Sunset over Muskoka Lake - campaign end

Just four of us are left to dismount the instruments from the airplanes at Muskoka. Muskoka is a small airport between Gravenhurst and Bracebridge, about 1.5 h drive north off Toronto. Polar 5 and Polar 6 have arrived here on Monday, May 26, after 2 stops, one to refuel at Yellowknife, and one overnight stop at Thompson, Manitoba. Here the spring really arrived, it welcomed us with really warm and sunny weather and a nice sunset over the Muskoka Lake. The hotel we stay is beautifully located on the shore of the lake. It offers a little more luxury than the row houses at Inuvik, but we all think that we deserve it.

Science Flight #11 - May 16

The weather situation was still not what we really wanted to have. But Necessity is the mother of invention.

With now low level clouds in close distance we aimed for a wide field of mid-level clouds which was predicted south of Inuvik. As these clouds were in the range of Polar 6 we decided to mirror our previous flight strategy. Polar 6 was still intended to fly into the clouds sampling microphysical properties but this time mostly at the cloud bottom, where precipitation was expected. Polar 5 now does remote sensing from below. Therefore the lidar was configured for zenith measurements. 

Take-off again was delayed. This time not due to weather or instrumental problems but because another aircraft arriving in Inuvik had to make an emergency landing. As we learned a sign in the cockpit for the landing gears did not work. So the pilots could not be 100% sure, that the landing gear is working properly. After flying a couple of circles to burn all the remaining fuel the aircraft fortunately could land without problem. Shortly after the safe landing, Polar 5&6 started south where a rectangular pattern was flow.

As this was also the first flight above land we got a very different view of the landscape. The still frozen Mackenzie was crossed several times. And also some mountains did show up. With Polar 5 flying in about 1000 ft above the surface we sometimes had to adjust the altitude to avoid a crash. Also scientifically the flight was much more successful than expected before. Polar 6 could penetrate the clouds from below and sampled a lot of different precipitation. At the same time, the lidar on Polar 5 did record the structure of the cloud bottom where nice fall streaks (virga) were visible. 



Unfortunately, the cloud base did decrease during the flight and also the altitudes with precipitation. When Polar 5 entered medium rain, we had to switch of the lidar to close the opening in the roof before water enters the optics of the instrument. Also Polar 6 had to fly lower and lower, so we decided to stop the measurements earlier and return to Inuvik. 





For details read here: http://www.uni-leipzig.de/~racepac/flights/flight_11.html

Spring???

Last week when we hit the 20°C mark, a kind of summer was in the air. Also animals become more and more visible in the area. Not only the eagles and ravens circle around in the air also sea gulls, ducks and snow grouses can be seen more often. Especially ducks and sea gulls are attracted by the lakes which become more and more ice free. 

Further rumors come up that bears might be get close to the town. After the end of their hibernation they get more and more vital and are especially now hungry. So they may search for garbage in the town. Another animal what already had finished its hibernation are the squirrels. Some of them make really loud noises when you come to close to their tree.

 

Science Flight #10 - May 14

Today again both aircraft should fly. After temperatures dropped after the incoming cold front from 20°C to negative values again, low level clouds remained above the Beaufort Sea. In Inuvik the sky cleared up during the morning and conditions were ideal for sampling the wide boundary layer cloud field in the north east. This cloud field we finally also found. Cloud as far as the horizon with just some inhomogeneities at cloud top and clear sky above. Similar to some of our computer models. 

 The general conditions were characterized by strong northerly winds. In cloud altitude about 40 kn were indicated by the aircraft. Above land additional turbulence made flying a bit bumpy. For today's mission the flight path of both aircraft was chosen to be like a horizontal raster. Five East-West 20 NM legs only separated by 10 NM build one Box in which we intend do investigate the small scale horizontal variability of the clouds. While Polar 5 does the remote sensing, Polar 6 tried to sample the clouds top along this track as best as possible. A second box was placed just 20 NM eastwards to the first box trying to follow the general flow of the cloud field.

For our means this was a really complicated flight pattern which did a lot of additional work for the co-pilots. These guys always have to enter the waypoints into the navigation system of the aircraft. 15 points took a while. Therefore, flying was not as boring as during a simple straight leg. The second additional work came for Polar 6 where the pilots had to take care for icing of the winds. The low clouds encountered to contain a large fraction of super-cooled liquid water which immediately freezes, when hitting any part of the aircraft. Also the wind shield in the cockpit loose lot of the free view. After trying to enter the cloud, this icing was finally to dangerous for operating long inside the cloud. That's why Polar 6 decided to stay only in the entrainment zone of the cloud tops. This had a funny effect. When climbing, the crew could see the path of Polar 6 in the clouds. A trench was dug into the cloud top. 

