APHH: Fluorescence Assay Gas Expansion measurements of OH, HO2 and RO2 made at the IAP-Beijing site during the winter and summer campaigns.

This dataset contains Fluorescence Assay Gas Expansion measurements of OH, HO2 and RO2 made at the Institute of Atmospheric Physics land station (IAP), Beijing site during the winter and summer APHH-Beijing campaigns for the Atmospheric Pollution & Human Health in a Chinese Megacity (APHH) programme.

The measurements were taken using the FAGE (Fluorescence Assay by Gas Expansion) technique which is a LIF (laser induced fluorescence) that measures on-resonance fluorescence at 308 nm. HO2 and RO2 are converted to OH via reaction with NO and NO + CO respectively.

The instrument is calibrated by photolysis of known concentration of water vapour at 185 nm to generate know concentrations of OH and HO2, same method used for HO2 but NO is injected into the flow to convert HO2 to OH. RO2 is calibrated by photolysing water vapur at 185 nm to generate OH but CH4 is added to convert OH to CH3O2, then CH3O2 is converted to OH using CO and NO. The calibration was preform every three days on campaign, and from this we can convert counts measured into concentration. The units for OH, HO2 and RO2 and there associated errors is molecules cm-3. The data has been filtered for instabilities in data collection including unstable pressure, unstable online, low laser power and not going online correctly. The data has been flagged for when the values were below limit of detection.

本数据集收录了北京大气物理研究所（IAP）在北京站冬季和夏季APHH-Beijing（大气污染与人类健康在中国大都市）项目期间，利用荧光气态膨胀法（FAGE）对羟基（OH）、过氧氢（HO2）和过氧自由基（RO2）进行的荧光分析法（LIF）测量数据。测量过程中，通过308 nm波长的共振荧光进行检测。HO2和RO2分别通过与NO和NO+CO的反应转化为OH。仪器校准采用185 nm波长的已知浓度水蒸气的光解，以生成已知浓度的OH和HO2，此方法与HO2的校准方法相同，但需向流动系统中注入NO以将HO2转化为OH。RO2的校准通过185 nm波长的水蒸气光解生成OH，随后添加甲烷（CH4）将OH转化为甲酸酯（CH3O2），再利用CO和NO将CH3O2转化为OH。校准操作在项目期间每三天进行一次，从而将测得的计数转换为浓度。OH、HO2和RO2及其相关误差的单位为分子每立方厘米。数据已过滤，以排除数据收集过程中的不稳定性，包括不稳定的压力、不稳定在线状态、低激光功率以及未能正确上线等情况。对于低于检测限的值，数据已被标记。