中文摘要：

分析了CRDS法测定CH4浓度与水汽含量间的关系,并建立了水汽含量在0.50%—2.45%（体积比,以V/V表示,下同）范围内的有效校正方法.采用CRDS法对水汽含量为0.93%的CH4标气进行多次测量,测量值经校正后与理论值的偏差均小于2.0×10-9（体积比,以V/V表示,下同）,最大偏差1.8×10-9,优于大气本底CH4观测质控标准.校正瓦里关站CRDS系统试运行期间的CH4实测数据（水汽含量为0.50%—2.45%）,与该站气相色谱-氢火焰离子化检测器系统（GC-FID系统,下同）同期测量结果相比,38.48%的数据偏差小于2.0×10-9,说明在系统未配备超低温冷阱除水单元之前,本文研究的校正方法适用于观测数据的校正.

英文摘要：

The Cavity Ring-Down Spectroscopy （CRDS） system has been introduced to measure methane （CH4 ） in the background area. It has been proved that the concentration of CH4 measured by CRDS system was affected by the water vapor distinctly. In order to ensure the reliability of the observed data. The relationship between CH4 and water vapor measured by CRDS system was studied, and an effective correction method for water vapor in the rang of 0. 50%--2.45% （V/V） was established. The method validation showed that the deviations between the correction results and the theoretical value were less than 1.8 ~ 10 -9, which was better than the goal of background atmospheric measurement. Finally, the correction method was used to deal with the CH4 data measured by the CRDS system at Waliguan Station （the water vapor ranged from 0.50% to 2. 45%, V/V）, and compared with the data measured by GC-FID system at the same time. The correction results showed the less deviation than 2.0 ~ 10-9 for 38.48% measured data.