By Patricia Craig January 12, 2015

UNIVERSITY PARK, Pa. -- Penn State will lead a five-year, $30 million mission to improve quantification of present-day carbon-related greenhouse gas sources and sinks. An improved understanding of these gases will advance our ability to predict and manage future climate change.

"Atmospheric Carbon and Transport-America" is one of five airborne studies funded by NASA's Earth System Science Pathfinder Program to improve our understanding of the Earth system and our ability to predict future changes.

In 2015, NASA aircraft will begin five studies around the world to investigate how global air pollution, climate forcing, warming ocean waters and fires in Africa affect our climate. The five studies were competitively selected as part of NASA's Earth Venture-class missions and are the second series of NASA's Earth Venture suborbital investigations.

Ken Davis, professor of meteorology in the College of Earth and Mineral Sciences, is the principal investigator on the Penn State project, which will measure atmospheric concentrations of carbon dioxide, methane and other gases and atmospheric properties within weather systems across the eastern United States. The study will improve detection and quantification of carbon dioxide and methane sources and sinks using airborne, satellite and ground-based observations.

ACT-America will bring together more than 30 scientists from 10 institutions including federal agencies, national laboratories, other universities and private industry. NASA Langley Research Center, located in Hampton, Virginia, is Penn State's lead partner in the effort. Other Penn State researchers on the project include Thomas Lauvaux, adjunct professor of meteorology and researcher at NASA's Jet Propulsion Laboratory, California; Natasha Miles, research associate in meteorology; Scott Richardson, senior research associate in meteorology; Charles Pavloski, senior research associate in meteorology; Bernd Haupt, senior research associate, Penn State's Earth and Environmental Systems Institute; Fuqing Zhang, professor of meteorology; and Klaus Keller, associate professor of geosciences.

On regional and continental scales, carbon dioxide and methane sources and sinks are poorly understood. ACT-America will employ a new generation of atmospheric inversion systems to estimate surface-to-atmosphere net carbon fluxes by using atmospheric concentration measurements and atmospheric transport models. These systems can provide accurate and precise diagnoses of carbon dioxide and methane fluxes for biomes, nations or other important ecological or geopolitical regions. These new systems will be the first with the precision, accuracy, and resolution needed to evaluate and improve terrestrial carbon cycle models, and monitor carbon fluxes to support climate-change mitigation efforts.

Understanding the terrestrial carbon cycle is essential for diagnosing current and predicting future climate change. The Earth's terrestrial biosphere has been a strong net sink of atmospheric carbon dioxide, substantially slowing the rate of accumulation of the greenhouse gas produced from the combustion of fossil fuels in the atmosphere. Methane, another form of carbon in the carbon cycle, is accumulating in the atmosphere and is the second largest contributor to anthropogenic climate change.

"This mission is focused primarily on ecosystem fluxes of carbon dioxide." Said Davis. "Ecosystem fluxes of carbon dioxide and methane are large forces in the climate system. Currently, ecosystems are sequestering carbon dioxide and offsetting fossil fuel emissions of carbon dioxide. About 25 percent of carbon dioxide emissions from burning fossil fuel gets absorbed by terrestrial ecosystems and about another 25 percent gets absorbed by oceans so only about half of the CO2 that we emit stays in the atmosphere. This is a huge benefit but we are not able to predict the future course of this sink."

"Methane is produced in wetlands, in the digestive tracts of ruminants, and in landfills, and it can escape to the atmosphere during fossil fuel extraction and use. The gas and oil boom in the U.S. may be increasing methane emissions. Our airborne measurements will improve quantification of these sources."

Researchers have made significant progress in quantifying the carbon cycle at the global scale and at the scales measured by flux towers -- about a square kilometer -- but the ability to diagnose carbon dioxide and methane sources and sinks at scales in between is missing.

ACT-America will run for five years and will include airborne, spaceborne and ground-based measurements to study carbon dioxide and methane sources, sinks and transport in the eastern United States. Aircraft flights will focus on the northeast, upper Midwest, and Gulf coast states.

"The mission will deploy five flight campaigns, each six weeks long," said Davis. "Each of the three study regions will be sampled during all four seasons and will also include sampling during both high and low pressure systems."

Research flights will use NASA's C-130 plane based at Wallops Flight Facility, Wallops Island, Virginia and NASA's UC-12 plane based at NASA's Langley Research Center, Hampton, Virginia. The aircraft will measure how greenhouse gases are transported through the atmosphere by both weather systems and the turbulent mixing generated at the earth's surface. The mission will also include flights under the path of NASA's Orbiting Carbon Observatory-2 to evaluate OCO-2 observations over the eastern U.S. The aircraft data will be used to evaluate the sensitivity of satellite-based measurements of CO2 from OCO-2 to regional variability in tropospheric CO2 content.