Application of a Unified Aerosol-Chemistry-Climate GCM to Understand the Effects of Changing Climate and Global Anthropogenic Emissions on U.S. Air QualityEPA Grant Number: R830959
Title: Application of a Unified Aerosol-Chemistry-Climate GCM to Understand the Effects of Changing Climate and Global Anthropogenic Emissions on U.S. Air Quality
Investigators: Jacob, Daniel J. , Fu, Joshua , Mickley, Loretta J. , Rind, David , Seinfeld, John , Streets, David G.
Institution: Harvard University , Argonne National Laboratory , California Institute of Technology , NASA Goddard Institute for Space Studies (GISS) , University of Tennessee - Knoxville
Current Institution: Harvard University , Argonne National Laboratory , California Institute of Technology , NASA Goddard Institute for Space Studies , University of Tennessee - Knoxville
EPA Project Officer: Chung, Serena
Project Period: January 1, 2003 through January 1, 2005 (Extended to January 1, 2006)
Project Amount: $900,000
RFA: Assessing the Consequences of Global Change for Air Quality: Sensitivity of U.S. Air Quality to Climate Change and Future Global Impacts (2002) RFA Text | Recipients Lists
Research Category: Climate Change , Air , Air Quality and Air Toxics , Global Climate Change
Weather is a key variable affecting air quality. Surface concentrations of pollutants are highly sensitive to mixing depth, boundary layer ventilation, winds, temperature, humidity, and other meteorological variables. As greenhouse gas concentrations increase and rapid climate change takes place over the next century, the consequences for air quality are likely to be significant but the magnitude and even the sign of the effects are completely unknown. We propose to address this issue by applying a unified aerosol-chemistry-climate general circulation model (GCM) to assess the effects of 2000-2050 changes in both climate and global anthropogenic emissions on air quality in the United States. Our focus will be on surface ozone and particulate matter (PM).
The study will provide an integrated assessment of the effects of global change, including changes in both climate and anthropogenic emissions, on ozone and particulate matter (PM) air quality in the United States from 2000 to 2050. It will represent the first-ever attempt to examine the response of air pollution meteorology to climate change. At present, the sign and magnitude of this response are essentially unknown. The study will identify and quantify the contributing impacts from (1) changes in atmospheric transport (e.g., mixing depths, frequency of stagnation episodes, regional ventilation, intercontinental transport), (2) climate-sensitive natural emissions of ozone and PM precursors, and (3) climate-sensitive ozone and PM chemistry. It will lay the foundation for investigation of the effects of climate change on exceedances of air quality standards through nesting of the CMAQ regional model into a unified aerosol-chemistry-climate general circulation model (GCM).
We will apply a unified aerosol-chemistry-climate GCM (the CACTUS model, based on the GISS GCM) to the simulation of 2000-2050 projected trends in long-lived greenhouse gases and anthropogenic emissions of ozone and PM precursors. The trends will be taken from current Intergovernmental Panel on Climate Change (IPCC) scenarios. The CACTUS model has been developed with NASA funding for studies of the interactions of global tropospheric chemistry and aerosols with climate. A coarse version is presently used, with EPA/ICAP support, to investigate perturbations to air pollution meteorology under 2000-2100 climate change scenarios. Our first step in this project will be to evaluate the ability of the CACTUS model to simulate ozone and PM air quality in the United States for present-day climatology. This analysis will include an empirical orthogonal function (EOF) decomposition of the principal modes of variability of ozone and PM in the United States, both in the observations and in the model, to facilitate future diagnosis of climate change impacts. Separate simulations with the CACTUS model will be used to investigate the effects of 2000-2050 changes in air pollution meteorology, ozone and PM chemistry, and natural and anthropogenic emissions of ozone and PM precursors. Particular care will be taken to separate the effect of climate change from that of interannual variability of weather, which in turn may be affected by climate change. We will nest the CMAQ regional model within the CACTUS model for more accurate predictions of the effects of global change on U.S. air quality, and determine the most efficient strategy for application of CMAQ to simulation of U.S. air pollution under a changing climate.
The project will provide a first-ever assessment of the effect of future climate change on ozone and PM air quality in the United States. Current interannual variability observed in air quality warns us that this effect could be large. We will develop a fundamental understanding of the processes involved and their relative importance through an integrated analysis of climate change and of the correlated changes in ozone and PM precursor emissions. The results will lay the foundation for quantifying the effects of future global change in both climate and anthropogenic emissions for long-term planning of air pollution control needs in the United States.