AERODYN
AERODYN (AEROsol DYNamics) is a new aerosol dynamics module used in ICON-ART. With AERODYN, secondary aerosol formations (e.g. the accumulation of SO2 on a volcanic ash particle) can be accounted for. Aerosol dynamic processes are the processes which change an aerosols properties after it has been released into the atmosphere. This change of properties (omitting chemical reactions) occurs either via condensation or coagulation. Since it is not feasible to account for every individual aerosol to calculate their movement, AERODYN uses a total of 12 categories for aerosol modes.
Aerosol Modes in AERODYN
Traditionally, There are three categories to account for the aerosol sizes Whitby et. Al. (1978) : Aitken mode, accumulation mode and coarse mode. In AERODYN there is also a fourth mode, called giant mode, which accounts for especially large Aerosols, e.g. some species of pollen.
Since condensation can occur on a solid aerosol particle, as well as for a number of other reasons, it is possible to obtain aerosol modes which are a mixture of solid and liquid modes. To account for this, AERODYN combines 4 modes of aerosol size with the 3 modes soluble, insoluble and mixed.
A Visual Representation is given here:
when also adding the giant mode, the following configurations are possible:
AERODYN mode configurations aitken accumulation coarse giant soluble sol_aitken sol_acc sol_coarse sol_giant insoluble insol_aitken insol_acc insol_coarse insol_giant mixed mixed_aitken mixed_acc mixed_coarse mixed_giant
Defining Aerosols with AERODYN
AERODYN is meant to be as flexible as possible, allowing the user to quickly define their own aerosols and then use ICON-ART to simulate their dynamics. Aerosols are defined in .xml files, which can then be included in the run by specifying their path in the runfile (see Input for more details)
AERODYN XML Parameters Parameter type description example aerosol id char specifies name of the aerosol "my_first_aerosol" moment int specifies which momentum scheme is used (???) 3 mode char mode name from AERODYN mode configurations (multiple modes can be given, seperated by a comma) insol_giant,sol_aitken unit char specify what unit the aerosol will have kg-1 mol_weight real specify the molar mass 30E-3 rho real specify the density in terms of unit2e3 ...