@InProceedings{MungerMaDaKiArGaWo:2002:VaCaMo,
               author = "Munger, J. William and Matross, Daniel M. and Dauber, Bruce C. and 
                         Kirchhoff, Volker Walter Johann Heinrich and Artaxo, Paulo and 
                         Gatti, Luciana Vanni and Wofsy, Steven C.",
                title = "Variations in carbon monoxide concentrations at a Central 
                         Amazonian site",
                 year = "2002",
         organization = "International LBA Scientific Conference, 2.",
             keywords = "GEOF{\'{\I}}SICA ESPACIAL.",
             abstract = "Carbon Monoxide (CO)plays a major role in controlling the global 
                         levels of OH in the atmosphere, and is a tracer of combustion 
                         sources. CO measurements are being made at a forested site near 
                         Santarem, Para, Brazil (km67 tower site)in order to determine 
                         background CO levels in the clean continental tropical atmosphere, 
                         to identify factors that control CO levels, and to serve as a 
                         tracer for emissions from local and distant biomass burning. A CO 
                         measurement system consisting of a Thermo Environmental 
                         Instruments model 48CTL analyzer, cold-trap at 2.5C to eliminate 
                         variations in water vapor interference, zeroing catalyst, and 
                         automated calibration with 100 and 500 nmol mol-1 standards was 
                         installed in April, 2001. Sample is drawn from an inlet above the 
                         forest canopy. CO concentrations were less than 100 nmol mol-1 on 
                         average, with no ignificant diel variation during the rainy 
                         season, April to June. The wet season data indicate a low regional 
                         background CO concentration and suggest that the local forest is 
                         neither a significant source nor sink for CO. In mid July, after 
                         local rain ended, there was a modest increase in CO concentration 
                         that was not accompanied by a large increase variance. This 
                         increase we attribute to increased transport from distant CO 
                         sources or to increased production by photochemistry of biogenic 
                         hydrocarbons contributing to regional enhancement in CO. In late 
                         August, the variability of CO concentrations begins to increase 
                         dramatically. Individual half-hour concentrations exceed 1000 nmol 
                         mol-1. By November, the frequency and magnitude of high CO events 
                         has increased. Maximum concentrations up to 5000 nmol mol-1 are 
                         observed and the minimum concentrations have increased to about 
                         200 nmol mol-1. The high CO levels and large variability are due 
                         to nearby fires. The diel variation during the late dry season 
                         when local fires are present shows a strong enhancement during the 
                         night as smoke is trapped in the nocturnal boundary layer. CO 
                         concentrations drop sharply after January 1, 2002 when heavy rains 
                         put an end to local burning. CO during the burning season will be 
                         used as a tracer to quantify the contribution by fires to CO2 
                         variability and to determine emission factors for aerosol 
                         components.",
  conference-location = "Manaus, Br",
      conference-year = "7-10 July 2002",
                label = "10274",
           targetfile = "munger_variations.pdf",
        urlaccessdate = "04 maio 2024"
}