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

Science Flight #7 - May 10

On Saturday after suffering from the continuously bad weather, we finally encountered our preferable measurement conditions, a wide field of persistent boundary layer clouds. Unfortunately, these clouds were also quite stable above the airport. With the aviation weather indicating icing conditions above YEV, we were not permitted to start until the cloud base stepped up and we could start and approach the measurement area flying below the clouds. The low clouds were investigated North East of the Mackenzie Delta. Two cloud legs in north-south direction, one at 133° W and one at 129° W were defined. In between Polar 6 was intended to measure aerosol and trace gases while Polar 5 continued with remote sensing of the clouds and the atmosphere.

The flight went pretty well. We found that the two cloud legs differ significantly. While on the western one the clouds were thin easily to be penetrated by Polar 6 and ended before the northernmost point, the clouds in the east were quite thick and caused a lot of icing on Polar 6 again, when flying in the cloud top layer. In this area also an enhanced aerosol concentration above the clouds was indicated by AMALi. Some thin haze layers at about 10,000 ft altitude were also observed from the remote sensing on Polar 5. In coordination Polar 6 tried to sample these clouds in situ as Polar 6 was just about to finish an extended profiling of the cloud free atmosphere. On the second cloud leg, the situation remained stable with no significant changes. Similar to the first cloud leg a drop sonde was released indicating cloud top temperature of about -10°C. Due to some instrument problems, Polar 5 had to repeat the sampling of this cloud leg and separated from Polar 6. On the direct way home to Inuvik another significant change of the aerosol concentration above the clouds was detected by the lidar. This change was visible throughout the column up to 11,000 ft.

For details read here: http://www.uni-leipzig.de/~racepac/flights/flight_07.html 

Almost History - II

It's only two weeks ago when we still could drive on the ice road. Now that seems to be miles away. The road was already close in begin of May. The melting is so fast that almost all snow is gone and even the lakes start to build a liquid surface. The same holds for the rivers. Close to the shore water is already flowing while in the center the ice still is solid. As from south more and more melt water flows north the days of the ice road are counted.

First the ice will not longer resist the pressure from below and break up. But as long as the way to the Beaufort Sea is not free the ice flows will not be able to drift away. This drift will start later and quickly. Usually then the ice is gone within a day. The negative consequence of the breaking ice are the mosquito. One of them was sighted already today. 

Almost History - I

The Sir Alexander MacKenzie school was! one of the most significant buildings in Inuvik and gave the center of Inuvik it's own view. Yes, it was!

When we arrived in Inuvik, we were surprised to find this impressive building in a bad shape. All walls have already be removed giving a strange view into the number of class rooms. Some of them looked as if still all inventory is present and classes may start at all time. However, the school was obviously closed and something should happen to the building either renovating or turning it down. A new school was already build some years ago not far away behind the North Market. 

Nothing happened during the first days, but then suddenly on one morning walking to the Aurora institute three big excavators stand in front of the school. Little later they started their work... Just tier it down. The workers must have had a lot of fun. The wooden walls were easy to break with the heavy machines. After an hour already big parts of the long stretched building were on ground level. Local citizens watched this spectacle, so did we. In the afternoon the show was over and a big heap of rubble remained on the site. 

For us it was a little sad to see the view of Inuvik change so dramatically. But later we learned that not all locals ware sad. This is due to the history of the MacKenzie school. Build in 1959 the school is a symbol for the compulsory integration of the first nations (the various aboriginal peoples in Canada) into the western society what meant also learning English, etc.

  

Science Flight #6 - May 8

After yesterday we had neither good chances to get airborne nor any area where we located good measuring conditions, for Thursday we planned an flight at 10 am. Unfortunately, the low level clouds of interest did not remain only above the sea but also in Inuvik, including some flurries in the morning. So the take-off had to be postponed to 12 local. Due to the later departure and an approaching midlevel cloud band moving eastwards into the measurement area, the planned rectangular flight pattern was skipped by only flying the easternmost leg.  

Polar 5 reported very good measuring conditions for remote sensing. A solid uninterrupted stratus cloud deck with 8/8 coverage at low levels was present all the time between roughly 1500 ft and 3000 ft. Different to the clouds the surface below the clouds was quite in-homogeneous with a mixture of open water, small and large ice flows. This looked very interesting for our investigations. Overall the wind in the area were very calm and conditions were stable. So the lidar profile showed an almost perfect symmetry for the flight in both directions.



Below Polar 5, Polar 6 sampled the cloud top entrainment zone in a long ''linear'' flight path for about 43 minutes. Sampling the cloud top was done at different altitudes, once inside the cloud, once closely above cloud top. Towards the end of leg significant icing on aircraft and wing probes occurred (as well as at the sampling inlets) such that the aircraft could not enter the clouds afterwards anymore. So Polar 6 returned directly to Inuvik performing a long staircase for aerosol and trace gas measurements in the cloud free, clear air for 100 minutes. 

