SPATIOTEMPORAL VARIATION OF NO2 AND SUB-REGIONAL TRANSPORT DURING WINTER POLLUTION EVENTS IN HAIKOU, CHINA

An ensemble of satellite measurements, statistic data from government and meteorological diagnosis in regional background site (Haikou, China) has revealed the spatial and temporal characteristics of NO2 and associated synoptic transport patterns over southern China from January 2013 to February 2014. The result are as follows. (1) Ozone Monitoring Instrument (OMI) satellite products have a good correlation with observation NO2 in Ilaikou. The correlation coefficients between Observation NO2 and tropospheric column NO2 and ratio of Tro NO2/ Tot NO2 (tropospheric column NO2/ total column NO2) have all passed the confidence level of 99.9% test. (2) Tro NO2 over southern China has an obvious seasonal variation, which is closely coupled with regional meteorology in each season. (3) NO2 concentration in Haikou revealed three pollution periods during December 2013 and January 2014. The variation of NO2 concentration in Haikou is related to the meteorological elements closely. (4) Compared to the monthly mean meteorological fields of the pollution periods, the results indicate that NO2 pollution event in Haikou is directly related to the exogenous transportation from PRD region. An ensemble analysis of meteorological dynamic factors, wind vectors and backward trajectories during the pollution periods further verifies this conclusion.