A Short Description of the NOAA HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) Model

Alice Gilliland
U.S. EPA Office of Research and Development,
Research Triangle Park, NC USA

Recent studies have developed "downscaled" regional climate simulations based on the Intergovernmental Panel on Climate Change (IPCC) greenhouse gas (GHGs) scenarios, global climate models (GCMs), and regional meteorological models. These regional climate scenarios have been used for assessment of climate impacts on a range of endpoints, including potential impacts on air quality with an emphasis on ozone. Here, we will present some examples of future (ca. 2050) changes in atmospheric deposition from a recent sensitivity study of climate impacts on air quality, but then focus more on evaluation of the precipitation predictions and potential impacts that precipitation uncertainties may have on atmospheric deposition of nutrients. This will include a comparison of the current regional climate results to observations and comparison of the future precipitation changes to IPCC's most recent GCM simulations over North America. Based on precipitation uncertainties under current climate conditions and the range of potential future precipitation scenarios, a range of future precipitation scenarios are needed when considering future climate impacts on atmospheric deposition and ecosystem effects. While not yet available, ensemble precipitation predictions such as the North American Regional Climate Change Assessment Program ( could prove to be most useful in considering how future climate may impact atmospheric deposition of nutrients on a regional scale.