Blocked out, Jeffco, 1611
T/O 1625
Because of strong headwinds, the pilots elected to refuel in Seattle rather than make Anchorage in one leg. We departed Jeffco in heavy fog and climbed to 20,000' for the entire transect to Seattle. Flying at 147 m/s TAS, the CAI shroud speed was 152 m/s and at the sampling plane was 13.4 m/s. Early in the flight we were frequently in very light clouds. We remained at 20,000' until 1954:20, when we descended into Seattle. We landed at Boeing Field at 2014 and blocked in at 2018. After fueling, we blocked out at 2055 and took off at 2104. At 2125:15 we were once again level at 20,000', heading for Anchorage. The APU remained on during fueling, so all the instruments stayed on. Seattle was clear and the entire region was free of clouds.
At 1655 the NO instrument began producing a phenolic smell. The cause was apparently overheating of the heating tape around the ozone-trap catalyst. After attempts at a repair failed, the system was shut down for the day. Although the thermocouple may be repairable, a power supply also malfunctioned and may not be repaired until Hawaii. The NH3 system is not operational, but the flow system is complete and the excimer lasers are being conditioned.
CO and O3 were operational, and CO2 worked until midway through the second leg. H2O2 was on and off, but is ready for the next flight. The CCN instrument worked until late in the second leg. Tanner got only a little sulfuric acid data, since a noise problem became quite serious after the first hour of flight. The reverse was true of the sulfur GC/MS, for which noise during the first hour of flight may have been due to cooling while on the ramp at Jeffco.
Range correction on the lidar wasn't quite right, but the raw returns sometimes showed aerosol layers below the plane and wave structures in the clouds above us. The lidar printer was not operational and probably won't be until Hawaii. An apparent vibration was reduced by changes on the ground in Seattle. Apparently due to this minor change, the lidar lost convergence (before 2220), so part of the second leg is without lidar data. It was working again by 2320, and showed a shallow 3-400 m MBL and elevated aerosol layers around 3-4 km. Near the end of the leg we were in clouds, and the upward-pointed lidar identified clouds at ~35,000', which is probably at or near the tropopause.
The various groups' CN counters are not agreeing well at all. Around 2215, for instance, Litchy's 3010 and 3760 agreed at 200/cc, while Weber's UCN read 460/cc, and Kok's read 100/cc.Greg found a 2x error in his flow calculation, which should bring them into line with each other. It is still uncler, though, why Rodney is getting more than 2x as high a concentration. Litchy's DMA got much smaller counts than the CN counters, perhaps due to a residence-chamber problem. It may be run directly from the inlet until the problem is resolved.
Nonetheless, we encountered some very interesting CN events, which deserve to be investigated further. Two time periods are 1802-1820's and 1910-1916. During some of these times, the Litchy's 3760 and 3010 CN dropped to ~10/cc, while the UCN rose to several hundred. During these times, Weber saw some UCN spectra, and Thornton noted the SO2 increased by about a factor of four. Weber saw ultrafine CN spectra much of the way up the coast on the second leg.
At about 0016 we entered a cloudy region. Greg's CN (which has a simple gooseneck inlet beneath the plane) became very spiky, in much the same manner that Tony's used to, presumably due to droplet shatter. Litchy's concentrations did move around a bit, but didn't show the spiking that has previously been indicative of droplet shatter. It appears that the CAI has at least minimized the problem of counting CN in clouds.
We blocked in at 0136 in Anchorage, and were pulled in to the FAA hangar for the night.
-Barry Huebert