Ground-based infrared remote sensing greenhouse gas (GHG) observations are extensively used for the validation of GHG measurements from satellites like SCIAMACHY, GOSAT and OCO-2. TCCON (Total Carbon Column Observing Network) is a network of about 23 stations distributed globally and measuring the total column abundances of GHGs using a Fourier-transform infrared (FTIR) solar absorption spectrometer of the type Bruker IFS 125HR. TCCON was set up with the aim to provide precise and accurate measurements of GHGs to be used primarily for satellite validation. However, the TCCON network has shown some deficiencies in terms of the gaps in the coverage, especially in remote locations, locations with high/low albedo. The TCCON spectrometer is very expensive, not so easy to move, and requires special operational conditions, trained personnel for operation and maintenance, therefore, it is very costly if further expansion of the network is desired.
Presently, several new portable spectrometers have been developed that have the potential to eliminate those deficiencies of the TCCON network: they are low cost, portable, easy to operate and maintain and require low operational cost. However their performances have not yet been fully characterized. In order to characterize the performance of these low cost portable spectrometers performing TCCON-type measurements simultaneously under different atmospheric conditions in comparison with a TCCON instrument, a campaign has been planned for approximately one year in 2017. In this campaign, the teams will install these candidate instruments together at the TCCON site in Sodankylä, Finland. In addition, regular AirCore launches will also be performed from that site and will provide in-situ reference profiles of the target gases, which will be useful to verify the instruments calibration.
The focus of this campaign will be on CO and CH4 in support of the S5P validation. The campaign will provide a significant dataset of GHG measurements which can be used for validation purposes during the S5P commissioning phase. Furthermore, it will also provide a comparative characterization of the participating instruments with respect to the standard TCCON instrument in terms of the precision, accuracy, stability, portability and ease of deployment, cost factor, etc. The outcome of the campaign will then be a guideline for the further development of new observation sites to complement the TCCON network and provide better support for the validation of the existing and future satellite missions.