Statistical Characteristics Of Heavy Air Pollution In Zhejiang Province And Discussion On Heavy Air Pollution Forecast Method In Southern Zhejiang

Using the data of daily and hourly averaged air quality indicator?AQI?in 11 cities of Zhejiang province from October 2012 to May 2015,the occurrence time,duration and its temporal variation characteristics of AQI in 61 heavy air pollution?AQI?200?events were analyzed,and then the spatial and temporal characteristics of heavy air pollution were discussed using the data of synoptic situation.The results show that: the heavy air pollution and severe pollution mainly occurred in winter?December to next January?,the main pollution was PM_2.5,the duration hours of heavy air pollution was high in the northwest and low in the southeast and had significant difference in different regions.The heavy air pollution process could be divided into three types: synchronous change,north-south transport and regional accumulation.North-south transport can be divided into two types: movement transport and diffusion transport,and the type of movement transport had two sub-types: local move and area move.The type of regional accumulation had larger duration time,and can develop into serious pollution easily.On the basis of research about the characteristics of temporal and spatial distribution about air pollution in Zhejiang province,the characteristic of synoptic situation of input-based and accumulation in southern Zhejiang were analyzed respectively.By the comparison of 14 heavy pollution processes in northern Zhejiang with strong north wind,it could be found that when the input-based heavy air pollution in southern Zhejiang occurred,it must establish a stratification stability and non-divergent transportation channel besides the upstream heavy air pollution and strong north wind.To the heavy air pollution processes accumulated in southern Zhejiang,it cloud be induced to five kinds of synoptic situation that were conducive to the gathering of pollutant.The result showed that the heavy air pollution processes which last more than 24 hours mostly had more than two types transition.In order to adapt to carry out air quality forecast business and establish forecast system of heavy air pollution in southern Zhejiang,the potential forecast index for input-based heavy air pollution in southern Zhejiang was established.To the input-based heavy air pollution in southern Zhejiang,the 24 hours AQI forecast equation was established using NCEP reanalysis data and observation data by the method of stepwise regression.