Abstract:By means of the relative humidity data from meteorological satellite, microwave radiometer, and regular meteorological observations, as well as NCEP reanalysis data and environmental monitoring data, through air flow backward trajectory simulation, the characteristics and causes of two haze weather events in 11 and 15 June 2012 over the eastern Hubei are analyzed. The results show that the pollution indexes (API) are 233 μg/m3 and 139 μg/m3, respectively, with the highest PM2.5 being 141 μg/m3 in 11 June; the visibility in the two days is below 2000 m, with the average visibility being only 565 m in 11 June and the minimum visibility 246 m. The two heavy haze events are closely related to the concentrated straw burning over the region, where is one of the main winter wheat producing areas in China. There existed a large range of temperature inversion layer around 115°E, 39° to 32°N; the vertical height of 950 to 850 hPa thickness was consistent with the northeast flow, so that the pollutant cannot diffuse into the air and transmit to the eastern Hubei with Northeast flow. At the same time, because of calm wind, uniform pressure field, temperature inversion, weak vertical shear, positive vorticity, negative divergence, and suitable humidity conditions, pollutants cannot be timely diffused or subsided, which is favorable for haze formation and aggravation.