河北省中南部对流层CH4时空分布特征的飞机探测研究

为研究河北省中南部对流层内CH₄时空分布特征，2018年6~7月利用空中国王350飞机搭载高精度CH₄分析仪和相关辅助设备，对河北中南部城市上空（600~5500m）CH₄浓度进行飞机探测.探测期间共飞行4架次，取得7组CH₄浓度垂直廓线数据.结果表明：探测期间CH₄浓度最小值为1884×10^-9，最大值为2038×10^-9，多架次垂直方向上平均浓度为（1915±90）×10^-9.不同探测架次CH₄浓度随高度变化趋势有较好的一致性，随高度增加，均出现先增大后减小，后稳定不变的趋势，且在混合层顶以下（约1000m）存在明显分界线.1000m以下，同高度层CH₄浓度变化较大，不同架次间浓度相差最大值达124×10^-9，同一架次CH₄浓度的垂直梯度变化受大气层结影响明显，位温垂直梯度接近零时，CH₄浓度的垂直梯度变化不明显.1000m以上，CH₄浓度垂直随高度增加呈指数减小，同高度层CH₄浓度变化较小，变化偏差在平均值的5%以内，4000m以上，同高度层CH₄浓度振幅最小，差值<15×10^-9，此时浓度可代表该区域背景大气的平均浓度.石家庄上空同高度层CH₄浓度白天整体大于夜间，随高度降低差值变大，说明石家庄白天CH₄排放源强度大于夜间.

Temporal and spatial distribution of tropospheric CH4 based on aircraft observation in central and southern Hebei Province

Aiming to characterize the spatial and temporal distribution of tropospheric CH₄ in central and southern Hebei province, CH₄ analyzer and associated auxiliary equipment with high precision were mounted on the King-Air 350 and used to acquire the concentration of CH₄ over central and southern Hebei province (600m~5500m) during June and July in 2018. Seven sets of vertical profiles were obtained by four flights for CH₄ concentration during the observation period, which was the first time in our country. Results showed that the maximum and minimum concentration of CH₄ were 2038×10^-9 and 1884×10^-9, respectively, and the average concentration of CH₄ was (1915±90)×10^-9. The vertical profiles of CH₄ concentration of different flights were in good agreement with the increase of altitude. The CH₄ concentration first increased, then decreased, and after that remained almost constant. A clear dividing line was found under the top of the mixed layer (about 1000m). Concentration of CH₄ at the same level varied greatly blow this line, and the maximum difference between different flights was 124×10^-9. The vertical gradient of CH₄ concentration at the same flight was significantly affected by atmospheric junction. The change of vertical gradient of CH₄ concentration was not obvious when the vertical gradient of potential temperature was near zero. Above 1000m, the CH₄ concentration decreased exponentially with the increase of vertical height. At the same height level, a small change of CH₄ concentration was found as the variation deviation was within 5% of the average value. The CH₄ concentration at the same height level had the smallest amplitude and the difference value was less than 15×10^-9. The CH₄ concentration in the same height layer over Shijiazhuang was larger during the daytime than at night, and the difference grew larger with the decrease of height, indicating that the CH₄ emission source intensity in Shijiazhuang was greater in the day than at night.