On both, Saturday and Sunday, high clouds hovered over the weather station and the Ridge Lab. While this still (awesome pictures etc. ) it is rather suboptimal for solar measurements. During Saturday, the temperature rose from around -23℃ in the morning to about -20℃ in the afternoon.
Sunday was another warm day at the Ridge Lab with more than -20℃ throughout afternoon. Since there was barely any wind, Erik and Sébastien left for an extended walk of about 2 hours shortly after 1:00pm. Kristof and Ellen followed them about 45 minutes later, easily spotting their tracks in the snow. It was the first walk outside for Kristof, who had been troubleshooting the PEARL-GBS all week and could finally enjoy the outstanding Arctic landscape.
A cloudy weekend prevented Sébastien and Erik from taking solar measurements with the Bruker 125HR. They spent Saturday afternoon performing a second N2O cell test measurement. Although they already completed a N2O cell test measurement, the second cell test allowed them to try different settings. In the first test, they used the same aperture size and scan velocity that is used for solar measurements. In the second test, the aperture size and scan velocity were reduced in order to match the parameters used for N2O cell tests performed by other groups. Unfortunately, Erik was not able to process the results of the cell tests due to issues accessing the UofT servers from Eureka, however, he sent the HBr cell test measurement to UofT where Dan Weaver performed the analysis. The results were found to be consistent with previous HBr cell test measurements. Erik hopes to process the N2O cell test measurements tomorrow once access to the UofT servers is restored. Sébastien and Erik will continue with mid-infrared solar measurements tomorrow if the weather permits.
After an unexpected delay of several days at the beginning of the campaign, Kristof moved the PEARL-GBS spectrometer to its permanent location in the IR lab. The PEARL-GBS sun-tracker is now operational, so finally both GBSs are active. Both are taking measurements in zenith sky - MAX-DOAS combination mode.
Since it was rather overcast on Saturday, Ellen decided to start cell measurements with PARIS-IR using the HBr cell. After about an hour, however, the connection between PARIS-IR and the laptop broke down. Ellen spent the rest of the day troubleshooting, but unfortunately she wasn't able to reestablish a connection to the instrument.
Ellen started her Sunday afternoon at the lab by giving PARIS-IR some extra time to boot. Saturday's connection problem persisted throughout the day, however, while she ran some more tests with Peter and got help from Pierre as well. Intensive troubleshooting is schedule for the following day. Ellen used the downtime of PARIS-IR to process the data from Friday. No problems arose during the conversion process and she is looking forward to creating some plots to have a closer look at the data.
The CRL measured for 24 hours on 4 March UTC, observing mostly clear skies with the occasional cloud drifting by. This was convenient as it allowed Emily to get some coding done for CRL data analysis in the afternoon and to work with Ghazal on the DIAL lidar data analysis in the evening while the DIAL was also running.
On March 5 , the CRL measured for 24 hours as well. The day began mostly clear with the occasional tiny cloud at 6 km altitude. From 8:00 UTC onward, most of the lidar returns were from clouds below 500 m. Clouds at 6 to 9 km altitude began at about 17:30 UTC, and were still present by the end of the day. It will be interesting to see the development of these higher-altitude clouds going into 6 March.
The weekend with the DIAL was fairly busy. On Friday night, the chiller stopped working, but the problem was resolved within an hour. Later during the operation, the power in the laser dropped down. Emily and Ghazal cleaned up the optics and refilled the laser gas. However, the cleaning process caused some misalignment in the laser beam. Intensive work during Saturday and Sunday led to a promising outlook. The primary receiving signals are strong and within the expected range. The final alignment will be done during a clear sky night.
During the weekend, both ozonesondes were again launched at 6:15pm. Saturday's Raven ozonesonde made it to approximately 187 km southeast of Eureka, ascending at a rate of 196 m/minute up to an altitude of 31516 m. Sunday's latex balloon ozonesonde was launched with the assistance of Ellen and made it to 32259 m at an ascent rate of 206 m/minute.