Characteristics of transport/transformation/deposition of air pollutants and the material balance in Nohbi plain and Ise bay area, Japan, a semi-closed airshed

众所周知，在秋末到初冬期间，关东、诺比平原等地的二氧化氮浓度很高，大气环境趋于恶化。这可能部分是由于这个季节特有的气象条件，在冬季季风来临之前，天气尺度风在周期性经过的高压系统下一般较弱，此外，由于白天不利的热力条件，海风等局域风从未发展得很强，即陆地表面的温度只比海上温度高1-2度，一天只有2个小时。在这项研究中，我们对诺比平原和伊势湾地区空气污染物的输送/化学/沉积进行了三维模拟，以阐明大气污染输送的特征。模拟的日子是1992年11月24日和25日，当时使用飞机、探空仪、多普勒声雷达和许多地面监测st…进行了广泛的现场观测。取得的研究成果如下：(1)对诺壁平原进行了污染源清查。根据单位产量排放强度、油耗等指标和工业生产、汽车保有量等的空间分布，估算了非甲烷VOCs的排放分布，并利用一维扩散/化学模型对这些排放源进行了检验和修正，使计算的VOCs浓度垂直分布与观测值相吻合。利用该程序对甲苯和二甲苯等芳香烃的排放量进行了重新评估，并将其削减到初始估计值的九分之一。(2)利用这些排放装置，对大多数重要的化学物质进行了两天的三维输送/化学/沉积模拟，包括NO、NO_2、HNO_3、SO_2、SO_4^=、O_3、H_2O_2、VOCs等。模拟结果表明：(1)地表NO_2浓度的计算值与观测值吻合良好，(2)模拟结果很好地再现了300米和600米高度上观测到的浓度分布的重要特征，白天赤田半岛和宫川湾地区出现高浓度区，表明赤田和宫川上游的诺比平原有较强的混合活动。(3)对所得结果进行了详细的分析，为研究该地区的有效排放控制奠定了基础。较少

It is widely known that during late autumn to early winter concerntration of nitrogen dioxide becomes very high over Kanto, Nohbi Plains etc., and thus atmospheric environment tends to be worse. This may be partly due to the characteristic meteorological condition in this season, when just before the beginning of winter monsoon synoptic scale wind is generally weak under periodically-passing high pressure systems, and in addition lacal wind such as sea breeze never develops strong because of adverse thermal condition during daytime, i. e. temperatures over land surface exceed those over sea by only 1 to 2 deg for only 2 hours a day. In this study to elucidate characteristics of air pollution transport we have performed 3D simulation for the transport/chemistry/deposition of air pollutants over Nohbi plain and Ise bay area. The simulated days were 24 and 25 November, 1992, when extensive field observations using air plane, rawin-sondes, Doppler-sodar, and many ground-based monitoring st … More ations were conducted.Obtained results are as follows :(1)Emission source inventories were investigated for Nohbi plain. Non-methane VOCs (Volatile Organic hydroCarbons) emission distributions were estimated on the basis of emission strength per unit production, fuel consumption, etc. and spatial distributions of industrial production, number of cars etc. Furthermore, these emission sources were tested and corrected by using 1D diffusion/chemistry model so that calculated vertical profiles of VOCs concentrations agree with those observed. Using this procedure, emissions of aromatic hydrocarbons such as toluene and xylene were reevaluated and cut to one-ninth of the initial estimation.(2)With these emission enventories, two days 3D transport/chemistry/deposition simulation was performed for most of important chemical species which include NO,NO_2, HNO_3, SO_2, SO_4^=, O_3, H_2O_2, VOCs etc. The simulation resultsshowed : (i) good agreement between calculated and observed NO_2 concentrations at surface level, (ii) important features of observed concentration distributions at 300 and 600 m high were well reproduced by the simulation, i. e. high concentration zones appear over Chita peninsula and Mikawa bay area during daytime, indicating strong mixing activity over Nohbi plain which is in upstream area of Chita and Mikawa.(3)Detailed analysis of the obtained results is left for investigation of effecte emission control in this region. Less