PM2.5の20年にわたる移動を動的時系列手法で解析(Dynamic Time Warping-Based Framework Traces Two-Decade PM2.5 Cross-Regional Movement in China)

2025-08-22 中国科学院(CAS)

中国科学院 航天信息研究院(Aerospace Information Research Institute)の研究チームは、2000年から2021年にかけて中国国内を横断するPM2.5(微小粒子状物質)の長期的な越境輸送経路を初めて明らかにしました。本研究は「Dynamic Time Warping(DTW)」というデータ駆動型の新たなフレームワークを導入し、従来の化学輸送モデルとは異なり、複雑な気象・排出データを必要とせず、シンプルな手法ながらも空間的・時間的に高い再現性を示しました。その結果、地域別では西北地域が34%と最も多く、次いで西南(22%)、華北(21%)、東北(10%)が続き、その他地域でも例外的な経路が確認されました。また、2013年以降、PM2.5の輸送経路の数が大幅に減少し、年間平均濃度の低下とも合致する傾向が認められました。DTWアプローチは、特に観測網が乏しい西北地域においても、従来手法では困難だった汚染の起源や輸送経路を特定するのに有用であり、「ビッグ・アース・データ」による汚染パターンの把握と、より効果的な大気質マネジメント戦略の構築に貢献できるとされています。

<関連情報>

新規時空間相関手法による2000年から2021年までの中国におけるPM2.5輸送経路の研究 A study of PM2.5 transport pathways in China from 2000 to 2021 with a novel spatiotemporal correlation method

Yiming Liu, Huadong Guo, Lu Zhang, Dong Liang, Qi Zhu, Zhuoran Lv, Xinyu Dou, Xiaobing Du
Geoscience Frontiers  Available online: 16 July 2025
DOI:https://doi.org/10.1016/j.gsf.2025.102116

Graphical abstract

PM2.5の20年にわたる移動を動的時系列手法で解析(Dynamic Time Warping-Based Framework Traces Two-Decade PM2.5 Cross-Regional Movement in China)

Highlights

  • The study pioneers a data-driven DTW-based method to chart transport pathways.
  • PM2.5 transport pathways show regional and inter-annual variations in China.
  • The method shows a potential for the study of spatiotemporal correlations.

Abstract

In the context of urbanization, air pollution has emerged as a significant environmental challenge. A thorough understanding of their transport pathways, especially at a national scale, is essential for environmental protection and policy-making. However, it remains partially elusive due to the constraints of available data and analytical methods. This study proposed a data-driven spatiotemporal correlation analysis method employing the Dynamic Time Warping (DTW). We represented the first comprehensive attempt to chart the long-term and nationwide transport pathways of PM2.5 utilizing an extensive dataset spanning from 2000 to 2021 across China, which is crucial for understanding long-term air pollution trends. Compared with traditional chemical transport models (CTMs), this data-driven method can generate transport pathways of PM2.5 without requiring extensive meteorological or emission data, and suggesting fundamentally consistent spatial distribution and trends. Our analysis reveals that China’s transport pathways are notably pronounced in the Northwest (34% of the total pathways in China), Southwest (22%), and North (21%) regions, with less significant pathways in the Northeast (10%) region and isolated occurrences elsewhere. Additionally, a notable decrease in the number of China’s PM2.5 transport pathways, similar to annual average concentrations, was observed after 2013, aligning with stricter environmental regulations. Furthermore, we have demonstrated the feasibility of applying our method to the transport pathways of other gaseous pollutants. The approach is effective in detecting and quantifying air pollutants’ transport pathways, even in regions like the Northwest with limited monitoring infrastructure, which may aid in environmental decision-making. The study will notably improve the current understanding of air pollutants’ transport process, providing a new perspective for studying the large-scale spatiotemporal correlations.

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