中文摘要：

采用1961~2011年冬季霾日数重建资料,揭示了华北黄淮地区冬季霾日数年代际增多以及与EAWM年代际减弱之间的关系.1986~2010年与1961~1970年相比,EAWM明显偏弱,环流形势在水平方向和垂直方向上都不利于污染物的扩散.海平面气压场为典型的AO正位相型分布,冷空气被限制在极区.华北黄淮的表面风速和湿度均为负距平,有利于霾的发生.高纬度经向环流较常年偏弱,华北黄淮上空以纬向环流为主,冷空气活动较弱,不能有效地南下到华北黄淮地区,不利于颗粒物的水平扩散.同时,华北黄淮上空的高压异常和逆温潜势,会有效抑制底层垂直运动的发展,也就抑制了空气中污染物的垂直扩散,导致空气中颗粒物的积聚在浅薄的层次中,增加了污染物的浓度.

英文摘要：

The relationship between the interdecadal increase of haze in winter over North China and the Huang-huai area （HW-NCHH） and the weakening of the East Asia Winter Monsoon （EAWM） was investigated. The trend of the HW-NCHH showed significant interdecadal variation with a slow increase from 1961 to 1970, rapid increase from 1971 to 1985, and slight decrease thereafter. The HW-NCHH trend was influenced considerably but not monotonically by the emission of pollution. Based on an 11-year running mean, the correlation coefficient between the HW-NCHH and EAWM was -0.77, above the 95% confidence level. Therefore, the EAWM should be considered a factor that has important influence on the HW-NCHH over the decadal scale. Compared with the climatic state from 1961 to 1970, the EAWM was clearly weaker from 1986 to 2010 and the horizontal and vertical circulations adverse to pollution diffusion. The distribution of sea level pressure was typical of the positive phase of the Arctic Oscillation, and thus cold air was restricted to the Arctic. The surface wind and humidity both presented negative anomalies over the NCHH area, which favored the production of haze. The meridional circulation in the high latitudes was weak and zonal circulation occupied the NCHH area, which prevented the advection of cold air southward to disperse the particulate matter in the NCHH area. Meanwhile, vertical diffusion was inhibited by an anomalous high pressure and thermal inversion potential over the NCHH area, such that the particulate matter gathered within a shallow layer, which exacerbated the concentration of pollution.