Articles | Volume 15, issue 5
Atmos. Chem. Phys., 15, 2535–2544, 2015
Atmos. Chem. Phys., 15, 2535–2544, 2015

Research article 06 Mar 2015

Research article | 06 Mar 2015

A science-based use of ensembles of opportunities for assessment and scenario studies

E. Solazzo and S. Galmarini E. Solazzo and S. Galmarini
  • European Commission, Joint Research Centre, Institute for Environment and Sustainability, Air and Climate Unit, Ispra, Italy

Abstract. The multimodel ensemble exercise performed within the HTAP project context (Fiore et al., 2009) is used here as an example of how a pre-inspection, diagnosis and selection of an ensemble, can produce more reliable results. The procedure is contrasted with the often-used practice of simply averaging model simulations, assuming different models produce independent results, and using the diversity of simulation as an illusory estimate of model uncertainty. It is further and more importantly demonstrated how conclusions can drastically change when future emission scenarios are analysed using an un-inspected ensemble. The HTAP multimodel ensemble analysis is only taken as an example of a widespread and common practice in air quality modelling.

Short summary
Ensembles of results from multiple models require systematic screening according to well-defined and analytical principles described in the paper. The screening guarantees more robust conclusions especially in the case of scenario analysis.
Final-revised paper