During our first day on site, Darby visited the Zero Altitude PEARL Auxiliary Laboratory (0PAL) for the first time with Pierre and learned where each instrument is located. Darby inspected the Pandora instrument’s indoor and outdoor components, cleared snow that had accumulated in the tube where sunlight enters the instrument and is directed toward a fiber optic cable that carries the signal to the spectrometer indoors. Removing snow from delicate optical equipment in –33°C temperatures with ice crystals is difficult; in addition to needing to wear winter gloves, the actual snow removal needs to be done without melting the snow, as it could then freeze and damage the equipment. Then, inside the lab, Darby swapped the Pandora power source to route through a web-controlled power switch to enable hard resetting of the spectrometer and its computer remotely, should problems arise in the future. Darby then restarted the Pandora and ran the usual measurement sequence. Since then, the Pandora instrument was able to successfully track the position of the sun and of the moon and has been running nominally. On March 8, Darby returned to 0PAL to test equipment and organize the lab.

On Sunday, March 9, the team were driven to the Ridge Lab in the ECCC mat-track truck for their first visit during this campaign. Upon arrival, it was –25°C and sunny at the Ridge Lab. Darby helped Pierre begin the clearing of a path through a layer of about 70cm of snow and ice on the staircase that leads up to the roof of the Ridge Lab.

Inside the lab, Kevin checked the status of the PEARL-GBS and UT-GBS and confirmed that both instruments are running nominally. These instruments make measurements of ultraviolet and visible sunlight to quantify the atmospheric concentrations of ozone and other trace gases. Kevin then gathered cameras that will be installed on the roof of the Ridge Lab. These cameras will enable remote monitoring of snow accumulation on the domes protecting the optics that guide sunlight into each GBS instrument. He also assembled lamps and filters to be able to perform upcoming calibration tests.

Petra was hoping to get near-infrared atmospheric measurements with the Bruker 125HR FTIR as it was a beautiful, sunny day, but technical issues with the suntracker system, which directs sunlight into the spectrometer, meant that she spent most of the afternoon troubleshooting these issues. There may be more bumps in the road in the coming weeks as she gets the system all warmed up for the season, but that’s why we’re here!

Cheers,
Darby Bates
[on behalf of the 2025 Canadian Arctic ACE/OSIRIS Validation Campaign]