Abstract:

Based on observed data from 122 weather stations during 1961 to 2010 in Sichuan basin, temporal and spatial distribution of the number of haze days and its seasonal and annual trends were analyzed. Relationships of the number of haze days with atmospheric extinction coefficients, wind speed, energy consumption and population and so on were discussed. The results indicate that the number of annual mean haze days at 122 weather stations is 62.5 days from 1961 to 2010 in Sichuan Basin, and the maximum could reach above 100 days for a certain station. The number of haze days has a significant seasonal variation, and its maximum occurs in winter with 28.4 days, and then in spring and autumn, and the minimum is in summer with 2.9 days. Annual variation of the number of haze days is in an increasing trend for 104 weather stations in Sichuan Basin, and there are 71 weather stations passing a confidence level of 99%. The maximum and minimum increasing rates occur in Qiyuan station with 42.0 days per decade and Xindu station with 0.4 days per decade. On the other hand, annual variation of the number of haze days is in a decreasing trend for 18 stations in Sichuan basin, and there are 7 weather stations passing a confidence level of 99%. The most significant decreasing rate occurs in Nanjiang station with -16.7 days per decade. Annual variation of the number of haze days is a positive correlation relationship with atmospheric extinction coefficients, regional energy consumption and population, and is a negative correlation relationship with wind speed.

Key words: Haze, Aerosol, Extinction coefficient