Abstract:  Based on the environmental air quality monitoring data, the conventional meteorological data, the sounding data and the NCEP reanalysis data, a typical pollution process in Tianjin during October 3-12, 2010 was analyzed. The synoptic background field of atmospheric environment, the atmospheric stratification stability and its effect on the pollution process were discussed. The results indicate that the pollution process is closely relative to the upper and lower environmental background fields. During the increasing stage of pollution concentration, the stratification stability increases rapidly, and the upper level situation field at 500 hPa is located in the front of the trough, the surface situation field is in the topographic trough of North China, and the upper and lower wind speed converges. During the stage of pollution concentration summit, the atmospheric stratification and the environmental background are stable, the inversion layer is strong, and the surface wind is weak. During the decreasing stage of pollution concentration, atmospheric stratification becomes unstable quickly| the surface cold front and upper trough pass over Tianjin area, precipitation occurs and the upper and lower north wind are enhanced. Meanwhile, PM₁₀ pollution process is significantly correlated with multiple stratification stability parameters and its correlation coefficient with convective condensation level is 0.84. As a result, the configuration of upper and lower environmental background and the variability of atmospheric stratification are the main reasons causing the PM₁₀ pollution.

Key words: PM₁₀, synoptic background, atmospheric stratification stability, temperature, air pressure, correlation, PM₁₀, Synoptic background field, Atmospheric stratification stability, Temperature, Air pressure