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中国甲烷浓度季节性变化与水稻种植关系研究

Seasonal Methane Concentration Variations Relatedto Rice Cultivation in China

  • 摘要: 甲烷是一种重要的温室气体,水稻种植是甲烷排放的主要人为源之一。传统地面观测手段受限于空间覆盖率和时间连续性,难以有效捕捉农业活动的动态变化过程,来自卫星的观测为精准解析甲烷浓度时空演变提供了全新视角。对流层观测仪(TROPOMI)作为搭载于Sentinel-5P卫星上的新型传感器,具备5.5 km×7 km的高空间分辨率和近实时观测能力。本研究创新性地结合STL区域时间序列分解方法,通过季节变化特征和K-means聚类方法,全面分析了2018~2022年中国区域的甲烷浓度时空变化特征,将中国区域甲烷浓度的季节性变化归纳为四类模态,并深入探讨了这些模态与水稻种植(种植密度、种植模式)之间的相互联系。研究表明,中国甲烷浓度空间分布与水稻主产区契合度较高,总体呈现东南沿海向西北内陆递减的梯度特征,在2018~2022年间甲烷浓度逐年上升,且大部分省份的甲烷四年平均增幅在0.6%以上。此外,首次揭示了四种主要的季节性模态(单峰型、双峰型、三峰型和多峰型)与不同地区的水稻种植密度、种植模式之间的关系,反映出地区的水稻种植是甲烷季节变化特征的决定性因素。

     

    Abstract: Methane is an important greenhouse gas, and rice cultivation is a major anthropogenic source of methane emissions. Traditional ground-based observation of methane are limited by spatial coverage and temporal continuity, hindering effective capturing of the dynamic process of agricultural activities. Satellite observations provide a new perspective for precisely analyzing the temporal and spatial evolution of methane concentration. The Tropospheric Monitoring Instrument, as a new type of sensor mounted on the Sentinel-5P satellite, has a high spatial resolution of 5.5 km×7 km and possesses near real-time observation capabilities. In this study, we applied seasonal and trend decomposition using Loess to extract seasonal and long-term trend components, and then used K-means clustering to analyze the spatiotemporal variations of methane concentrations in China from 2018 to 2022. Furthermore, we categorized the seasonal variations of methane concentration in China into four modes and comprehensively explored the interconnections between these modes and rice cultivation (planting density and patterns). The results indicate that the spatial distribution of methane concentration in China aligns well with the main rice production areas and generally decreases from the southeast coast to the northwest inland regions, with methane concentration increasing year on year from 2018 to 2022. The four-year average increase of methane in most provinces is above 0.6%. In addition, the relationship between the four main seasonal modes (namely, single-peak, double-peak, triple-peak, and multi-peak) and rice planting density and planting patterns in different regions is identified for the first time, reflecting that regional rice planting is a determinant of the seasonal variation characteristics of methane.

     

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