海南岛甲烷浓度空间异质性规律解析

Spatial heterogeneity of methane concentration in Hainan Island

温室气体排放升高对全球气候变暖有重要影响,其浓度分布的空间异质性及与局地气候变化和社会经济的关系是影响温室气体减排策略制定的关键因素.海南岛是国家生态文明建设的试验区,温室气体减排方面也面临着目标考核的压力与责任.本研究使用GHGSat的CH_(4)浓度产品、气温、降雨、GDP和人口数据集,采用Theil⁃Sen趋势分析、Mann⁃Kendall(MK)检验构建地理加权回归(GWR)模型,分析了2020—2021年海南岛CH_(4)浓度变化趋势及规律.结果表明:1)时空尺度上,2020—2021年海南岛CH_(4)浓度整体呈下降趋势,CH_(4)浓度均值为1848.40×10^(-9) mol/mol,8—11月的CH_(4)浓度低于均值,其余月份均值皆高于均值;海南岛46􀆰42%的区域CH_(4)浓度呈显著减小趋势,主要集中在海南岛的西部及东部地区.2)CH_(4)浓度时空分布的异质性规律方面,GWR模拟结果显示,海南岛CH_(4)浓度与气温回归系数值分布于-114.92~127.80,CH_(4)浓度与降雨回归系数分布集中于-297.40~399.91,而CH_(4)浓度与GDP和人口的回归系数较高,分别集中于-4125.55~4509.07和-1751.43~1556.41,GWR能够揭示像元尺度上CH_(4)浓度分布对气候与社会经济因子的响应规律.3)拟合方法选择上,基于普通最小二乘法(OLS)与GWR方法对CH_(4)浓度与气温、降雨、GDP和人口的拟合结果的R2分别为0.14和0.83,表明海南岛CH_(4)浓度分布受气候和社会经济的局地效应影响显著,GWR方法在解释CH_(4)浓度分布影响因素方面比OLS的拟合效果更优.本研究揭示了海南岛CH_(4)浓度变化趋势及其空间变异规律,能够为海南CH_(4)浓度时空分布的动态评估提供方法参考.

Increasing greenhouse gas emissions has become an important factor affecting global warming.The spatial heterogeneity of CH_(4) concentration and its relationship with local climate and social economy are important factors affecting the ecological policy formulation.Greenhouse gas emission reduction is a challenging and imperative task for Hainan Island,which is a pilot zone for the national ecological protection drive.Here,the trend and driving fac⁃tors of CH_(4) concentration in Hainan Island during 2020-2021 were analyzed through the Geographically Weighted Regression(GWR)model,which was established by using GHGSat CH_(4) product,temperature,rainfall,GDP and population datasets,as well as Theil⁃Sen trend analysis and Mann⁃Kendall test.The results showed a slight decreasing trend of CH_(4) concentration in Hainan Island from 2020 to 2021 with the mean value of 1848.40×10^(-9) mol/mol;as for its spatial distribution,no obvious variation in 52.95%areas and a significant decrease in 46.42%areas were observed in Hainan Island.In addition,the GWR can reveal the response of CH_(4) concentration distribu⁃tion to climate factors on pixel scale,specifically,the regression coefficients between CH_(4) concentration and temper⁃ature ranged from-114.92 to 127.80,and those between CH_(4) concentration and rainfall ranged from-297.40 to 399.91;the regression coefficients of CH_(4) concentration with GDP and population were relatively high,ranged at-4125.55-4509.07 and-1751.43-1556.41,respectively,suggesting possible big impacts of GDP and popula⁃tion on CH_(4) concentration distribution.The R2 of Ordinary Least Squares(OLS)and GWR for CH_(4) concentration with temperature,rainfall,GDP and population were 0.14 and 0.83 respectively,indicating that GWR model outper⁃formed the OLS model in explaining the spatial pattern of CH_(4) concentration.This study revealed the trend and driv⁃ing factors of CH_(4) concentration in Hainan Island,thus provides a method guidance for evaluation of the dynamic CH_(4) concentration in Hainan.