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，在秋末至冬初，关东、诺比平原等地区的二氧化氮浓度非常高，因此大气环境趋于恶化。部分原因可能是由于本季特有的气象条件，即在冬季季候风开始前，在周期性经过的高压系统下，天气尺度风一般较弱，此外，由于白天不利的热条件，例如每天只有两小时的地面温度只比海面高1至2度，局地风（例如海风）永远不会发展得很强。在这项研究中，为了阐明空气污染运输的特征，我们对Nohbi平原和伊势湾地区空气污染物的运输/化学/沉积进行了三维模拟。模拟的日子是1992年11月24日和25日，当时利用飞机、降雨探空仪、多普勒雷达和许多地面监测设备进行了广泛的实地观测。结果表明：(1)对诺比平原进行了污染源清查。基于单位生产排放强度、燃料消耗等指标以及工业生产、汽车保有量等空间分布特征，估算非甲烷挥发性有机烃（VOCs）排放分布。此外，利用一维扩散/化学模型对这些排放源进行了测试和校正，使计算的VOCs浓度垂直分布与观测值一致。使用这一程序，重新评估了甲苯和二甲苯等芳香烃的排放量，并将其减少到初始估计的九分之一。(2)利用这些排放清单，对NO、NO_2、HNO_3、SO_2、SO_4^=、O_3、H_2O_2、VOCs等主要化学物质进行了为期2天的三维迁移/化学/沉积模拟。模拟结果表明：(1)地表NO_2浓度计算值与实测值吻合较好；(2)300和600 m高空NO_2浓度分布的重要特征得到了较好的再现，即白天在赤田半岛和三川海湾地区出现高浓度区，表明赤田和三川上游的诺比平原有较强的混合活动。(3)对所得结果的详细分析，可用于研究该地区有效的排放控制。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