Documentation of the Evaluation of CALPUFF and Other Long ...

5.2.1 MM5 Prognostic Meteorological Modeling
The most recent version of the publicly available non‐hydrostatic version of MM5 (version
3.7.4) was used. The MM5 preprocessors pregrid, regrid, little_r, and interpf were used to
develop initial and boundary conditions. Nine separate MM5 sensitivity tests were performed
for the CTEX5 field experiment period as listed in Table 5‐1. As noted previously, for CTEX3
period no 80 km MM5 modeling was performed and historical 80 km MM4 data were used for
the CTEX3 CALPUFF sensitivity tests.
The MM5 modeling for this study was based on three vertical structures designed to replicate
common vertical structures of meteorological modeling from the 1980’s to 2000’s with vertical
definitions of 16, 33, and 43 layers. The MM5 vertical domain definition for the 33 and 43 layer
MM5 sensitivity simulations are presented in both sigma and height coordinates in Tables 5‐2
and 5‐3. Topographic information for the MM5 system was developed using the NCAR and the
United States Geological Survey (USGS) terrain databases. Vegetation type and land use
information was developed using the most recent NCAR/PSU databases provided with the
MM5 distribution [available at ftp://ftp.ucar.edu/mesouser]. Standard MM5 surface
characteristics corresponding to each land use category were used.
Four different grid configurations were defined for the MM5 sensitivity modeling. The first
experiment (EXP1) was a baseline run using the horizontal and vertical configuration of MM4
simulations of the late 1980’s and early 1990’s (similar to the original MM4 dataset published
by the EPA). The baseline simulation uses a single domain (no nests) with a horizontal grid
resolution of 80 km and 16 vertical levels. The baseline configuration used older physics
options more consistent with physics options available at the time of publication of the original
EPA MM4 dataset. Physics options include the Blackadar (BLKDR) Planetary Boundary Layer
(PBL) parameterization, Anthes‐Kuo (AK) convective parameterization, Dudhia Radiation
(DRAD), Dudhia Simple Ice Microphysics (SIM), and a 5‐layer soil model (5LAYSOIL).
The second MM5 experiment (EXP2) was designed to reflect common grid and physics
configurations used in numerical weather modeling for air quality simulations in the late 1990’s
and early 2000’s. EXP2A through EXP2C used three nested domains (108, 36, and 12 km) with a
33 vertical layer vertical structure (Table 5‐2). Physics options include the Medium Range
Forecast model (MRF) PBL parameterization, Kain‐Fritsch (KF) convective parameterization,
rapid radiative transfer model (RRTM) radiation, SIM microphysics, and the 5LAYSOIL soil
model. EXP2H is a variation of EXP2C, reflecting another common configuration of the period,
but using the BLKDR PBL parameterization instead of the MRF PBL.
The third MM5 experiment (EXP3) was designed to reflect the more recent advances in
numerical weather modeling for air quality simulations, both in terms of grid configuration and
physics options. These options are largely consistent with annual MM5 simulations conducted
by the EPA and the Regional Haze Regional Planning Organizations (RPOs). Consistent with
EXP2, EXP3 uses three nested domains (108, 36, and 12 km). EXP3 uses the Pleim‐Xu (PX) PBL
parameterization, the Kain‐Fritsch 2 (KF2) convective parameterization, DRAD radiation, and
the Pleim‐Xu (PX) land surface model (LSM).
A key facet in the MM5 sensitivity modeling was to measure the effectiveness of various four‐
dimensional data assimilation (FDDA) strategies on meteorological model performance and also
determine the importance of assimilated fields in enhancing the performance of long range
transport (LRT) model simulations. In EXP1 and EXP2 series, there are a minimum of three
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