The team tries its hand at weather forecasting...

After the past couple of days of cloud, Tobias, Richard M. and I consulted the Environment Canada website last night to see if we could get a weather prediction for somewhere near Eureka. The closest we could find was at Grise Fiord (76.4 N, 83 W) and it was predicting cloud for today. Next, we resorted to the IR satellite imagery to see if we could determine which way the clouds were moving. This was also not so helpful since the clouds in the images didn't appear to follow what we had observed from the ground during the day. In the end, we gave the best forecast we could: the weather will probably be the same as yesterday.

Once the Sun came up, there was still some thick cloud on the horizon with thinner cloud at higher elevations. The Sun managed to get high enough that it was possible to make FTS measurements. The variable thin cirrus cloud made setting the gains on the instruments a bit of a challenge as the signal strength could change significantly during a set of measurements. PARIS measured 9 sets of 20 scans and the DA8 took 9 sets of dat over four hours of observing time

Hongjiang's SPS measurements are going very well. There is very little NO2 present so she is working at the limit of what can be retrieved from the spectra. The heaters were removed from the SPS a couple of days ago and the instrument temperature dropped by about 10 C. This has improved the instrument performance significantly.

Annemarie was also having some difficulty making preliminary retrievals of NO2 from her DOAS spectra. A quick check of the results from the GOME satellite instrument showed that the very low NO2 results from the SPS and DOAS are consistent with what is being seen from orbit. She is still waiting for the Sun to reach a high enough elevation angle to measure a good reference spectrum.

The daily ozonesonde was launched with the synoptic radiosonde at 23:15 UTC. To make things interesting, Andre, Charlene and I made guesses as to how high the Raven balloon would take the sondes. Andre was highly optimistic with a guess of 4.9 mbar and Charlene and I were more conservative with 5.6 mbar and 6.5 mbar, respectively. Charlene came closest and won the contest when the sondes made it to an altitude of 6.0 mbar (32.6 km). This may be the beginning of a new obsession for the ACE Arctic Validation team - guess the maximum ozonesonde altitude.

A Eureka Saturday night involved a lot of applied physics (a pool tournament) that went on into the wee hours of the morning. It was demonstrated that the laws of physics still apply within the Arctic Circle and that physicists cannot "just play pool".

The temperature inversion has returned. This morning it was -44 C at the Weather Station and -32 C at AStrO.

Best regards,
Kaley.