上海北侧区域海陆风对污染物扩散的影响

利用数值模拟方法研究了上海北侧区域海陆风对污染物扩散的影响,包括上海城郊-崇明岛-启东市区及这三区域之间的北支水道与南支水道.使用当量法表征太阳辐射和长波辐射引起的近地面空气热量变化,模拟结果与ECMWF再分析数据呈现较好的一致性.结果表明,在海风阶段,宽海(南支水道)、窄海(北支水道)区域都能形成海风,前者较后者发生...

Effects of land and sea breeze on pollutant diffusion in northern Shanghai

The north side of Shanghai has complex sea and land terrain and is a heavily polluted area. Numerical simulation method is employed to study the influences of sea and land breeze on pollutant diffusion in this area, including the zones of Shanghai suburb-Chongming Island-Qidong and the north branch channel and the south branch channel between the three areas. The equivalent method is adopted to characterize the near ground air heat change caused by solar radiation and long wave radiation. The simulations are in good agreement with ECMWF reanalysis data. The results show that the sea breeze forms in both the wide sea (South Branch waterway) and the narrow sea (North Branch waterway) regions during the sea breeze period, and the former one occurs about one hour earlier than the latter. During the land breeze period, only the two sides of the wide sea have obvious land breeze, among which land winds from Shanghai can cross the wide sea region to Chongming. The effect of the sea breeze on the diffusion and dilution of air pollutants depends on the temporal and spatial relationship between the sea breeze front and the pollutants. When the pollutants are discharged and accumulated before the sea breeze front, they will be drawn into the reflux zone by the front to the high altitude, and the sea breeze blows with a cleaning effect. Conversely, when the pollutants are emitted and dispersed behind the sea breeze front, the sea breeze will push the pollutants into the inland area and cause a lasting pollution process. The land wind blows the pollutants discharged at midnight away from the Shanghai land area, but the pollutants will enter the Chongming area with the land wind, and deteriorate the local air quality. The pollutants emitted in the early morning will only be blown to the offshore area by the land wind, and will pollute the land area again with the subsequent sea wind.