Measurements of properties of marine aerosols on research vessel

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It is difficult to measure the size distribution of atmospheric aerosol in laboratory because humidity of sample is different between outdoor and indoor. The artifact of sample on the filter is also a sever problem in chemical analysis.To solve the problem of the humidity effects on size measuring two systems were using to measure size distribution in dry and wet conditions (Miura). An intermixture structure of individual particles was examined by a water dialysis (Niimura and Miura). To solve the problem of the artifact sulfate and nitrate concentration were measured with real time analyzer continuously (Uematsu). Radon concentration was measured continuously as a tracer of continental air mass (Kojima).Main results are as follows :1. Humidity properties of marine submicron particles were investigated with the TDMA. Growth fraction of marine aerosol was almost 100 % and growth factor was a little smaller than that of NaCl. But the deliquescence humidity of these aerosols agreed with that of NaCl. Growth factor and growth fraction of aerosols decrease as they are affected by continental air mass. These properties are dependent on aerosol sources and weather condition.2. The mixing properties of individual particles were studied by using a combination of TEM, EDX and a water dialysis. For the particles collected over the North Pacific, the elemental analysis showed that most of particles contained water-soluble material. A number fraction of "Mixed" particles in all particles ranged from 40 to 80%. For particles collected over the East China Sea, the elemental analysis showed that a number fraction of "Mixed" particles of Kosa event was twice or three times that of non-Kosa event. These results imply that marine atmosphere is influence by soot or Kosa particles mixed with water-soluble materials, when the air mass is transported from the Continent.