应用常规观测资料、NCEP 1°×1°再分析资料,分析2013年山东分别出现雾和霾的两次严重污染过程,结果表明:(1)大气静稳状态时,500 h Pa为脊前西-西北气流,850 h Pa为暖脊,有弱暖平流,地面气压场较弱,易出现逆温、混合层高...应用常规观测资料、NCEP 1°×1°再分析资料,分析2013年山东分别出现雾和霾的两次严重污染过程,结果表明:(1)大气静稳状态时,500 h Pa为脊前西-西北气流,850 h Pa为暖脊,有弱暖平流,地面气压场较弱,易出现逆温、混合层高度低、风速小,导致大气水平和垂直扩散能力差。850 h Pa弱上升和700 h Pa弱下沉,造成高空干洁大气和地面"脏"空气对峙的局面,垂直交换停滞是雾-霾和污染持续的根本原因。(2)强冷空气驱散雾-霾的过程,正是打破了空气垂直交换停滞的状态,使得高空清洁大气能够下沉到地面。空气质量的根本改善由垂直交换完成。(3)弱冷空气伴随的弱下沉运动和锋面附近整层上升运动能够减轻污染。(4)冷锋过后剧烈下降的地面露点温度即是高空干洁大气到达地面的标志。展开更多
Beijing experienced serious haze pollution from 24 November 2015 to 2 December 2015.To investigate the planetary boundary layer characteristics,especially turbulence characteristics,the authors analyzed the wind,tempe...Beijing experienced serious haze pollution from 24 November 2015 to 2 December 2015.To investigate the planetary boundary layer characteristics,especially turbulence characteristics,the authors analyzed the wind,temperature,humidity,and turbulence characteristics during heavily polluted weather by using the observational data of the 325-m meteorological tower in Beijing.The results indicate that the pollution was mainly caused by the easterly and southerly winds.There were negative correlations between wind speed,turbulent kinetic energy,friction velocity,and the PM2.5 concentration.During clean days,the wind speed greatly enhanced with height;however,during the period of heavy pollution,the wind speed changed a little from the nearsurface layer to the top of the tower.In contrast,the spatial variability of TKE from the nearsurface layer to the upper layer was not so obvious.The heavy haze pollution in this study was often characterized by the emergence of an inversion layer;therefore,the diurnal variation of the boundary layer temperature was very small.At the time of serious pollution,the relative humidity was near 100%.The diurnal variations of sensible heat flux and water vapor flux were significantly reduced when severe pollution occurred.展开更多
Residents of China’s capital deal with air pollution The Chinese Government has set a stringent standard for the quality of the masks being sold to combat the effects of pollution in Beijing on January 18.The news co...Residents of China’s capital deal with air pollution The Chinese Government has set a stringent standard for the quality of the masks being sold to combat the effects of pollution in Beijing on January 18.The news comes against the backdrop of the unprecedentedamount of heavy haze that had shrouded the Chinese capital for more than 20 days.展开更多
文摘应用常规观测资料、NCEP 1°×1°再分析资料,分析2013年山东分别出现雾和霾的两次严重污染过程,结果表明:(1)大气静稳状态时,500 h Pa为脊前西-西北气流,850 h Pa为暖脊,有弱暖平流,地面气压场较弱,易出现逆温、混合层高度低、风速小,导致大气水平和垂直扩散能力差。850 h Pa弱上升和700 h Pa弱下沉,造成高空干洁大气和地面"脏"空气对峙的局面,垂直交换停滞是雾-霾和污染持续的根本原因。(2)强冷空气驱散雾-霾的过程,正是打破了空气垂直交换停滞的状态,使得高空清洁大气能够下沉到地面。空气质量的根本改善由垂直交换完成。(3)弱冷空气伴随的弱下沉运动和锋面附近整层上升运动能够减轻污染。(4)冷锋过后剧烈下降的地面露点温度即是高空干洁大气到达地面的标志。
基金Supported by the National Key Research and Development Program of China [grant numbers 2017YFC0209600 and 2016YFC0208802]
文摘Beijing experienced serious haze pollution from 24 November 2015 to 2 December 2015.To investigate the planetary boundary layer characteristics,especially turbulence characteristics,the authors analyzed the wind,temperature,humidity,and turbulence characteristics during heavily polluted weather by using the observational data of the 325-m meteorological tower in Beijing.The results indicate that the pollution was mainly caused by the easterly and southerly winds.There were negative correlations between wind speed,turbulent kinetic energy,friction velocity,and the PM2.5 concentration.During clean days,the wind speed greatly enhanced with height;however,during the period of heavy pollution,the wind speed changed a little from the nearsurface layer to the top of the tower.In contrast,the spatial variability of TKE from the nearsurface layer to the upper layer was not so obvious.The heavy haze pollution in this study was often characterized by the emergence of an inversion layer;therefore,the diurnal variation of the boundary layer temperature was very small.At the time of serious pollution,the relative humidity was near 100%.The diurnal variations of sensible heat flux and water vapor flux were significantly reduced when severe pollution occurred.
文摘Residents of China’s capital deal with air pollution The Chinese Government has set a stringent standard for the quality of the masks being sold to combat the effects of pollution in Beijing on January 18.The news comes against the backdrop of the unprecedentedamount of heavy haze that had shrouded the Chinese capital for more than 20 days.
