Artificial rainfall technique based on the aircraft seeding of liquid carbon dioxide near Miyake and Mikura Islands, Tokyo, Japan

Abstract

This experiment of artificial rainfall was carried out by an aircraft seeding operation of liquid carbon dioxide on Feb. 26-27, 2012, near Miyake Island of the Izu Islands in Tokyo, Japan. The development of convective clouds was significant after 0.5 to 1 h of the seeding near Miyake Island and reached to the heights of 3000 m and 4000 m on Feb. 26 and 27, respectively. Artificial clouds appeared and rain was recognized by eye around Mikura Island on Feb. 27 as a direct effect, and it was presumed that the amount of rain increased on the mountainous area. It was clearly successful that the artificial cloud echoes were recognized about 1.5 h later after the seeding on Feb. 27 as a chain-type cloud echo at east-northeast of Mikura Island on the composition radar echo of Japan Meteorological Agency as an indirect effect. The echo height reached from 3000 m to 5000 m when the artificial cloud moved to the leeward side of Miyake Island. It was recognized that the seeding rate of liquid carbon dioxide with about 5 g/s is suitable in a little inside convective cloud with an air temperature below-5℃.

Artificial rainfall experiment by seeding liquid carbon dioxide above the Izu Islands of Tokyo on March 14 in 2013

“…3. This was significantly different from the case on February 26−27, 2012 (Maki et al, 2013a(Maki et al, , b, 2014. Clouds can develop quickly by the original upstream in a natural cloud and by the artificial upstream mainly based on latent heat of condensation.…”

“…The amount of rain produced presumably by the artificial rainfall was observed 1 mm on Feb. 27, 2012 at the sloped north point of 139 m elevation in Mikura by Tokyo Water Disaster Prevention Information System (Maki et al, 2014). As the rain and cloud hole were found above the sea in this case on Mar.…”

“…Hence, the range of total induced precipitation was from 0.8 to 2.7 million tons, or a round estimation of about 1.8 million tons. The estimated amount of rainfall on March 14, 2013 was relatively larger than that on February 27, 2012 (Maki et al, 2013a(Maki et al, , b, 2014 because of high inducing efficiency by the strong inversion layer. The success of the experiment on March 14, 2013 as a function of the inversion layer (Fig.…”

“…The induction of artificial rainfall by LCD seeding followed a different type of rainfall system as the experiment at the same area of Miyake and Mikura Islands conducted in February 26−27, 2012 (Maki et al, 2013a(Maki et al, , b, 2014, approximately one year earlier. One of our research objectives was to show the successful result of this experiment and the other was to compare the two cases of experiments done on Feb.…”

An artificial rainfall experiment based on the seeding of liquid carbon dioxide by aircraft on December 27, 2013, at Saijo, Ehime, in the Inland Sea of Japan

“…4(H)), a cloud appeared in the Iya Valley area with the rain at Deai, Oiya, Aruse, Ohtaki, and Minamidaiou. This rain was first explained as virga that changed continuously from a higher cloud with the moving of wind for a long distance and also seemed to be artificial rain with the similar result of the chaintype cloud at Mikura Island in the secondary effect of artificial seeding (Maki et al, 2013a, b) and topographical effects (Seto et al, 2011;Maki et al, 2013b). The low cloud developed and could be detected by radar based on the artificial effect in the leeward valleys and mountains.…”