RESEARCH ON SURFACE O₃ WITH METEOROLOGICAL CONDITIONS UNDER ATMOSPHERIC BACKGROUND CONDITIONS IN NORTHEAST CHINA^*

Surface O3 concentration and its precursors have been observed at Longfengshan station,Heilongjiang Province for a period of one year from August 13,1994 to July 30,1995. Relationship between surface O3 and the meteorological conditions during this period is analyzed in this study.Observation results show that diurnal variation of surface O3 follows a pattern of double-peaks with amplitude of 27-28 ppb under fine days in summer and autumn.Although the diurnal variation is small(14 ppb),it is still detectable when it is overcast.Diurnal variation of O3 is irregular under rainy days.Surface O3 concentration rises when wind speed starts to increase at 0800 BT(Beijing Time)from 0 to 6 m s-1in autumn,winter and summer.Relative high surface O3 concentration is noticed frequently when S,SSW,SW and WSW wind are encountered at the station during all seasons.At 0800 BT and 1400 BT the surface O3 concentration increases with the increase of global radiation accordingly during fine days in winter,spring and autumn.During fine days average peak of O3 concentration in summer is 20 ppb higher than that in winter while the average peak of global radiation in summer is almost twice as high as that in winter.The average surface O3 concentration under fine days in autumn at Longfengshan station is 14 ppb lower in comparison to the observation results from Lin'an station where Lin'an is at about the same longitude and lower latitude,with same environment,which is mainly caused by the difference of global radiation due to different latitudes in these two areas(difference of average peak global radiation about 100 W m-2).