Abstract:Based on pollutantion data from environmental monitoring stations, observation data from surface automatic weather stations, L-band dense sounding data and EC 0.125°×0.125° reanalysis data, and combined with fire point data from satellite remote sensing and simulation results of HYSPLIT4 backward trajectory, this paper analyzes the atmospheric boundary layer features, diffusion and transport meteorological conditions of two serious pollution events in Liaoning Province caused by crop residue burning of Northeast China on 8 November 2015 and 5 November 2016. The result shows that PM2.5 concentrations increased and decreased rapidly during the two pollution 〖JP2〗events. The serious pollution event on 8 November 2015 had stronger intensity and longer duration than the event on 5 November 2016. In the 8 November 2015 event, the mixing layer height was lower, on which neutral layer changed into inversion layer restraining the development of mixing layer height. At the same time, the cold advection in lower layer invaded below warm advection in higher layer, making the atmosphere more stable and lasting longer. The enhanced vertical subsidence motion and long-distance horizontal regional transportation of pollutants in southwestern Heilongjiang and western Jilin provinces resulted in rapid accumulation of pollutants on the surface in Liaoning. Due to stronger cold air, regional transportation in west of Northeast China and surface wind convergence strengthened are the main reason for the rapid increase of pollutant concentration in the event on 5 November 2016.