On Saturday March 9th, the temperature at the Eureka Weather Station was -42 degrees C, with a very calm wind of 1 knot (2 km/h) giving a windchill index of -45 degrees C (although high winds early on Saturday morning brought temperatures as low as -57 degrees C). At PEARL, temperatures were approximately -29 degrees C, with winds of 11.6 knots (21.6 km/h), giving a windchill index of -43 degrees C. This was another sunny day with clear skies, allowing the team to continue to take a large number of solar measurements. On Saturday, the team had a total of 9 hours and 30 minutes of sunlight.
Since the sunny conditions continued through Saturday, Tyler started up the Bruker 125HR and EM27/SUN for solar measurements in the morning when he first arrived at the PEARL Ridge Lab. He monitored the progress of the instruments through the day as they made solar measurements. By the end of the day, the Bruker 125HR collected a total of 104 solar spectra, while the EM27/SUN made over 1700 measurements.
On Saturday, surface ozone concentrations at the Eureka Weather Station dropped below 10 ppbv, indicating that an ozone depletion event is in progress. Kristof hopes to see corresponding BrO enhancement in the PEARL-GBS MAX-DOAS measurements. He also set the Pandora to start taking MAX-DOAS measurements on Saturday; this second set of measurements will be an interesting addition to the BrO dataset.
Xin and Peter started their Saturday by visiting all three sampling sites, and collected surface samples as well as a snow core sample at the inland sampling point. A small layer of frost was collected from the tray on the roof of PEARL. Later in the afternoon, at 0PAL Xin continued his salinity measurement work for those selected samples. He also re-bagged some samples for storage.
When Ali arrived at the Ridge Lab on Saturday morning he repeated his usual daily procedure of checking the quality of the SPS spectra collected within the previous 24 hours, as well as cleaning the frost off of the lenses of the SPS on the roof. He spent the remainder of his day finishing up his analysis of the temperature profiles retrieved from the DIAL data.
On Sunday March 10th, temperatures at the Eureka Weather Station hovered around -36 degrees C, with a light wind of 1.6 knots (3 km/h) giving a windchill temperature of -40 degrees C. Up at the PEARL Ridge Lab, temperatures were around -31 degrees C, with winds of 17.8 knots (33.1 km/h), bringing the windchill index down to -48 degrees C. Sunday brought with it the end of the streak of sunny and clear days, and was mostly cloudy with light snowfall. On Sunday, there was a total of 9 hours and 52 minutes of sunlight.
Although the cloudy conditions prevented Tyler from taking solar measurements today, he made use of the day to make some fine-tuning adjustments to the Bruker 125HR. With the help of Pierre, he adjusted the circular focusing mirror in the source compartment of the Bruker so that there is more light reaching the detectors from the mid-infrared (MIR) and near-infrared (NIR) source lamps, improving the signal-to-noise ratio of the cell-tests. Afterwards, he ran a background measurement, and then an N2O cell-test (for the MIR region) to confirm that there was an improvement in the signal strength. Preliminary analysis of the tests showed that the signal was indeed stronger, and it was actually higher than the background measurements made at the end of last campaign and the beginning of the current campaign. Tomorrow he plans to run an HCl cell test to check the signal strength in the NIR wavelengths.
Kristof continued to monitor the Pandora and the PEARL-GBS on Sunday. Cloudy conditions meant that the Pandora solar measurements will be of lower quality, but MAX-DOAS measurements continued unimpeded.
On Sunday morning, Xin and Peter collected another set of snow samples from all of the sampling sites. Xin, Pierre and Peter then discussed the continuity of the snow sampling strategy after Xin’s departure on March 13th. Pierre and Peter agreed to continue the routine of collecting surface snow samples from three sampling sites and the two trays mounted outside of 0PAL and PEARL until March 27th. This will allow more time to capture ozone depletion events and/or possible bromine explosion events. Xin then worked at 0PAL on his salinity measurements, as well as preparing his samples for long-term storage.
Ali finished up his temperature retrieval project for the DIAL data from early in the current campaign as well the data from the 2004 campaign. He then began writing up a report to present the results of his temperature retrievals and comparisons to radiosonde data. He spent most of the day running his retrieval code on the full set of data to add to the report.
Cheers,
Tyler Wizenberg
[On Behalf of the 2019 Canadian Arctic ACE/OSIRIS
Validation Campaign team]
* Instrument Status *
Bruker FTIR: Offline (for cell measurements)
EM/27 SUN FTIR: Nominal operations
Ozonesonde: On Saturday, a Raven Balloon was launched at 6:15pm (local time) and reached a height of 30.34 km (7.6 hPa). A 600-gram balloon was launched on Sunday at 6:15pm (local time), but a malfunction in the software caused the connection to be lost and no data was collected.