A low‐level penetration seeding experiment of liquid carbon dioxide in a convective cloud

Abstract

Abstract:In order to bring large amounts of precipitation, the new seeding method using liquid carbon dioxide (LC) was suggested by Fukuta (1996a). The method was applied to the supercooled convective cloud in a post-frontal weather condition in northern Kyushu, Japan, on October 27 1999. In the seeding experiment, LC seeding and the subsequent observation by aircraft were carried out and the features of a seeded echo were observed by radar. Consequently, the aircraft observation confirmed the further development of the seeded cumulus together with a fuzzy aspect of the cloud surface, which indicates the feature consisting of ice particles. Furthermore, the observed cloud top was quite consistent with the cloud top estimated by the thermodynamic analysis following parcel theory. Therefore, the observed results indicate the artificial effects by LC seeding. On the other hand, the radar observation confirmed an artificially induced echo, which showed spreading of the echo area and took a unique mushroom shape in the RHI pictures. The maximum width of the echo reached 24 km and the total amount of estimated radar precipitation of the seeded cumulus was approximately 2.4 million ton, traversing a distance of 60 km in 1 h 40 min. The observed and estimated results are consistent with the hypothesis of the new seeding method, which induces the dynamic and microphysical processes consisting of two fundamental processes. In addition, it was found that dynamical interaction between the seeded and the adjacent natural cumuli was an important factor in the formation of the secondary cumulus. The observational fact will give new viewpoint into the future seeding study.

Comparative study of liquid carbon dioxide and silver iodide seeding effects on cumulonimbus clouds rainfall enhancement and hail suppression

“…However, for the same clouds, the cumulative rainfall amount enhancement through the LCO 2 seeding is substantial. These results are in good agreement with those of Fukuta (1996) and Wakimizu et al (2002). In fact, quantitatively, the current model illustrates a cumulative rainfall enhancement from 1 to 52 % in LCO 2 seeding versus to only 19 % in AgI seeding.…”

“…Moreover, based on the model results, for clouds with the CTL more than 9 km, the LCO 2 seeding shows to enhance the cumulative rainfall amount significantly compared to the AgI seeding. These results are in good agreement with those of Fukuta (1996) and Wakimizu et al (2002). This observation shows that the releasing methods of the seeding agents are sensitive to CTLs.…”

“…The effects of aerosols on mid-latitude clouds and storms have been investigated to a less extent Levin 2005, 2006). There are many field projects and numerical models which concentrate on some aspects of seeding materials and their effects on rainfall enhancement, hail suppression, and fog dissipation (e.g., English and Marwitz 1981;Fukuta 1996;Wakimizu et al 2002;Xiao et al 2005;Guo et al 2006;Javanmard 1999;Javanmard et al 2008;Karimpirhayati 2010;Seto et al 2011;Zipori et al 2012;Javanmard and Mohammad-Hosseinzadeh 2012). However, these studies concentrate on specific clouds or weather conditions.…”

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

“…An artificial rainfall technique of liquid carbon dioxide (LCD) was invented by Fukuta (1988), and it was proven successful at Fukuoka on Feb. 2, 1999 as the first effective rainfall production method. Several rainfall investigations confirmed the LCD method's property and efficiency on Feb. 2 and Oct. 27, 1999 (Fukuta et al, 2000;Wakimizu et al, 2002), Feb. 4 and Nov. 7, 2006, Jan. 8 and 17, 2007, Jan. 24, 2009, and other experiment results included (Maki et al, 2011;2012). The experimental results on Feb. 27, 2012 and Mar.…”

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

“…However, these methods produce only small amounts of rainfall, and they have environmental and economical problems. A seeding technique using liquid carbon dioxide (LCD), invented by Fukuta (1988a, b), was tested and shown to be effective at Fukuoka on February 2, 1999 and in nu-merous later trials (Fukuta et al, 2000;Wakimizu et al, 2002;Nagata et al, 2005;Nishiyama et al, 2005;Ota et al, 2005;Maki et al, 2008Maki et al, , 2011Maki et al, , 2012.…”