The Sun makes a final appearance...

The last day of the intensive part of the ACE Arctic validation campaign started rather early. We left the Weather Station at about 7 am. This was done to ensure that Keeyoon could transfer all of the PARIS data from yesterday and back it up before starting today's measurements. We had a beautiful, clear view of the Moon setting over the other side of the fjord during our early breakfast. This provided hope for a good day for solar observations.

After completing a night of reasonable lidar measurements, Richard B. returned to the lab with us. He had to finish packing up the lidar accessories and preparing the equipment for another year of storage. The last vestiges of sleep were knocked out of the campaign team when Richard started up the compressor to blow the water out of the laser's cooling loop. He then filled the loop with ethylene glycol to reduce the risk of damage to the system if the temperature in the lab drops below zero.

The FTS team started their solar absorption measurements at 9 am and continued until past 5 pm. The Sun was in thin haze for most of the day but we had one of the better measurement days of the campaign. It was a positive result on which to end this part of the campaign. Keeyoon made 29 sets of measurements with PARIS and Keith measured each filter band at least twice for a total of 19 sets of observations.

Annemarie spent the day continuing to do battle with frost build up on the window of the plywood "dome" over the grating spectrometer. The outside temperature has dropped by about 10 C over the last few days and this is playing havoc with the carefully balanced heating system in the DOAS lab. Over the last few days, Annemarie has been alternately increasing and decreasing the temperature in the lab and has even tried blowing hot air at the "dome" window. She is hoping to leave a frost-free "dome" for the instrument to start the extended phase of the validation campaign.

Clive also had problems trying to get the frost off of the MAESTRO input windows. In the end, he had to use a knife after his fingernails could not do the job.

Hongjiang spent today trying to get the maximum number of measurements out of the SPS before packing it up. All was going well until she had to go out on to the roof and dismantle the instruments and the tracker. The temperature was -36 C but the wind was blowing quite strongly. Clive estimated the wind chill to be at least -65 C (based on the calculations made at the Weather Station where the temperature was -45 C but the winds were lighter). Clive, Keith and Hongjiang were outside for what seemed like 6 hours though it was probably closer to 30 minutes. Essentially, today it was not very pleasant outside. It always seems to be the case that, when you need to spend time outside with the instruments, the weather will not cooperate.

Meanwhile, in Resolute, Tobias and Richard M. took some time to go climbing on the ridge that overlooks the townsite. The weather started out overcast but got better in the afternoon. We are hoping that they have not exhausted all of the sightseeing possibilities in Resolute before we join them.

By 8 pm, we had packed up the PARIS, MAESTRO and SPS instruments and all of their related equipment and had it loaded into the truck to go back to the Weather Station. There was a bit of a rush at the end, as I tried to complete the backups of all of the raw data from each of the instruments. The desktop pc that I brought now has a copy of the raw data for all of the instruments including the daily radiosonde and ozonesonde flights.

The final ozonesonde of the intensive phase of the campaign was launched at 23:15 UTC using a Raven balloon. The radiosonde/ozonesonde reached a height of 6.9 mbar (31.7 km). The winner of the final instalment of the "guess the sonde height" competition was Keeyoon with a value of 7.0 mbar.

Best regards,
Kaley.