ESRL Global Systems Division

GSD’s Contributions to Summer 2013 Intensive Field Studies

In the summer of 2013, intensive field studies took place in the Southeast U.S., a region with significant anthropogenic emissions and meteorological conditions that are conducive to active photochemistry, and where natural hydrocarbon emissions are the highest in the nation. These six-week field studies were SENEX 2013 - Studying the Interactions Between Natural and Anthropogenic Emissions at the Nexus of Climate Change and Air Quality, and the Southern Oxidant and Aerosol Study (SOAS) that took place in Alabama and focused on biosphere-atmosphere interactions. Both studies included many national and international scientists and organizations.

ESRL/Global Systems Division's (GSD) contribution to these studies was to provide forecasts of air quality and weather using the state-of-the-art fully coupled Weather Research and Forecasting (WRF) model with the addition of chemistry (known as the WRF-Chem application). The application uses the Rapid Refresh (RAP) WRF configuration including its North American domain, similar to the operational NOAA/NCEP RAP, but with the addition of chemistry. Chemical boundary conditions were provided by NASA and NOAA's Real-time Air Quality Modeling System (RAQMS). Dr. Steven Peckham (GSD Assimilation and Modeling Branch - AMB) was in charge of the real-time set up and execution of WRF-Chem model runs for these studies. Dr. Georg Grell (GSD/AMB) and Dr. Stuart McKeen (ESRL/Chemical Sciences Division (CSD) provided interpretations of the model runs, as well as answering questions on the runs.

The atmospheric abundances of many climate forcing agents and air pollutants are high in the Southeast. However, the extent to which these abundances are controlled by natural vice anthropogenic emissions is poorly understood. For aerosols in particular, the climate radiative forcing, defined as the change in net irradiance at the tropopause between present and pre-industrial, is very uncertain. In addition, the Southeast U.S. has not warmed like other parts of the U.S. in response to global climate change, and the temperature anomaly has been suggested to be related to aerosols derived from a combination of anthropogenic and biogenic precursors. These studies will help to provide answers to many of these questions.

NOAA has one of the world's leading research programs to improve our understanding of the most important climate forcing agents. The program includes monitoring abundances and quantifying emissions of the chemical formation of agents such as ozone and aerosols, and the characterization of their climate-relevant properties. NOAA/ESRL also has the lead in developing the WRF-Chem model that can be used to study these climate relevant processes with greater accuracy and at cloud resolving resolutions. With this combination of measurement and modeling capabilities, NOAA is poised to make major advances in understanding key interactions among climate and air quality, and of the relative importance of natural processes versus human activities in controlling the atmospheric distribution of climate forcing agents.

Contact information
Name: Georg Grell
Tel: 303-497-6924