Atmospheric Carbon and Transport – America (ACT-America) Datasets: Description, Management, and Delivery

Abstract

The ACT-America project is a NASA Earth Venture Suborbital-2 mission designed to study the transport and fluxes of greenhouse gases. The open and freely available ACT-America data sets provide airborne in situ measurements of atmospheric carbon dioxide, methane, trace gases, aerosols, clouds, and meteorological properties, airborne remote sensing measurements of aerosol backscatter, atmospheric boundary layer height and columnar content of atmospheric carbon dioxide, tower-based measurements, and modeled atmospheric mole fractions and regional carbon fluxes of greenhouse gases over the Central and Eastern United States. We conducted 121 research flights during five campaigns in four seasons during 2016-2019 over three regions of the US (Mid-Atlantic, Midwest and South) using two NASA research aircraft (B-200 and C-130). We performed three flight patterns (fair weather, frontal crossings, and OCO-2 underflights) and collected more than 1,140 h of airborne measurements via level-leg flights in the atmospheric boundary layer, lower, and upper free troposphere and vertical profiles spanning these altitudes. We also merged various airborne in situ measurements onto a common standard sampling interval, which brings coherence to the data, creates geolocated data products, and makes it much easier for the users to perform holistic analysis of the ACT-America data products. Here, we report on detailed information of data sets collected, the workflow for data sets including storage and processing of the quality controlled and quality assured harmonized observations, and their archival and formatting for users. Finally, we provide some important information on the dissemination of data products including metadata and highlights of applications of ACT-America data sets.

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

“…Two airborne platforms (NASA Wallops C130 and NASA Langley B200) equipped with in‐situ sensors were employed during the campaigns to measure greenhouse gases (e.g., [CO 2 ] and CH 4 ) and other trace gases (e.g., CO, C 2 H 6 , and O 3 ), as well as meteorological variables (e.g., horizontal wind, temperature, pressure, and water vapor). The C130 also included lidars measuring planetary boundary layer height (PBLH) and partial $${\chi }_{{\text{co}}_{2}}$$ (Campbell et al., 2020; Wei et al., 2021). In total, 182 research flights were flown in four seasons and the tracks of flights in each season are shown in Figure 1.…”

“…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.])…”

“…In addition to [CO 2 ] observations, airborne in‐situ measurements of wind speed and lidar measurements of PBLH made during the campaigns are used in our model evaluation. In‐situ wind speeds were measured on both airborne platforms (Wei et al., 2021). PBLHs were determined by the aerosol backscatter profiles measured with the Goddard Cloud Physics Laboratory lidar aboard on C130 using a wavelet method (Davis et al., 2000; Pal et al., 2010).…”

Evaluation of CarbonTracker's Inverse Estimates of North American Net Ecosystem Exchange of CO2 From Different Observing Systems Using ACT‐America Airborne Observations

“…All flights were conducted during midday hours (15-0 UCT) in order to sample well mixed ABL conditions. The detailed instrument, deployment and data set of ACT-America are described in (Davis et al, 2021;Wei et al, 2021). The calibration of the CO 2 measurements are described by (Baier et al, 2020).…”

Examining CO2 Model Observation Residuals Using ACT‐America Data

“…This work uses 5 s averaged aircraft dry mole fractions measured using a Picarro G2401‐m cavity ring down spectrometer and calibration is traceable to X2007‐scale. Data are published in the ACT‐America: L3 Merged In Situ Atmospheric Trace Gases and Flask Data, Eastern USA data set (Update: March 04, 2019; Davis et al., 2018), which is freely available from the Oak Ridge National Lab Distributed Archive Center (ORNL DAAC; Wei et al., 2021). The NASA Langley Beechcraft B‐200 King Air and the NASA Goddard Space Flight Center's C‐130H aircraft were used to collect high quality in situ and remote sensing measurements across the Eastern United States.…”