For details read here: http://www.uni-leipzig.de/~racepac/flights/flight_10.html

Science Flight #9 - May 13

Today only Polar 6 was in the air while the Polar 5 crew still could get some rest. Stable high pressure conditions did bring no low clouds in the area but a very thick cirrus field which did not allow reasonable good radiation measurements for a second clear sky mission. Polar 6 instead repeated the flight pattern from May 11 profiling the atmosphere at two locations with a ''curtain'' of horizontal legs in different altitudes.

The first profile was flown somewhat further north compared to the last flight above sea ice while the second profile again was located close to Tuk. However, there was a closed unstructured, diffuse cloud deck (low altostratus) around 20000 ft altitude, probably with 8/8 coverage present throughout the entire flight. It was optically fairly thick although the sun could be seen through at times. Outbound North the approaching frontal system can be seen to the West like a cloud wall.

During the profiling legs at 10000 ft, 8000 ft, 6000 ft, 4000 ft, 3000 ft, 2000 ft, 1500 ft, 1000 ft and 500 ft, were flown. In general higher aerosol concentrations were found compared to May 11. The highest concentrations were not measured at ground level but in the higher legs of the profile.



For details read here: http://www.uni-leipzig.de/~racepac/flights/flight_09.html

Polar research in summer

The RACEPAC campaign wants to investigate the role of clouds in the phenomenon of Arctic Amplification - the intensified warming in the Arctic due to rapid melting of sea ice. 

The above photo, taken at a recent BBQ in front of our row houses, gives first insights into current weather conditions in Inuvik. During the last two days, warm air masses influenced our weather and yesterday temperatures rose to +20°C (yes, the sign is +). Perfect conditions for T-shirt and jandals. We were all amazed by the summerly weather, but a look back in history shows that we barely came close to the record temperature for the month May in Inuvik of 34°C (12th May 1971). Nevertheless, we witnessed something very remarkable: after having reached 20°C, a cold front passed Inuvik and temperatures dropped close to 0°C and it started to snow - perfect conditions for warm coats and heavy boots. Summer and winter on the same day. Of course, we prefer colder temperatures to get better measurement conditions for mixed-phase clouds, but especially for BBQs warm weather is highly appreciated.

Science Flight #8 - May 11

Clear sky conditions were forecasted for wide areas around Inuvik. This was the first chance to perform the clear sky mission as proposed for RACEPAC. Although the satellite images showed a little smaller cloud free area, we found perfect conditions over the beaufort sea. As some clouds might appear in the area all PMS probes were operated during the flight. In Polar 5 the configuration of the AMALi lidar was changed for zenith view for this flight. Take-off was scheduled for early afternoon as the cloud free area was forecasted to increase during the day.

For the clear sky mission, Polar 5 and Polar 6 operated individually. The aim of Polar 5 was to measure as much different surface albedo as possible while Polar 6 flight was intended to characterize aerosol and trace gas in different altitudes. For this purpose, two "curtains" with nine different altitudes were flown by Polar 6. One above the ocean, one above the ground station in Tuk. The results were interesting. Different to mid-latitudes enhanced aerosol was found in the uppermost atmospheric layers. This is common as there are just no big aerosol sources in the arctic and transport of aerosol happens in higher altitudes. 

Polar 5 could cover a wide area with different sea ice conditions. Although no completely closed sea ice was found anymore. Therefore, melting did just progress to fast the last days. However the measurements will be very useful. Above one 50 miles leg, Polar 5 flow in four different altitudes which allows to investigate the impact of surface heterogeneity. 

In general Polar 5 was flying very low today. This is required for the albedo measurements but also for the lidar system, which was turned into zenith view for this mission. In the quicklooks of AMALi no significant aerosol layer could be observed. The atmosphere was rather well mixed. The low flight level also has another advantage. The flight is very scenic. Flying over the ice flows with all the big ridges is very impressive. Even wildlife could be observed. Mostly birds, we (especially the pilots) saw also a moose, seals and a polar bear. 

For details read here: http://www.uni-leipzig.de/~racepac/flights/flight_08.html