Simultaneous Aircraft Observations of Aerosol and Cloud Droplet Concentrations Related to Global Cooling

Aircraft observations were carried out in order to study the relationship between aerosol concentration and cloud droplet concentration as basic research on the in· direct effect of aerosol. We analyzed data for clouds that satisfied two standards: clouds of measured aerosol concentrations but without precipitation. The results showed the horizontal and vertical structures of clouds, which can be characterized as follows. The maximum values in cloud droplet concentration and liquid water content are located at the center portion of cloud. Also, cloud droplet concentrations show nearly equal values regardless of the height, and the liquid water content increases with increasing height. The relationship between the aerosol concentration under the cloud base and the cloud droplet concentration in the clouds is represented by the regression formula Y=178Xo.26, which asserts that the rate of increase of the cloud droplet concentration in large aerosol concentrations is less steep than in small aerosol concentrations. 1