Meteorological conditions,particularly the vertical wind field structure,have a direct influence on the PM2.5 concentrations over the Pearl River Delta(PRD).In October 2012,an exceptional air pollution event occurred ...Meteorological conditions,particularly the vertical wind field structure,have a direct influence on the PM2.5 concentrations over the Pearl River Delta(PRD).In October 2012,an exceptional air pollution event occurred in the PRD,and a high concentration of PM2.5 was registered at some stations.During days with PM2.5 air pollution,the wind speed was less than 3 m s-1 at the surface,and the vertical wind field featured a weak wind layer(WWL)with a thickness of approximately 1000 m.The mean atmospheric boundary layer height was less than 500 m during pollution days,but it was greater than 1400 m during non-pollution days.A strong negative correlation was detected between the PM2.5 concentration and the ventilation index(VI).The VI was less than 2000 m2 s-1 during PM2.5 air pollution days.Because of the weak wind,sea-land breezes occurred frequently,the recirculation factor(RF)values were small at a height of 800 m during pollution days,and the zones with the lowest RF values always occurred between the heights of 300 and 600 m.The RF values during PM2.5 pollution days were approximately 0.4 to 0.6 below a height of 800 m,reducing the transportation capacity of the wind field to only 40%to 60%.The RF and wind profile characteristics indicated that sealand breezes were highly important in the accumulation of PM2.5 air pollution in the PRD.The sea breezes may transport pollutants back inland and may result in the peak PM2.5 concentrations at night.展开更多
General features of 3-dimensional mesoscale wind and temperature structure over Shandong Peninsula are described in this paper.Results are achieved by numerical simulation with the 3- dimensional non-hydrostatic mesos...General features of 3-dimensional mesoscale wind and temperature structure over Shandong Peninsula are described in this paper.Results are achieved by numerical simulation with the 3- dimensional non-hydrostatic mesoscale model METRAS.For the onset and cessation time of sea- land breezes,the simulation results agree well with the statistical analyses of observational data available for the studied area.One interesting result is the 3 hour response time of wind field to the thermal change.Further statistic analysis based on the observational data is needed to make sure of this correlation.Important effects of coastal mountains on the wind structure are also exposed in detail by the model.Convergence and divergence centers resulting from the conjunction of sea-land breezes and complex terrain are clearly shown,which are not noticed before by conventional synoptic observation and theoretical analysis.展开更多
基金National Key R&D Plan of China(2017YFC0209606,2016YFC0203305)Major Program of National Natural Science Foundation of China(41630422,41801326,41275017)Science and Technology Program of Foshan Meteorological Bureau(201804)
文摘Meteorological conditions,particularly the vertical wind field structure,have a direct influence on the PM2.5 concentrations over the Pearl River Delta(PRD).In October 2012,an exceptional air pollution event occurred in the PRD,and a high concentration of PM2.5 was registered at some stations.During days with PM2.5 air pollution,the wind speed was less than 3 m s-1 at the surface,and the vertical wind field featured a weak wind layer(WWL)with a thickness of approximately 1000 m.The mean atmospheric boundary layer height was less than 500 m during pollution days,but it was greater than 1400 m during non-pollution days.A strong negative correlation was detected between the PM2.5 concentration and the ventilation index(VI).The VI was less than 2000 m2 s-1 during PM2.5 air pollution days.Because of the weak wind,sea-land breezes occurred frequently,the recirculation factor(RF)values were small at a height of 800 m during pollution days,and the zones with the lowest RF values always occurred between the heights of 300 and 600 m.The RF values during PM2.5 pollution days were approximately 0.4 to 0.6 below a height of 800 m,reducing the transportation capacity of the wind field to only 40%to 60%.The RF and wind profile characteristics indicated that sealand breezes were highly important in the accumulation of PM2.5 air pollution in the PRD.The sea breezes may transport pollutants back inland and may result in the peak PM2.5 concentrations at night.
基金The research was financially supported by BMBF(Bundesministerium Fur Bildung,Forschung und Technologie)of Germany the Natural Science Foundation of Shandong Province(No.Y97e03080).
文摘General features of 3-dimensional mesoscale wind and temperature structure over Shandong Peninsula are described in this paper.Results are achieved by numerical simulation with the 3- dimensional non-hydrostatic mesoscale model METRAS.For the onset and cessation time of sea- land breezes,the simulation results agree well with the statistical analyses of observational data available for the studied area.One interesting result is the 3 hour response time of wind field to the thermal change.Further statistic analysis based on the observational data is needed to make sure of this correlation.Important effects of coastal mountains on the wind structure are also exposed in detail by the model.Convergence and divergence centers resulting from the conjunction of sea-land breezes and complex terrain are clearly shown,which are not noticed before by conventional synoptic observation and theoretical analysis.
