CIFEX Experiment # 3

April 3, 2004.

Flight Scientist: V. Ramanathan

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Flight #3: Take off about 10 am. Lasted about 3 hours

Flight#4: Take off about 4.30 pm; Lasted about 3 hours

Objectives: The flights had two objectives

• Asian Dust : A gradient flight to flu across the older Asian dust close to the coast to the newer dust about 150 miles away from the coast, past 127 Longitude. This was achieved in flight 3B
• Indirect Effect: To sample polluted low clouds which were spotted south west of Arcata, about 150 to 200 miles away. This objective was accomplished in Flight 3A.

Instrument Status: All instruments except the SIO CCN and CPC was operating.

Flight# 3: On the outbound leg, climbed to about 10000 feet to sample the dust layer; see very little dust in instruments although a dark layer was located on the western horizon. It was farher than we had assumed. At about 11 AM , we located the low clouds between 1000 and 1700 feet and sampled the low clouds along the southern trajectory. Sampled the clouds for about 45 minutes. The CN was around 1500 to 2000; drop concentration was 200 to 300 per cc and mean diameter was very low around 5 to 8 microns. On the outbound, we encountered the dust layer around 6000 to 7500 feet; CN around 650. On the return leg, we spotted another lower deck closer to the coast. Sampled for another 20 minutes; CN larger at 4000 CC; drop number was also more around 300 to 400; dimater was also larger around 9 to 12 microns..

The dust situation was a bit confusing: Could see it clearly visually; but diffuclt to spot in instruments; ultimately pinned it to be around 6000 to 7500 feet.

Flight #4 : Was delayed by about 1 hour; took off at about 4.30 pm, with end point around 40 N and 128 E, roughly about 230 miles away. Two low clouds were located; one close to the coast; one at the farthest point.. near perfect start-Cus. Unfortunately due to denied clearance we could not descend to below 11000 feet to sample the low clouds at the farthest point. Was very frustrating and disappointing to see the clouds within reach without being to sample it.

However, the dust part was a success. Was located at about 150 miles away, just as predicted by the forecast model. The altitude of the dust was around 10500 to 11000 feet; CN shot up to 1000 per cc, but it was mostly very small particles, less than 30 nm. The CN dropped to less than 200 per cc when we got closer to the coast. Before landing sampled coastal low clouds; very polluted with 5000 CC.