On Friday evening some of the team again watched the ozonesonde launch. At this point doing so has become ingrained in our daily routine. The team then spent a quiet evening working on various projects or playing ping-pong with each other.
Saturday morning started off bright and sunny with temperatures around -44 degrees, seemingly wonderful for taking advantage of the 10 hours of sun up for that day. Unfortunately the clear skies lasted about as long as the drive up to the PEARL Ridge Lab and shortly after arriving the sun was well hidden by clouds. Over the course of the day the temperature warmed up to -36 degrees, with ice crystals in the afternoon, light snow in the evening, and fairly high wind speeds throughout. During the early afternoon there was a brief window of clear skies and the team tried to make a couple measurements during that time. The team went for a brief walk after losing the sun, but eventually had to turn back due to the blowing snow and windy conditions.
Saturday evening saw Paul and Kristof watch the ozonesonde launch, Emily and Ghazal remain up at the PEARL Ridge Lab to finish the shutdown of the DIAL, and Erik and Sébastien return to PEARL to work on the Bruker instrument. After several hours the team members at the Ridge Lab eventually returned, and the team spent the evening socializing with the Eureka weather station staff, watching (and poking fun at) a "haunted house" tv show, and planning out our actions for the rest of the campaign.
Sunday began with brunch, followed by the team heading up to the PEARL Ridge Lab for our second last day there. The weather was a warm -32 degrees with fairly little wind, falling ice crystals and cloud cover on the horizon. We expected 10 hours and 20 minutes of sun over the course of the day. Variable cloud cover interfered with making solar measurements to an extent, but this was a minor effect and by the later afternoon the sky was mostly clear with ice crystals. The temperature through the day reminded in the low -30s.
Over the weekend at the Ridge Lab Gurpreet finalized a set of SPS instructions for Pierre to use during the extended phase of the validation campaign. In addition he ensured that SPS continued to operate in zenith mode. Finally Gurpreet continued the backup of SPS data to the CANDAC archives.
At 0PAL CRL made 24 hours of measurements on both March 10th and 11th.
With the increasing hours of sunlight, the seasonal operation of the DIAL lidar (which requires darkness) came to an end over the weekend. Ghazal and Emily spent Saturday at the Ridge Lab shutting down the lidar and closing up the DIAL lab for the season. All procedures for this went according to plan.
Paul spent part of Saturday finishing an instruction manual for PARIS operation during the extended portion of the campaign and packing PARIS equipment that will not be used during the extended phase. On Saturday he took advantage of the brief period of sun to make 9 solar measurements. On Sunday Paul could not make any solar measurements as the beam of light was blocked by Erik and Sébastien working on the Bruker instrument's alignment. He spent time looking at raw spectra measurements made over the course of the campaign and doing data backup.
Using the brief Saturday sunshine, Kristof aligned the PEARL-GBS netcam and pickoff mirrors. Over the rest of the weekend, he packed up all the testing equipment and straightened up his corner of the lab. On Sunday Kristof removed the shutters from the GBSs, which was done as a safety measure as the shutters tend to break frequently.
After discovering earlier that the Bruker-FTS was slighlty misaligned, Erik and Sébastien, with the help of Pierre, spent the weekend performing the alignment procedure to correct this. This involved setting up a telescope to view the fringe patterns of a HeNe laser source, and centring them on the entrance aperture. Then the fixed corner cube was adjusted to correct for a slight shear misalignment. After adjustments the fringe pattern was found to be centred at all optical path differences. The exit aperture was also slightly adjusted to ensure it was aligned with the entrance aperture. The laser alignment was also checked at all optical path differences. The Bruker-FTS is now aligned and Erik and Sébastien will continue with cell tests to asess the impact of the alignment.