Aerosol input file

The aerosol (salsa) driver contains surface-emission information of aerosol particles for the aerosol module SALSA. Aerosol emissions can be given using two levels of detail (lod):

• lod=1: given as total mass emissions per emission category without information on the size distribution
• lod=2: given as total aerosol number containing information also on the aerosol size distribution

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Global attributes

No mandatory attributes. For good documentation, please consider applying global attributes listed for the static driver.

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List of attributes

The following list gives an overview of attributes that can be assigned to variables in an aerosol driver file.

Attribute	Type	Value	Description
_FillValue	Variable-specific	Variable-specific	Fill value for missing data
lod	NC_INT	Variable-specific	Level of detail used for some variables
long_name	NC_CHAR	Variable-specific	Variable long name
source	NC_CHAR	Variable-specific	Data source
units	NC_CHAR	Variable-specific	Units of the variable

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List of dimensions

The following list provides an overview of all dimension variables that can be used in an aerosol driver file.

Dimension	Type	Value	Description
composition_index	NC_INT	-	Index of each chemical component in composition_name and emission_mass_fracs
max_string_length	NC_INT	25	Maximum string length in composition_name and emission_category_name
ncat	NC_INT	-	number of elements in pavement_pars
npavement_subsurface_pars	NC_INT	2	Number of emission categories in emission_category_name, emission_mass_fracs, emission_number_fracs and aerosol_emission_values
nhoursyear	NC_INT	8760/8784	Number of hours per year in emission_time_factors (sum must equal to 1).
nmonthdayhour	NC_INT	91	Number of required input values for emission time rescaling factors in emission_time_factors: Index Description 1-12 scaling per month (sum must be 1) 13-19 scaling per day of week (sum must be 1) 20-43 scaling per hour for a working day (sum must be 1) 44-67 scaling per hour for a Saturday (sum must be 1) 68-91 scaling per hour for a Sunday (sum must be 1)

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List of coordinate variables

The following list provides an overview of all coordinate variables that can be used in an aerosol driver file.

Variable	Type	Attributes	Remarks
Dmid	NC_FLOAT	long_name="geometric mean diameter of an aerosol size bin units="m"	Geometric mean diameter of a aerosol size bin (in m). Has to conform the size bin description given using nbin and reglim in salsa_parameters.
time	NC_FLOAT	long_name="time units="seconds since YYYYMMDD hh:mm UTC"	Time in seconds since the beginning of the simulation (in UTC time). E.g., 7am (UTC+3) = 14400
x	NC_FLOAT	axis="X" long_name="distance to origin in x-direction units="m"
y	NC_FLOAT	axis="Y" long_name="distance to origin in y-direction units="m"

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Emission categories

The following list provides an overview of all variables to describe the emission categories in an aerosol driver file.

Input variable	Type	Attributes	Remarks
emission_category_index(ncat)	NC_BYTE	long_name="emission category index"	Index of the emission category(ies) given in emission_category_name.
emission_category_name(ncat,max_string_length)	NC_CHAR	long_name="emission category name"	Currently available categories:

"traffic exhaust", "road dust" and "wood combustion".

Applied to construct size distributions for aerosol emissions if aerosol_emission_values:lod=1, i.e., the size distributions are not specifically given using emission_number_fracs.

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Number size distribution and mass composition of aerosol emission per category

The following list provides an overview of all variables to describe the number size distribution and mass composition of aerosol emissions in an aerosol driver file.

Input variable	Type	Attributes	Remarks
composition_name(composition_index,max_string_length)	NC_CHAR	long_name="aerosol composition name"	Name of different chemical components in emission_mass_fracs. List of the available chemical components: Component Description 'H2SO4', 'SO4', 'h2so4', 'so4' Sulphur / sulphuric acid 'OC', 'oc' Organic carbon 'BC', 'bc' Black carbon 'DU', 'du' Dust 'SS', 'ss' Sea salt 'HNO3', 'NO3', 'NO', 'hno3', 'no3', 'no' Nitrares / nitric acid 'NH3', 'NH4', 'NH', 'nh3', 'nh4', 'nh' Ammonium / ammonia
emission_mass_fracs(ncat,composition_index)	NC_FLOAT	_FillValue=-9999.f long_name="mass fractions of chemical components in aerosol emissions"	Mass fraction of different chemical components listed in composition_name.
emission_number_fracs(ncat,Dmid)	NC_FLOAT	_FillValue=-9999.f long_name="number fractions of aerosol size bins in aerosol emissions"	Number fraction of each aerosol size bin. Bin mean diameters are given in Dmid. Only applied when aerosol_emission_values:lod=2.

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Temporal scaling variables

The following list provides an overview of all variables used to scale aerosol_emission_values if aerosol_emission_values:lod=1.

Input variable	Type	Attributes	Remarks
emission_time_factors(ncat,[nmonthday,[nhoursyear])]	NC_FLOAT	lod=1/2 long_name="emission time scaling factors"	Emission time scaling factors for aerosol_emission_values. Two levels of detail (lod) are possible: lod=1: scaling according to month-day-hour classification (see nmonthdayhour) lod=2: scaling for each hour of the year (see nhoursyear)

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Surface emission data

In order to enable surface emissions of aerosol particles, one must set salsa_emission_mode = 'read_from_file' in salsa_parameters.

Input variable	Type	Attributes	Remarks
aerosol_emission_values([time,y,x,ncat)]	NC_FLOAT	_FillValue=-9999.f lod=1/2 long_name="aerosol emission values" units='#/m2/s'	Emission values of aerosol particles. The coordinates vary based on the chosen level of detail. lod=1: Emissions are provided per emission category and yearly as total PM in dimensions aerosol_emission_values(y,x,ncat). They are then scaled by pre-defined rescaling factors emission_time_factors. Default categories are traffic exhaust, road dust, wood combustion, other. lod=2: Emissions are provided per emission category at given points in time and space in dimensions aerosol_emission_values(time,y,x,ncat) and in units # m-2 s-1. Total number emissions are then scaled to size bins by emission_number_fracs.

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Example static driver file

An example aerosol driver file can be downloaded ​here. Furthermore, example scripts for creating a salsa driver (and also a salsa dynamic driver including background concentrations) is attached in the end of this page.