2015 Volume 25 Issue 1 Pages 1-10
The artificial rainfall experiment was carried out on December 27, 2013 by the aircraft seeding of liquid carbon dioxide (LCD) near the north area of Saijo, Ehime, a dry area of climatic type of Seto Inland Sea in Japan. The obtained results were as follows:(1) The height of cloud top was 2740 m with air temperature -13°C, wind direction WNW, the height of cloud bottom was -2°C, WNW, and the cloud thickness was 1670 m. LCD was seeded with the rate of 5.5 g/s at the height of 1370 m with -5°C for about 14 minutes during 11:23-11:48.(2) The rain with about 5 mm/h as a little stronger rain intensity was observed by eye for 5-10 minutes around 11:50 at the city office area in Saijo City. The precipitation was observed 0.5 mm until 13:00 (estimated just after 12:00) at the Saijo Fire Station. They were supposed to be an artificial rainfall.(3) After the seeding of LCD, the convective cloud of cumulus developed quickly above Saijo during 11:30-11:50 and it was rain in a short time. The high cloud of cumulus was decreased by a local artificial rain. The cloud over a mountainous area was almost disappeared rapidly until 12:30 in about 1 hour after the seeding of LCD.(4) The estimation of no rain by the seeding time, seeding position and wind direction was agreed that raining did not observe at the south area of Saijo City, however, artificial rain was significant at the south mountainous area of Niihama City and it could be clearly observed by eye throughout.(5) The artificial rain was observed 0.5 mm and 4.0 mm at Ohjoin and Besshiyama of Niihama Fire Station, respectively by the seeding time, seeding position, wind direction, wind speed and so on.(6) At AMeDAS Tomisato located at the south mountainous area of Shikokuchuo City, the rain was observed 0.5 mm as an artificial rain during 11:50-12:00 by the seeding time, seeding position, wind direction of WNW and wind speed of 15 m/s.(7) It was supposed to be already arrived under the condition of natural rainfall decreased around 11:30, i.e., seeding time. It was highly possibility to be artificial rainfall from the cloud expected as no more than natural rain.(8) The rains of 0.5 mm at AMeDAS Ikeda and of 2.0 mm at AMeDAS Kyojo in Miyoshi, Tokushima were supposed to be the artificial rain by the seeding time, seeding position, wind direction and wind speed. The main line rainfall was Besshiyama-Kyojo in east-west direction and the effect of artificial rain was continued to 80 km in the leeward.(9) Consequently, the experiment of artificial rainfall by the seeding of LCD on December 27, 2013 was succeeded clearly.
