State Key Joint Laboratory of Environmental Simulation and Pollution Control, Department of Environmental Science, Peking University, Beijing 100871, China.
State Key Joint Laboratory of Environmental Simulation and Pollution Control, Department of Environmental Science, Peking University, Beijing 100871, China.
Sci Total Environ. 2019 Jan 10;647:1011-1020. doi: 10.1016/j.scitotenv.2018.08.088. Epub 2018 Aug 7.
Temperature inversion tends to inhibit the transfer of momentum, heat and moisture in the atmospheric boundary layer, which is often accompanied by severe air pollution. Recently, severe haze pollution has frequently occurred in North China. In this study, the characteristics of temperature inversion on severe polluted days (SPDs) in Beijing were investigated by using radiosonde data with standard pressure levels from 2011 to 2016. Both surface-based inversion (SI) and elevated inversion (EI) were analyzed. 93% of the SPDs were accompanied by temperature inversion, most of which occurred in wintertime. Annual frequency of SI (F) and EI (F) showed slight fluctuations with mean value of 0.18 and 0.67, respectively. Overall, the annual SI was stronger and deeper than annual EI. Seasonally, the SI was most frequent (0.39) in autumn, in contrast to EI that occurred most frequently (0.95) in summer. Both SI and EI were weakest in summer and strongest in winter. Average monthly SI strength was about 0.38 °C in summer and 2.40 °C in winter, average monthly EI strength was about 0.64 °C in summer and 2.20 °C in winter. The average monthly SI and EI were deepest in winter and shallowest in summer. SI depth were 778 m and 221 m in winter and summer, EI were 630 m and 336 m in winter and summer. The substantially strong liner relationship was found between seasonal inversion strength and PM concentration, and the inversion strength was found to be better compared with the inversion depth at predicting the PM concentration during SPDs. Obvious lower air outflow and turbulent kinetic energy were found in SPDs compared to non-SPDs, which indicated weaker turbulence in SPDs. Future efforts should focus on accurate model simulations of temperature inversions in SPDs.
逆温现象往往会抑制大气边界层中动量、热量和水汽的传递，这通常伴随着严重的空气污染。近年来，华北地区频繁发生严重雾霾污染事件。本研究利用 2011 年至 2016 年标准气压层的探空数据，探讨了北京严重污染日（SPD）逆温特征。分析了地面逆温（SI）和抬升逆温（EI）。93%的 SPD 伴随着逆温现象，其中大部分发生在冬季。SI（F）和 EI（F）的年频率都有轻微波动，平均值分别为 0.18 和 0.67。总体而言，年 SI 比年 EI 更强、更深。季节上，秋季 SI 最为频繁（0.39），而 EI 则在夏季最为频繁（0.95）。夏季 SI 和 EI 都最弱，冬季最强。夏季 SI 平均每月强度约为 0.38°C，冬季约为 2.40°C；夏季 EI 平均每月强度约为 0.64°C，冬季约为 2.20°C。冬季 SI 和 EI 的平均每月强度最大，夏季最小。冬季 SI 深度为 778m，夏季为 221m；冬季 EI 深度为 630m，夏季为 336m。在 SPD 期间，季节逆温强度与 PM 浓度之间存在明显的线性关系，逆温强度在预测 PM 浓度方面比逆温深度更好。与非 SPD 相比，SPD 中明显发现较低的低空流出和湍流动能，这表明 SPD 中湍流动能较弱。未来的研究应集中于准确模拟 SPD 中的逆温现象。
