基于飞机观测的北京地区气溶胶特征

运12飞机和空中国王飞机在2007~2018年的飞机观测资料，分析了北京地区大气气溶胶近12a来的时空变化特征.结果表明，气溶胶数浓度随时间变化显示负增长趋势，而与之相反，气溶胶有效直径表现出正增长趋势.气溶胶垂直廓线的季节变化和气候条件以及边界层的季节变化紧密相关.在边界层高度，季节性气候变化和地面污染物排放强度的影响下，不同季节以及地面天气形势下的气溶胶垂直廓线特征差异也十分明显.气溶胶在边界层内混合均匀，但由于夏季边界层高度较冬季更高，气溶胶能够在更高的高度范围内混合均匀，从而降低了夏季近地面的气溶胶数浓度.此外，气溶胶在550nm的入射波长下散射系数的垂直变化与气溶胶数浓度有较好的一致性，其高值多出现在冬季以及污染物浓度较高的天气条件下.

Aircraft observations of aerosol properties in Beijing

Spatial and temporal characteristic of aerosol in Beijing were analyzed based on 12-year (2007 to 2018) aerosol observation data through aircraft Yun-12 and King Air. It denoted that the aerosol number concentration in early years has a significant negative growth trend, while the effective diameter has a positive trend. The seasonal variation of aerosol vertical profile was closely related to the seasonal meteorology variation and seasonal PBL variation. The vertical profiles of aerosols in each season or under different weather system were affected by PBL height. The aerosols mixed adequately under PBL height. However, the number concentration near ground in summer is lower than that in winter. It was because higher PBL height in summer allows pollutant mixed evenly in a large vertical extent. The vertical variation of scattering coefficients on 550nm was in good agreement with the aerosol number concentration. High values were usually found in polluted days and winter.