LAUSR

Methane (CH 4 ) is one of the most important greenhouse gases in the atmosphere, making it worthwhile to study its temporal and vertical distributions in source areas, e.g., North China. For this purpose, a ground-based high-resolution Fourier transform infrared spectrometer (FTIR), the Bruker IFS 125HR, along with an in-situ instrument, the Picarro G2301, were deployed in Xianghe County (39.8°N,117.0°E), Hebei Province, China. Data have been recorded since June 2018. For the FTIR measurements, we used two observation modes to retrieve the mole fraction of CH 4 : the Total Carbon Column Observing Network (TCCON) method (retrieval algorithm: GGG2014), and the Network for the Detection of Atmospheric Composition Change (NDACC) method (retrieval algorithm: SFIT4). Combining FTIR with in-situ measurements, we found the temporal and vertical distributions of atmospheric CH 4 within three vertical layers (near the ground, in the troposphere, and in the stratosphere), and throughout the whole atmosphere. Regarding the diurnal variation of CH 4 near the ground, the concentration at night was higher than during the daytime. Regarding the seasonal variation, CH 4 was low in spring and high in summer, for all three vertical layers. In addition, there was a peak of CH 4 in winter near the ground, both in the troposphere and the whole atmosphere. We found that variation of CH 4 in the tropospheric column was close to that of the in-situ measurements near the ground. Furthermore, the variations of CH 4 in the stratospheric column could be influenced by vertical motions, since it was higher in summer and lower in winter. 甲烷(CH 4 )是大气中最重要的温室气体之一,研究其浓度在源排放地区如我国华北的时空变化特征具有科学意义。为此,中国河北省香河县(北纬39.8°,东经117.0°)部署了地基高分辨率傅里叶变换红外光谱仪(FTIR)、Bruker IFS 125HR,以及原位测量仪器Picarro G2301。香河站FTIR观测数据自2018年6月开始正式记录。对于FTIR的测量,我们使用了两种观测模式来获取CH 4 的摩尔分数:总碳柱观测网络(TCCON)方法(反演算法: GGG2014)和大气成分变化检测网络(NDACC)方法(反演算法:SFIT4)。结合FTIR地基遥感和地面采样测量,本文揭示了大气CH 4 在三个垂直层(近地、对流层、平流层)和整个大气中的时间和垂直分布。TCCON观测结果显示的平均值(标准偏差)为1.8839 ppm (0.0129 ppm);NDACC观测结果显示的平均值(标准偏差)为1.9234 ppm (0.0193 ppm)。Picarro仪器测量的CH 4 摩尔分数近地面的平均值(标准偏差)为2.2049 ppm (0.0945 ppm)。近地面的CH 4 摩尔分数比高13%左右,这主要是由于香河附近地表有很强的CH 4 排放。平流层CH 4 摩尔分数远低于对流层CH 4 摩尔分数。在地面附近、对流层和平流层也发现了类似的CH 4 季节变化。平流层CH 4 摩尔分数随季节变化,这可能与平流层-对流层交换的影响有关。