Observational study of OH, HO2 and precursor species in maritime atmosphere

我们研制了一种用于测量大气中OH寿命的仪器，以获得有关氧化能力的信息。采用激光闪光光解和激光诱导荧光技术测量了大气OH寿命。利用Nd：YAG四倍频激光作为泵浦光，在臭氧光解过程中产生人工OH自由基。利用时间分辨激光诱导荧光技术，利用探测激光跟踪OH自由基浓度变化。对仪器进行了表征，发现了OH自由基在大气中的未知反应伙伴，并对在西太平洋海域进行的海上考察所获得的采样数据进行了分析。除VOC外，我们还分析了含氧VOC（OVOC）。OVOCs尤其是乙醛的氧化贡献率约为23%，因此OVOCs在海洋大气氧化中的作用被认为是重要的。DMS的日变化可以用OH自由基的调节来解释。人为挥发性有机化合物的浓度控制为与源区距离的函数，OVOCs在海洋中的浓度很低，这意味着OVOCs在海洋大气中的光化学产生。我们分析了在冲绳海多角获得的数据集，这里是检测纯海洋大气或来自亚洲的远距离传输污染空气的理想地点之一大陆我们申请使用后向轨迹分析来可视化气团起源。我们将到达该站的气团来源分为4组，如中国，韩国，日本和海洋。最常见的空气来自中国南部在深秋和冬季。接下来是韩国和日本。海洋性的空气尤其在夏季盛行。春季和秋季被认为是气团来源交换的过渡期。从冬季到春末，中国大陆臭氧的季节变化趋势明显为正。

We developed the instrument for the measurement of OH lifetime in the atmosphere in order to get information about oxidation capacity. Laser flash photolysis and laser induced fluorescence technique were employed to measure atmospheric OH lifetime. The forth harmonic of Nd:YAG laser was used to prepare artificial OH radical in the photolysis of ozone as a pump laser. Time resolved LIF was applied to trace concentration change of the OH radicals using probe laser. We characterized our instrument and found unknown reaction partner of OH radical in the atmosphere.We analyzed sampled data obtained by the ship cruise carried out at the western part of Pacific ocean. In addition to VOCs we analyzed oxygenated VOCs (OVOCs). OVOCs were highlited to play a role in the maritime atmospheric oxidation because contributions of oxidation of OVOCs, especially acetoaldehydes are estimated around 23%. Diurnal cycle of DMS was explained by the modulation of OH radicals. Concentration of anthropogenic VOCs are controlled as a function of the distance from source area, however OVOCs remain their concentration even at the middle of the ocean which implies the photochemical production of OVOCs in the oceanic atmosphere.We analyzed data set obtained at Cape Hedo Okinawa island where is one of ideal place for detecting air samples such as either pure oceanic atmosphere or long range transported polluted air from Asian continent. We applied to use backward trajectory analysis to visualize air mass origin. We classified air mass origin reaching the station into 4 groups such as China, Korea, Japan, and Ocean. Most frequently air comes from the southern part of China during late fall and winter. Next are from Korea and Japan. Oceanic air prevailed especially on summer. Spring and fall are recognized as transition period for exchanging of air mass origin. Seasonal trend of ozone from Chinese continent is obviously positive from winter to late spring.