Today gave us the chance to get a first taste of some juicy cumulus clouds with the phase Doppler interferometer (PICT), recently arrived from Michigan Tech thanks to grad student and courier extraordinaire Matt Beals. The flight began at 09:45 local time and after a vertical profile to 6500 feet we dropped low enough to sample the tops of actively growing cumulus clouds at a flight level of approximately 3500 feet. As can be seen in the accompanying photograph, these clouds were covered by a solid cloud layer well above the flight level. Peak liquid water contents in the cumulus clouds were around 2 grams per cubic meter. Cloud tops were sampled for the next 50 minutes, and then we dropped to cloud base at a flight level of approximately 1800 feet to perform a last level flight before heading to the helipad.
Unfortunately the phase Doppler instrument was not functioning properly, so we could not obtain drop size distributions, beyond a general picture of drop diameters between 15 and 35 micrometers. Post-flight tests finally localized the instrument problem to a slight misalignment of the laser, which we were able to correct with the expert advice of our Artium Technologies colleagues, and a lot of patience and alignment help from Tina, Dieter, Holger, and Sylwester. When we finally got home at about 21:45, 12 hours after the flight began, we were all very happy to have reached the point where we can measure nice Doppler bursts and we have every indication that the instrument will work properly on the next flight.
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