2012 年 27 巻 3 号 p. 256-263
The aerosol impacts on warm clouds (aerosol indirect effects) are generally categorized into the cloud albedo effect (the Twomey effect) and the effects including cloud feedbacks, such as the cloud lifetime effect. As evidence of the Twomey effect, a number of in-situ observations over the world, including those over the Western Pacific, has shown an increase in cloud droplet number concentration near the cloud base in response to an increase in aerosol number concentration below cloud. Cloud feedbacks have also been intensively studied, however, they appear to change depending on meteorological regimes (called a buffered system) and are not as simple as hypothesized initially as the cloud lifetime effect. Because of a unique meteorology in addition to the world highest aerosol loading over the East Asia-Western Pacific region, further studies should be made to understand how aerosols can affect cloud lifecycle (such as precipitation) and macro-structure of cloud (such as cloud liquid water path and cloud fraction) in this region.