Processing categories: point
The Elevpoint program is used to select elevated point sources and to prepare certain input files for special elevated source or PinG processing. Elevpoint selects the major point source (MPS) and major elevated point source emissions (MEPSE) records using a variety of criteria, such as stack parameters, emissions, and analytical plume rise calculations. (Note that MEPSE is another name for a PinG source.)
Elevpoint distinguishes PinG sources from non-PinG elevated sources based on emission thresholds, highest day-specific emissions rank
compared to other sources, analytical plume rise, and/or stack parameters such as height. Elevpoint flags sources as either elevated or PinG based on instructions given in an input configuration file, the PELVCONFIG file. Elevpoint also permits grouping of stacks at the same facility if the stack parameters are similar, within tolerances you specify with
the PELVCONFIG file; the result is call a “stack group”. For more information on selecting and grouping elevated and PinG sources, refer to Section 6.9.3.1, “PELVCONFIG: Elevated source selection file”.
Elevpoint can also be used to calculate plume rise using the “cutoff” method. This is the method traditionally used to prepare input files to the air quality models UAM-IV, UAM-V and CAMX, which require a separate model-ready input file containing emissions for elevated point sources. Below, we refer to this path as the “UAM style” of emissions processing.
For the cutoff method, the Elevpoint program uses the stack parameters of the point sources and estimates the plume rise for each source using a Briggs analytical
solution (but not actual gridded meteorology data); the details of this process are given in Section 4.3.1.1, “Plume rise calculation”. Elevpoint then records all of the sources that have an estimated plume rise greater than a specified cutoff as defined in the PELVCONFIG file using the “RISE” instruction. Using the PELVCONFIG file, this cutoff method can be combined with selection of elevated sources based on stack parameters and/or emissions values.
When emissions values are part of these selection criteria, Elevpoint computes the maximum daily emissions using one or more PTMP files. Elevpoint computes the maximum daily value of any pollutant used as a selection criterion across all of the days that you input. You
have the option of providing either a list of paths and file names of one or more PTMP files, or a single PTMP file. The day or days that Elevpoint uses to compute each source’s maximum depends on the time zone in which the source resides, based on the county and the COSTCY file setting for the time zone (the time zone is stored in the PNTS file output from Smkinven). When using emissions values as a selection criterion, Elevpoint only considers sources that are within the grid domain.
Elevpoint also creates a report file that contains all SMOKE sources that have been selected as elevated, their source characteristics (including stack parameters), emissions values used as selection criteria, stack-group numbers, status as either elevated or PinG, and which selection criteria were used to assign the status to the source. The report does not include any low-level sources. This report is in semicolon-delimited format for easier reading into a spreadsheet for sorting, review, and making charts.
The Elevpoint program is not needed if the environment variables SMK_PING_METHOD and SMK_ELEV_METHOD are both set to 0.
The Briggs solution is documented in the following:
Briggs, Gary A., 1971: Some Recent Analyses of Plume Rise Observation, pp. 1029-1032 in Proceedings of the Second International Clean Air Congress, edited by H. M. Englun and W. T. Beery. Academic Press, New York.
Briggs, Gary A., 1972: Discussion on Chimney Plumes in Neutral and Stable Surroundings, Atmos. Environ. 6, 507-510.
The following formula is used in Elevpoint:
F = 0.25 x G x VS x DS2 x (TS - T)/TS
For F less than 55,
Plume rise = HS + 21.31311057 x F0.75/U
Otherwise,
Plume rise = HS + 38.87776061 x F0.6/U
where
This represents an improved algorithm over the original so that the discontinuity at F = 55 no longer exists. Now, the second term in the plume rise formula approaches 595 as F approaches 55 from either side.
In summary, Elevpoint permits the following combinations of source selection and processing:
Identify MEPSE/PinG sources for outputting to special PinG files only (all other point sources will be treated as potentially elevated by Laypoint).
Identify elevated sources (MPSs) with the PELVCONFIG file, which might include using the cutoff method alone or in combination with other criteria.
Identify elevated sources (MPSs) and MEPSE/PinG sources with the PELVCONFIG file with cutoff method (Laypoint not used) and identify MEPSE/PinG sources with the PSPLIT file for outputting to special PinG files.