On Saturday March 3 the temperature at the Eureka weather station started just below -19 degrees, and after a few hours of this it proceeded to steadily drop to almost -28 degrees by the evening. Up at the PEARL Ridge Lab the temperature was much the same throughout the day. During the day 7 hours and 20 minutes of sunlight was expected, however only for a brief window was the sun capable of piercing the clouds, and only weakly at that.
In the morning Paul and Tom verified that SPS had stopped working the previous day due to an internal power short. They disassembled the SPS instrument, replaced the internal power supply, and used electrical tape to cover any potentially exposed wires in the SPS internal computer to prevent them from contacting the casing and causing a short. After testing they found that SPS was operational again, and Paul installed it back on the roof of the Ridge Lab with help from Pierre. Paul ran the SPS and tracker software and left it running overnight.
As it has done the previous few days the CRL made measurements for 24 hours.
Kristof spent the day monitoring the GBSs, and he started updating some of the outdated measurement and troubleshooting manuals used for them.
Ghazal and Alexey found a 3 hour window of clear sky, during which DIAL was operated.
Sébastien and Erik spent Saturday performing further tests of the Bruker FTIR alignment. The periscope used for this was modified to use larger mirrors to ensure the full collimated beam is observed by the telescope. With this new setup, pictures of the Haidinger fringes were to be taken at all optical path differences. No adjustments to the instrument alignment were made.
Xin revisited, for the first time since the 26th of February, the sampling site next to the creek behind 0PAL and collected snow samples there down to a depth of 29 cm. In the afternoon, he collected some snow samples from a new sea ice site just in front of the weather station, which has an average snow depth of about 7 cm. Finally, about 50 surface snow samples were collected from both inland and sea ice surfaces.
In the afternoon the majority of the campaign team and weather station staff went down to the Eureka airport as a produce flight arrived. This flight was carrying a CANDAC operator, John, along with more weather station staff that would be replacing some staff who were finishing their rotation in Eureka. The team bid farewell to the station staff who were leaving, along with Tom, Emily, Peter and Alexey, all of whom were heading home after their time here for the pre-campaign and part of the intensive phase of the campaign.
On Sunday March 4, the temperature at the PEARL Ridge Lab started at about -28 degrees and climbed steadily throughout the day up to nearly -20 degrees. Meanwhile at the weather station the temperature remained around -30 degrees all day. The sun was up for approximately 7 hours and 40 minutes, but a persistent light snowfall prevented the campaign team from taking advantage of this for measurements.
Upon first arriving at the Ridge Lab Paul found that the SPS instrument remained operational but the tracker had stopped tracking at some point. He tried to reset the tracker repeatedly but the tracker refused to connect to the control software on either of the SPS/tracker computers. Pierre aided Paul in fixing the communication error, but over the course of the day the tracker lost connection with the software twice more. Paul is currently looking into options for preventing this, and meanwhile left SPS and the tracker running overnight.
Kristof continued to monitor the GBSs, and spent time debugging the PEARL-GBS measurement software to resolve issues with occasional CCD overheating. It appears, however, that the problem is not software-related.
Due to the overcast weather DIAL was not operated last night. It is fully operational and Ghazal is waiting for a clear night.
Sébastien and Erik continued the tests of the Bruker FTIR alignment that they started on Saturday. Again no adjustments to the instrument alignment were made. At the end of the day, Sébastien started a HCl cell test. They are hoping for clear-skies tomorrow in order to perform solar measurements.
In the morning Xin visited the site near the creek behind 0PAL and then the sea ice site in front of the weather station to collect more snow samples for comparison. An increased sampling of snow from the various sites was spurred by ozone analyzer data that indicated that ozone concentrations have dropped below 10 ppbv since Saturday afternoon. With help from the newly arrived CANDAC operator John, Xin visited the two sampling sites that are about 5 km away from the station in the afternoon. Included in the numerous snow samples taken today were surface samples from the current snowfall.
Sunday evening saw the launch of the first Raven ozonesonde of the 2018 campaign. Several members of the campaign team turned out to watch the launch, which is often an impressive sight as the large balloon rapidly expands as it ascends. Afterwards the team, along with some of the weather station staff, gathered to watch the Oscars, competing with each other to see who would be best able to guess the various winners.
Cheers,
Paul Jeffery
[On Behalf of the 2018 Canadian ACE/OSIRIS Arctic Validation Campaign Team]