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

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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.