@Article{KirchhoffSilvBrow:1990:DrSeVe,
               author = "Kirchhoff, Volker Walter Johann Heinrich and Silva, I. M. O. da 
                         and Browell, E. V.",
                title = "Ozone measurements in Amazonia: dry season versus wet season",
              journal = "Journal of Geophysical Research",
                 year = "1990",
               volume = "95",
               number = "D10",
                pages = "16913--16926",
                month = "Sept",
             keywords = "GEOFISICA ESPACIAL.",
             abstract = "The concentration of atmospheric ozone was measured in the 
                         Amazoniam rain forest. Observations were made almost continuously 
                         at the surface, and in addition, 20 ozone profiles were obtained 
                         in the troposphere and stratosphere. These ozone measurements were 
                         part of a field expedition to the Brazilian Amazon region, the 
                         ABLE 2B mission, a joint American-Brazilian effort to measure 
                         local concentrations of several species, relevant to atmospheric 
                         chemistry. The time period of this expedition was April-May 1987, 
                         during the local wet season. For the surface ozone data the 
                         measurement technique used was UV absorption. Ozone profiles were 
                         obtained with electrochemical concentration cell sondes, launched 
                         on balloons. The major site of operaton was set up near Manaus (3 
                         degrees S, 60 degrees W). The results are presented and compared 
                         with a previous dry season experiment. Surface ozone mixing ratios 
                         show diurnal variations that have maxima in the daytime and minima 
                         at night. The diurnal maximum at noontime, considered very low (12 
                         ppbv) in the dry season was even lower in this wet season period 
                         (6 ppbv). A significant difference can be seen between clearing 
                         and forest data, and between different height levels above the 
                         surface, showing the existence of a large positive gradient of 
                         ozone with height. The ozone profiles in the troposphere show that 
                         there is less ozone not only at the surface but in the whole 
                         troposphere, with the wet season average showing between 6 and 12 
                         ppbv less ozone. This difference is much smaller in the 
                         stratosphere, where there is slightly more ozone in the region of 
                         the peak, during the wet season. An isolated shower or 
                         thunderstorm in the dry season could produce transient ozone 
                         variations (mixing ratio increases or decreases) that were not 
                         observed in the wet season.",
                 issn = "0148-0227 and 2156-2202",
                label = "7210",
           targetfile = "5873.pdf",
        urlaccessdate = "09 maio 2024"
}