Longtime in-situ measurements of total ozone from the ground-based Brewer observatories at Longfengshan in Heilongjiang Province and Waliguan in Qinghai Province were analyzed together with the according geopotential height data from NCEP R1 reanalysis series. Abnormal day-to-day fluctuations in the total ozone amount were found at times, which were analyzed in respect to synoptic processes. Results show that the impact of synoptic conditions is highly related to the variation of the total ozone amount. The anomaly in total ozone amount mostly appears in winter and spring (from November to May in the following year). The abnormal high total ozone amounts (the first kind of abnormal data points) always occur when the station is at the rear of the near surface (1000 hPa) cyclone with a simultaneous air pressure trough approaching in lower stratosphere (250 to 70 hPa). The abnormal low total ozone amounts (the second kind of abnormal points) always occur when the station is behind a near surface anticyclone with a simultaneous air pressure ridges approaching in lower stratosphere. The anomaly in total ozone amount can be considered as a signal for the upcoming transition between near surface cyclone and anticyclone.

The ozone experiment at three sities (LinAn, KunMing and Hong Kong) was simultaneously conducted for the first time in China during March-April 2001. Based on the ozone data obtained by this experiment and the ozone sounding data of Hong Kong from 1994 to 2000, we analyzed and compared the characteristics of ozone vertical distribution above these three sites. The results show that there exist different and general characteristics among the three sites ozone vertical distributions. The main difference of the three sites ozone vertical distributions is as follows: both the maximum ozone partial pressure and its altitude are different; the ozone concentration at 10～16km height of Lin'an is much higher than that of Kunming and Hong Kong; there exists one high ozone concentration layer over the Hong Kong and Kunming, but Hong Kong is more obvious; in the upper troposphere there is no lower ozone distribution over Lin'an. Based on the NCEP analyzed data, the atmospheric circulations of March 2001 reveals that the different atmospheric circulations can lead to the different ozone vertical distribution above these three sites.