Abstract:In the context of increasing haze days in China, a significant feature is that the persistence of haze weather is enhanced. Based on the statistical haze data over the Jingjinji (a region referred to Beijing along with Tianjin and Hebei Province) during the period 1981-2013, the climatic characteristics of spatial and temporal distribution of persistent haze events, which refer to the haze events lasting for 2 or more days, are analyzed. The result shows that the increase in both the frequency and days of persistent haze events is the main reason leading to the growth of total haze events while the variation of non persistent haze days has no noticeable trend since 1981. The persistent haze events are mainly recorded in Beijing, the northern part of Tianjin and the southwest of Hebei Province, where the annual mean persistent haze days account for more than half of the total haze days in general. The areas affected by persistent haze events have expanded in an interdecadal increasing trend and the expansion has further accelerated since 2000.