Participants: DS,ST,JEJ,BMS,ACB,MG,HF,PW,MS

Possible reasons:

* pH dependency of SO2 ox rate
* wet scavenging (in ice, scavenging rates …)
* emission heights (probably not important)

* Size of vertical layers, boundary layer mixing
* Secondary Organic Aerosol contribution
* Agricultural and Industrial dust in windy, dry conditions
* BIC for aerosols, dust in southern Europe
* Wood burning emissions underestimated
* Station representativity for some specific sites (Susceptibility to inversion situations in winter?)
* Ammonium nitrate formation
* Emission seasonality for SO2 missing

Which Analysis :

* Separate discussion by aerosol component
* AMS measurements EUSAAR ?
* Caliop extinction profiles for European subregions become available shortly, extinction profile in model needed,
* EUCAARI aircraft measurements?
* Seasonal and spatial bias analysis