The temperature at Eureka dropped significantly during the night of March 4 to March 5, so when the team left for the Ridge Lab around 8:45 AM the temperature was at -43°C (-51°C with the windchill). However, the drive up to PEARL provided breathtaking views over Ellesmere Island and Slidre Fiord thanks to high visibility. At the Ridge Lab, temperatures were more moderate at slightly below -30°C. Wind speeds were still low and the skies were clear for the entire day. These excellent conditions allowed the team to continue working on the roof and taking an entire day of solar measurements for the first time. They also drove the foxes back out of their burrow and they spend some time chasing each other around before checking out the humans close by. The Sun was up from 9:10 AM to 4:50 PM, providing slightly over 7.5 hours of daylight. After a picturesque day at the lab, the team made their way back to the weather station at 4:30 PM.
Thanks to the excellent conditions, Beatriz and Tyler started solar measurements as soon as they arrived at the Ridge Lab. They started with solar measurements in the mid-infrared region with the Bruker 125HR and in the near-infrared region with the EM27/SUN. By the end of the day, with the Bruker 125HR, they had collected a total of 87 solar spectra with a good signal and low noise across all of the 7 spectral filters, and around 1700 interferograms with the EM27/SUN. They were also able to fix the issues with the suntracker camera by doing a full calibration with the Sun centred in the field of view. They continued performing tests with the PTU30T pressure sensor and the long intake tube. As the sensor is able to register changes in pressure when the tube is raised above the height of the sensor, they put the intake tube at the height of the suntracker dome. They found that the PTU30T was making accurate pressure measurements, but the data was highly variable due to the wind. To reduce the wind impact on the measurements, they connected the intake tube to a windproof pressure head located in front of the dome. Altogether, it was another successful day for the FTIRs.
Kristof and Ramina continued troubleshooting the PEARL-GBS tracker today. They found that the elevation motor controller was not able to power the motor, and so they replaced the controller. After extensive testing to make sure the current setup worked well, they levelled the tracker base, and put the tracker dome back in place with help from Pierre. The PEARL-GBS is now operational, and it is collecting zenith sky measurements. Since the skies cleared up today, the Pandora was left in alignment mode for the entire day.
Last night was calm and clear, a good night for the DIAL. Ali collected measurements from 8 PM on Wednesday, March 4, to 7 AM the next day. For the first hour of the measurements the background was high which indicates measurements should be started later. Ali experienced a similarly high background during the last couple of hours of measurements. Ali and Alexey decided to shorten the time of observation for the following night.
The CRL began March 4 UTC with 14.75 hours of measurements using both lasers, again with uncalibrated depolarization. Then the sky conditions improved marginally, just enough to do the start delay calibration with the Polarotor spinning polarizer. Because the Polarotor has just been reinstalled after repairs involving some replacement parts, and because of the complicated sky conditions, this calibration had to be more extensive than it usually would be. After 4.25 hours of calibration, testing the response at a variety of polarizer angles, the results were good, and the CRL then continued with another 5 hours of calibrated measurements to finish out the day.
A "Raven" was launched today at 6:22 PM. With barely any winds, the balloon rose almost perfectly straight upwards and made it to a final altitude of 21957 m (28.2 hPa).
The team is in high spirits as of the weather and the successful day, and is looking forward to more days with conditions this great.
Cheers,
Ellen Eckert
[on behalf of the 2020 Canadian Arctic ACE/OSIRIS Validation Campaign]