For details read here: http://www.uni-leipzig.de/~racepac/flights/flight_06.html 

Campaign Photo

As it is tradition for a field campaign, we also took a campaign photo with "all" participants. This one was made during the first week of RACEPAC. Unfortunately by now more than half of the people which are on the photo traveled already back home. Therefore new crew members arrived as exchange. Today the last new participant was picked up at the airport. So we are more than at half time.

In total 38 scientists and engineers participated during RACEPAC. Additionally the crews of Polar 5 and 6 count 9 people including four pilots, three co-pilots and two engineers. All the exchange had not been on a specific day, so one picture with all people is unfortunately not possible. We may take a second one.

Science Flight #5 - May 6

Seemed for us to be like a Déjà Vu: Again a frontal system with light precipitation crossed Inuvik during the night and the early morning. Similar to the flight on April 30, we intended to follow the front after it had passed and sample low clouds in its back. The forecast predicted an increasing cloud top altitude towards East and closer to the front what we could confirm pretty well during the flight. Takeoff was scheduled for 11 am. Even the front passed a little earlier, we kept to this schedule. This flight Polar 5 was to start first. Unfortunately takeoff of Polar 6 was delayed due to another aircraft. The time difference could be minimized until the begin of the cloud leg with Polar 5 already slowing down to 120 kn observation speed during the ferry.

Forecast from ECMWF

Lidar signal indicating cloud top
for the grey shaded area in the forecast.

The cloud situation we found in the measurement area was surprisingly close to the forecast. At the start of the cloud leg only a low stratiform cloud layer remained. This cloud was also present later, when flying towards North East, but showed increasing cloud top altitudes. About 25 NM after starting the cloud leg a second cloud layer in higher altitudes about 2000 m was detected by AMAli. First this layer was thin enough to be pentrated by AMALi, later it almost vanished before about 30 MN to the return point the higher cloud layer thickened. The cloud top also increased so that we had to adjust the flight altitude to 11,000 ft. 

Polar 6 could sample these clouds at three levels during the flight: (1) the lowest fog layer, (2) thin layers/sheets of cloud sometimes only haze roughly between 3000 and 3500 ft, (3) layers of Stratus translucidus and sometimes Stratus translucidus undulatus above 7300 ft to 7600 ft. Straight legs and staircases were flown to sample droplets and ice crystals. Mostly liquid droplets were found to dominate the cloud. 

During all the time the horizon looked very hazy. Cirrus, although very homogeneous, was observed by the radiation measurements above Polar 5 almost all the flight. Polar 6 also tried to sample the hazy layer above the cloud for about 15 minutes before approaching Tuk for another overpass intended to inter compare the aerosol measurements at ground and in the air.  

For details read here: http://www.uni-leipzig.de/~racepac/flights/flight_05.html 

Science Flight #4 - May 3

In the night from Friday to Saturday, a frontal system passed Inuvik. After it went trough a wide field of low level clouds remained above the Beaufort Sea. The clouds were forecasted to become thinner and disappear during the course of the day. That's why the flight was scheduled early with take-off at 10 am local. The target area for the cloud sampling was chosen straight north of Inuvik up to 71° North.At the airport fog again delayed the departure about 15 minutes.

Soon north of Inuvik low level clouds showed up. A cloud top altitude of 900 m above ground was observed by AMALi, the backscatter lidar on Polar 5. Only a few miles later, a second cloud layer with tops of about 1200 m overlayed the lower clouds. These clouds remained with no visible variability until end of the leg. So we decided to release only one drop sonde which confirmed the two layer structure of the low clouds. Temperatures were quite warm with a cloud top temperature of about -3° C while in flight level -5° C were measured. During the entire leg high cirrus clouds were observed by eye and by the radiation sensors. For Polar 6 penetrating the cloud was easy, as only liquid droplets were found and no icing occurred. 

On the way back to the shore line the clouds did not change. Observations of glories indicate pure liquid water clouds. Sometimes large glories related to small particles and narrow size distributions were seen. The transition of the two layer cloud to a single layer cloud was again detected by the lidar. Surprisingly in the altitudes between both tops of the layers an aerosol signal was measured by AMALi. This single layer cloud remained during the overpass of Tuk. While Polar 5 did fly only once above Tuk, Polar 6 measured at different altitudes to connect the airborne aerosol measurements with the ground station in Tuk. On the lowest level, the people in the ground station could easily see Polar 6 what was a big success for this flight.

For details read here: http://www.uni-leipzig.de/~racepac/flights/flight_04.html 

The Arctic as seen by scientists

At other times, however, scientific analyses might provide deeper insights into processes which cause such phenomena that are, admittedly, simply magnificent to look at. For instance, take this photo captured by the fish-eye camera showing a homogenous low-level cloud: do you spot anything unusual?

