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OTC CMAQ Air Quality Model Configuration

Science Options Configuration Details/Comments

Model CMAQ Version 4.5.1

Horizontal Grid Mesh 36km/12km

36-km grid 145x102 cells

12-km grid 172x172 cells

Vertical Grid Mesh 22 Layers

Grid Interaction One-way nesting

Boundary Conditions GEOS-CHEM

Emissions

Baseline Emissions 

Processing

SMOKE (Version 2.1) MM5 meteorology input to SMOKE & 

CMAQ

Sub-grid-scale Plumes No Plume –in-Grid 

(PinG)

Chemistry

Gas Phase Chemistry CBM-IV

Aerosol Chemistry AE3/ISORROPIA

Secondary Organic 

Aerosols

Secondary Organic 

Aerosol Model 

(SORGAM)

Aerosol Mass 

Conservation Patch Yes Schell et. al., (2001)

Cloud Chemistry RADM-type aqueous 

chemistry Includes sub-grid cloud processes

N2O5 Reaction Probability 0.01-0.001

Meteorological Processor MCIP Version 3.0

Horizontal Transport

Eddy Diffusivity Scheme K-theory with Kh grid 

size dependence

Multi-scale Smagorinsky (1963) 

approach

Vertical Transport

Eddy Diffusivity Scheme K-theory

Diffusivity Lower Limit Kzmin = 1.0

Planetary Boundary Layer No Patch

Deposition Scheme M3dry Directly linked to Pleim-Xiu Land 

Surface Model parameters

Numerics

Gas Phase Chemistry

Solver

Euler Backward 

Iterative (EBI) solver

Hertel et. Al. (1993) EBI solver ~2x 

faster than MEBI

Horizontal Advection 

Scheme

Piecewise Parabolic 

Method (PPM) scheme

Simulation Periods 2002

Platform Linux Cluster
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OTC MM5/SMOKE/CMAQ Modeling System Grid Configurations

OTC MM5/SMOKE/CMAQ modeling system for 2002 annual simulation is applied with a 

Lambert Conformal Conic projection with parallels at 33N and 45N. A spherical earth radius of 

6370km is used in these programs.

MM5 Setup

MM5 was run with two-way nesting at 36 and 12km horizontal grid spacing and with 29 vertical 

layers. The top is at 50 mb.

For 36km domain, the center is at 97W and 40N. There are 149 grids (dot-points) in east-west 

direction and 129 grids (dot-points) in north-south direction. The south-west corner is at (-

2664km, -2304km) and the north-east corner is at (2664km, 2304km)

For 12km domain, there are 175 grids in east-west direction and 175 grids in north-south 

direction. The south-west corner is at (252km, -900km) and the north-east corner is at (2340km, 

1188km)

The 30 sigma-levels for the 29 vertical layers are:

1.0000, 0.9974, 0.9940, 0.9890, 0.9820, 0.9720, 0.9590, 0.9430, 0.9230, 0.8990, 0.8710, 0.8390, 

0.8030, 0.7630, 0.7180, 0.6680, 0.6180, 0.5680, 0.5180, 0.4680, 0.4180, 0.3680, 0.3180, 0.2680, 

0.2180, 0.1680, 0.1230, 0.0800, 0.0400, 0.0000

CMAQ Setup

CMAQ 36km modeling domain has 145 cells in east-west direction and 102 cells in north-south 

direction. The south-west corner is at (-2628km, -1728km) and the north-east corner is at 

(2592km, 1944km)

CMAQ 12km modeling domain has 172 cells in east-west directions and 172 cells in north-south 

direction. The south-west corner is at (264km, -888km) and the north-east corner is at (2328km, 

1176km)

There are 22 vertical layers for CMAQ. The sigma-levels for these 22 layers are:

1.0000, 0.9974, 0.9940, 0.9890, 0.9820, 0.9720, 0.9590, 0.9430, 0.9230, 0.8990, 0.8710, 0.8390, 

0.8030, 0.7630, 0.7180, 0.6680, 0.5680, 0.4680, 0.3680, 0.2680, 0.1680, 0.0800, 0.0000

SMOKE Setup

SMOKE modeling domains are same as CMAQ, except that the emissions are limited to the 

lower 16 CMAQ layers.
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OTC Grid Definitions for MM5 and CMAQ

Model Columns

Dot

(nx)

Rows

Dot

(ny)

X-Origin

(km)

Y-Origin

(km)

MM5 36-km 149 129 -2664 -2304

CMAQ 36-km 145 102 -2628 -1728

MM5 12-km 175 175 252 -900

CMAQ 12-km 172 172 264 -888

OTC Vertical Layer Definition for MM5 Simulations and Approach For Reducing 

CMAQ Layers By Collapsing Multiple MM5 Layers

MM5 CMAQ

Layer Sigma Pres(mb) Height(m) Depth(m) Layer Sigma Pres(mb) Height(m) Depth(m)

29 0.000 50 18600 2145 23 0.000 50 18600 4290

28 0.040 88.5 16450 2145

27 0.080 127.1 14300 1460 21 0.080 127.1 14300 2920

26 0.123 168.5 12800 1460

25 0.168 211.8 11400 1200 20 0.168 211.8 11400 2390

24 0.218 260.0 10200 1200

23 0.268 308.1 8990 934 19 0.268 308.1 8990 1870

22 0.318 356.3 8060 934

21 0.368 404.5 7120 772 18 0.368 404.5 7120 1540

20 0.418 452.6 6350 772

19 0.468 500.8 5580 662 17 0.468 500.8 5580 1320

18 0.518 549.0 4920 662

17 0.568 597.1 4250 581 16 0.568 597.1 4250 1160

16 0.618 645.3 3670 581

15 0.668 693.4 3090 532 15 0.668 693.4 3090 532

14 0.718 741.6 2560 455 14 0.781 741.6 2560 455

13 0.763 785.0 2110 388 13 0.763 785.0 2110 388

12 0.803 823.5 1720 337 12 0.803 823.5 1720 337

11 0.839 858.2 1380 290 11 0.839 858.2 1380 290

10 0.871 889.0 1090 247 10 0.871 889.0 1090 247

9 0.899 916.0 844 207 9 0.899 916.0 844 207

8 0.923 939.1 637 169 8 0.923 939.1 637 169

7 0.943 958.3 468 133 7 0.943 958.3 468 133

6 0.959 973.7 334 107 6 0.959 973.7 334 107

5 0.972 986.3 227 82 5 0.972 986.3 227 82

4 0.982 995.9 145 57 4 0.982 995.9 145 57

3 0.989 1002.6 89 40 3 0.989 1002.6 89 40

2 0.994 1007.5 48 27 2 0.994 1007.5 48 27

1 0.9974 1010.7 21 21 1 0.9974 1010.7 21 21

0 1.000 1013.24 0 0 0 1.000 1013.24 0 0

Note: Layer-top pressures assume a surface pressure of 1013.24 hPa. Layer- top heights are determined by 

averaging MM5 (CMAQ)-calculated layer-top heights over time and space (the entire 172x172 domain).