Analysis Of The Distribution And Variation Of Ground-level Ozone In The Northern Hemisphere

Content of surface ozone influences the environment and meteorology on the earth. Restricted by the observation data of surface ozone content, most studies were about short-term variation characteristics of a certain local place, while little was know about long-term variation characteristics in continental scale. In the thesis, surface ozone data of Mauna Loa and other 14 monitoring sites of altitude lower than 1000m in the northern hemisphere were used to give a joint discussion for the distribution and variation features of surface O3. The data, based on ground observation, were collected, processed, and distributed by WDCGG(The World Data Centre for Greenhouse Gases) in GAW(Global Atmosphere Watch). he monthly mean and hourly data of surface ozone in these 15 sites were analysed to sum up the difference of surface ozone annual and seasonal variations in different districts of the northern hemisphere. The results showed that:Firstly, the monthly mean of surface O3 was like a sinusoid curve with one peak in April and one trough in October in the districts with relatively clean air in land while the peak might be delayed to one month later or the content might be high in several months in the late spring and summer in the districts where the air was relatively heavily polluted,. And the minimum of surface ozone appeared in summer for the sites of latitude between 20° N—35° N in the oceans and along the coasts.Secondly, as to the mean diurnal cycle of the four seasons of 1995, the clean area did not show strong diurnal variability of surface ozone with a relatively straight line, while in the polluted area the diurnal variability are obvious especially in summer with the maximum in about 3 p.m. and the minimum before sunrise.Thirdly, CWT(Continue Wavelet Transform) were used to analyze the period of surface O3 of the sites, and contents of surface ozone of the sites showed quasi-biennial , quasi-four year and quasi-eleven year periods besides the obvious annual variation. Not the surface ozone content of every sites showed these three periods, some showing one or two out of these 3 periods and some showing them all. It differed with the location of the sites.