基于飞机观测资料的石家庄秋季对流层CH4垂直分布特征

为研究石家庄秋季对流层内CH₄垂直分布特征，2018年9月使用“空中国王350”飞机搭载Picarro温室气体在线观测仪和气象要素观测设备，对石家庄上空（600—5500 m）CH₄浓度进行探测。探测期间共飞行7架次，取得7条CH₄浓度廓线数据。结果表明: 石家庄上空近地面层（1000 m以下）CH₄平均浓度与同时间段区域背景站上甸子站CH₄浓度呈显著正相关（r=0.81，P < 0.03）。探测到的CH₄浓度最小值为1898×10^-9摩尔分数，最大值为2219×10^-9摩尔分数，平均浓度为1981×10^-9摩尔分数。观测得到的7条廓线均有较好的一致性，2000 m以上，浓度均随高度呈先增大后减小的趋势。利用后向轨迹模式（HYSPLIT）对探测时段内石家庄上空不同高度层主要气流传输路径进行统计分析表明，600 m高度输送路径较短，CH₄浓度受本地排放影响较大; 3000 m受输送作用影响较大，偏西和西南路径可能将较高CH₄浓度气团输送至石家庄上空; 5000 m气团传输对CH₄浓度影响较小，浓度相对较稳定，对传输路径的变化不敏感。

Characteristics of the vertical distribution of CH4 in the troposphere in autumn in Shijiazhuang based on aircraft observations

To study the vertical distribution characteristics of CH₄ within the troposphere in autumn in Shijiazhuang, the King Air 350 aircraft with Picarro greenhouse gas online observer and meteorological observation equipment were used to detect CH₄ concentrations over Shijiazhuang (600-5500 m) in September, 2018.A total of seven flights were made during the survey period, and seven CH₄ concentration profiles were obtained.The results show that the average concentration of CH₄ near the surface layer (below 1000 m) over Shijiazhuang is positively correlated with that at Shangdianzi station during the same period (r=0.81, P < 0.03).During the detection period, the minimum CH₄ concentration of the seven profiles is 1898×10^-9, the maximum is 2219×10^-9, and the average concentration is 1981×10^-9.The seven profiles obtained by observations are all consistent.The concentration above 2000 m increases first and then decreases with height.The backward trajectory mode-HYSPLIT model is used to analyze the main air transport paths at different altitudes over Shijiazhuang during the detection period.The transport pathways at 600 m are shorter, and the concentration of CH₄ is greatly influenced by local emissions.At 3000 m, the air mass with higher CH₄ concentration may be transported over Shijiazhuang by the west-southwest path.The air mass transport at 5000 m has little influence on CH₄ concentration.The CH₄ concentration at this level is relatively stable and insensitive to the change of transport path.