The Atmospheric Carbon and Transport (ACT)-America Mission

Abstract

The Atmospheric Carbon and Transport (ACT) – America NASA Earth Venture Suborbital Mission set out to improve regional atmospheric greenhouse gas (GHG) inversions by exploring the intersection of the strong GHG fluxes and vigorous atmospheric transport that occurs within the midlatitudes. Two research aircraft instrumented with remote and in situ sensors to measure GHG mole fractions, associated trace gases, and atmospheric state variables collected 1140.7 flight hours of research data, distributed across 305 individual aircraft sorties, coordinated within 121 research flight days, and spanning five, six-week seasonal flight campaigns in the central and eastern United States. Flights sampled 31 synoptic sequences, including fair weather and frontal conditions, at altitudes ranging from the atmospheric boundary layer to the upper free troposphere. The observations were complemented with global and regional GHG flux and transport model ensembles. We found that midlatitude weather systems contain large spatial gradients in GHG mole fractions, in patterns that were consistent as a function of season and altitude. We attribute these patterns to a combination of regional terrestrial fluxes and inflow from the continental boundaries. These observations, when segregated according to altitude and air mass, provide a variety of quantitative insights into the realism of regional CO2 and CH4 fluxes and atmospheric GHG transport realizations. The ACT-America data set and ensemble modeling methods provide benchmarks for the development of atmospheric inversion systems. As global and regional atmospheric inversions incorporate ACT-America’s findings and methods, we anticipate these systems will produce increasingly accurate and precise sub-continental GHG flux estimates.

Multi‐Season Evaluation of CO2 Weather in OCO‐2 MIP Models

“…In total, 182 research flights were flown in four seasons and the tracks of flights in each season are shown in Figure 1. Each research flight spanned from 4 to 6 hr during daytime with a spatial extent of 600 km or more (Davis et al., 2021; Wei et al., 2021). There are 2–4 vertical levels during each flight extending from the PBL (∼300 m above ground level [a.g.l.])…”

Joint CO2 Mole Fraction and Flux Analysis Confirms Missing Processes in CASA Terrestrial Carbon Uptake Over North America

“…This product provides integrated measurements and metadata flag information, including flight pattern, airmass type, and boundary layer information at five-second intervals. More information about the ACT-America campaign and measurements can be found at https://actamerica.ornl.gov/ and Davis et al (2021). The nearest point interpolation is applied to extract modeled [CO 2 ] along the flight tracks.…”

Seasonal Variability in Local Carbon Dioxide Biomass Burning Sources Over Central and Eastern US Using Airborne In Situ Enhancement Ratios

“…The ACT-America campaign was a NASA Earth Venture Suborbital project focused on reducing errors in inversion models of the transport and emissions of atmospheric carbon dioxide and methane over the continental United States (Davis et al, 2021;Wei et al, 2021). ACT-America consisted of seasonal six-week intensives with three deployments per intensive; sampling locations and dates are shown in Table 1.…”