Figure 4.8: Mid-tropospheric
O3 abundance (ppb) in northern mid-latitudes (36°N-59°N) for
the years 1970 to 1996. Observations between 630 and 400 hPa are averaged from
nine ozone sonde stations (four in North America, three in Europe, two in Japan),
following the data analysis of Logan et al. (1999). Values are derived from the
residuals of the trend fit with the trend added back to allow for discontinuities
in the instruments. Monthly data (points) are shown with a smoothed 12-month-running
mean (line).
