Document ID: EPA-R01-OAR-2008-0445-0033
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2010-09-20T04:00Z

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

	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.

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).  

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