Studies on strategic control of photochemical oxidants in mega-cities

我们研制了用于精确测量臭氧前体物（NOx、HNO_3、PAN、VOCs和CO）、OH和HO_2自由基以及光化通量的仪器。在2003-2005年的不同季节，使用这些仪器开展了测量活动。特别是在2004年7月至8月，在两个地点进行了密集测量;一个在东京，另一个在琦玉的木西市。同时，使用Aerodyne气溶胶质谱仪测量了每个尺寸范围的气溶胶化学成分。离开东京的气团在下午到达琦玉，为研究运输过程中的化学过程提供了理想的条件。8月中旬，在稳定高压系统的影响下，海陆风发展。在这些条件下，O_3在东京北方1300 LT左右达到高水平。这O_3水平进一步增加，而空气质量被输送到琦玉海风。在输运过程中，NOx的氧化和O_3的生成同时发生。在高O_3条件下，有机气溶胶的形成是有效的。3D-CTM是考虑到化学和运输过程而开发的。该模式较好地模拟了关东地区的O_3和前体物。利用该模型计算表明，O_3在中午前后的几个小时内产生。

We have developed instruments for precise measurements of ozone precursors (NOx,HNO_3,PAN,VOCs, and CO), OH and HO_2 radicals, and actinic flux. Measurement campaigns using these instruments were conducted in different seasons in 2003-2005. Especially, in July-August 2004, intensive measurements were made at two sites ; one in Tokyo and the other in Kisai-city in Saitama. At the same time, aerosol chemical composition at each size range was measured using an Aerodyne Aerosol Mass Spectrometer. Air mass which left Tokyo reaches Saitama in the afternoon, providing ideal conditions for investigationg chemical processes during transport. In mid-August, sea-land breeze developed under the influence of stable high pressure system. Under these conditions, O_3 reached high levels in northern Tokyo around 1300 LT. This O_3 levels further increased while the air mass was transported to Saitama by sea breeze. During the transport, NOx oxidation and O_3 formation occurred simultaneously. Organic aerosol was observed to be formed efficiently under high O_3 conditions. 3D-CTM has been developed taking into account the chemical and transport processes. This model well reproduces O_3 and precursors in Kanto area. By this model, it is indicated that O_3 was produced within a few hours near noon.