Artificial rainfall experiment by seeding of liquid carbon dioxide above the Izu Islands of Tokyo on December 15-16 in 2013

Abstract

An artificial rainfall technique of liquid carbon dioxide (LCD) was used in experiments operated on Nii, Miyake and Mikura Islands in the Izu Islands of Tokyo in Japan on December 15-16, 2013. On Dec. 15, rain particles or graupel pellets struck the aircraft front window and virga or rain was observed under a cloud from the aircraft on the east leewardside of the seeded area under the condition of thin cloud of 760 m in depth until 30 minutes. On Dec. 16, rain or graupel struck the aircraft front window at 15 minutes after seeding and virga or rain under the cloud was observed at 37 minutes after the seeding under the condition of a thinner cloud of 610 m in depth. On Dec. 15, rain was recognized along the route of the seeding and a line-type trail of cloud disappeared was visibly recognized with an average width of 2 km. The development and disappearance of clouds were evaluated using satellite images near Mikura Island. On Dec. 16, a cloud developed immediately after the seeding and a line-type cloud running in the NNE-SSW direction was recognized on the satellite image. The cloud developed decreased in scale due to rain and the cloud disappeared was also recognized on a satellite image near Nii Island. On Dec. 15, an analysis showed the existence of following local effects of the seeding; the development of clouds at 700 hPa level higher than the seeding height, the appearance of rain at 850 hPa level around the seeding height, rainfall (virga) and a drastic increase in relative humidity at 925 hPa level lower than the seeding height, and finally the occurrence of artificial rains that were clarified by the upper weather maps based on meso scale model (MSM). The artificial rainfall experiments were succeeded.

Artificial rainfall experiment involving seeding of liquid carbon dioxide at Karatsu in Saga

“…Thus, a large amount of precipitation was produced. The fact that the rainfall continued for over 1 h 30 min was also consistent with the experimental results 2014;2015a, b;2016 . However, the echoes had almost disappeared at 15: 20 Fig.…”

“…The distance of this distribution was fairly long at 40 km. The information on cloud movement in terms of time and distance, and the amount of rainfall were consistent with other experiments 2014;2015a, b;2016 . That is, in general, there is a period when the snow and / or rain particles fall from a higher cloud and the ice crystal particles circulate up and down in the clouds. These particles increase as time passes.…”

“…14, 2013Maki et al, 2014and 0.1 m.t. Dec. 16, 2013Maki et al, 2016around Miyake and Mikura I., and 1.3 m.t. at Saijo, Ehime Dec. 27, 2013Maki et al, 2015a .…”

“…This experimental result is similar to the example at Saijo on Dec. 27, 2013. We are interested as an evaluation of the topographic effects of inland mountains 2014;2015b;2016 andinland terrain Maki et al, 2015a . The distances artificially affected by LCD seeding were over 100 km W-E direction around Miyake I. and Mikura I. in the Izu Islands 2014 , and near 100 km at Saijo, Ehime to the east of Sugao, Tokushima and at Nii I. to the east of Mikura I.…”

“…The distances artificially affected by LCD seeding were over 100 km W-E direction around Miyake I. and Mikura I. in the Izu Islands 2014 , and near 100 km at Saijo, Ehime to the east of Sugao, Tokushima and at Nii I. to the east of Mikura I. Maki et al, 2015a;2016 . In the present study, the LCD technique was used in experiments conducted in the Karatsu, Saga, and Fukuoka regions in Japan on Dec.…”