Influence of model grid resolution on NO₂ vertical column densities over East Asia

Figures & data

Table 1. Model setup or WRF and CMAQ

WRF		CMAQ
Microphysics	Thompson	Advection	PPM
PBL physics	ACM2	Vertical diffusion	ACM2(inline)
Longwave	RRTM	Gas chemistry	SAPRC99
Shortwave	Dudhia	Solver	EBI
		Aerosol chemistry	AERO5
		Cloud module	cloud_acm_ae5

Figure 1. Model domains with NO₂ emissions for D1 (80 km), D2 (40 km), and D3 (20 km).

Figure 2. Monthly averaged spatial distributions of NO₂ VCDs (units: e16 molecules cm^-2) on a 1° × 1° grid based on satellite retrievals including (a) GOME-2, (b) SCIAMACHY, and (c) OMI, and (d)–(f) CMAQ simulations using D1 (80 km) for three different local times (09:30, 10:00, and 13:40–13:50) in June 2007. Absolute biases, calculated as (CMAQ-simulated NO₂ VCDs) – (satellite NO₂ VCDs), are shown in (g)–(i).

Figure 3. Monthly averaged spatial distributions of NO₂ VCDs (units: e16 molecules cm^-2) on a 1° × 1° grid based on satellite retrievals including (a) GOME-2, (b) SCIAMACHY, and (c) OMI, and (d)–(f) CMAQ simulations using D1 (80 km) for three different local times (09:30, 10:00, and 13:40–13:50) in December 2007. Absolute biases, calculated as (CMAQ-simulated NO₂ VCDs) – (satellite NO₂ VCDs), are shown in rows (g)–(i).

Table 2. Diagnostic areas

Diagnostic areas		Longitude/latitude	Region type
CHN1	(near Beijing)	113°E-118°E/34°N-39°N	Land, China
CHN2	(near Shanghai)	119°E-122°E/29°N-32°N	Land, China
CHN3	(central eastern China)	111°E-121°E/27°N-40°N	Land, China
SEOL	(near Seoul)	125°E-129°E/34°N-38°N	Land, no China
TOKY	(near Seoul)	135°E-141°E/34°N-36°N	Land, no China
ECHS	(over the East China Sea)	121°E-125°E/32°N-40°N	Sea

Figure 4. Scatterplots between monthly averaged NO₂ VCDs of satellite retrievals (GOME-2 in the first row, SCIAMACHY in the second row, and OMI in the third row) and CMAQ simulations at different horizontal resolutions: D1 (80 km) in the first column, D2 (40 km) in the second column, and D3 (20 km) in the third column. Simulations were conducted for six diagnostic areas: CHN1 (near Beijing), CHN2 (near Shanghai), CHN3 (central eastern China), SEOL (near Seoul), TOKY (near Tokyo), and ECHS (over the East China Sea); details of these areas for June 2007 are listed in Table 2. Error bars represent the maximum and minimum values of the daily data for the diagnostic areas.

Figure 5. Scatterplots between monthly averaged NO₂ VCDs of satellite retrievals (GOME-2 in the first row, SCIAMACHY in the second row, and OMI in the third row) and CMAQ simulations at different horizontal resolutions: D1 (80 km) in the first column, D2 (40 km) in the second column, and D3 (20 km) in the third column. Simulations were conducted for six diagnostic areas: CHN1 (near Beijing), CHN2 (near Shanghai), CHN3 (central eastern China), SEOL (near Seoul), TOKY (near Tokyo), and ECHS (over the East China Sea); details of these areas for December 2007 are listed in Table 2. Error bars represent the maximum and minimum values of the daily data for the diagnostic areas.

Table 3. Increases in CMAQ simurated NO₂ VCDs due to model spatial resolution change (e16 molecules cm^–2)

	09:30 LT		10:00 LT		13:40–13:50 LT
	D2-D1	D3-D2	D2-D1	D3-D2	D2-D1	D3-D2
June
CHN1	0.27	0.14	0.25	0.03	0.08	0.04
CHN2	0.64	0.14	0.56	0.05	0.40	0.13
CHN3	0.16	0.06	0.14	0.03	0.05	0.03
SEOL	0.10	0.04	0.19	0.02	0.08	0.05
TOKY	0.01	0.06	0.26	0.04	0.11	0.24
ECHS	0.01	0.02	0.04	0.06	0.02	0.00
December
CHN1	0.45	0.02	0.40	0.09	0.28	0.03
CHN2	0.43	0.18	0.52	0.31	0.48	0.09
CHN3	0.24	0.09	0.18	0.13	0.18	0.07
SEOL	0.12	0.06	0.19	0.19	0.10	0.04
TOKY	0.07	0.07	0.02	0.11	0.04	0.06
ECHS	0.00	–0.03	0.04	–0.11	0.03	–0.07