新型垂直探测资料在污染天气分析中的应用

针对2017年1月上旬广州地区出现的一次持续时间长的重污染天气过程，基于地面观测资料、激光雷达、风廓线雷达和微波辐射计数据，从水平和垂直扩散条件2个方面分析了此次污染过程的形成和维持的原因.结果表明：（1）本次污染过程期间，广州地区地面风速基本为小于2m/s的偏北风，在300m高度以下普遍存在平均水平风速低于2.6m/s的小风层；污染前期640m高度内的各层回流指数廓线小于0.6，100m高度小于0.4，污染缓解后回流指数高于0.7.（2）地面PM_2.5浓度与逆温强度的相关系数为0.42，过程平均逆温厚度167m，平均逆温强度为1.08℃/100m；（3）PM_2.5浓度与边界层高度的相关系数为-0.56，清洁时段的平均边界层高度（876m）约为污染时段（620m）的1.4倍，过程最低边界层高度为267m；PM_2.5浓度与边界层通风量的相关系数为-0.61，清洁时段的平均边界层通风量（2538m²/s）约为污染时段（1136m²/s）的2.2倍，使用边界层通风量能更好表征大气污染的程度.

Application of new vertical detection data in the analysis of a heavy pollution weather

A long-lasting air pollution episode was occurred in Guangzhou in early January 2017. Based on the data set of ground observation, Lidar, wind profiler and microwave radiometer, the formation mechanism of this episode was investigated and discussed from two aspects of horizontal and vertical diffusion conditions. The results showed that:(1) During the pollution process, the surface wind speed in Guangzhou area was basically northerly wind and less than 2m/s. A small wind speed layer with an average wind speed less than 2.6m/s was below 300m; The return index profile of each layer within the height of 640m in the pre-pollution period was less than 0.6, and within the 100m height was less than 0.4. (2) The correlation coefficient between surface PM_2.5 mass concentration and inversion temperature was 0.42. The average temperature during the polluted period was 167m, and the average inversion temperature was 1.08℃/100m. (3) The correlation coefficient between PM_2.5 mass concentration and the boundary layer height was -0.56, and the average boundary layer height (876m) during the clean period was approximately 1.4times higher than that of the polluted period (620m). The minimum boundary layer height during the process was 267m. The boundary layer ventilation showed a higher anti-correlation with PM_2.5 concentration (-0.61), and the average boundary layer ventilation volume (2538m²/s) during clean period was 2.2times of the polluted period (1136m²/s), indicating that the boundary layer ventilation can be more useful to characterize the degree of atmospheric pollution.