Tropospheric ozone evolution between 1890 and 1990

[ 1] In this study, we have performed a set of simulations to detail the evolution of tropospheric ozone from 1890 to 1990. The simulations are compared with available measurements for present-day conditions and earlier. Using our best estimates of ozone precursors emissions ( based on the work by van Aardenne et al. ( 2001)), we have found a tropospheric ozone burden increase of 71 Tg between 1890 and 1990, an increase of similar to 30%. When no anthropogenic emissions in 1890 are considered, this burden increase reaches 88 Tg. The ozone lifetime is shown to have decreased by similar to 30%, especially after 1930. It is also shown that the net chemical production in the lower troposphere exceeded that in the free troposphere for the first time in the 1950 - 1970 period. In addition, the ozone production in this study increased rapidly between 1890 and 1930 and from 1970 to 1990. However, the ozone production efficiency in the troposphere is shown to have decreased during the 20th century, making the troposphere less NOx limited. Finally, a decrease in the OH burden is estimated to be on the order of 8%, matched by a similar increase in the CO lifetime.