RESEARCH ON SIMULATION OF EFFECTIVE RANGE FOR CLOUD SEEDING BY AIRCRAFT WITHIN SUPER-COOLED STRATUS

It is important to know the range affected by seeding agent in rain enhancement with aircraft. Based on the requirement of effective seeding concentration (101/L), the concept of ef fective range is put forward. And its charact eristics such as effective area and volume, expanding depth and width as well as horizontal transport and diffusive rate are obtained by simulating results from at hree-dimensional model, which deals with transport and diffusion of seeding agent with in super-cooled stratus. Taking an operational case of rain enhancement as example in the simulation, the results show that:(1) the cloud seeding by airplane takes 45 minutes, the length is 327 km. Five minutes af ter finish seeding, maximum effective volume and maximum projectively effective area on the ground reach their extremes, 298.0 km3 and 707 km2, respectively, its effective expanding depth is 0.42 km, and its width 2.51 km. (2) Effective duration lasts from 20 to 80 minutes. During that time, average projectively effective area is 513.3 km2, and average effective expanding depth and width are 0.45 km and 2.41 km, respectively. (3) With the effect of turbulence, the effective area and volume increase with the time, and decline after reach their extremes. Effective range disappears 55 minutes after finish seeding. For this while, average projectively effective area is 389.7 km2, average effective expanding depth and width are 0.44km and 2.41km, respectively. (4) Horizontal transport distance is only related to wind. The avenage reached 65 km after 1 hour. And diffusive rate is connected with wind, temperature and turbulence, 1 hour s average is 0.82 m/s. (5) The scheme design of cloud seeding should be scientific to prompt ef ficiency of rain enhancement.