On Friday, March 1st temperatures at the Eureka weather station were around -34 degrees C, with strong winds of 19.4 knots (36 km/h), bringing the windchill temperature down to a frigid -51 degrees C. Up at the Pearl Ridge Lab, temperatures were significantly warmer than Eureka, at -19.1 degrees C with relatively calmer winds of 8 knots (15.5 km/h), bringing the windchill index to -28 degrees C. Today was cloudy and overcast, with a consistent light dusting of ice crystals (referred to as ‘diamond dust’ by the Eureka locals) throughout the day. Beneath the cloud cover, we had a total of 6 hours and 29 minutes of sunlight (approximately 25 minutes longer than yesterday). The team is patiently awaiting a sunny day so they can begin solar measurements with the Bruker 125HR and Pandora.
Sebastien and Tyler spent their day in the IR lab finishing up the alignment process for the Bruker 125HR which they started yesterday. The final stages of the alignment included centring the entrance and exit apertures and bringing them into focus with each other, and then carefully adjusting the system of mirrors so that the internal laser passes straight through both apertures without hitting the edges (the smallest aperture is 0.5mm in diameter, so this is not an easy task). Following the full alignment, they ran another series of HCl and N2O cell tests, as well as background measurements to verify the success of the alignment. Preliminary analysis of the HCl cell test showed a significant improvement in the modulation efficiency from ~0.7 prior to the alignment to approximately 1.005, with 1 being the ideal value, at all optical path differences. Tomorrow they will analyze the results of the N2O cell tests, and then if everything looks good, the Bruker will be ready to take solar measurements when the next sunny day arrives.
Since the Pandora alignment was not possible due to the overcast skies, Kristof spent the day performing the lab tests for the PEARL-GBS. He carefully replaced the fibre (that brings in light from the roof) with a shorter testing fibre. He then performed resolution tests for all the diffraction gratings using elemental lamps. In the afternoon, he set up a halogen lamp and collected measurements to characterize spectral noise and nonlinearity of the detector, as well as polarization and light leaks. Before heading down for dinner, he installed a shutter in the spectrometer, and left the instrument to take dark current measurement overnight.
Xin and John continued with their usual routine and collected a set of snow samples from a sampling site near to the PEARL Ridge Lab. Xin also collected some falling snow from the tray on the roof of PEARL. Around noon, Xin and John headed back down to the Eureka Weather Station, where the high winds of 36 km/h created the perfect conditions to capture some blowing snow. However, due to the bad visibility and gusting winds, they had to cut their snow sampling at the site to the west of the Weather Station short. Instead, Xin collected a few samples behind the 0PAL lab, as well as a bottle of blowing snow. He was very excited to sample blowing snow, as he did not manage to collect any during last year’s campaign. More excitingly, the ozone analyzer at the 0PAL lab measured a significant drop in ozone concentration from the background level of ~30 ppbv to less than 20 ppbv over the course of 5 hours.
In the morning, Ali sat down with Tom, who showed him how to analyze the SPS data. Ali spent his afternoon working on his temperature retrieval code, and did some preliminary comparisons of the DIAL data to temperature profiles captured by radiosondes. Alexey ran a few more tests on his drone, and did a couple of drone flights near the PEARL Ridge Lab, while Ali and Tyler looked on from the roof.
At the end of day the team, tired from a long week of work, mostly split off to relax and catch up on some sleep. A few team members gathered in the rec room to watch TV and play a few games of billiards.
Cheers,
Tyler Wizenberg
[On Behalf of the 2019 Canadian Arctic ACE/OSIRIS
Validation Campaign team]
* Instrument Status *
Bruker FTIR: Offline (cell measurements)
EM/27 SUN FTIR: In transit to Eureka