Precipitation Augmentation by A New Method of Cloud Seeding in Northern Kyushu (2)

In order to solve draught problems, a precipitation augmentation experiment based on a new airborne liquid carbon dioxide (LC) seeding at low level of supercooled convective clouds, was carried out in the northern Kyushu, February 2, 1999. On this day, a cold air mass began to flow from the Siberia toward the Japanese Islands. This wind was very strong and cloud bands consisting of many cumuli ranged at constant interval above the Genkai Sea. Under the weather condition, three seedings were carried out. The second and third seedings resulted in rainfall of approximately 1.3 million tons during the lifetime of the seeded cumuli. At the same time, unique, large mushroom-shaped radar echoes were discovered in the range height indicator (RHI) scans of Kyushu University (KU) radar for the plan position indicator (PPI) echoes near the maxima, which has never been observed among natural clouds. Based on the observations, the optimum design of seeding operation for winter season is discussed.