aerosol Radiative Forcing with the MACv2 Aerosol Climatology

Aerosol is highly diverse in space and time. And many different aerosol optical properties as well are environmental properties (e.g. clouds, surface, solar insolation) are needed for the determination of aerosol radiative effects and forcing. Here results from radiative transfer off-line simulations with monthly maps of the MACv2 aerosol climatology are presented. The MACv2 aerosol climatology is based on a top-down approach, where monthly statistics of trusted sun-photometer measurements from the ground are combined with spatial context from global (bottom-up AeroCom ensemble) modeling. The direct forcing by today’s anthropogenic aerosol is near -0.35W/m2 TOA cooling. In addition, aerosol direct effects are also stratified into sulfate, organic, soot, dust and seasalt components and their anthropogenic contributions. The indirect (Twomey) forcing by today’s anthropogenic aerosol is close to -0.65W/m2, thus the more influential climate change agent compared to the direct effect. Hereby, satellite retrieval relationships between fine-mode AOD and CDNC are applied. Finally also the temporal component by anthropogenic aerosol forcing is investigated. Over the last 30 years this TOA aerosol forcing has not changed much despite strong changes in regional contributions.