中国XCO2时空分布与影响因素分析

结合OCO-2卫星观测的CO₂柱浓度混合比数据（XCO₂），研究2014~2018年间中国CO₂的时空分布及季节波动，并对影响XCO₂分布的因素进行相关分析.结果表明，XCO₂在研究时段内以2.56×10^-6/a的速度增长；年均季节波动为3.26×10^-6.在2014~2018年间观测到中国植被呈显著的上升趋势，尤其是在西北和东南沿海地区.植被活动是影响XCO₂季节变化的重要因素，在东北地区观测到XCO₂与归一化植被指数（NDVI）呈显著负相关（r=-0.58）.人为排放是影响XCO₂空间分布的重要因素，二者具有空间分布一致性（r=0.397，P<0.05），尤其是在人为排放较强（>10³t）的区域，人为排放量与XCO₂的相关性更强（r=0.714）.最后分区域统计人口、电力消耗和路网密度等社会经济因素对XCO₂的影响，相关性分析的结果分别为0.78，0.69和0.34，证明中国XCO₂分布与社会经济因素的相关性.

Spatial and temporal variations of XCO2 in China and its influencing factors analysis

We comprehensively analysed the spatio-temporal changes and seasonal patterns in the CO₂ concentrations in China from 2014 to 2018 using OCO-2XCO₂ data. Moreover, influencing factors of XCO₂ were evaluated. Regarding the temporal distribution, the CO₂ concentration in China increased at an average rate of 2.56×10^-6/a, with significant annual seasonal variations of 6.78×10^-6. A significant increasement of vegetations was observed in China between 2014 and 2018, especially in the northwest and southeast coastal, which was mainly related to the returning farmland to forest program. Seasonal variations of XCO₂ in China were generally controlled by vegetation activities, and a significant negative correlation between XCO₂ and NDVI was observed, especially in northeast China (r=-0.58). Anthropogenic emissions were identified as the dominant contributor of XCO₂ distributions, and the spatial correlation were quantified (r=0.397, P<0.05), especially for those regions with larger emissions (emissions>10³t,r=0.714). Finally, the socio-economic factors such as population, electricity consumption and road network density were found to affect XCO₂ by region, and the results of the correlation analysis were 0.78, 0.69 and 0.34, respectively.