Presentation on theme: "Linking GEOS-Chem with CMAQ: Consistency in meteorology and chemistry Linking GEOS-Chem with CMAQ: Consistency in meteorology and chemistry Institute for."— Presentation transcript:
Linking GEOS-Chem with CMAQ: Consistency in meteorology and chemistry Linking GEOS-Chem with CMAQ: Consistency in meteorology and chemistry Institute for Multidimensional Air Quality Studies (IMAQS) University of Houston Institute for Multidimensional Air Quality Studies (IMAQS) University of Houston Daewon W. Byun, Nankyoung Moon, Heejin In, Chang-Keun Song Harvard University Daniel Jacob, Rokjin Park GEOS-Chem: Goddard Earth Observing System-CHEMisrty CMAQ: EPA’s Community Multiscale Air Quality modeling system
Introduction One of key problems of regional air quality models is finding accurate initial and boundary conditions (BCs) Most popular method is running a coarse regional model with fixed profiles for a reasonable period to spin-up the coarse domain, then use nesting for fine scale simulations. Profile BCs could be different at each side of domain reflecting certain regional differences but cannot account for changes caused by long-range air pollution transport events. Key Issues linking global model output for regional models are differences in; 1.Chemical species 2.Scales and grid structure - Spatial interpolation of global data for regional BC 3. dynamic descriptions in Global and Regional Models
24 species O 3 -NO X -Hydrocarbon chemistry : 24 species CMAQ MAPPING Table CB4 O3-NOx-Hydrocarbon chemistry [NO2 ][NOx ]-[NO] [O3 ][Ox ] - [NOx ] [N2O5] [HNO3] [PNA ][HNO4] [H2O2] [CO ] [PAN ][PAN ] + [PMN ] + [PPN ] [MGLY][MP ] [ISPD][MVK ] + [MACR] [NTR ][R4N2] [FORM][CH2O] [ALD2][ALD2] + [RCHO] [PAR ][ALK4] + [C3H8] + [C2H6] [OLE ][PRPE] [ISOP] GEOS-CHEM 16 species CB4 : 16 species Un-used species : ACET, ALD2 Chemical species:Currently, chemical mechanisms in global and regional models are not “consistent”: use species mapping Mechanics of Linkage
LAT-LON 2 degree X 2.5 degree 30 layers in Sigma P LAMBERT CONFORMAL 108 km X 108 km 23 layers in Sigma Po Initial & Boundary Condition IO/API Format in 108 km resolution GEOS-CHEM MODEL3 CMAQ ( Multi-pollutant Air Quality model) Mechanics of Linkage Linkage of scales: grid structures of the global and regional models are not “consistent” Requires horizontal & vertical interpolation Implementation Example: Horizontal interpolation Future – requires “geocentric” coordinates (from a flat-earth to a spherical earth, if not spheroid)
Comparison of wind field This difference can be cause the uncertainty to regional air quality simulations. MM5NASA-GMAO General patterns of wind fields are well Some difference shows in circled area. - CMAQ/MM5 shows parallel to the grid - GEOS-CHEM/NASA-GMAO shows inflow Let’s see how big the problem is:
CMAQ vs. O3 RAOBS (GEOS-CB4 vs.Profile) Profile BC GEOS_CHEM BC GEOS-3
Example with RAQMS: CMAQ/CB-4 vs. O3 RAOB O3 met SITE #LocationNationLAT.LON.ALT. STN02 1 EDMONTON/STONY PL AIN CAN53.55-114.10766.00 STN07 6 GOOSE BAYCAN53.30-60.3640.00 STN07 7 CHURCHILLCAN58.75-94.0735.00 STN10 7 WALLOPS ISLANDUSA37.90-75.4813.00 Stratospheric O3 data assimilation issues: Chemistry and dynamics tropopause heights STN021 STN076 STN077STN107 Note: other than Wallops island, the o3 zonde sites are different from those used in previous page
What is the best method to link global/regional scale dynamics? Comparison of wind fields among four different MM5 results. Case 1; MM5 results with EDAS first guess Case 2; MM5 results with EDAS first guess and GMAO objective analysis Case 3; MM5 results with GMAO, 36-km single domain Case 4; MM5 results with GMAO, 108/36-km nesting ~ trying to get closer wind fields to GMAO ~ typical MM5 simulation for regional air quality study
Case 1&2 vs. GMAO (wind components) 00z Case 2Case 1
Case 3 & 4 vs. GMAO (wind components) Case 3Case 4 00z agreement with observation : CASE1 > CASE2 > CASE4 > CASE3 agreement with GEOS-3 : CASE1 < CASE3 < CASE2 < CASE4 Is CASE2 the winner?
Conclusion Conducted sensitivity CMAQ simulations with fixed profile data, GEOS-Chem BC, CB-4 and SAPRC99 mechanisms, and different MM5 outputs Boundaries for global-regional scale linking must be located where direct emission sources are minimum; e.g., US-continental domain (Pacific to Atlantic Oceans). Careful assessment of chemical species linkage and horizontal & vertical interpolation schemes required Optimal mesoscale meteorological input obtained with EDAS first guess and GMAO objective analysis Studied chemical and meteorological consistency issues between the global and regional models.