Right, in the top right corner of the photo, you can observe cloudbow and glory. Adjusting the contrast of the photo helps identifying them:

Depending on parameters such as its phase, shape and diameter, each particle scatters light differently. Liquid water drops, for instance, tend to scatter light in the forward direction. But the scattering phase function also shows prominent maxima at scattering angles of approximately 138° and scattering angles greater than 175°, corresponding to the visible phenomena of the cloudbow and the glory, respectively. This way, a decent amount of light is backscattered at the water cloud and captured by the camera. Conversely, measurements of the cloudbow and the glory allow to derive cloud parameters such as the effective radii of the droplets. By the way, prominent maxima of the scattering phase function are also responsible for rainbows and haloes. Science and beauty are not mutually exclusive, quite the contrary...

The Arctic as seen by Polar 5

Sometimes one should just forget about data analysis and simply enjoy the beauty of the Arctic. With P5 we usually fly at 10,000 ft, which enables the digital camera with a fish-eye lense installed at the underside of the aircraft to take breathtaking pictures of sea ice and broken clouds over the Beaufort Sea. One can clearly identify the sun glint caused by specular reflection of the sunlight at the water surface.

Science Flight #3 - May 1

On Wednesday, a frontal system was approaching Inuvik and the Beaufort Sea from the west. In the north-east an area with very low clouds probably fog touching the surface was forecasted and visible in the satellite images. This cloud field was predicted to disintegrate during the days. From the west a second band with low level clouds was approaching. These clouds where expected to be higher but overcast by cirrus. The flight plan intended to sample both cloud layers.

When arriving at the airport, we were surprised how less 15 km driving can be. In town the weather was clear but at the airport fog was all over the place. Both aircraft were covered with a layer of hoar frost which produced a couple of nice photograph scenes. Later, we could also see by eye some small ice crystals falling out of the fog, what was pretty nice to observe. When all instruments did run on ground power our PMS probes even could do some measurements of the fog and the ice crystals without flying.

After the fog was gone, we finally could start for the flight. Unfortunately at the first destination, where the leg for cloud sampling was to begin, from Polar 5 no clouds could be seen in the vicinity. Polar 6 only cached some low clouds or even fog. Because it was not worth to fly and search for any cloud band behind the horizon, the fight was stopped and both aircraft went back to Inuvik, with Polar 6 flying some horizontal legs in different altitudes for the trace gas measurements. When the highest level was reached, both aircraft could see each other, so many pictures were made.

For details read here: http://www.uni-leipzig.de/~racepac/flights/flight_03.html 

Science Flight #2 - April 30

On Wednesday a small but intense low pressure system moved north of the shore line fast from west to east. The severe weather with freezing rain did not allow an early flight. At about 9 am rain and shortly after that snowfall reached Inuvik. After the low pressure system crossed Inuvik, the conditions improved. As forecasted, at the rear side of the low pressure system in the cold air mass, low level clouds were situated. Mid-level and cirrus clouds were not predicted for the area north east of Inuvik which was the target of this flight. The flight strategy was not changed compared to flight #1. One straight leg between C1 and C2 was sampled in collocation by Polar 5 and Polar 6.

Chasing Polar 6

On the first leg we observed clouds with different cloud top altitudes. In the first quarter, cloud top was below 600 m. In parts, the clouds were thin enough to be penetrated by AMALi. Later, the cloud top altitude increased in steps. First up to about 750 m above ground then to 1000 m. Towards the end of the log close to and behind C2 multiple thin cloud layers were detected, some reaching altitudes above 2000 m. The varying cloud structure made it hard for Polar 6 to define the vertical steps for covering the clouds profile. However on the long leg tree complete staircase profiles were sampled. 

For P5 the first leg was extended for some miles to let P6 pass and get in front position for the leg back to C1. While P6 again penetrated the clouds and finally climbed up to 10,000 ft for a trace gas profile, from Polar 5 four drop sondes were released. Each intended to characterize one of the different cloud sequences identified before by Amali. The drop sondes also detected the multilayer clouds. Close to C1, the clouds intensified showing a homogeneus cloud field. To probe this cloud with sufficient data and to release a further dropsonde, the second leg was expended for 20 NM behind C1.

For details read here: http://www.uni-leipzig.de/~racepac/flights/flight_02.html 

Full Power

To get to our aircraft at the airport and back, we need rental cars. The selection of rental cars and the number of rental companies is limited so far north. So the best choice were trucks from the company driving force. Prices are very expansive here first because of the remoteness, second due to the high probability for broken windshields or tires when driving on the gravel road of Dempster Highway.

The good thing is that the trucks have much space for transporting equipment and people and are quite comfortable on the bumpy ice road. However, large cars also need big tanks and these drain quite quick when driving. The electronic driving information in the display indicates 99 liter/100 km when accelerating quickly. I suppose, this is only the upper end of the display...  Last days having snow and wet streets, we could observe strange icicles growing below the trucks.