caa a22 4500 475823613 CHVBK 20180406123825.0 cr unu---uuuuu 170329e20000301xx s 000 0 eng 10.1023/A:1006270911796 doi (NATIONALLICENCE)springer-10.1023/A:1006270911796 Boundary Layer Ozone in the Tropical America Northern Hemisphere Region [Elektronische Daten] [Eugenio Sanhueza, Enmanuel Fernández, Loreto Donoso, Johnny Romero] In recent field campaigns, boundary layer ozone concentrations were measuredat different sites in the Orinoco river basin (mainly savannahs) and nearbylocations (cloud forest and coastal sites), during dry and wet seasons. Theresults provide a comprehensive description of boundary layer ozone in atropical region north of the equator where scarce information is available.Ozone measurements were made using photometric ozone analyzers. In thesavannah region, ozone profiles (up to 1000 m) were also obtained usingelectrochemical concentration cell sondes, launched in a tethered balloon.The results, in comparison with other parts of the world, confirm the lowvalues for the concentration of ozone in the boundary layer of the studyregion. Throughout the entire region (marine, coastal, and continental areas),higher concentrations were produced during the dry season (20-30 ppbv)than during the wet season (13-17 ppbv), likely due to the photochemicalproduction of ozone from biomass burning emissions. This seasonal variationobserved in the boundary layer contrasts with satellite data, that show highertotal tropospheric ozone columns during the wet season in the 0-15°Nregion; this means that the ozone annual cycles in the boundary layer and freetroposphere are out of phase.At the most pristine continental sites in the southern part of Venezuela,quite a 'speculiar' diurnal variation was observed, with maximum concentrationsin the morning and a steady decrease of ∼0.6 ppbv hr-1 duringthe hours of high solar irradiation. Although dynamic aspects cannot be ruledout, the daytime ozone decrease, which cannot be explained by thewell-established 'sclassical' continental O3 sinks, suggests thatin this region part of the ozone consumption is caused byHO x cycles at low NO x levels. Futurestudies to elucidate the causes of the daytime ozone decrease at thesecontinental sites should be undertaken. Kluwer Academic Publishers, 2000 ozone nationallicence tropical atmosphere nationallicence boundary layer ozone nationallicence biomass burning nationallicence Venezuelan savannah nationallicence Sanhueza Eugenio IVIC, Atmospheric Chemistry Laboratory, Apartado 21827, 1020A, Caracas, Venezuela aut Fernández Enmanuel IVIC, Atmospheric Chemistry Laboratory, Apartado 21827, 1020A, Caracas, Venezuela aut Donoso Loreto IVIC, Atmospheric Chemistry Laboratory, Apartado 21827, 1020A, Caracas, Venezuela aut Romero Johnny IVIC, Atmospheric Chemistry Laboratory, Apartado 21827, 1020A, Caracas, Venezuela aut Journal of Atmospheric Chemistry Kluwer Academic Publishers 35/3(2000-03-01), 249-272 0167-7764 35:3<249 2000 35 10874 https://doi.org/10.1023/A:1006270911796 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1006270911796 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Sanhueza Eugenio IVIC, Atmospheric Chemistry Laboratory, Apartado 21827, 1020A, Caracas, Venezuela aut NATIONALLICENCE 700 1- Fernández Enmanuel IVIC, Atmospheric Chemistry Laboratory, Apartado 21827, 1020A, Caracas, Venezuela aut NATIONALLICENCE 700 1- Donoso Loreto IVIC, Atmospheric Chemistry Laboratory, Apartado 21827, 1020A, Caracas, Venezuela aut NATIONALLICENCE 700 1- Romero Johnny IVIC, Atmospheric Chemistry Laboratory, Apartado 21827, 1020A, Caracas, Venezuela aut NATIONALLICENCE 773 0- Journal of Atmospheric Chemistry Kluwer Academic Publishers 35/3(2000-03-01), 249-272 0167-7764 35:3<249 2000 35 10874 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer