Center for Environmental Research and Technology/Air Quality Modeling University of California at Riverside Modeling Source Apportionment Gail Tonnesen, University of California, Riverside RPO Meeting, Denver, CO, May 25, 2004

Center for Environmental Research and Technology/Air Quality Modeling University of California at Riverside Motivation Need to understand which emissions sources contribute to haze and other pollutants. Use this information to assist in developing control strategies.

Center for Environmental Research and Technology/Air Quality Modeling University of California at Riverside Modeling Approaches Sensitivity Studies: –Brute Force: Zero-in or Zero-out a single source. –DDM Sensitivity – efficient but non-linear. Use tracers or “tagged species” to track mass from a single source: –UCR and ENVIRON are implementing similar tracer algorithms in CMAQ and CAMx.

Center for Environmental Research and Technology/Air Quality Modeling University of California at Riverside Other Modeling Approaches Modeling back-trajectories. Chemical Mass Balance (CMB).

Center for Environmental Research and Technology/Air Quality Modeling University of California at Riverside Tagged Species Approach Use “Tagged Species” tracers to track chemical transformations and the movement and chemical conversion of mass across domain. Add tracers for key species and for defined regions & source categories. Outputs 3-D fields showing transport of secondary species. Also outputs bar plots showing contributions at each receptor site.

Center for Environmental Research and Technology/Air Quality Modeling University of California at Riverside Tagged Species for Nitrates NOX = reactive N family. = { NO, NO2, NO3, 2*N2O5, HONO, PNA} HNO3 PAN RNO3 ANO3J ANO3I

Center for Environmental Research and Technology/Air Quality Modeling University of California at Riverside Chemical Transformations Emissions are as NOx = NO + NO2 Use integrated reaction rates at each time step to update the tagged species: –NOX  PAN –NOX  RNO3 –NOx  HNO3 –HNO3  ANO3

Center for Environmental Research and Technology/Air Quality Modeling University of California at Riverside Transport & Loss Terms Use CMAQ transport solvers for advection and dispersion of each tracer. Also update for mass export in CLOUD and aqueous chemistry algorithms. Update tagged species for emissions and deposition terms. Check for mass conservation at each step and adjust mass if needed. Halt if large errors.

Center for Environmental Research and Technology/Air Quality Modeling University of California at Riverside Traced Area: WRAP Modeling Domain Source Area Mapping File: Each state is distinguished by a unique number

Center for Environmental Research and Technology/Air Quality Modeling University of California at Riverside Traced Source Tags TypesSource CategoryNotes ICON Initial Concentration BCON Boundary Concentration EmissionsMV_*Mobile sources of any state BG_*Biogenic sources of any state RD_*Road dust of any state NR_*Non- Road dust of any state PN_*Point sources without SO2 of any state PS_*Point sources with SO2 of any state AR_*Area sources of any state WF_*WF Fire of any state AG_*AG Fire of any state RX_*RX Fire of any state MX_*Mexico Fire ET_*Total Emission of any state *_WRAPAny type of emission of WRAP domain OthersOTHERSAny sources other than all of the above

Center for Environmental Research and Technology/Air Quality Modeling University of California at Riverside CA Mobile Source Sensitivity – Zero-out

Center for Environmental Research and Technology/Air Quality Modeling University of California at Riverside CA Mobile Source contribution using tracers

Center for Environmental Research and Technology/Air Quality Modeling University of California at Riverside Contributions to NO3 at Yosemite

Center for Environmental Research and Technology/Air Quality Modeling University of California at Riverside Future Work Test alternate treatments of HNO3  NO3 and H2SO4  SO4 equilibrium. Improve Graphics/Statistics Program to automate Tracer Result Evaluation. More testing- comparisons with zero out sensitivity runs. Scalability in supporting other modeling domains –Create corresponding source area mapping files – county domains.