Overview

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Emissions of gases and/or passive compounds can be provided by the user in different levels of detail (LOD). Three modes were implemented. Two modes require emission data from file. Gridded emission information can be provided in two LODs via a netCDF file (see PALM Input Data Standard document​):

• LOD 1 files require gridded annual emission information which are temporally disaggregated by PALM-4U using sector-specific standard time factors

• LOD 2 files must contain gridded pre-processed emission information that is already temporally disaggregated. At the moment hourly emission data is required. Other temporal intervals will be possible in later versions. IMPORTANT: In this mode the initial date of the simulation has to coincide with the first day for which emission values are available.

In a third mode traffic emissions are parameterized on the basis of the street type classification provided by Open Street Map (​https://www.openstreetmap.org) and street type specific emissions factors. This option, named ’Parameterized’ mode, is currently only implemented for the traffic sector:

• LOD 0 requires a mean surface emission per day (in micromol/m2/d for gases and in kg/m2/d for particulate matter) for each desired species contained in the applied chemical mechanism together with a weight differing between main and side road emissions defined in the PALM Fortran namelist file (see Fortran namelist file and chemistry parameter list). Furthermore, the street type classification provided by Open Street Map must be included in the PALM static driver (see Static input file).

To account for the temporal distribution of the parameterized traffic emissions a diurnal profile based on urban traffic counts is implemented to disaggregate the total emission of the different species to hourly values. Currently, the applied temporal profile is the same for all species and main and side roads.

Please note that LOD 0 is currently not applicable if the horizontal grid exceeds 10 to 15 m at maximum (depending on the width of the streets in the considered area). In this context, it must also be considered, that streets, which are only one grid point wide in the STATIC file will probably be eliminated the topography filtering during runtime, i.e. emissions from steets which are only one grid point wide will be supressed.