重霾天气气溶胶辐射效应对近地面臭氧峰值的影响

Impact of Aerosol Radiative Effect on Surface Ozone Peaks during Heavy Haze Events

重度灰霾(或重霾)条件下,大气气溶胶颗粒物显著衰减到达地表的太阳紫外辐射,对臭氧O3光化学过程形成产生重要影响。通过对2013年12月1-10日发生在长三角地区的一次重霾过程进行详尽分析,结合对流层紫外和可见光模型(TUV)及NCAR箱式模型(MM),探讨气溶胶辐射效应对地面臭氧形成和浓度峰值的影响。研究表明,区域输送、稳定边界层累积和二次气溶胶过程等是导致本次重霾发生的主要原因;重霾条件下,臭氧光化学反应明显减弱,臭氧日峰值明显降低,但光化学反应仍缓慢进行;受各种因素如区域输送、边界层累积效应及二次气溶胶等过程影响,臭氧浓度随细颗粒物PM10浓度升高而缓慢上升。TUV和MM模拟结果与观测吻合较好,模拟结果进一步显示,当气溶胶光学厚度AOD由0.8增加到2.0时,到达地表的紫外辐射衰减63%,地面臭氧峰值浓度降低近83%,表明随着灰霾污染加重,近地层臭氧浓度有所降低。

Aerosols attenuate solar ultraviolet radiation, and exert an important impact on surface ozone forma- tion during heavy haze events. This observational analysis was combined with the simulations of TUV （Tropo- sphere Ultraviolet and Visible radiation） model and NCAR MM model （Master Mechanism Box model, MM） to quantify the impact of aerosol radiative effect on surface ozone concentrations during a heavy haze event in Yan- gtze River Delta region of China from 1 to 10 December, 2013. The results indicate that regional transport, trap- ping effect of the stable boundary layer, and the secondary formation processes were responsible for the occur- rence of the heavy haze event. During the heavy haze event, 03 photochemical reactions were significantly slowed down, daily peak values were substantially decreased while photochemical reactions proceeded slowly. 03 concentrations showed a slowly increasing trend with increasing aerosol concentrations due to the combined effect of the regional transport, the stable boundary layer, and the secondary aerosol formation processes. The TUV and MM model simulations were matched well with the observations. The surface-reaching ultraviolet radiation and ozone peak concentration were reduced by 63% and 83%, respectively, when the aerosol optical depth （AOD） was increased from 0.8 to 2.0 which indicated that heavy haze events may alleviate the surface ozone pollution.