During the second week at PEARL, the on-site team experienced varying weather conditions. The week started with cold, windy conditions with temperatures of less than -30C and winds reaching 16 kts. Throughout the week, weather conditions improved at the Ridge Lab with milder temperatures reaching up to -13C. Winds also subsided leading to calm conditions. There was variable cloud cover throughout the week, with generally cloudy conditions in the morning, and clear skies in the afternoon at the Ridge. These weather conditions were favourable for working on the instruments on roof of the Ridge Lab roof.
During cloudy conditions, Erik was able to perform a series of cell tests for the Bruker FTIR. Several HCl and N20 cell tests were performed. Running several cell tests with each gas cell confirmed that the internal optical alignment of the Bruker FTIR has remained consistent.
Erik and Pierre worked on the Bruker FTIR's solar tracker to improve the alignment of the solar beam on the input aperture of the FTIR. This involved checking the level of the sun-tracker’s base, and making small adjustments to level it. After levelling it, they found an improvement in the in the alignment of the solar beam on the input aperture. Erik and Pierre are currently investigating altitude and azimuth corrections for the sun sun-tracker to further improve the alignment of the solar beam.
Throughout the week during clear-sky conditions, Erik recorded both mid-infrared and near-infrared solar measurements with the Bruker FTIR. Pierre had setup the liquid nitrogen generator to produce LN2 required to cool the mid-infrared detectors of the Bruker FTIR.
Over in the UV-vis lab, Ramina spent some time working the Pandora instrument and the UT-GBS. The Pandora was brought inside the lab for some tracker testing and rearrangement of the plastic cable guide to ensure that there was no obstruction in the movement of the head sensor, which had been occurring previously. The Pandora was then re-installed on the roof and after a manual alignment to locate the Sun, it ran several alignment sequences on a clear-sky day. Measurements will resume once a sufficient number of alignments have been obtained.
As for the UT-GBS, Ramina spent the last few days performing tests to measure polarization effects, dark current & bias, and resolution of the instrument. Results were very similar to previous years and indicate that the instrument performance remains optimal. Ramina will be performing similar tests for the PEARL-GBS this upcoming week, and will also aim to install a new tracker mirror for the PEARL-GBS when the weather permits.
Ramina Alwarda and Erik Lutsch
[On behalf of the 2023 Canadian Arctic ACE/OSIRIS Validation Campaign team]