Aim: WP2 will develop a consistent treatment of tropospheric aerosol forcing by harmonizing CMIP6 and CAMS datasets and it will propose prototypes of new capabilities in the C3S services: the capacity to simulate large biomass burning emissions; and a treatment of volcanic stratospheric aerosol suitable for both re-analyses and seasonal forecasts.
Approach and methodology: Aerosols will be treated in different ways according to their type. Anthropogenic aerosols which are continuously emitted such as tropospheric sulphate will continue to be represented by a climatology, but the climatology will now be slowly time-varying. It will be created by applying the time variation of sulphate aerosol as represented in CMIP6 datasets, and applying this on a regional basis to our best estimate of recent climate conditions estimated by CAMS modelling and re-analysis. For biomass burning, which is much more intermittent, we will prepare the necessary datasets and model changes to allow fire emission studies, and then investigate the impact of specifying sources of biomass burning aerosol on a seasonal forecast system which includes a prognostic treatment of radiatively interactive black carbon aerosol. For volcanic aerosol, we will upgrade the model representation to include vertical profile information and implement a version of the stand-alone EVA_H model to provide a predictive capability for the evolution of volcanic aerosol following a major eruption. We will also create a real-time system using Copernicus data to estimate SO2 injection masses, so as to be able to initialize our volcanic aerosol prediction model.
Suitability of the research approach: WP2 will create a new time-varying tropospheric anthropogenic aerosol climatology that is an optimal blend of the emissions histories developed for CMIP6 and the satellite-constrained climatologies developed by CAMS. Biomass burning emissions can be very episodic, so will receive in-depth investigation with emissions taken from the CAMS Global Fire Assimilation System (GFAS) and evaluation of both climatological and prognostic schemes. Improved representation of volcanic aerosol will be developed and validated in two different models, using the latest observed datasets and stand-alone modelling developments – this will allow an accurate, validated and cost-effective treatment that can easily be incorporated in other C3S seasonal forecasting systems. Work will be carried out by two modelling groups to ensure a scalable and yet robust developments. The complementary and multi-disciplinary expertise of the participants will result in efficient developments.
Measures for Success of the Work Package/ KPIs:
- New merged CMIP6 and CAMS/C3S tropospheric aerosol dataset is produced, and is verified as reproducing the required spatial and temporal structures.
- New observed biomass burning emission dataset from the CAMS Global Fire Assimilation System (GFAS), and an evaluation of the potential benefits of including explicit treatment of biomass burning in seasonal forecast systems
- Verified improvements in the representation and predicted evolution of stratospheric volcanic sulphate aerosol, and creation of a basic system to initialize real-time forecasts