estimating terrestrial methane flux based on global earth observation big data

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K21849
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 63:Environmental analyses and evaluation and related fields
• Research Institution: Osaka Prefecture University
• Principal Investigator: Ueyama Masahito 大阪府立大学, 生命環境科学研究科, 准教授 (60508373)
• Project Period (FY): 2020-07-30 – 2022-03-31
• Keywords: メタンフラックス / 温室効果気体収支 / 陸域生態系 / モデリング / ビッグデータ

Outline of Final Research Achievements

This study has developed a method (CH4) for partitioning methane flux observed by the eddy covariance method into CH4 production, oxidation, and transportation (plant-mediated transportation, diffusion, ebullition). The method constrains parameters for a newly-developed process model with the observed data based on a Bayesian method. The developed method was tested for a temperate bog in Hokkaido, Japan. The method was then applied for a database of global terrestrial CH4 fluxes (FLUXNET-CH4) for estimating CH4-related processes for wetlands (bog, fen, and marsh), tundra, and rice paddies. The estimated processes suggest that spatial variations in CH4 emissions are mostly explained by those by CH4 production across the sites, and then CH4 oxidation is the important factor for CH4 emissions. The model estimated that plant-mediated transport was the most important transport process in fen and rice paddies, but ebullition was the important process in bog and tundra.

Free Research Field

環境動態解析

Academic Significance and Societal Importance of the Research Achievements

陸域のCH4収支やその変動要因を定量評価することは、全球の温室効果気体収支や温暖化予測を向上させる上で喫緊の課題である。これまで陸域CH4収支の評価法は、個別の地点で観測されたCH4収支と環境要因とを統計解析するか、検証が不十分なモデルによる広域推定にとどまっていた。多地点の地球観測データを用いて数理モデルのパラメータを直接的に決定し、データ駆動による陸域CH4収支を決定する要因や気候応答を評価できたことは、プロセスモデルの高度化に貢献できる。数理モデルを使ったデータフュージョンを行うことで、得られたCH4収支の変動を粗過程に遡って評価できるホワイトボックス型の推定が可能となった。