HR: 0830h
AN: A31D-0083    [PDF]
TI: Linkage Issues Between Global Tropospheric Chemistry Model and Regional Air Quality Model
AU: * Moon, N
EM: nkmoon@math.uh.edu
AF: Institute for Multi-dimensional Air Quality Studies, University of Houston, 312 Science and Research Building 1, Houston, TX 77204
AU: Byun, D W
EM: dwbyun@math.uh.edu
AF: Institute for Multi-dimensional Air Quality Studies, University of Houston, 312 Science and Research Building 1, Houston, TX 77204
AB: One of key problems of regional air quality models, such as U.S. EPA­_s CMAQ, is finding accurate initial and boundary conditions for the simulations. Most popular method for this is running a regional air quality model at a coarser resolution with seasonal profile data and surface emissions input for a long-enough period of time for the spin-up process. However, the procedure is not able to account for the change in the boundary conditions due to certain air pollution long-range transport events. For this reason, we attempt to use outputs of global tropospheric chemistry model simulations to provide the reasonable boundary conditions for the regional air quality simulations. To provide the initial and boundary conditions for regional modeling, we have used the GEOS-CHEM model to link with CMAQ. To link the GEOS-CHEM output in the Latitude-Longitude coordinates at 2 ­’X2.5 of horizontal resolution and 48 vertical layers to the CMAQ in the Lambert-Conformal coordinate at 36kmX36km horizontal resolution over the US-continental domain and 23 vertical layers, it is necessary to perform the horizontal and vertical interpolations. Chemical species mapping is needed because of the different chemistry reaction mechanisms are used such as the O3-NOx-hydrocarbon chemistry in GEOS-CHEM and CB4 and SAPRC99 in CMAQ. In this study we discuss issues in liking the global and regional scale models, such as compatibility of model dynamics, differences in emissions data used and effects of different chemical mechanisms between GEOS-CHEM and CMAQ. To investigate the effects of using GEOS-CHEM output as initial and boundary conditions instead of the profile data on regional CMAQ simulations we have conducted 4 sensitivity CMAQ simulations for the combination of using GEOS-CHEM output and profile data for the boundary conditions and with the CB4 and SAPRC99 as the chemical mechanisms. Analysis shows that there were no significant differences in wind fields and O3 distributions between the GEOS of the NASA DAO in GEOS-CHEM and MM5 in CMAQ. We also compared emissions inputs used for the GEOS-CHEM and CMAQ, in particular for the NOx and VOC species. To verify the CMAQ results after liking with GEOS-CHEM, we have compared the CMAQ results of each simulated cases with AIRS data.
DE: 0317 Chemical kinetic and photochemical properties
DE: 0345 Pollution--urban and regional (0305)
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting