Atmospheric Dispersion and Boundary Layer Characterization
The accidental or intentional release of chemical, biological, or nuclear agents, as well as ash associated with volcanic eruptions, can have significant health, safety, national security, economic, and ecological implications. The Air Resources Laboratory (ARL) provides critical modeling and observation data to understand how, where, and when chemicals and materials are transported through the atmosphere. Having this understanding is essential for emergency managers and the aviation industry to respond appropriately and minimize or prevent disaster. A primary tool developed by ARL is the HYSPLIT modeling system. HYSPLIT is designed to support a wide range of simulations related to the atmospheric transport and dispersion of pollutants and hazardous materials, as well as the deposition of these materials to the Earth’s surface. Some of the applications include tracking and forecasting the release of radioactive material, volcanic ash, wildfire smoke, and hazardous chemicals. ARL regularly improves, tests, and distributes HYSPLIT to hundreds of users around the world. Operationally, the model is used by NOAA’s National Weather Service through the National Centers for Environmental Prediction and at local Weather Forecast Offices. It is also used by NOAA’s National Environmental Satellite, Data, and Information Service Satellites and the National Ocean Service. In addition, ARL sponsors a web-based system providing rapid access to HYSPLIT dispersion simulations and supporting information.
ARL advances the understanding of atmospheric boundary layer processes that occur on a small-scale within complex environments. Through design, evaluation, and operation of high resolution observing networks and tracer field studies, ARL research improves the accuracy of atmospheric dispersion predictions and the characterization of the boundary layer in support of the dispersion community and for other research applications. The boundary layer has a significant influence on a number of important atmospheric and environmental issues, including the dispersion of airborne hazardous materials; low-level winds and turbulence; convective initiation; evolution of hurricanes; air quality; regional climate changes; the transfer of compounds between land/water and the atmosphere; and the behavior of wildland and agricultural fires and the smoke they produce. ARL conducts dispersion and boundary layer research in various locations around the country and also provides meteorological and consequence assessment support for the safe operation of major U.S. Department of Energy research facilities in Idaho and Nevada.
Atmospheric Chemistry and Deposition
Pollutants released into the air can impact air quality, as well as terrestrial and aquatic ecosystems when the pollutants deposit to Earth. Effective targeting of air pollution controls depends on having good scientific understanding of which specific pollutant sources and regions are contributing to air and water quality issues. While much progress has been made in reducing releases of harmful air pollutants, many locations in the U.S. continue to experience problems associated with air pollutants and poor air quality. On an annual basis, air pollution contributes to tens of thousands of premature deaths from cardiovascular and respiratory diseases. Chemicals in the atmosphere also damage crops and forests, degrade aquatic ecosystems, and contribute to climate change. ARL evaluates and improves computer models used by the National Weather Service in support of state and local forecasters who predict the occurrence of ground-level ozone and fine particulate matter. These forecasts improve the ability of communities and individuals to respond to anticipated episodes of poor air quality by reducing pollutant emissions (e.g., limiting driving) and by taking personal protective measures (e.g., limiting outdoor exercise).
ARL also conducts a variety of research on the exchange of pollutants between the air and the Earth’s surface, which improves understanding and guides policy concerning air quality management and ecosystem health. ARL focuses on pollutants, such as mercury, reactive nitrogen, and sulfur compounds, which can have significant impacts on the environment and—in the case of mercury—human health. ARL activities include a) developing and applying a specialized HYSPLIT modeling system that tracks mercury emissions and links these emissions to atmospheric transport, transformation, and deposition; b) conducting long-term, intensive ambient air monitoring of mercury; c) conducting short-term, process-level field studies for mercury and reactive nitrogen compounds; and d) supporting long-term, research-grade monitoring of acids and nutrients in precipitation.
Climate Observations and Analyses
Changes in the climate can influence economic prosperity, human and environmental health, and national security. Citizens, communities, businesses, governments, and international organizations are requiring climate information and products to cope with climate variability and to adapt to and mitigate climate change. ARL’s Climate Observations and Analyses research provides essential information for decision-makers to understand how and why climate has changed and what changes might occur in the future. ARL’s activities focus on advancing the quality and quantity of reference observations; evaluating selected observing systems for their ability to satisfy ongoing and evolving climate requirements; improving the understanding of air-surface interactions; and analyzing long-term observational datasets and models to understand climate variability and change.
ARL provides high quality, reference-grade measurements of critical climate parameters, such as air temperature, precipitation, winds, land surface temperature, and solar radiation. As a key participant in climate observing networks, both nationally and internationally, ARL develops methods for measuring climate parameters with high accuracy and reliability. ARL designs, evaluates, and maintains the instrument suites and the infrastructure for the U.S. Climate Reference Network, which provides the Nation with a climate-quality benchmark observing system that meets national commitments to monitor the climate of the United States for the next 50-100 years. ARL also conducts long-term field studies to improve the understanding of interactions between the atmosphere, the land surface, and plants, which leads to better climate and weather predictions. Additionally, ARL conducts energy, water, and greenhouse gas flux measurements and analyzes their relationships. A predictive understanding of the surface energy budget and related feedbacks is critical to the understanding of climate forcing factors at the land surface and the ability to credibly predict future conditions, especially those related to water resources.