The overarching objective of M-Phase is to reduce the uncertainty in how mixed-phase clouds will respond to changes in climate, and thereby reduce uncertainty in climate sensitivity. We will do this by improving our understanding of the physical processes that determine the properties of mixed-phase clouds and their response to climate drivers (sea-surface temperatures and aerosols). This will be achieved by addressing the following specific objectives:

1) Experimentally define the relationship between aerosol, dynamics, and mixed-phase cloud radiative properties in the climatically critical mid-to high-latitudes (WP 1).

2) Define high-latitude ice-nucleating particle (INP)concentrations and sources across the northern hemisphere (WP 2).

3) Determine the response of mixed-phase cloud systems to SST and INP in order to estimate cloud responses to changing environmental conditions on a regional basis (WP 3).

4) Use the improved models of cloud microphysics as well as INP to extend the analysis of mixed-phase cloud properties to other regions of the world (WP 3).

The M-PHASE project will use the FAAM aircraft to study cold-air outbreaks (CAOs), a frequent source of mixed-phase clouds, which offer the opportunity to study the physical processes that control the formation and evolution of cloud systems in a relatively well-defined flow.