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 StudiesInstitute for Multidimensional Air Quality Studies(IMAQS)(IMAQS)

University University ofof Houston Houston

Institute for Multidimensional Air Quality StudiesInstitute for Multidimensional Air Quality Studies(IMAQS)(IMAQS)

University University ofof Houston Houston

Daewon W. Byun, Nankyoung Moon, Heejin In, Chang-Keun SongDaewon W. Byun, Nankyoung Moon, Heejin In, Chang-Keun SongDaewon W. Byun, Nankyoung Moon, Heejin In, Chang-Keun SongDaewon W. Byun, Nankyoung Moon, Heejin In, Chang-Keun Song

Harvard UniversityHarvard UniversityHarvard UniversityHarvard University

Daniel Jacob, Rokjin ParkDaniel Jacob, Rokjin ParkDaniel Jacob, Rokjin ParkDaniel Jacob, Rokjin Park

GEOS-Chem: Goddard Earth Observing System-CHEMisrtyCMAQ: EPA’s Community Multiscale Air Quality modeling system

IntroductionIntroductionOne 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 species2. Scales and grid structure

- Spatial interpolation of global data for regional BC

3. dynamic descriptions in Global and Regional Models

O3-NOX-Hydrocarbon chemistry : 24 species24 species

CMAQ

MAPPING Table

CB4O3-NOx-Hydrocarbon

chemistry

[NO2 ] [NOx ]-[NO]

[O3 ] [Ox ] - [NOx ]

[N2O5] [N2O5]

[HNO3] [HNO3]

[PNA ] [HNO4]

[H2O2] [H2O2]

[CO ] [CO ]

[PAN ] [PAN ] + [PMN ] + [PPN ]

[MGLY] [MP ]

[ISPD] [MVK ] + [MACR]

[NTR ] [R4N2]

[FORM] [CH2O]

[ALD2] [ALD2] + [RCHO]

[PAR ] [ALK4] + [C3H8] + [C2H6]

[OLE ] [PRPE]

[ISOP] [ISOP]

GEOS-CHEM

CB4 : 16 species16 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

Mapping Table

SAPRACO3-NOx-Hydrocarbon

chemistry

[NO2 ] [NOx ] – [NO]

[PAN] [PAN]

[CO] [CO]

[ALK3] [ALK4]+[ALK5 [ALK4]

[ISOPRENE ] [ISOP]

[HNO3] [HNO3]

[H2O2] [H2O2]

[ACET ] [ACET]

[MEK] [MEK]

[CCHO] [ALD2]

[RCHO] [RCHO]

[MRTHACRO] [MACR]

[MA_PAN] [PMN]

[MVK] [MVK]

[PAN2] [PPN]

SAPRACO3-NOx-Hydrocarbon

chemistry

[RNO3] [R4N2]

[OLE1] + [OLE2] [PRPE]

[ALK2] [C3H8]

[HCHO] [CH2O]

[ALK1] [C2H6]

[N2O5] [N2O5]

[HNO4] [HNO4]

[COOH ] [MP]

CMAQ

GEOS-CHEM

SAPRAC-99

Linkage of Chemistry

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 interpolationImplementation 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.

MM5 NASA-GMAOGeneral 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:

MM5 GMAO

CMAQ O3 Boundary Flux (2wk avg, Aug 16-30, 2000)

Profile BCGEOS_CHEM BC

N

S

W

E

Solid: in-fluxDashed: out-flux

Current Progress B.C. by Height: GEOS-CHEM 4 x 5 Vertical interpolation

WN

E S

Current Progress B.C. by pressure: GEOS-CHEM 4 x 5Vertical interpolation

WN

SE

Current Progress Cf: B.C. by pressure : RAQMS 2 x 2.5 Vertical interpolation

E S

NW

Comparison of CMAQ O3 with AIRS

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 metSITE # Location Nation LAT. LON. ALT.

STN021

EDMONTON/STONY PLAIN

CAN 53.55 -114.10 766.00

STN076

GOOSE BAY CAN 53.30 -60.36 40.00

STN077

CHURCHILL CAN 58.75 -94.07 35.00

STN107

WALLOPS ISLAND USA 37.90 -75.48 13.00

Stratospheric O3 data assimilation issues:Chemistry and dynamics tropopause heights

STN021

STN076 STN077 STN107

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

Study importance of the dynamic consistency Comparison of the first guess field used in MM5:

between EDAS and GMAO

PREGRID MYPREGRID

REGRIDDER

EDAS GMAO

GMAO MM5/Case-1

00z

GMAO & MM5/Case-1 vs. RAOBs (wind components)

Case 1&2 vs. GMAO (wind components) 00z

Case 2Case 1

Case 3 & 4 vs. GMAO (wind components)

Case 3 Case 4

00z

agreement with observation  : CASE1 > CASE2 > CASE4 > CASE3agreement 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.