Comparison of SAMBBA Aerosol-Chemistry Observations with ECMWF Reanalyses

Abstract:

We have explored the new multiannual chemistry-aerosol assimilated datasets, available from the European Centre for Medium-Range Weather Forecasts (ECMWF) MACC (Monitoring Atmospheric Composition and Climate) reanalysis, and tested their validity by comparison with independent observations from biomass burning regions. Our aim is to focus on quantifying the budget of primary and secondary emitted species and test current descriptions of chemical feedbacks between assimilated and non-assimilated species.

As emissions significantly influence gas-phase chemistry and aerosol concentrations, tropical biomass burning (BB) is an area of key uncertainty regarding regional atmospheric composition and climate. The recent SAMBBA (South AMerican Biomass Burning Analysis) field campaign in 2012 provides high quality ground and aircraft biomass burning observations. By comparing the MACC reanalysis, the same model system not initialised using chemical data assimilation, and in-situ observations from SAMBBA, we can quantify the influences of data assimilation on assimilated and non-assimilated species in BB regions.

In initial comparisons MACC O₃ has a negative bias when compared to SAMBBA flight data, which is more significant in BB plumes and at high altitudes. Previous MACC data validation with other datasets generally showed a positive bias. This could indicate a greater influence of BB plumes on O₃ concentrations, which is not picked up by the coarser reanalysis resolution. The high CO concentrations seen in biomass burning plumes in the campaign data is not picked up by the MACC reanalysis. This is likely due to the poor sensitivity of the IASI and MOPITT satellite at low altitudes which is used in the assimilation. The poster will show further comparisons with chemical and aerosol fields, including black carbon.