2200:00 Takeoff Hobart, climb to 19,000'
2224:40-0031:03 Level at 19,000'
Upon exiting cloud bank at 2302, UCN 800-1000/cc
0031:03-0049:00 500 fpm descent to lidar leg
0049:00-0102:00 Lidar leg at 10,000', heading toward north end of MI
0102:00-0127:41 500 fpm spiral descent near northern tip of MI
BL top at about 1600'
0127:41-0157:41 30 min Lenschow circle CW at 100'
90/270 climb to 800'
0201:16-0231:16 30 min Lenschow circle CCW at 800'
90/270 climb to 2000'
0234:12-0304:12 30 min Lenschow circle CW at 2000'
High UCN at start of leg, penetrated tops of some clouds
late in leg
Climbed to 2500' to start sounding to 100'
0305:18-? 500 fpm descent to 100'
~0310-0319:46 100' leg downwind (east) of MI, about 1-2 km offshore
High NH3 detected near south end.
0319:46 90/270 turn to start sounding northbound along island
0323:16-? 500 fpm climb behind MI
Stopped in layer w/ 3 clear modes, at 1600-1800'
?-0337:40 Spiral climb to 10,000'
0337:40-0352:40 Lidar leg in direction of Hobart
0352:40-0406:00 500 fpm climb to 18,000'
1200-1500 CN (few UCN) until ~0425
0513-0517 Climbed to 20,000' and returned to layer of UCN at 19,500'
0522 Entered cloud and both CN and UCN decreased dramatically
0552 Exited cloud and encountered high UCN layer briefly
0555-0601 Porpoised between 19,000 and 21,000' to seek high UCN
0627:00 Began 500 fpm descent into Hobart
0700 Landed Hobart
We had an excellent (not to mention beautiful) flight around Macquarie Island. The air near the island was hazy, with only scattered clouds. Both going and coming from MI we encountered high CN and/or UCN layers, in which we flew for tens of minutes. On the return we porpoised a bit to try to stay in one layer, and found that we had flown out the end of it, at approximately the time we encountered clouds well below us in the BL.
We found during the initial lidar leg near MI that the boundary layer was 1600' deep and very distinct. The CN concentrations in the BL were steady at 500-600/cc, much more uniform than on any previous flight. This may be due to the relative freedom from clouds on this mission. We flew two Lenschow circles in the BL (100 & 800') and one just above the inversion at 2000'. Although we touched the tops of a flew clouds late in the leg, we elected to remain at the same altitude for the duration of the circle.
We tried to ensure that the cirles were flown as close to the island as possible, without getting into the island's emissions. It is important to note, however, that the subsequent legs (100' southbound leg past the MI observatory and a slow climb to the final lidar leg) were flown in the lee of the island, and were therefore potentially polluted by the island's emissions. This is no doubt the reason that "high levels of ammonia" were reported on the 100' leg. (Needless to say, it was a cause of great rejoicing to hear that _any_ levels of ammonia were reported, meaning that the LIF instrument is now operational.)
During our 800' leg we received a report from MI that they were seeing 95-100 pptv DMS, 500 CN/cc, and 300 CCN/cc@ 0.5% supersaturation. Because of the need to attend to the flight, we did not reciprocate with corresponding data, although our CN were clearly in the same range. Our CCN spectrometer was not fully functional until after the BL sampling, so it may not provide a useful intercomparison. We will have DMS data to compare, however.
As we descended to 100' for a low leg east of the island, we encountered a layer of UCN at about 16,000'. We returned to that layer after flying the length of the island, and found three clear modes the likes of which Pete McMurry has never seen before.
Northbound we found high UCN or CN layers on both sides of the front. (We entered cloud at ~0522 and exited by 0552 on the return.) South of the front (shortly after reaching 18,000') we followed a high CN/low UCN layer for quite a while. When it ended, a porpoise confirmed that it had not simply drifted off above or below us. The high UCN layer on the north side was apparently very short, since a porpoise between 21,00 and 19,000' couldn't find it again. The porpoise raised the possibility that there were sloping potential temperature surfaces near the front.