TCCON at Twenty

In May of 2004, TCCON observations began at Park Falls, WI (USA) and Lauder (New Zealand). TCCON or the Total Carbon Column Observing Network is a network of ground-based Fourier Transform spectrometers that record direct solar spectra in the near-infrared. Now, just over two decades later, TCCON has expanded to over 29 sites worldwide with new sites coming online nearly every year. While COVID-related restrictions impacted our community, TCCON maintained most of its data collection and continued to contribute significantly to satellite validation and carbon cycle science.

Here, we will discuss this international network/partnership and TCCON’s vicennial results and highlights as we continue to strive towards improving the accuracy and precision of our column-averaged abundances of atmospheric constituents (CO₂, CH₄, N₂O, HF, CO, H₂O, and HDO). This includes the release of the GGG2020 retrieval algorithm, which is a substantial improvement over GGG2014. Data time series, several twenty-years long, and the resulting discoveries about regional sources and sinks of CO₂ and CH₄, will be presented, as will TCCON’s many contributions to space-based measurements. Finally, we will briefly mention ongoing efforts to reduce intra-network biases and to extend measurement capabilities into the mid-infrared spectral range where a number of other carbon-containing gases can be measured and quantified.