SCICHEM 3.3
SCICHEM 3.3 is a reactive puff model that can be used to calculate
single or multi-source impacts of emissions at downwind locations. The
model can be used for both short-range calculations (for example,
1-hour SO2, 1-hour NO2, 24-hour secondary PM2.5, or 8-hour ozone
concentrations at fenceline receptors, or long-range calculations for
primary and secondary pollutant impacts. For 1-hour NO2 applications,
the model uses an optimized near-source NO-NO2-O3 chemistry scheme.
For long-range applications or near-field PM2.5/ozone, the full
chemistry option can be used to calculate downwind ozone and PM2.5
concentrations.
The full chemistry modules includes a gas-phase chemistry module based
on the latest version of the Carbon Bond mechanism (CB6r2), while the
aerosol and aqueous-phase chemistry modules are based on those found
in the Community Multiscale Air Quality (CMAQ) Model version 4.7.1. A
user-provided input file determines which chemistry option is used.
Sample input files for both 1-hour NO2 concentrations and full
chemistry options are provided with the case studies in the SCICHEM
distribution. In addition to the source code and executable files, the
package includes the following:
This distribution includes a limited version of a Graphical User
Interface (GUI), named "SCIPUFFgui, which is provided for the 64-bit
Windows 8 or higher operating system as an aid to the user for
visualization of model results. The GUI can plot concentration contour
plots for surface, horizontal, or vertical slices for all source types.
Note that SCIPUFFgui can also be used to create and run SCICHEM
namelist-type projects. Note that it does not generate keyword-type
projects (introduced in SCICHEM 3.x) and cannot be used to define area
sources. It is recommended to use the GUI primarily for viewing simulation
results or modifying input from existing projects.
This distribution consists of three readme files, namely "README.txt"
(this file),README-Examples.txt and "READMe-Build-Instructions.txt",
three documents, "3002022845 User's Guide.pdf" and "3002022845 Technical
Documentation.pdf" and "3002022845 Support Document.pdf" and the following
four zipped files (to limit the size of the individual zipped files):
All the files should be unzipped in the same directory. These can be
unzipped on Windows using the free software 7-Zip. For running
SCICHEM, the appropriate scipuff.ini file (in the bin/windows/x64 or
bin/linux directory) should be edited so that the paths for the sciData
directory and landuse.dat file point to the correct directory on the
User's system. Details for running the SCIPUFFgui on Windows is
provided in the User's Guide.
Building downwash in SCICHEM 3.3 is based on PRIME (Schulman et al., 2000).
PRIME has not been updated in over 15 years, and has been shown to overpredict
concentrations by factors of 2 to 8 for certain building types (Petersen et al., 2017).
New treatments for building downwash are being developed (Petersen et al., 2017)
and it is anticipated that future releases of SCICHEM will include these improvements.
Thus, the current default in SCICHEM is to ignore building downwash effects (RUNPRIME = N).
However, in case the user wishes to activate the building downwash option,
the user can do so by setting RUNPRIME to Y and providing the building dimensions
from the BPIPPRM output in the SO section. See the User's guide for details.
The Mesoscale Model Interface Program (MMIF) on the U.S. EPA SCRAM web
site can be used to convert prognostic meteorological model (MM5 and/or
WRF) outputs to SCICHEM ready meteorological inputs. SCICHEM 3.2 or later
requires MMIF version 3.4 or later for compatibility.
This is a full release that has been tested for a number of conditions.
Windows and Linux versions of the executables are provided with the
distribution. Both the Windows and Linux builds were created using the
Intel compiler. For users interested in building the executable files
on Linux or Windows machines, build scripts and Visual Fortran project
files for the Intel compiler are provided. Users can create builds
using other compilers but builds with non-Intel compilers have not been
tested.
Additional details and user instructions are provided in the documents
bundled with the package. Users are requested to offer feedback to EPRI
and the model developers on the model, including bug reports, and
additional features that would make the model more useful to the air
quality modeling community.
BEST PRACTICES
Some guidelines for creating good project input files for SCICHEM are
provided below:
1) With observed meteorology, if a terrain file is being provided
separately then the terrain grid dimensions should be limited to a grid
of less than 100x100 cells. Using more grid cells will result in
significant increases in run time, because SCICHEM conducts mass
consistent wind field calculations. For high resolution runs, mass
consistent wind fields should be generated using a meteorological model
(e.g., WRF) and provided to SCICHEM as gridded meteorological fields.
Note that WRF fields can be directly read by SCICHEM, or the MMIF
processor mentioned above can be used to create gridded meteorological
files in SCICHEM format.
2) The model can output time-averaged concentrations at selected
receptor locations at runtime. However CPU requirements increase
significantly with the number of samplers/receptors specified ahead
of time. Hence, for surface samplers/receptors, it is recommended
that the user calculate these concentrations as a post-processing
step using the provided postprocessor sciDOSpost. SciDOSpost can read
the surface deposition and dosage files, and calculate output (averaged
concentrations, deposition, visibility obscuration) at arbitrary
receptors (i.e. not specified before the SCICHEM run). For samplers
that are not at the surface (e.g., at locations corresponding to
aircraft measurements), the user can define a maximum of 5000
sampling locations.
3) The large scale variance type (ENSM_TYPE) should be set to none for
small domains (~<150 kms)