Today we had very clean conditions and the lower atmosphere was predominantly influenced by marine aerosol. After a short shower we took off sharp at 13:51 UTC under cloud-free conditions. At the beginning we flew a short horizontal leg near sea level to Charly 1, followed by a vertical profile up to 8.000 ft to Charly 2, as usual. The CCN concentration was very low and almost constant with increasing altitude. It ranged from 50 to 100 #/cm³ at 0.3 % supersaturation. Afterwards we decided to go for low level cumulus clouds above the sea. But in reality the helicopter had to climb up to about 10.000 ft for these clouds, because they were quit convective and developed so fast, as can be seen in the first figure. At about 14:25 UTC, 
ACTOS had the first cloud contact and by the means of PICT a mean droplet size of about 35 µm was measured. We had the chance to fly on top and at the edge of this cumulus congestus cloud three times. A shift in droplet sizes to larger values was found. Possible explanations for this effect are (a) growing droplets in a still towering cloud or (b) PICT measured droplets at different cloud heights. During the whole flight no cirrus pertubated the radiation measurements, only a very thin fast disappearing stratocumulus was located at our flight altitude. Then we went for other cumulus clouds, some of them contained clearly smaller droplets of about 25 µm and others also larger ones of about 35 µm in diameter, 
see second figure. Being quite northward of Barbados over the sea and becoming really tired because of the lack of oxygen at this high altitude, we decided to turn back to Charly 2 and to descend down to 3.000 ft, which was approximately the height of the cloud base. A horizontal leg at 3.000 ft to Charly 1 and also one at 1.500 ft was performed on the way back to the airport under cloud-free conditions. Considering the former leg, a maximum CCN concentration of 250 #/cm³ was determined by the mini-CCNc operating in the scanning mode, see third figure. At the higher supersaturation values we can assume that all the potential CCN are already been activated to cloud droplets.
Now we are done, that was our last scheduled measurement flight of CARRIBA 2011 with the helicopter CFNHG carrying ACTOS and SMART-Helios. Many thanks to all contributors and the people who gave me the opportunity to be a part of this project!
ACTOS had the first cloud contact and by the means of PICT a mean droplet size of about 35 µm was measured. We had the chance to fly on top and at the edge of this cumulus congestus cloud three times. A shift in droplet sizes to larger values was found. Possible explanations for this effect are (a) growing droplets in a still towering cloud or (b) PICT measured droplets at different cloud heights. During the whole flight no cirrus pertubated the radiation measurements, only a very thin fast disappearing stratocumulus was located at our flight altitude. Then we went for other cumulus clouds, some of them contained clearly smaller droplets of about 25 µm and others also larger ones of about 35 µm in diameter, 
see second figure. Being quite northward of Barbados over the sea and becoming really tired because of the lack of oxygen at this high altitude, we decided to turn back to Charly 2 and to descend down to 3.000 ft, which was approximately the height of the cloud base. A horizontal leg at 3.000 ft to Charly 1 and also one at 1.500 ft was performed on the way back to the airport under cloud-free conditions. Considering the former leg, a maximum CCN concentration of 250 #/cm³ was determined by the mini-CCNc operating in the scanning mode, see third figure. At the higher supersaturation values we can assume that all the potential CCN are already been activated to cloud droplets.Now we are done, that was our last scheduled measurement flight of CARRIBA 2011 with the helicopter CFNHG carrying ACTOS and SMART-Helios. Many thanks to all contributors and the people who gave me the opportunity to be a part of this project!
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