Chemical Transport of O 3, Aerosol, & Reactive Tracers over the Pacific

Transcription

1 Chemical Transport of O 3, Aerosol, & Reactive Tracers over the Pacific C. Jerry Lin 1, Li Pan 1, David G. Streets 2, Carey Jang 3, Terry Keating 4, H. Chu 1 and T. C. Ho 1 1 College of Engineering, Lamar University, Beaumont, TX 2 ANL Decision & Information Sciences Division, Argonne, IL 3 USEPA OAQPS, Research Triangle Park, NC 4 Office of Air & Radiation (OAR/OPAR), USEPA, Washington, DC International Workshop on Regional and Intercontinental Transport of Air Pollution Hanoi, Vietnam October 13, 28

2 HTAP Experiments SR1: Base-case simulation for year 21. SR3: 2% anthropogenic NOx emission reduction in East Asia (EA) and North America (NA) SR7: 2% anthropogenic mercury emission reduction in EA and NA TP1x: Primary and secondary reactive tracers with various atmospheric lifetime emission from EA and NA (CO, VOC, & Hg) NA EU SA EA

3 Model and Data Model: CMAQ V4.6 (released Oct. 26), chemistry codes modified for reactive tracer simulations Modeling period: Year 21 (SR), Years 2 & 3 (TP1x) Domain: ICAP trans-pacific domain in Lambert Conformal projection covering EA and NA, 18-km spatial resolution Emission Inventory: NEI99 and modified Trace-P (SRs), China Hg inventory by Streets t et al. (25), and HTAP TP1x inventory Meteorology: ICAP 21 MM5, model-ready Chemistry: CB-IV/AERO4(SR), 1 st order decay (TP1x) Initial and boundary conditions: re-gridded from GEOS- Chem (SRs) and Mozart (TP1x)

4 Spatial Distribution of O 3 SR1: Base Case Stronger domestic impacts (annual mean) ppbv 5 SR1 SR3_EA NOx effect SR1 SR3_NA NOx effect 2 1.5

5 Domestic Impact (2% NOx reduction) 3 Ch hange in Surfa face Ozone (p ppbv) NA EA (ppbv) rface Ozone Change C in Su Month in 21 Boxplot shows within-region variability Red line shows regional mean by CMAQ Green line shows results from Fiore et al. (28) -6 Month in 21

6 Foreign Impact (2% NOx reduction)*.5 Ozone (p ppbv) Change in Surface Month in 21 Red line shows the foreign impact by CMAQ from EA ONLY Green line shows the foreign impact from three foreign regions COMBINED (EA+EU+SA) [Fiore et al., 28]

7 Import Sensitivity* ( O 3,fr / O 3,do ) by 2% NOx emission reduction Monthly IS from Fiore et al. (28) Annual IS from Fiore et al. (28) Annual IS from CMAQ results Monthly IS from CMAQ results *Data from Fiore et al. (28) consider O 3,fr from ALL foreign source region.

8 Spatial Distribution of Surface PM2.5 SR1: Base Case Stronger impacts in EA (annual mean). Difference mainly contributed by NO 3 aerosol 1-1 Kg/Kg 45 SR1 SR3_EA NOx effect SR1 SR3_NA NOx effect 2 5.5

9 Domestic vs. Foreign Effects NO 3 change in NA caused by 2% NOx reduction in EA (foreign effect) NO 3 change in NA caused by 2% NOx reduction in NA (domestic effect)

10 Annual Mean Hg Conc. & Deposition ng/m 3 SR1: TGM Conc. ng/m 2 /day SR1 Dry Deposition ng/m 2 /day CMAQ_Hg (µg m -2 yr -1 ) SR1 Wet 4 Deposition R=.82 R 2 =.6735 Comparison with MDN wet deposition MDN(µg m -2 yr -1 )

11 Trans-Pacific Transport of Hg

12 Imp port Sensitivity Import Sensitivity ( Hg EA / Hg NA ) by TGM Conc. 2% Hg emission reduction Month in 21 Foreign impact is important because: (1) the greater Hg emission in EA compared to that of NA (2) Hg deposition mainly driven by oxidation of background GEM except near the emission sources Deposition Import Se ensitivity on Dry Sensitivity on Wet Deposition Import Dry Dep. 14 Month in Wet Dep Month in 21

13 CO Tracers (τ = 5 days) ppbv CO from CH 4 Oxidation CO EA /CO 27.8 Mass conservation check passed Transport pattern ppbv CO from Emission 1 Annual mean concentration

14 CO - Domestic vs. Foreign in EA.7.6 in EA.15 COea/CO COna/CO Domestic Month in 21 In EA Foreign Month in n NA COna/CO5 i in NA COea/CO5 i Domestic Month in 21 In NA Foreign Month in 21

15 Hg Tracers - Effect of Lifetime τ = 18 days τ = 36 days ng/m 3 2 ng/m years of spin-up Probably not sufficient for Hg tracers: Hg36 =.5-.6 ng/m 3 τ = 54 days Global background = ng/m 1-2 ng/m 3 3 2

16 Hg Tracers - Effect of Elevation -3 Km: Hg36EA/Hg Km: Hg36EA/Hg36 Stronger transport at higher elevation.6

17 Conclusions 2% domestic NOx emission changes monthly mean surface O 3 by +7.1 to -6.4 ppbv. 2% NOx emission reduction in EA decreases up to.5 ppbv of monthly surface O 3 in NA, spring being the strongest t transport t season. Annual O 3 import sensitivity in NA caused by 2% NOx reduction is about.2 with a large monthly variability. 2% EA NOx reduction has little impact on PM 2.5 in NA. Transport events of Hg from EA to NA identified. Annual Hg import sensitivity in NA caused by 2% Hg reduction ranges from 3 to 5 for concentration ti and dry & wet deposition. Reactive tracer experiments indicate that west coast of NA can be affected by plumes from EA. 5-2% of CO in NA is contributed tib t dby emission i in EA. Results from Hg tracer experiments show that about half of Hg in NA is contributed by emission in EA. This indicates that the transport of Hg from EA to NA can contribute a small but significant deposition in locations away from local Hg emission in NA.

18 Acknowledgements Task Force of Hemispheric i Transport of Air Pollutants (TFHTAP) United States Environmental Protection Agency (USEPA) Texas Commission on Environmental Quality y( (TCEQ)