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The Ongoing Development of a Water Vapour Retrieval from the PARIS-IR Arctic Springtime Dataset

The Arctic is currently warming at approximately twice the rate of the global mean. As atmospheric composition is tied intrinsically to climate, studying changes in trace gas species can lead to a more thorough understanding of the changing Arctic conditions. One way to study these changing gas concentrations is through the use of ground-based remote sensing instruments, such as the Portable Atmospheric Research Interferometric Spectrometer for the InfraRed (PARIS-IR). Between 2004 and 2017 PARIS-IR operated on a yearly basis out of the Polar Environment Atmospheric Research Laboratory (PEARL; 80.05° N, 86.42° W) located in Eureka, Nunavut, as part of the Canadian Arctic ACE/OSIRIS Validation Campaigns. These springtime measurement campaigns commenced in mid-February and continued for approximately six weeks into early April. Throughout the duration of these campaigns PARIS-IR recorded solar absorption spectra within the range of 750 – 4400 cm-1, with 0.02 cm-1 spectral resolution, every seven minutes, weather permitting.

Prior studies have focused on retrievals of eight trace gas species (O3, HNO3, HCl, HF, CH4, C2H6, N2O and CO) from the PARIS-IR Arctic measurement dataset, however the focus here is on the ongoing development of a ninth retrieval for water vapour. This additional species was chosen for study due to its importance as a greenhouse gas and the positive feedback relationship it exhibits with surface temperature. The PARIS-IR Arctic dataset is well suited for this study, not only for the length of the dataset, but also for the instrument’s characteristics, particularly its portability and comparatively low spectral resolution, which makes it a useful test case for the development of a robust retrieval scheme. The talk will cover the implementation thus far, and initial findings from the first iterations of the PARIS-IR water vapor retrieval scheme.