Theoretical Approach for an Optimum Cloud Seeding Operation using Liquid Carbon Dioxide Seeding

抄録

　To solve the crucial drawback of the competition process among ice particles caused by the conventional seeding method using AgI and dry ice, a new seeding method on the basis of a new airborne liquid carbon dioxide (LC) seeding at low levels of supercooled convective clouds is suggested. The method can cause effective growth of falling ice particles with the expanding cloud volume.
　In this study, by simplifying the complicated processes of dynamics and microphysics and the associated thermodynamics in the artificially induced thermal by LC seeding, a simple method for estimating the properties of artificial ice particles and the resultant radar reflectivity is suggested. The theoretical formula, which depends on cloud thickness as well as seeding rate, showed the drastic increase in artificial radar reflectivity at a cloud top with an increase in the cloud thickness in supercooled temperature region. The theoretical consideration is quite consistent with the observed results of the seeding experiment conducted in northern Kyushu, Japan, on February 2, 1999.
　Therefore, it is expected that the application of the simple formula for evaluating the validity of an actual seeding plan will provide useful information for an optimum seeding operation.