Detailansicht

Study of ozone depletion events in the Weddell Sea, Antarctica during the Winter Weddell Outflow Study from August until October 2006

Elena Johanna Stautzebach

Art der Arbeit

Diplomarbeit

Universität

Universität Wien

Fakultät

Fakultät für Geowissenschaften, Geographie und Astronomie

Betreuer*in

Reinhold Steinacker

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DOI

10.25365/thesis.18666

URN

urn:nbn:at:at-ubw:1-29812.53863.893262-1

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Abstracts

Abstract

(Deutsch)

Der plötzliche Abfall der Ozonkonzentration in der Troposphäre ist bereits seit Mitte der achtziger Jahre bekannt. Katalytische Prozesse, die sogenannte “Bromexplosion”, erzeugen reaktive Bromatome, die in weiterer Folge bodennahes Ozon zerstören und zu einem Anstieg der BrO Vertikalsäule führen. Diese chemischen Reaktionen sind allerdings an das Vorhandensein von Meereis und solarer Einstrahlung gebunden. Sie sind daher auf die Polarregionen und auf die Frühlingszeit beschränkt. In der Arktis sind die sogenannten “Ozone depletion events” schon zahlreich erforscht worden, in der Antarktis hingegen gibt es nur Messungen an den Küsten- sowie Inlandstationen, aber keinerlei Beobachtungen direkt in den Meeresregionen. Während der Forschungsreise “Winter Weddell Outflow Study” im Frühling (August-Oktober) 2006 an Bord des deutschen Polarschiffes “Polarstern” wurden zum ersten Mal Ozondaten im Weddellmeer, Antarktis gesammelt. Weiters wurden meteorologische Parameter gemessen und die BrO Vertikalsäule anhand eines DOAS-Messgerätes (Differential Optical Absorption Spectroscopy) ermittelt. Ziel der Arbeit ist es nun diese erworbenen Ozondaten zu analysieren und mit Ozondaten der Forschungsstationen Neumayer (GER), Halley (GB) und Cape Point (ZA) zu vergleichen. Eventuelle Zusammenhänge zwischen der Ozonkonzentration, den vorherrschenden meteorologischen Bedingungen und der BrO Vertikalsäule sollen erläutert werden. Weiters soll geklärt werden, ob es Unterschiede zwischen dem Ablauf der “Ozone depletion events” in beiden Polarregionen gibt.

Abstract

(Englisch)

So-called ozone depletion events have been investigated since their first appearance in the mid 1980s. They are characterized as drops of the ozone levels in the lower troposphere in a timescale of minutes to several days and have mostly been observed in polar regions. Chemical catalytic cycles known as the bromine explosion generate reactive bromine atoms that destroy surface ozone and lead to an increase of the BrO vertical column. These chemical reactions are linked to sea ice covered regions as well as insolation and are limited to the springtime in both polar regions. Ozone depletion events have already been well-probed in the Arctic Ocean. However in Antarctica only ozone concentrations observed at coastal and inland sites have been analysed. During a scientific cruise (“Winter Weddell Outflow Study”) with the German research vessel Polarstern ozone investigations were performed for the first time in the north-western Weddell Sea southward of the South Orkney Islands. Several meteorological parameters were recorded as well. Furthermore a 2-channel multiaxis DOAS (Differential Optical Absorption Spectroscopy) instrument allowing the detection of BrO was installed onboard and data from the SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) sensor were used. The entire data was analysed to investigate the connection between the ozone concentrations, the prevailing meteorological conditions and the BrO vertical column during ozone depletion events in the Weddell Sea. During the Winter Weddell Outflow Study four ozone depletion events were recorded. The investigations allowed a distinction between chemically and meteorologically induced ozone depletion events. The meteorologically induced ODEs were characterized by the advection of air masses already depleted in ozone. Using backward-trajectories, the origin of the depleted air masses was detected. The ozone concentrations and the BrO VC observed onboard have been compared. The similar increase of the BrO concentration and decrease of the ozone concentration indicates that the ozone depletion events measured onboard were in fact activated by the presence of Br in the atmosphere. Ozone measurements at the German research station Neumayer as well as at the British station Halley were also analysed. The origin of the depleted air masses reaching the RV Polarstern and both Antarctic stations is identical. In the majority of cases, the chemical reactions destroying ozone took place over the Central Weddell Sea. In most cases, enhanced BrO vertical columns were observed simultaneously in the same region. Finally the role of low pressure systems in the generating of BrO was analysed. High wind speeds favour the turbulent mixing and, therefore, the increase of salinity and reactive bromine atoms in the boundary layer. Since low pressure systems are often accompanied by high wind speeds, a link between low pressure systems and enhanced BrO vertical columns is proposed.

Autor*innen

Elena Johanna Stautzebach

Haupttitel (Englisch)

Study of ozone depletion events in the Weddell Sea, Antarctica during the Winter Weddell Outflow Study from August until October 2006

Paralleltitel (Deutsch)

Untersuchung von plötzlichen troposphärischen Ozonabfällen im Weddell Meer, Antarktis während der Forschungsreise “Winter Weddell Outflow Study” im Frühling (August-Oktober) 2006

Publikationsjahr

2011

Umfangsangabe

IV, 117 S. :Ill., graf. Darst., Kt.

Sprache

Englisch

Beurteiler*in

Reinhold Steinacker

Klassifikationen

35 Chemie > 35.99 Chemie: Sonstiges ,

38 Geowissenschaften > 38.81 Atmosphäre

AC Nummer

AC09405783

Utheses ID

16730

Studienkennzahl

UA | 415 | | |

Detailansicht

Abstracts

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