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APPENDIX B -RML Background utility
model units to µg/m3, if required.
The .pst file can include one or more receptors within the nesting domain. If more than one
receptor is located in the nesting domain and listed in the input file, the .pst concentrations
from all the listed receptors are averaged when calculating the nesting background
concentrations. When used in the ADMS-Urban RML system, the .pst file is expected to
include one receptor in the centre of each regional model grid cell, but the RML Controller
will include any receptors found within the cell.
If the nesting domain includes multiple regional model cells, the concentrations from each
cell included in the nesting domain are averaged when calculating the nesting background
concentrations.
If a negative nesting background concentration is calculated for any ADMS species at any
hour, the output concentration of that species is set to zero for that hour. The total number of
hours with negative nesting background concentrations for any pollutant is written to a
warning file at the end of the utility run. If the number of hours with negative nesting
background is greater than 1% of the total number of hours included in the run, this may
indicate a discrepancy in magnitude and/or time-variation between the regional model and
ADMS-Urban emissions, which should be investigated. Common causes for negative nesting
background concentrations are described in Section 6.7.6.
B.3 Input file format
The input file for the RML Background utility is a text file which contains a version string and
three sections of data. The first two sections, whose elements are defined in Table B.1, are
common to both modes of the program, whereas the keyword and contents of the third
section, defined in Table B.2, control which mode of the program will be run. The order of
the sections and the variables within each section must be as defined in Tables B.1 and B.2.
Each element should be given on a new line; blank lines may be included before each section
keyword but not within a section. An example input file is shown in Figure 9.4.
The nesting domain should cover a whole number of regional model grid cells to within a
tolerance of 10% of the regional model grid spacing. The nesting domain may cover any
rectangular area of grid cells, it is not required to be square.
ADMS-Urban RML User Guide
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