Analysis of Persistent Air Pollution Process and Its Meteorological Cause in Chongqing

The general situation of air quality and characteristics of persistent air pollution process in Chongqing urban area was investigated based on the dataset obtained from daily reports of air quality. The variation of Air Pollution Index (API) and its relationship with meteorological parameters during period from November 29 to December 31was discussed in more detail. The results showed that the occurrence frequency of persistent air pollution process, which is defined as continuous situation when API exceeds 100 more than three days, was 10 in 2005. The accumulated days of persistent air pollution process added up to 61, accounting for 61.6% of the total days when API exceeded 100.In general. There were some common meteorological conditions such as lower wind speed, non-precipitation or rare precipitation, stable air stratification, and lower mixed layer height that were predominated during the persistent air pollution process.