Evaluation of the First Negative Ion-Based Cloud Seeding and Rain Enhancement Trial in China

Wei Zheng,Jianhua Mu,Zhiliang Shu,Fengming Xue,Ming Zhang,Kexun Yu,Yong Yang,Wenqing Yang,Hengben Ma,Shaoxiang Ma,Chuliang Wang,Xianzhi Yin,Yuan Pan

doi:10.3390/w13182473

Abstract

Negative ion-based cloud seeding has been shown to be an effective means in the laboratory. China’s first negative ion-based cloud seeding outfield trial was conducted in the northwestern interior. This paper briefly introduces the principle of the ion-based precipitation enhancement, and the trial location is described. The design of the ionization system and meteorological monitoring network are presented. The implementation plan of the outfield trial is explained. In addition, the evaluation of experimental effects is detailed in this paper. We designed various analytical methods to investigate both the overall precipitation variation of the experimental area and the precipitation variation within the experimental area. The overall precipitation of the experimental area was predicted using a neural network, and then the actual precipitation was compared with the predicted precipitation to evaluate the effectiveness of the experiment. The effectiveness of the experiment was also evaluated using historical precipitation data and the result of the randomized comparative trial. This paper also explores the effects of geographic location differences and wind direction differences on the precipitation differences within the trial area. The changes in the number of negative ions and clouds in the sky were also analyzed. From these analyses, we obtained quantitative assessment results. These results could indicate that the outfield trial basically met the expected requirements, which is to increase the rainfall of the trial area by 20%.

Highlights

During the 1930s, the Bergeron–Findeisen process theorized that supercooled water droplets present while ice crystals released into clouds would cause precipitation [2]
Traditional weather modification methods mostly rely on solid carbon dioxide or silver iodide and other hygroscopic salts
We study the precipitation data for this period from 2008 to 2020 to find the increase as a representative of this experimental area, whose location is 37◦ 110 5100 N, 102◦ 520 0400 E

Summary

Introduction

The concept of cloud seeding was first put forward by Louis Gathmann in 1891, suggesting that shooting liquid carbon dioxide into rain clouds might accelerate the raining process [1]. In the 1940s, multiple studies and experiments were performed with the discovery of artificial ice nucleation by both dry ice and silver iodide. Traditional weather modification methods mostly rely on solid carbon dioxide or silver iodide and other hygroscopic salts. Whether cloud seeding is effective in producing a statistically significant increase in precipitation is still a matter of academic debate, with contrasting results depending on the study in question. Traditional weather modification usually delivers catalyst via aircraft or rockets, which would be too costly and complex to perform

Methods

Results

Conclusion