2016 Volume 26 Issue 1 Pages 17-24
The experiment of artificial rainfall by the aircraft seeding of liquid carbon dioxide (LCD) was carried out near Miyake and Nii Islands of Izu Islands, Tokyo, Japan on Dec. 16, 2013. The obtained results were as follows:
(1) Rain particle or graupel pellet struck the aircraft front window was observed 15-20 minutes after the LCD seeding, and a virga or rain under cloud was observed 37 minutes after from the aircraft window under the condition of thinner cloud of about 600 m depth as a first time.
(2) The cloud developed immediately after the LCD seeding in spite of narrow and thin cloud, and a partially significant line-type cloud running in the NNW-SSE direction was also recognized using satellite image. As rain was induced from clouds, the cloud track partially decreased in the line-type cloud was also recognized using satellite image.
(3) The areas of significantly developed convective cloud and disappeared cloud track due to the LCD seeding were timely evaluated as three parallel line-type clouds and no clouds of NNE-SSW direction, respectively, in the main cloud running in the NNW-SSE direction by the images of satellite Terra and satellite Aqua on Dec. 16, 2013. The estimated amount of rain by artificial rainfall was 0.14 million ton from the change of satellite images.
(4) The artificial rainfall experiment on Dec. 16, 2013 was clearly succeeded. The best technique is recognized and synthetically generalized from many experiments that liquid carbon dioxide of seeding rate with about 5 g/s over 10 minutes is directly seeded in a convective cloud over thickness 600 m near a cloud bottom under an air temperature condition below 0°C (-2 to -5°C) using a siphon type gas cylinder loaded in an aircraft.
