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Research: Atmospheric Transport and Dispersion

The accidental or intentional release of chemical, biological or nuclear agents can have significant health, safety, national security, economic, and ecological implications. ARL provides essential tools and information for decision-makers and the research community to improve prediction of how, where, and when chemicals and materials are atmospherically transported and deposited. Having this understanding is critical for responding appropriately and preventing disaster.

HYSPLIT/ALOHA model results for a fictitious chlorine 
HYSPLIT model results for a fictitious chlorine spill near Washington, D.C. using the NOAA ALOHA toxic release model to describe the time-varying release rate to the atmosphere. Colors depict decreasing concentrations of the chlorine plume as it disperses away from the source area (red color). Image credit: NOAA/ARL

What We Do

ARL focuses its Dispersion Research on the development and improvement of sophisticated dispersion models and other tools for air quality and emergency response applications. This includes volcanic eruptions, forest fires, nuclear accidents, and homeland security incidents. ARL also designs and evaluates high resolution observing networks, develops instrumentation, and conducts tracer field studies to improve the accuracy of atmospheric transport and dispersion predictions.



ARL's HYSPLIT model is a highly-valued tool that helps explain the transport, dispersion, and deposition of chemicals and harmful material. HYSPLIT is used to track and forecast the release of radioactive material, volcanic ash, wildfire smoke, and pollutants from various emission sources. The strength of the dispersion modeling is the broad and effective transition from research to applications. Within NOAA, HYSPLIT is run operationally by the National Weather Service's National Centers for Environmental Prediction for a variety of events. It is also heavily relied upon by local Weather Forecast Offices across the U.S. For more information on HYSPLIT, click here.

The Real-time Environmental Applications and Display sYstem (READY)

READY is a web-based system developed by ARL to access and display meteorological data and to run trajectory and dispersion simulations. The System is unique in that it brings together the HYSPLIT model, graphical displays, and textual forecasts into a form that is readily available and easy to use by anyone. READY is particularly useful for weather and air quality forecasters, but it is also used by weather- sensitive industries and hobbyists (e.g.,balloonists, hang gliders) and the general public. For more information on READY, click here.

ARL performing maintenance on tower equipment
ARL performs routine maintenance of one of the meteorological stations located at the top of Big Southern Butte in Idaho. Photo: NOAA


High Resolution Observing Networks

ARL designs and evaluates high resolution meteorological observing networks (e.g., stations typically 10 miles or less apart, compared to 100 miles or more apart for the national weather observing network) to capture small-scale air flows that can have a significant impact on how and where airborne chemicals and materials are transported. ARL also evaluates how this high resolution information can be incorporated into NOAA's large-scale weather models to improve predictions of surface wind fields.

Field Studies

The flow of airborne materials in urban, coastal, and mountainous regions is very complex. Terrain, water, and man-made structures distort the wind fields that carry materials. To improve and evaluate dispersion models, it is important to gather field data on atmospheric flows in different types of situations. ARL collects such data by tracking the concentrations of tracer materials that can be readily followed back to a known source. This provides basic information required to ground truth dispersion models used for emergency response applications.

Additional Material:

Modified: August 4, 2016
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