Vertical turbulent mixing of O3, DMS and other reactive species during ACE-1 Lagrangian B: a moving column model approach

K. Suhre, C. Mari, T. Bates, J. Johnson, R. Rosset
Laboratoire d'Aerologie, TOULOUSE, FRANCE

The boundary layer (BL) encountered during ACE-1 Lagrangian B is characterized by warm air moving southward over colder water, resulting in a stable shear-driven MBL. In contrast to the buoyancy driven BL layer encountered during ASTEX/MAGE 1, where cold air moving over warmer water resulted in a well mixed BL, turbulent vertical mixing of the air column encountered in ACE-1 B cannot be assumed to be instantaneous and thus makes a simple box model approach to the budgets of chemically reacting species with surface sinks or sources difficult. To overcome this obstacle, we use a one dimensional BL-model (MesoNH) which prognostically calculates turbulent mixing in the air column as it moves with the wind. Cloud formation, radiative heating and cooling, and large scale subsidence are taken explicitly into account using a vertical resolution of about 20-40m. The dynamics of MesoNH have been successfully tested on the ASTEX/MAGE 1 case (GCSS intercomparison). A chemistry module which is coupled online to MesoNH is used to study the budgets of reacting species measured during ACE-1 (e.g. O3, DMS, H2O2, CH3I).