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ACT-America: Science

Science Overview

ACT-America, or Atmospheric Carbon and Transport – America, will conduct five airborne campaigns across three regions in the eastern United States to study the transport of atmospheric carbon. The eastern half of the United States is a region that includes a highly productive biosphere, vigorous agricultural activity, extensive gas and oil extraction and consumption, dynamic, seasonally varying weather patterns and the most extensive carbon cycle and meteorological observing networks on Earth, serves as an ideal setting for the mission.

Each 6-week campaign will accurately and precisely quantify anomalies in atmospheric carbon, also known as Carbon Flux. Accurate carbon flux data is necessary to address all terrestrial carbon cycle science questions. ACT-America addresses the three primary sources of uncertainty in atmospheric inversions — transport error, prior flux uncertainty and limited data density.

ACT-America will advance society’s ability to predict and manage future climate change by enabling policy-relevant quantification of the carbon cycle. Sources and sinks of atmospheric carbon dioxide (CO2) and methane (CH4) are poorly known at regional to continental scales. ACT-America will enable and demonstrate a new generation of atmospheric inversion systems for quantifying CO2 and CH4 sources and sinks.

ACT-AMERICA Transport Diagram

ACT-America Goals:

  1. To quantify and reduce atmospheric transport uncertainties.
  2. To improve regional-scale, seasonal prior estimate of CO2 and CH4 fluxes.
  3. To evaluate the sensitivity of Orbiting Carbon Observatory (OCO-2) column measurements to regional variability in tropospheric CO2.

ACT-America will achieve these goals by deploying airborne and ground-based platforms to obtain data that will be combined with data from existing measurement networks and integrated with an ensemble of atmospheric inversion systems. Aircraft instrumented with remote and in situ sensors will observe how mid-latitude weather systems interact with CO2 and CH4 sources and sinks to create atmospheric CO2/CH4 distributions. A model ensemble consisting of a mesoscale atmospheric transport model with multiple physics and resolutions options nested within global inversion models and surface CO2/CH4 flux ensembles will be used to predict atmospheric CO2 and CH4 distributions.

Beyond the conclusion of the mission, application of the knowledge gained from this mission will improve diagnoses of the carbon cycle across the globe for decades.

Study Area

ACT-AMERICA Science Study Area
Figure 1. Sustained airborne and tower-based measurements will be focused over three regional CO2 and CH4 source/sink regions
in the U.S. The campaign will build upon and improve the utility of our nation’s existing investment in long-term CO2 and CH4 observations,
noted on the figure. The study areas are identified with a box that has the dimensions of the proposed flight patterns.

The three study regions indicated in Figure 1 are chosen because:

  • The U.S. east of the Rockies is the dominant North American biogenic source/sink region for CO2 (Huntzinger et al., 2012) and is a major source region for biogenic and anthropogenic CH4 emissions (Miller et al. 2013; Allen et al., 2013);
  • The regions encompass a variety of biomes (Midwest agriculture, Northeast forests, Southeast coastal forests and agriculture) and oil and gas extraction zones (Bakken – midwest; Marcellus – northeast; Fayetteville/Haynesville – southeast);
  • Each region is large enough to encompass the weather systems that are the target of the study, and the regions encompass a broad range of mid-latitude weather environments.

Investigation Timeline
ACT-AMERICA Investigation Timeline