1. THE IMPACTS OF TRANS-BOUNDARY TRANSPORT OF AEROSOLS ON THE REGIONAL AIR QUALITY: A case study of Mexican wildland fire on May 1998 Hee-Jin In 1, Daewon W. Byun 1, Soontae Kim 1,Nan-Kyoung Moon 1, Sharon Zhong 1 Rokjin J. Park 2 2nd GEOS-CHEM USERS’ MEETING, Harvard University, April 4-6, 2005 GEOS-CHEM linked to Regional CMAQ Simulation

2. Biomass burning due to ENSO-related drought in Mexico and Central America during April ~ June 1998 May 13 1998 May 14 1998 May 15 1998 May 16 1998 TOMS Aerosol Index

3. Monthly mean EC/OC by IMPROVE network 1998 annual mean EC : 0.5 – 0.8 ugm -3 (E) 0.1 – 0.3 ugm-3 (W) OC : 2-3 ugm-3 (E) 1-2 ugm-3 (W) CMAQ Domain 36 km × 36 km Lambert Conformal 23 Sigma vertical layers (P top = 50 mb) Period : May 1998 EC OC

4. Four Case Runs Emissions Boundary conditions ● NEI99 ● Pre-defined fixed profiles ● NEI99 + Biomass-burning ● GEOS-CHEM Linkage

5. EMISSION monthly total NEI99 Biomass burning 1 o x1 o global inventory Duncan et al. (2002) Park et el. (2003) NEI99 + Biomass burning ECOC

6. BOUNDARY CONDITIONS linking with GEOS-CHEM NORTH SOUTH WEST EAST OC

7. Linking with GEOS-CHEM (2 o x2.5 o ) Spin-up with NEI99 emission INITIAL CONDITIONS ECOC

8. Simulated aerosol evolutionary feature vertically integrated daily mean EC+OC simulation (g m -2 ) TOMS AI

9. Monthly mean simulated vs. observed OC

10. EC OC R= 0.69 R= 0.68 R= 0.77 R= 0.83R= 0.75 R= 0.33 R= 0.68 Monthly mean simulated vs. observed concentration R= 0.79

11. ● IMPROVE AZTX TN AR NEI99 (thick: with GC BC, thin: no) NEI99+ Biomass emission (thick: with GC BC, thin: no) Daily variation of OC - - - GEOS-CHEM

12. SUMMARY We present carbonaceous aerosol simulation for May 1998 when severe biomass burning occurred in Mexico and Central America due to an ENSO- related drought. In this simulation, we link the GEOS-CHEM output to CMAQ lateral boundary values through interpolation with coordinate transformation and species mapping between the chemistry mechanisms. The CMAQ simulation using GEOS-CHEM as a lateral boundary condition brings out appreciable improvement of carbonaceous aerosol concentrations, especially in the southern United States, demonstrating successful effects of trans-boundary transport of aerosols. We evaluate monthly mean aerosol concentrations with Interagency Monitoring of Protected Visual Environments (IMPROVE) network data. The correlation coefficient between simulated and observed monthly mean organic/elemental carbon concentrations are 0.68 and 0.83 with the GEOS- CHEM linkage, much higher than 0.33 and 0.68 with default constant lateral conditions. 2nd GEOS-CHEM USERS’ MEETING, Harvard University, April 4-6, 2005