TYPICAL WEATHER CHARACTERISTICS ASSOCIATED WITH AIR POLLUTION IN HONG KONG AREA

With the hourly data of Air Pollution Index (API) by Hong Kong Environmental ProtectionDepartment (HKEPD) during the 6 years of 2000 - 2005 and NCEP / NCAR reanalysis data of 2.5° ×2.5° wind and pressure fields, the characteristics of API in Hong Kong area and the impacts of typicalweather characteristics on the air pollution in Hong Kong have been studied. The results are shown asfollows. (1) The API exhibits obvious seasonal variability as the number of air pollution days increases bythe year. For most of the local monitoring stations, it is the most from January to March, a little less fromJuly to September and the least from April to June. (2) There are four typical types of weather situationsthat are responsible for the air pollution in Hong Kong: tropical cyclones, continental cold highs,transformed highs that have moved out to sea and low pressure troughs.