Abstract:

Based on air pollution index (API) data from 2001 to 2012 and ground observed meteorological data in Beijing, API characteristics in different solar terms and its relationships with meteorological factors were analyzed. The results indicate that API values in spring and winter from 2001 to 2012 is the highest in Tomb-sweep solar term and Lesser Snow solar term respectively, so air quality is the worst during these two periods. API value is the lowest in the beginning of Autumn of the solar term, so the air quality is the best. The primary pollutant is PM₁₀ from Vernal equinox to Frost fall solar terms, while it is SO₂ from the beginning of Winter to Great cold and from the beginning of Spring to Insects awaken solar terms, especially in Slight cold solar term. The air quality in Beijing is influenced by temperature, wind speed and relative humidity. Pressure plays an important role for API from the beginning of Spring to Grain rain solar terms, and relative humidity and sunshine duration are important from the beginning of Winter to Great cold solar terms. API has a significant correlation with mean air temperature and maximum air temperature from the beginning of Summer to Frost fall solar terms. Wind speed mainly affects air quality in solar terms of spring and autumn.

Key words: Air pollution index (API), Twenty-four solar terms, Meteorological elements