Study on atmosphere-ocean interaction through marine biogehic sulfur compounds (dimethylsulfide)

在这笔赠款的支持下，我们执行了以下条款：(1)研制大气DMS自动测量系统；(2)春冬季对北太平洋西部海域海水和大气DMS进行测量；(3)在八丈岛建立观测站，获取大气DMS时间序列。此外，利用等熵轨迹分析法分析了空气包裹的运输路径，并分析了气溶胶的化学成分，检测了海洋空气中Kosa颗粒和DMS的氧化产物。此外，为了获得该地区叶绿素a的分布，还对SeaWiPs卫星的叶绿素a遥感数据进行了分析。利用表层海水和大气中DMS浓度、海表温度和地面风速估算海气DMS通量。分析了海气DMS通量与大气DMS丰度的关系。分析结果表明，该地区春季海水DMS比12月高1.5 ~ 2倍。海水中叶绿素-a的浓度在4月份也高于12月份。这些结果是由于春季海洋产量的增加。另外，在1 ~ 2 d内，从叶绿素a升高的地区输送空气包，气溶胶中MSA和非海盐硫酸盐浓度较高。根据柱模型方法，气溶胶中DMS浓度的升高主要是由于在叶绿素-a升高区域DMS的高排放和高臭氧条件下DMS的快速氧化所致。虽然在这些观测中观察到了科沙事件，但我们没有成功获得足够的数据来显示科沙对海洋生产的任何影响迹象。

With support of this grant-in-aid, we performed following terms ; (1) development of automatic measurement system of atmospheric DMS, (2) measurement of DMS in the seawater and atmosphere over the western North Pacific in spring and winter, (3) setting up an observation station at Hachijojima Island to obtain time series of atmospheric DMS. In addition, analysis of transport pathway of air parcel by an isentropic trajectory Analysis was also performed, and we analyzed aerosol chemical compositions to detect the Kosa particle and oxidation products of DMS in the marine air. Moreover to obtain the distribution of chlorophyll-a in this area, remote sensing chlorophyll-a data derived from SeaWiPs satellite was analyzed.Sea-air DMS flux was estimated with DMS concentrations in the surface seawater and atmosphere, SST and surface wind speed. Relationship between sea-air DMS flux and atmospheric DMS abundance was analyzed.As a result of analysis, seawater DMS in spring was higher than in December by a factor of 1.5〜2 in this area. Chlorophyll-a concentration derived from SeaWiES was also higher in April than in December. These results were due to an increase of marine production in spring. In addition, high MSA and non sea-salt sulfate concentrations in aerosol were observed when air parcel was transported from the elevated chlorophyll-a area within 1〜2 days. According to column model approach, these elevated concentrations in aerosol were mainly due to the, high emission of DMS in the elevated chlorophyll-a area and rapid oxidation of DMS under the high ozone condition. Although Kosa events were observed in these observations, we did not succeed getting enough data to show any sign of impact of Kosa on marine production.