Validation of Column-averaged Dry-air Mole Fractions of Atmospheric CO2 and CH4 at the Burgos TCCON Site in the Philippines

The Total Carbon Column Observing Network (TCCON) is a network dedicated to the precise remote sensing measurements of the column-averaged dry-air mole fractions (DMF) of CO₂, CO, CH₄, N₂O and H₂O. Column-averaged DMF of gases (denoted as X_Gfor gas G) can be used in combination with in situ measurements to disentangle the effects of atmospheric mixing and surface exchange of greenhouse gases, providing a better understanding of the regional-scale fluxes. However, TCCON measurements rely on spectroscopic parameters that are not known with sufficient accuracy. TCCON measurements of X_G must therefore be validated by comparison to World Meteorological Organization (WMO) in situ trace gas measurement scales.

We installed a newly-constructed TCCON FTS (Fourier transform spectrometer) in Burgos, Ilocos Norte, Philippines, which followed rigorous site assessments and discussions at several TCCON and GOSAT-2 science team meetings. After installation and setup of the instruments in March 2017, we started operations in the Philippines using TCCON protocols.

Here, we present a validation of the Burgos TCCON data using instrumentation aboard the HALO aircraft that measured profiles during its transfer flight in the scope of the EMeRGe-Asia mission. Measurements of X_CO2, X_CH4 and X_CO with a portable FTS (Bruker EM27/SUN) were also made, coincident with TCCON and the HALO flight.