AirCore profiles of greenhouse and trace gas species for sites within the Total Carbon Column Observing Network (TCCON) and comparisons to models and ground-based Fourier Transform Spectrometer (FTS) retrievals

The AirCore is an innovative, balloon-borne sampling system that collects a continuous atmospheric sample from the surface to the stratosphere. We have analyzed this sample for carbon dioxide (CO₂), methane (CH₄), and carbon monoxide (CO). This unique system provides a low-cost, effective method for sampling more than 95% of the atmospheric column, thereby providing an essential constraint for evaluation of satellite and ground-based greenhouse gas column retrievals. In addition, the AirCore provides detailed sampling of the stratosphere, where our observations are currently limited. Since 2012, more than 80 profiles have been collected at multiple locations, providing valuable constraints on both stratospheric circulation and model estimates of stratospheric CO₂ and CH₄. Over this period, many valuable scientific and technological improvements have been made to the AirCore, including additional species sampled and expanded participation from the international community. These improvements were exemplified during a recent campaign where AirCore profiles were collected at several sites for the TCCON in the U.S. and in Finland. Our results highlight the value of these improvements to the AirCore and the value that this system adds as a comparison to models and ground-based Fourier Transform Spectrometer (FTS) column greenhouse gas retrievals, which are in turn necessary for evaluating satellite greenhouse gas retrievals.