CIFEX Experiment # 11

April 14, 2004.

Flight Scientist for #15: Carl Schmitt

Flight Scientist for #16: V. Ramanathan

Flight Engineer: Perry Wechsler

_______________________________________________________________________________________

Flight #15: Take off in the morning.

Objective: The goal of the morning flight was to observe Mixed-phase clouds.

We headed up and west trying to get above the clouds. The plan was to do a spiral 80 miles out. On the ascent a heavy dust layer was observed at about 10,000 feet. A brown layer on the horizon was clearly visible. We leveled off at 14000 feet and proceeded further west until we were above a thicker cloud layer. We started a spiral descent and encounter cloud at 7000 feet, just a few degrees below freezing. The cloud contained some ice but in general was not too interesting. We resumed our heading to the west and climbed up to 11000 feet, then descended to an aerosol layer at 10400 feet. We maintained course in the aerosol layer for fifty minutes until we needed to turn around. During the straight leg, the cpc levels rose constantly from 1000/cc to 3000/cc.

The return flight was spent in low-level clouds. Passes through clouds were generally taken at about 5000-7000 feet, which was at the –2C level. The larger clouds contained some ice particles. The most common ice crystal habit was columns or aggregates of columns consistent with what would be expected to grow at those temperatures. Regions between clouds were generally very clean. Most of the cloud systems were precipitating.

Flight #16: Take off at 3pm

Objective: Sample precipitating clouds, preferably mixed-phase clouds, since the morning flight was not successful in locating the mixed-phase cloud systems.

Report: This is to be considered a relatively clean sky conditions and most clouds were precipitating. Sampled both mixed phase and stratocumulus systems. Closer to the coast, the clouds were mixed phase type and switched to strato cumulus type systems over the open ocean. There were clear skies in between. Very few new particles were seen at the low levels and the CCN and PCASP were registering comparable number densities suggesting mostly nucleating mode aerosols. Should be useful for examining precipitating low cloud systems.