2009 Progress Report: Impact of Global Change on Urban Air Quality via Changes in Mobile Source Emissions, Background Concentrations, and Regional Scale Meteorological Feedbacks
EPA Grant Number:
Impact of Global Change on Urban Air Quality via Changes in Mobile Source Emissions, Background Concentrations, and Regional Scale Meteorological Feedbacks
Kleeman, Michael J.
, Chen, Shuhua
, Schauer, James J.
University of California - Davis
University of Wisconsin Madison
EPA Project Officer:
March 1, 2007 through
February 28, 2011
(Extended to February 28, 2013)
Project Period Covered by this Report:
March 1, 2009 through February 28,2010
Consequences of Global Change For Air Quality (2006)
Global Climate Change
The current project aims to quantitatively assess the consequences of Global Change on California air quality by (1) measuring emissions from mobile sources powered by alternative fuels as a function of temperature and humidity, (2) creating a source-oriented PM module for the Weather Research & Forecasting (WRF) model to quantify feedback between air quality and regional meteorology, and (3) calculating California air quality in the year 2030 during a range of O3
Source-oriented emissions fields now can be read into the source-oriented WRF-CHEM model using the WRF standard input / output routines. Emissions records have been produced for area and point source emissions and these can be read by the modified WRF-CHEM model but we have not yet implemented plume rise calculations into the model. All point source emissions are therefore currently represented as ground level sources.
We have introduced a 6D PM chemistry variable into the WRF-CHEM framework including 3 spatial coordinates, a size bin coordinate (8 bins currently specified), a source coordinate (5 sources currently specified) and a chemical species coordinate (31 chemical species + tracers currently specified). This variable will form the basis for source-oriented calculations within WRF-CHEM.
We have implemented the ISOROPIA thermodynamics code in the WRF-CHEM framework using the dynamic approach for gas-particle conversion described by Jacobson (2005). This enables accurate gas-particle conversion calculations for the condensation of diffusion limited species such as sulfate and N2O5 onto existing particle size distributions.
We have implemented a coagulation routine into the WRF-CHEM model based on the source-oriented coagulation routines developed for the UCD/CIT air quality model.
The source-oriented PM concentration variable introduced into the WRF-CHEM framework now is tied into all of the major aerosol processes within the model including emissions, advection, turbulent mixing, deposition, coagulation, and gas-particle conversion. Initial simulations have been performed to test memory load, communications overhead, and overall computational burden. Preliminary results are favorable, with further results forthcoming.
A source-oriented gas concentration variable has been introduced into the WRF-CHEM framework in parallel to the original “CHEM” variable used to represent gaseous species. The new variable will eventually be used to replace the original WRF-CHEM gas-phase chemistry with source-oriented gas-phase chemistry so that the sources of particulate nitrate, ammonium ion, and sulfate can be retained through the photochemical calculations.
We have started work on feedback effects from source-oriented aerosols to regional meteorology by creating and testing subroutines to calculate the optical properties of model layers containing source-oriented external mixtures of particles. These programs will be implemented in the source-oriented WRF-CHEM model and tied to the existing radiative transfer calculations within the WRF framework. The new calculations will illustrate how the urban particle matrix influences the vertical temperature structure of the atmosphere, wind speed, cloud cover, precipitation, etc.
The latest version of WRF-CHEM 3.2 has been installed on Prof. Kleeman’s computer cluster and currently is undergoing testing. Model development under WRF-CHEM V3.1.1 will be ported to V3.2 in the coming months.
A manuscript describing the fuel based catalyst (FBC) results has been published in the journal Energy and Fuel.
A series of tests addressing the impact of biofuel blends on emissions from off-road diesel engines has been completed. Ultra Low Sulfur Diesel (ULSD) fuel was blended with soybean and beef tallow based Biodiesel to examine fuels containing 0% (B0), 25% (B25), 50% (B50), 75% (B75), and 100% (B100) biodiesel. Samples were collected using a dilution source sampler to simulate atmospheric dilution. Diluted and aged exhaust was analyzed for particle size distribution, PM2.5 particle mass, PM2.5 organic and elemental carbon, and speciated organic compounds. Data analysis of these results is finalized and a manuscript has been prepared for submission.
A series of tests looking at the impact of temperature and fuel on emissions of gasoline engines has been completed. The fuels that were examined were natural gas, E6, E10, E85, and intermediate blends of the ethanol fuels. In all cases, particle mass emissions were found to be extremely low but significant changes to the particle size distributions were observed as a function of fuel and ambient temperature. These results currently are being finalized and will be used as the basis for a manuscript that will be submitted for publication. Tailpipe VOC emissions also were found to depend on fuel and ambient temperature and these results currently are being analyzed and are intended to be used as the basis for a publication.
Future measurement efforts are directed at completing data analysis for the source tests, which will be the basis of several manuscripts that describe: 1) role of ambient temperature of diesel engine emissions, 2) impact of biofuels on current and future on-road diesel engine technologies, and 3) the role of seed aerosol on emissions of PM from gasoline and diesel engines.
During the coming reporting period we will link the source-oriented gas-phase variables and the source-oriented radiative transfer calculations directly into the WRF-CHEM calculations. Simulations will be conducted for the State of California during the years 2000 and 2050. Results will be compared to simulations using the WRF model coupled (offline) with the UCD source-oriented air quality model.
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RFA, Scientific Discipline, Air, Ecosystem Protection/Environmental Exposure & Risk, particulate matter, Air Quality, Air Pollutants, Chemistry, climate change, Air Pollution Effects, Monitoring/Modeling, Atmospheric Sciences, Environmental Engineering, Atmosphere, ambient aerosol, environmental monitoring, anthropogenic stress, atmospheric dispersion models, aerosol formation, atmospheric particulate matter, meteorology, climatic influence, emissions monitoring, future projections, air quality models, ozone, global change, atmospheric transport, greenhouse gases, climate models, atmospheric aerosol particles, airborne aerosols, environmental stress, regional emissions model, climate model, ecological models, greenhouse gas, aerosols, atmospheric chemistry, climate variability, Global Climate Change, ambient air pollution
Progress and Final Reports:
2007 Progress Report
2008 Progress Report
2010 Progress Report
2011 Progress Report