Atmospheric Carbon and Transport – America (ACT‐America) Data Sets: Description, Management, and Delivery

Abstract

 ACT-America provides a unique, weather-oriented collection of high-quality measurements of atmospheric CO2, CH4, trace gases and meteorological properties. ACT-America data are free and open to the public from the ORNL DAAC. ACT-America data are uniquely suited to improve the accuracy and precision of regional inverse GHG flux estimates.

Covariation of Airborne Biogenic Tracers (CO2, COS, and CO) Supports Stronger Than Expected Growing Season Photosynthetic Uptake in the Southeastern US

“…Approximately 10-12 flask samples were captured during each flight. We screen data for overlapping high quality samples of CO 2 , CO, and COS and fair-weather days (∼50% of total samples, ranging from 32% in fall 2017 to 59% in summer 2019) using provided air mass flags (Wei et al, 2021). CO 2 samples collected during summer 2016 were replaced by continuous data from in situ systems on board both aircraft due to CO 2 depletion in undried flask air samples at water vapor levels above 1.7% (Baier et al, 2020).…”

“…We focus on enhancements of tracer concentrations within BL relative to background variability in order to maximize sensitivity to local-regional (∼100-500 km) surface flux influences. We estimate BL enhancements as the difference between BL and free troposphere (FT) flask data as indicated by metadata flags (Wei et al, 2021). Baier et al (2020) show that FT data provides an effective measure of background conditions for CO 2 in winter.…”

“…Atmospheric Carbon and Transport (ACT)-America, is a NASA Earth Venture Suborbital airborne mission that targeted multi-species vertical profiles in the eastern US for improved understanding of CO 2 sources and sinks (Davis et al, 2021;Wei et al, 2021). ACT-America conducted five airborne campaigns across four seasons from 2016 to 2019, capturing vertical gradients of CO 2 , CO, and COS across three unique regions including the humid sub-tropical, evergreen-dominated South, seasonally warm-to hot-crop-dominated Midwest, and the warm temperate, deciduous broadleaf forest dominated Northeast.…”

The Atmospheric Carbon and Transport (ACT)-America Mission

“…The C-130 carried additional instrumentation, including an in situ nitrous oxide (N 2 O) analyzer (Kostinek et al 2019), a downward-pointing backscatter lidar able to detect clouds and clear-air atmospheric structure including atmospheric boundary layer (ABL) depth (McGill et al 2004;Pal et al 2020b), and a downward-pointing integrated path differential absorption (IPDA) lidar to measure either column CO 2 (XCO 2 , first four flight campaigns; Campbell et al 2020) or column CH 4 (XCH 4 , aerosol/cloud, and ABL depth, final flight campaign). More details on the instruments, performance metrics, calibration procedures and data archives are found in Wei et al (2021).…”

“…All in situ aircraft data were complemented with three flags that identify whether or not the observations are within the ABL, the airmass position of the data point (warm/prefrontal, cold/postfrontal, or ambiguous), and the aircraft maneuver (level leg, takeoff, landing, spiral ascent/descent, en route ascent/descent). Flags exist for every ACT-America in situ data point and these are integrated into the flight data stored at the Oak Ridge DAAC (Wei et al 2021;Davis et al 2018) and as an additional download accompanying NOAA's ObsPack product (Schuldt et al 2020). OCO-2 tropospheric XCO2 variability.…”