Problems to be solved

The potentially great climatic importance of aerosol urgently requires improvement of the estimates of the climate effect of aerosol and better evaluation of the associated uncertainties.

PHOENICS is a focused global modelling project to study the direct climate effect of multi-component mixed tropospheric aerosol. The impact of European emissions on the European and global environment and climate, and the influence of other world regions on Europe will be assessed focusing on the role of the Mediterranean. This information is a prerequisite for the definition of EU directives and international negotiations for protection of the environment and of human health, measures with obvious financial and political impacts.

Scientific objectives and approach

The project has 2 general objectives:

Progress will be achieved following an innovative approach to represent the optical, chemical and hygroscopic properties of the multi-component mixed aerosol considering all major aerosol components in a size-dependent aerosol dynamic model embedded within a global 3-dimensional atmospheric general circulation model (A-GCM). Thorough validation of the developed parameterisations, the A-GCM results and detailed evaluation of the uncertainties associated with the calculations of the direct aerosol effect will be based on selected observations and optimal use of satellite data. The parameterisations of i) the formation of particulate nitrate and secondary carbonaceous aerosol, ii) the wet and dry removal of aerosols, iii) aerosol processing in clouds, iv) the optical and hygroscopic properties of aerosol will be specifically improved on the basis of detailed process models and constrained by selected in-situ measurements. A novel high resolution two-way nested Chemistry Transport Global Model with a zoom domain over Europe will be used to assess the impact of European emissions on global aerosol formation, and the influence of other world-regions on Europe. PHOENICS will focus on the Mediterranean region that provides excellent conditions for detailed studies of the direct aerosol effect on climate, and will benefit from an increasing amount of data obtained during campaigns in-and-around the Mediterranean. The inter-annual variability of the direct effect of aerosol will also be simulated. The over-all uncertainty of the aerosol-forcing calculations will be evaluated utilising ground based sun-photometer measurements and satellite data. A new strategy for optimal use of satellite data will be developed considering sampling issues and aerosol optical properties.