TIME (UTC) REMARKS
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08:00 TAKEOFF AND FERRY WEST AT 18,000'
09:20 In and out of cloud tops.
09:30 Descend to 11,500'
09:42 Aerosol layers near cloud tops.
10:11 Level at 16,000 over clear spot behind front.
10:13 Start 5 min calibration leg.
10:19 Descend to surface over clear area, 45.00 S and 138.22 E.
10:28 In nuclei layer at 5,500'.
10:36 Drop to 500' for lidar leg under back of frontal outflow.
10:59 Run into rain - front? 44.53 S and 140.35 E.
11:08 Turn and climb to 1000'.
11:21 Back out of "front". (44.51S and 140.46E)
11:34 End 1000' leg and climb to 3,500'.
11:46 Rain, estimate rainband moving at 9m/s.
11:51 End 3,500' leg, turn and climb to 6,000'.
11:55 level at 6,000'
12:26 Descend to surface at 500'/min. (45.13 S & 139.09 E)
12:39 Start circle (center at 44.8 S and 139.6 E)
13:09 End leg and climb to 800'.
13:15 Start 800' circle.
13:45 End 800' circle and start porpoise across weak inversion at
1,500'.
13:55 End and climb to aerosol layer.
14:20 Descend through layers to 3,000' and start 5 min leg at cloud
top.
14:30 Climb to 6,000' through layer at 5,000'.
14:46 Descend to 500' behind front through rear edge of frontal cloud
outflow stratus.
14:50 Ascend from 500' to 8,000' through body of frontal cloud outflow
stratus.
15:24 Turn back
15:28 Descend to cloud top.
15:34 Climb at 1,000'/min to 12,000'.
16:40 TOUCHDOWN
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This night mission has two major objectives. It was designed to support the Lagrangian by flying in post frontal air expected to be similar to that selected for the Lagrangian. This included locating and flying in a clear air region behind the front that was likely to advect to the position of the R/V Discoverer and provide a suitable study region for it to launch the balloons used for the following Lagrangian flights. A suitable clear region was successfully identified and the ship was able to position itself appropriately for the passage of the front. The mission included vertical profiles and boundary layer circles in order to assess entrainment rates. These were completed at 500' and 800'.
Second, and because the Lagrangian is in part to study the evolution of nuclei previously observed in post frontal subsidence, this mission was also designed to evaluate the potential sources for these nuclei. These included entrainment of particle seen above shallow clouds near the front, subsidence entrainment of nuclei from higher layers often seen aloft or subsidence of particles formed by cloud process associated with the frontal inversion aloft. Neither the first nor the last possibility was clearly evident in the data. Descent profiles flown at the boundaries of the clear area both toward and away from the front showed layers associated with frontal outflow evident at 4,500' to 6,500' while in the intervening clear region this layer was extended down to 3,000'. This suggests that lowering of these layers in post frontal subsidence might bring them close enough to the surface to be influenced by small scale convective elements present in this "clear" region that might help mix them to the surface. More extensive analysis of the data and the horizontal legs flown perpendicular to the front to assess "potential vorticity advection" will be needed to clarify this process.