Flight May 16

Inuvik from above

Another flight into the same area. Having snow showers (flurrys as the showers with low intensity are called here) at the airport we were sure that these clouds have to contain ice. In the target area this time we continued heading west expecting a change in the cloud properties indicated by a second cloud field in the satellite images and almost reached US airspace. The cloud field in the west we just missed. But indeed the clouds did change. Cloud top decreased and thickness as well. On the way back we first did not found many ice particles. Later further east the number of ice crystals increased more and more. On our way back to Inuvik we stayed below cloud bottom and collected some more precipitating ice crystals and images of Inuvik and the Mackenzie Delta,

(Some) ice is back: Flight on 15 May

Turning back to go through this nice
Cumulus cloud once more.

Today we flew into the same area as yesterday. The cloud was still there, and it was in fact a little different than the first time. We even saw ice crystals in the cloud! We probed it on a east-western and a north-southern leg, and found differences between all the waypoints. The "icing on the cake" of this flight was a cumulus cloud on the way home. There were no convective clouds in this area before yesterday, so this something new for VERDI, and of course we did a few turns inside it. The cumulus contained aggregate ice particles, and finally the flights became a little bumpy.

Flight into clouds, 14 May

Canada Is the country of lakes. There is no
official estimate of the total number of
lakes in Canada; three millions is a first
inofficial guess. Start counting here: The
Mackenzie delta is nothing but river arms and
lakes between small dry stretches with trees.
The contrast between dark trees and white
ice makes the counting easier in winter!

Finally, after a couple of days of sunshine and leisure, the clouds came back. Inuvik itself is still sunny, but a low cloud deck has formed over the southern Beaufort Sea. And it seems it's there to stay, so probably today's flight is the first of a series. We targeted two cloud areas. The first ended earlier than expected, and the second had a double cloud layer. We probed the cloud at several altitudes in both layers, and inbetween. Alas, it is too warm to find ice particles in the cloud! Nevertheless, clouds over the sea ice are always of interest. And these ones were different from the ones on all the previous flights, so we are quite happy.

After flight on May 10th the big melting started

Thursday was temporalily the last flight for the next days. Since yesterday spring has started in Inuvik. Everything melts, ponds an small lakes are filling up, cars and other things appear again below the melting snow. Unfortunately the temperatures are above zero as well in the altitude levels of potential clouds. This means, there is defenitely no ice in this clouds. That's why we decided to have a break and wait for colder temperatures before having further flights. From Monday conditions are predicted to improve. Until then we hope to reassamble all instruments on board of Polar 5. The repaired 115V-inverters will be installed again and hopefully the CAS-DPOL will arrive everyday that we can start the last week of measurements with full strength.   

A short recapture of Thursdays flight. Again we probed low level clouds above the beaufort sea. Close to the coast we also observed a second higher cloud layer which we intended to probe on our way back. Unfortunately these clouds almost have cleared away when we arrived. Only a small fraction could be probed. The low level showed up to be thicker than the days before. The icing was heavier forcing us to leave cloud top before the probing was complete. After letting the ice melt in the sun the last remaining probing level could be repeated. 

Flight on 3rd of May

Thin clouds that are barely visible
on the satellite image (NASA
MODIS-Terra, 3 May 2012)

On the third day of May, our flight brought us to a very low and shallow cloud deck over the sea ice of the Beaufort Sea. We had taken the coordinates for our flight destination from cloud forecasts and satellite images, but by the time we arrived at the location where the cloud should have been, all we saw was the sea ice and a blue sky. So we kept going north (whither the cloud was withdrawing), and soon we could see first patches of clouds. We cannot go into a cloud when it is very low, because the aircraft needs a safe distance from the ground. But with AMALi, our lidar instrument, we knew that the cloud was in fact just high enough to go in. So we scanned the cloud from above for a while, and then went down and flew through the cloud on the same way back.

Ice clouds and snow

A 22° halo brightened by a lower
tangent arc indicates columnar
ice crystals

On 30 April, we flew through a more complex cloud pattern, with a patchy layer of an ice cloud at around 3 km altitude, and a low mixed-phase cloud near the surface. A snowing cloud was probed at various levels, and should provide a good challenge to test precipitation models.

The perfect low cloud

The ideal model cloud

On the flight on 29 April, we found the ideal textbook cloud: an extensive low-level mixed-phase cloud with clear sky above it. This is what one-dimensional radiative transfer models have been written for! In this cloud, we found liquid droplets that were 20 micrometers large on the top and 10 micrometers at the bottom. Toward the bottom, ice crystals were also found in this cloud.

Double Flight

On 27 April, we performed two flights in a row. The flight track was the same for both flights. A few mid-level and a closed deck of low-level clouds was observed on the first flight. On the second flight in the afternoon, both layers were already dissolving. It will be interesting to compare these two development stages in the data.

A closed layer of low clouds before noon

The same layer dissolving in the afternoon,
revealing the sea ice under it

Third flight, 23 April

A pingo in the snow.

We headed out north-west for another sea-ice study. Unfortunately, continuous low clouds made it impossible to deploy the EM Bird this time. Instead, we probed a haze layer which the mass spectrometer detected at around 2400 m altitude. On the way back, we could see a few pingos near Tuktoyaktuk, hills created by the permafrost.

Second flight, 22 April

The EM Bird is installed under
the aircraft belly.

Thin ice on a re-frozen open lead in the ice.

The ice looks fascinating from
this close perspective.

The EM Bird is monitored by a video camera.
Here you can see it in the top center.

A successful flight for the sea-ice studies was conducted today over the Beaufort Sea. The EM Bird is an electromagnetic sonde that uses the conductivity of sea water to detect the bottom of the sea ice. The top of the ice is observed with a lidar altimeter, and the difference is the sea-ice thickness. For these surveys, the aircraft flies 65 meters above the ice, at 55 m/s, and the Bird is towed on a 200-ft rope so it is near the ice.

Test Flight

Today (17 April) we accomplished a two-hour test flight starting and landing at Muskoka Airport. Take-off was delayed by snowfall, but by the end of the flight the sky was clear. The instrumentation of the 'Sea-ice' configuration was installed on the aircraft and put to a test in airborne action. The flight was also used for certain calibration procedures. You can see how many circles there were in the flight track, including two at a bank angle of 45°. Funny enough, after completion of such a circle the aircraft encounters its own wake, which could be felt distinctively. The atmosphere was pretty bumpy to begin with, so it was a pleasant ride for those who love rollercoasters. The views of the Lake Huron and of Muskoka's forests and lakes were magnificent. Unfortunately, the test flight also revealed a few faults that need to be fixed.