On Monday, February 24, the temperature hovered around -39°C at the Eureka weather station, while the PEARL Ridge Lab saw noticeably warmer temperatures of -29°C to -27°C. The wind wasn't particularly strong at either site, but haze and occasional clouds yielded less than ideal measurement conditions. Eureka had a total of almost 4 hours of sunlight today.
The team headed out to the Ridge Lab after breakfast and made good use of their time before returning to the weather station at 5 PM for dinner.

Because today was cloudy Beatriz and Tyler decide to run HBr and HCl cell measurements with the Bruker 125HR. However, there was a period with enough solar intensity to allow them to align the EM27/SUN. They ensured that the beam was centred on both detectors. They continued running some tests for the Vaisala PTB330 pressure sensor and the Raspberry Pi, but unfortunately the pressure sensor failed during this process. They tried to revive the sensor but were unsuccessful. They are currently exploring different alternatives to resolve the problem.

Kristof and Ramina took the PEARL-GBS offline today, since they will use it for training purposes over the upcoming days. They have disassembled the instrument, and moved it from its regular location on the IR lab mezzanine to the UV-Vis lab. Ramina then reassembled the spectrometer, CCD, and the input optics, with directions from Kristof. In the afternoon they covered the basics of the CCD focusing procedure. They also set up the lamps and fibre used for lab tests, so they are ready for more practice tomorrow.

Sunday night, Ali started collecting measurements with the DIAL around 7:40 PM. The clear sky conditions were promising. Ali re-aligned the laser at approximately 11:30 PM. Clouds appeared in the sky around midnight and started to thicken by 4 AM. Ali and Alexey kept collecting measurements up to 7 AM this morning. Ali also joined Alexey at 0PAL, where he closely observed Alexey's work with the CRL. Emily is now running the CRL remotely and testing final performance. So far, everything is looking good and the CRL will hopefully be back to nominal observations within a day or two.

Yesterday, the SPS and tracker were installed on the roof of the Ridge Lab. Both operated successfully overnight and restarted observations in the morning. The observing conditions and the short observation period have resulted in a limited data set. At noon today the pointing was adjusted and the system should now be ready for the extended campaign.

With most of the instruments running nominally now, the team is eagerly awaiting longer days and clear skies to increase the number of measurements. These observations will be used for a variety of applications, ranging from the validation of satellite missions like the Atmospheric Chemistry Experiment (ACE) and the Optical Spectrograph and InfraRed Imager System (OSIRIS), to understanding transport prosesses in the atmosphere.

Cheers,
Ellen Eckert
[on behalf of the 2020 Canadian Arctic ACE/OSIRIS Validation Campaign]