长江中下游六省大气甲烷柱浓度时空分布

甲烷(CH4)是造成气候变暖的主要温室气体之一。为了了解长江中下游水稻种植区CH4浓度的分布情况,本次研究基于温室气体观测卫星(greenhouse gases observing satellite,GOSAT)和大气红外探测仪(atmospheric infrared sounder,AIRS)卫星反演的数据产品,对我国长江中下游六省大气CH4柱浓度的时空分布特征进行了研究。研究结果表明,由GOSAT反演的长江中下游六省大气CH4浓度呈逐年增长趋势,其年均浓度由2011年的1817×10^?9增长至2018年的1875×10^?9,高于东三省、华北平原和全国平均水平。区域平均年增长量为8.2×10^?9 a^?1。各省年际增长幅度略有差异,纬度偏低的江西、湖南和浙江三省大气CH4浓度高且增长量偏大,纬度偏高的湖北、安徽和江苏三省大气CH4浓度略低且增长量偏小。长江中下游六省大气CH4呈现较强的季节变化特征,湖北、湖南、江西和浙江峰值出现在9月,安徽、江苏峰值出现在8月。垂直方向上长江中下游六省CH4浓度随气压降低,浓度逐渐减小,呈现出明显的季节变化特征,近地面层GOSAT反演的最高值出现在夏季,最低值出现在春季;高层最高值出现在秋季,最低值出现在春季。AIRS反演的大气CH4浓度空间分布上北高南低,与GOSAT反演结果不一致,可能由于AIRS主要反映了对流层中层大气状况而GOSAT更多的反映了近地面层大气CH4的变化。其垂直方向上呈现高度越高,浓度越低,不同高度上秋季浓度均最高。

Spatial and temporal distribution of atmospheric methane in middle-low reaches of Yangtze River based on satellite observations

Methane(CH4)is one of the most important greenhouse gases that contribute to climate change and global warming.Based on the retrieved CH4 data from the Greenhouse Gases Observing Satellite(GOSAT)and Atmospheric Infrared Sounder(AIRS),the spatial and temporal distribution characteristics of CH4 in the middle-low reaches of the Yangtze River were analyzed in this paper.The results showed that the annual CH4 retrieved from GOSAT increased from 1817×10^?9 in 2011 to 1875×10^?9 in 2018,with a growth rate of 8.2×10^?9 per year.The annual means in the middle-low Reaches of the Yangtze River were higher than those of the northeastern China region,the north China plain,and the whole of China.The growth rate was slightly different among the provinces over the middle-low reaches of the Yangtze River.Higher growth rates of CH4 were observed in Jiangxi,Hunan,and Zhejiang,whereas lower growth rates were observed in Hubei,Anhui,and Jiangsu.The atmospheric CH4 presented relatively strong seasonal variations;its peak appeared in September for Hubei,Hunan,Jiangxi,and Zhejiang,whereas in August for Anhui and Jiangsu.For the vertical profile distribution,the concentration of CH4 decreased with air pressure and presented strong seasonal variations.The CH4 retrieved from GOSAT near-surface layer presented the highest and lowest values in summer and spring,respectively.The spatial distribution of CH4 concentration retrieved by AIRS was higher in the northern area than in the southern area,which was incompatible with that from GOSAT,because CH4 retrieved from GOSAT may better reflect the characteristics of CH4 variations near the ground surface whereas AIRS reflects the CH4 variation in mesosphere condition.