Study of relationship between global electric circuit and clouds

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K03679
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17030:Human geosciences-related
• Research Institution: Chiba University
• Principal Investigator: Ohya Hiroyo 千葉大学, 大学院工学研究院, 助教 (00241943)
• Co-Investigator(Kenkyū-buntansha): 鷹野 敏明 千葉大学, 環境リモートセンシング研究センター, 名誉教授 (40183058) ; 高橋 幸弘 北海道大学, 理学研究院, 教授 (50236329)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 大気電場 / グローバルサーキット / 雲

Outline of Final Research Achievements

The purpose of this study is to clarify the effects of lightning and thunderclouds on the global electric circuit using a field mill and the 95 GHz cloud radar FALCON-I. We installed new field mills in Iitate, Fukushima, and Sendai, Miyagi, and conducted regular cloud observations at Chiba University, obtaining the following results. We proposed a method for estimating cloud base height and cloud amount using two all-sky cameras, and confirmed that it can be estimated with high accuracy. We investigated the periodicity of the atmospheric electric field and radar reflectivity when lightning occurs, and found that it is influenced by thunderclouds and precipitation. Analysis of the thunderstorm in Chiba on June 3, 2022 revealed the fluctuation pattern of the atmospheric electric field. During the Chiba sleet on January 22, 2018, we found high correlation between the oscillations of the atmospheric electric field with the movement of cloud particles in the lower layers of snow clouds.

Free Research Field

超高層物理学、大気電気学

Academic Significance and Societal Importance of the Research Achievements

本研究では、地表と下部電離圏間に形成されるグローバルサーキットと雲との関連性を調べ、雷雲や雪雲により地表の大気電場が大きく変動する様子を定量的に明らかにした。本研究は、対流圏（気象現象）―下部電離圏（高度60-100 km)結合を解明可能にするだけでなく、電離圏の外側に位置する磁気圏―電離圏電流系をも含めた太陽活動と地球の気候との関連性の解明に貢献できる可能性があり、学術的に波及効果をもたらすものと思われる。