United States Environmental Protection Agency Office of Research and Development National Exposure Research Laboratory Research Abstract Government Performance Results Act (GPRA) Goal #4 Annual Performance Measure #551 Significant Research Findings: An Examination of the Downscaled Regional Climate Model (RCM) Scenarios for Assessing Air Quality Response to Climate Variability and Change Under the U.S. EPA Global Change Research Program, EPA is investigating the potential impacts of climate change on air quality so that air quality managers can consider interactions between climate and air quality in their decision making process. Air quality is largely determined by the air pollutant emissions and the meteorological conditions. Climate change and climate variability are factors that could strongly influence both emissions and meteorological variables in the future. A careful examination of present and future climate conditions and associated variability will help improve our understanding of the climate predictions and associated changes in air quality conditions in the future. This research contributes to the U.S. Climate Change Science Program (CCSP) assessment of the effects of global change on human health and welfare and human systems. Global climate simulations have been derived from the NASA Goddard Institute for Space Studies (GISS) version IF (two prime) Global Climate Model (GCM) and the Intergovernmental Panel on Climate Change Special Report on Emission Scenarios (SRES) A1B "business as usual" emission scenario. Scientists with the Department of Energy's (DOE) Pacific Northwest National Laboratory have used these scenarios to provide boundary and initial conditions to a regional climate model (RCM) based on the Fifth Generation Pennsylvania State/National Center for Atmospheric Research (NCAR) Mesoscale Model (MM5). The RCM was then used to generate 10 years worth of possible hourly climate data, based first on current (-2000) conditions and then based on predicted future (-2050) conditions. These simulations provided a range of possible hourly climate conditions across the continental United States at a horizontal grid cell size of 36 km x 36 km. Surface temperature and pressure, dominant surface wind direction, annual precipitation, and upper level winds are evaluated for the base case (current) and future year conditions. Our work focuses on analyzing atmospheric features such as cyclones (e.g., low pressure systems, hurricanes, tropical storms, etc.), anticyclones (e.g., high pressure systems, etc.), and fronts that are largely responsible for the day-to-day changes in weather. Methods employed include distributional and time series analyses at individual locations or grid cells and spatial analyses across the coterminous United States. The data were analyzed with regard to 1) the simulated temporal and spatial characterization of regional climate parameters under current conditions relative to present-day observations of those same parameters, and 2) the changes in climate parameters between the modeled values using current conditions the modeled results predicted -50 years Scientific Problem and Policy Issues Research Approach ------- into the future (-2050). Results and Impact Research Collaboration and Research Products The GISS-driven base case RCM scenarios agree with current observations of regional climate conditions of particular relevance for air quality for some, but not all seasons, and for some geographic regions of the continental U.S. Based on comparison of current base case to future model climate scenarios, the modeling predictions suggest changes in atmospheric conditions over the next 50 years (e.g., warmer surface temperatures and weaker surface and upper level atmospheric transport) that could impact the way the US manages air quality for ozone and particulate matter. The GCM scenarios were developed by scientists at Harvard University under the STAR Grant program. These GCM scenarios were shared with scientists at DOE's Pacific Northwest National Laboratory for boundary and initial conditions to the RCM. Output from the RCM was transferred to the EPA/National Exposure Research Laboratory and forms the starting point for the analysis reported here. Two research products have been completed for internal use and are undergoing peer review. Publicly available versions of the products will be prepared after peer reviews are completed: Twenty-years of MM5 RCM predictions under the current and future (2050) climate conditions have been archived at USEPA (more than 4 terabytes of model output). Future Research Contacts for Additional Information Cooter, E.J.; R. Gilliam, A. Gilliland and J. Swall. "An Examination of the Downscaled Regional Climate Model (RCM) Scenarios for Assessing Air Quality Response to Climate Variability and Change." Internal Report, September 2005. RCM analysis results will be used to develop air quality model scenario outcomes at NERL during FY06. At the same time, additional primary and derived RCM variables such as ventilation will be explored. Opportunities to collaborate with other federal agencies conducting assessment research dealing with climate variability and change (e.g., NOAA, NASA and the DOE) that would facilitate the development of an ensemble of GCM and RCM model results suitable for air quality assessment application are being pursued. Questions and inquiries can be directed to: Ellen Cooter, Ph.D. U.S. EPA, Office of Research and Development National Exposure Research Laboratory (MD-E243-04) Research Triangle Park, NC 27711 Phone 919/541-1334 E-mail: cooter.ellen@epa.gov Alice Gilliland, Ph.D. U.S. EPA, Office of Research and Development National Exposure Research Laboratory (MD-E243-01) Research Triangle Park, NC 27711 Phone 919/541-0347 E-mail: gilliland.alice@epa.gov Funding for this project was through the U.S. EPA's Office of Research and Development, National Exposure Research Laboratory, and the work was ------- conducted by the Atmospheric Modeling Division. ------- |