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dc.date.accessioned2016-05-20T10:34:12Z
dc.date.available2016-05-20T10:34:12Z
dc.date.created2010-06-23T21:47:17Z
dc.date.issued2010
dc.identifier.citationSsenyonga, Taddeo Stamnes, Jakob J. Dahlback, Arne Steigen, Andreas L Okullo, Willy Frette, Øyvind . Analysis of Ozone (O3) and Erythemal UV (EUV) measured by TOMS in the equatorial African belt. South African Journal of Science. 2010, 106(1-2), 19-25
dc.identifier.urihttp://hdl.handle.net/10852/50324
dc.description.abstractWe presented time series of total ozone column amounts (TOCAs) and erythemal UV (EUV) doses derived from measurements by TOMS (Total Ozone Mapping Spectrometer) instruments on board the Nimbus-7 (N7) and the Earth Probe (EP) satellites for three locations within the equatorial African belt for the period 1979 to 2000. The locations were Dar-es-Salaam (6.8° S, 39.26° E) in Tanzania, Kampala (0.19° N, 32.34° E) in Uganda, and Serrekunda (13.28° N, 16.34° W) in Gambia. Equatorial Africa has high levels of UV radiation, and because ozone shields UV radiation from reaching the Earth’s surface, there is a need to monitor TOCAs and EUV doses. In this paper we investigated the trend of TOCAs and EUV doses, the effects of annual and solar cycles on TOCAs, as well as the link between lightning and ozone production in the equatorial African belt. We also compared clear-sky simulated EUV doses with the corresponding EUV doses derived from TOMS measurements. The TOCAs were found to vary in the ranges 243 DU − 289 DU, 231 DU − 286 DU, and 236 DU − 296 DU, with mean values of 266.9 DU, 260.9 DU, and 267.8 DU for Dar-es-Salaam, Kampala and Serrekunda, respectively. Daily TOCA time series indicated that Kampala had the lowest TOCA values, which we attributed to the altitude effect. There were two annual ozone peaks in Dar-es-Salaam and Kampala, and one annual ozone peak in Serrekunda. The yearly TOCA averages showed an oscillation within a five-year period. We also found that the EUV doses were stable at all three locations for the period 1979−2000, and that Kampala and Dar-es-Salaam were mostly cloudy throughout the year, whereas Serrekunda was mostly free from clouds. It was also found that clouds were among the major factors determining the level of EUV reaching the Earth´s surface. Finally, we noted that during rainy seasons, horizontal advection effects augmented by lightning activity may be responsible for enhanced ozone production in the tropics.en_US
dc.languageEN
dc.language.isoenen_US
dc.rightsAttribution 2.5 South Africa
dc.rights.urihttp://creativecommons.org/licenses/by/2.5/za/
dc.titleAnalysis of Ozone (O3) and Erythemal UV (EUV) measured by TOMS in the equatorial African belten_US
dc.typeJournal articleen_US
dc.creator.authorSsenyonga, Taddeo
dc.creator.authorStamnes, Jakob J.
dc.creator.authorDahlback, Arne
dc.creator.authorSteigen, Andreas L
dc.creator.authorOkullo, Willy
dc.creator.authorFrette, Øyvind
cristin.unitcode185,15,4,0
cristin.unitnameFysisk institutt
cristin.ispublishedtrue
cristin.fulltextoriginal
cristin.qualitycode1
dc.identifier.cristin340699
dc.identifier.bibliographiccitationinfo:ofi/fmt:kev:mtx:ctx&ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=South African Journal of Science&rft.volume=106&rft.spage=19&rft.date=2010
dc.identifier.jtitleSouth African Journal of Science
dc.identifier.volume106
dc.identifier.issue1-2
dc.identifier.startpage19
dc.identifier.endpage25
dc.identifier.doihttp://dx.doi.org/10.4102/sajs.v106i1/2.12
dc.identifier.urnURN:NBN:no-53957
dc.subject.nviVDP::Økologi: 488VDP::Rom- og plasmafysikk: 437
dc.type.documentTidsskriftartikkelen_US
dc.type.peerreviewedPeer reviewed
dc.source.issn0038-2353
dc.identifier.fulltextFulltext https://www.duo.uio.no/bitstream/handle/10852/50324/1/12-698-1-PB.pdf
dc.type.versionPublishedVersion


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