基于地面微脉冲激光雷达的上海冬季霾强度及高度分析

利用2009—2013年冬季地面气象观测数据筛选出非霾和不同强度霾的影响时次,采用能见度与消光系数的定量关系和冬季波长系数对微霾冲激光雷达反演修正得到的气溶胶消光系数,分析了上海地区气溶胶在垂直高度上的集中范围,当地面出现轻微霾、轻度霾、中度霾、重度霾时气溶胶分别主要集中于近地面0.81、0.49、0.41、0.40 km以下,非霾时气溶胶主要集中在近地面1.35 km以下;在此基础上,根据判别不同强度霾的能见度标准和能见度与消光系数的定量关系,将能见度换算为消光系数,再对微脉冲激光雷达反演消光系数进行修正,从而判断高空霾的强度及所处的高度;另外还探讨了云对产生重度霾的影响、降水与中度霾和重度霾的关系以及颗粒物质量浓度与不同强度霾的关系,发现48.53%的重度霾是受云影响而产生的,37.11%中度霾发生前后伴有降水现象,51.14%的重度霾发生前后伴有降水现象,非霾、轻微霾,轻度霾、中度霾、重度霾期间的颗粒物浓度和细颗粒物占的比例依次增大.

Analysis of intensity and altitude of haze at Shanghai in winter based on surface micro-pulse lidar

Using the meteorological data from 2009 to 2013, we selected the affecting hours of non-haze and haze with different degrees in Shanghai in winter. The aerosol extinction coefficient was retrieved from micro pulse lidar and corrected with wavelength coefficient in winter and the quantitative relationship between visibility and extinction coefficient. The altitude ranges of aerosols were then analyzed. Aerosols were mainly concentrated below the altitudes of 0.81, 0.49, 0.41 and 0.40 km when slight, mild, moderate and severe hazes occurred, respectively, and were predominantly under 1.35 km during non-haze condition. Visibility was further transferred into extinction coefficient with the visibility standards of hazes in different intensities and quantitative relationship between visibility and extinction coefficient. The micro pulse lidar extinction coefficient was then corrected to determine the intensity and altitude of haze. In addition, the impact of clouds on severe haze, relationship among precipitation, moderate haze and severe haze, and relationship between mass concentrations of particulate matter and hazes in different intensities were discussed. The results showed that 48.53% of moderate haze was affected by clouds. The percentage of rainfall occurrence around moderate haze was 37.11% and that around severe haze was 51.14%. The concentration of particulate matter and the proportion of fine particulate matter increased along with the increase of haze intensity.