Use of satellite data to study tropospheric ozone in the tropics

Abstract

Three independent examples are discussed which suggest that photochemical ozone production in the troposphere can be observed in the tropics from an analysis of total ozone data. The first finding shows that the seasonal cycle of total columnar ozone is dominated by the seasonal cycle of tropospheric ozone, even though tropospheric ozone accounts for only 5–15% of the total ozone. Second, a case study is presented which shows that enhanced total ozone observed over the Amazon Basin can be associated with the presence of biomass burning. In situ measurements have confirmed that biomass burning does result in the production of photochemically generated ozone, analogous to the formation of “smog” near industrialized areas. Third, an analysis of the distribution of carbon monoxide obtained from a space shuttle platform is strongly correlated with the concurrent distribution of total ozone between 5°S and 10°N. Because all of the sources of carbon monoxide are located in the troposphere, this finding likewise suggests that the gradients of total ozone at low latitudes must also reflect processes occurring in the troposphere.