Trace gas retrievals from infrared emission spectrometry in the Arctic

Trace gas measurements are routinely performed using ground-based solar absorption spectroscopy in measurement networks such as NDACC (Network for Detection of Atmospheric Composition Change) and TCCON (Total Carbon Column Observing Network). For water vapour there exist radiosonde measurements providing high vertical resolution but limited temporal resolution. Retrievals from infrared emission spectrometry bridge a temporal gap in the measurement of trace gases during polar night. Measurements are possible dayround under cloud free conditions. At the AWIPEV site in Ny-Ålesund, Svalbard, we deploy a Bruker Vertex 80 FTIR emission spectrometer with a maximum resolution of 0.08 cm⁻¹ which is able to resolve individual spectral lines. We present optimal estimation retrievals of water vapour and methane. The results are compared to daily radiosonde measurements and TCCON retrievals. First results of applying our retrieval to emission spectra with a reduced resolution are also shown. This will in the future allow to include the retrieval on E-AERI-type instruments with their lower resolution deployed e.g. during the MOSAiC campaign.