@phdthesis{Aue2024,
  author    = {Aue, Lars},
  title     = {Cyclone impacts on sea ice in the Atlantic Arctic Ocean},
  doi       = {10.25932/publishup-63445},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-634458},
  school      = {Universit{\"a}t Potsdam},
  pages     = {VIII, 131},
  year      = {2024},
  abstract  = {The Arctic is the hot spot of the ongoing, global climate change. Over the last decades, near-surface temperatures in the Arctic have been rising almost four times faster than on global average. This amplified warming of the Arctic and the associated rapid changes of its environment are largely influenced by interactions between individual components of the Arctic climate system. On daily to weekly time scales, storms can have major impacts on the Arctic sea-ice cover and are thus an important part of these interactions within the Arctic climate. The sea-ice impacts of storms are related to high wind speeds, which enhance the drift and deformation of sea ice, as well as to changes in the surface energy budget in association with air mass advection, which impact the seasonal sea-ice growth and melt. The occurrence of storms in the Arctic is typically associated with the passage of transient cyclones. Even though the above described mechanisms how storms/cyclones impact the Arctic sea ice are in principal known, there is a lack of statistical quantification of these effects. In accordance with that, the overarching objective of this thesis is to statistically quantify cyclone impacts on sea-ice concentration (SIC) in the Atlantic Arctic Ocean over the last four decades. In order to further advance the understanding of the related mechanisms, an additional objective is to separate dynamic and thermodynamic cyclone impacts on sea ice and assess their relative importance. Finally, this thesis aims to quantify recent changes in cyclone impacts on SIC. These research objectives are tackled utilizing various data sets, including atmospheric and oceanic reanalysis data as well as a coupled model simulation and a cyclone tracking algorithm. Results from this thesis demonstrate that cyclones are significantly impacting SIC in the Atlantic Arctic Ocean from autumn to spring, while there are mostly no significant impacts in summer. The strength and the sign (SIC decreasing or SIC increasing) of the cyclone impacts strongly depends on the considered daily time scale and the region of the Atlantic Arctic Ocean. Specifically, an initial decrease in SIC (day -3 to day 0 relative to the cyclone) is found in the Greenland, Barents and Kara Seas, while SIC increases following cyclones (day 0 to day 5 relative to the cyclone) are mostly limited to the Barents and Kara Seas. For the cold season, this results in a pronounced regional difference between overall (day -3 to day 5 relative to the cyclone) SIC-decreasing cyclone impacts in the Greenland Sea and overall SIC-increasing cyclone impacts in the Barents and Kara Seas. A cyclone case study based on a coupled model simulation indicates that both dynamic and thermodynamic mechanisms contribute to cyclone impacts on sea ice in winter. A typical pattern consisting of an initial dominance of dynamic sea-ice changes followed by enhanced thermodynamic ice growth after the cyclone passage was found. This enhanced ice growth after the cyclone passage most likely also explains the (statistical) overall SIC-increasing effects of cyclones in the Barents and Kara Seas in the cold season. Significant changes in cyclone impacts on SIC over the last four decades have emerged throughout the year. These recent changes are strongly varying from region to region and month to month. The strongest trends in cyclone impacts on SIC are found in autumn in the Barents and Kara Seas. Here, the magnitude of destructive cyclone impacts on SIC has approximately doubled over the last four decades. The SIC-increasing effects following the cyclone passage have particularly weakened in the Barents Sea in autumn. As a consequence, previously existing overall SIC-increasing cyclone impacts in this region in autumn have recently disappeared. Generally, results from this thesis show that changes in the state of the sea-ice cover (decrease in mean sea-ice concentration and thickness) and near-surface air temperature are most important for changed cyclone impacts on SIC, while changes in cyclone properties (i.e. intensity) do not play a significant role.},
  language  = {en}
}
@phdthesis{Littmann2024,
  author    = {Littmann, Daniela-Christin},
  title     = {Large eddy simulations of the Arctic boundary layer around the MOSAiC drift track},
  doi       = {10.25932/publishup-62437},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-624374},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xii, 110},
  year      = {2024},
  abstract  = {The icosahedral non-hydrostatic large eddy model (ICON-LEM) was applied around the drift track of the Multidisciplinary Observatory Study of the Arctic (MOSAiC) in 2019 and 2020. The model was set up with horizontal grid-scales between 100m and 800m on areas with radii of 17.5km and 140 km. At its lateral boundaries, the model was driven by analysis data from the German Weather Service (DWD), downscaled by ICON in limited area mode (ICON-LAM) with horizontal grid-scale of 3 km. The aim of this thesis was the investigation of the atmospheric boundary layer near the surface in the central Arctic during polar winter with a high-resolution mesoscale model. The default settings in ICON-LEM prevent the model from representing the exchange processes in the Arctic boundary layer in accordance to the MOSAiC observations. The implemented sea-ice scheme in ICON does not include a snow layer on sea-ice, which causes a too slow response of the sea-ice surface temperature to atmospheric changes. To allow the sea-ice surface to respond faster to changes in the atmosphere, the implemented sea-ice parameterization in ICON was extended with an adapted heat capacity term. The adapted sea-ice parameterization resulted in better agreement with the MOSAiC observations. However, the sea-ice surface temperature in the model is generally lower than observed due to biases in the downwelling long-wave radiation and the lack of complex surface structures, like leads. The large eddy resolving turbulence closure yielded a better representation of the lower boundary layer under strongly stable stratification than the non-eddy-resolving turbulence closure. Furthermore, the integration of leads into the sea-ice surface reduced the overestimation of the sensible heat flux for different weather conditions. The results of this work help to better understand boundary layer processes in the central Arctic during the polar night. High-resolving mesoscale simulations are able to represent temporally and spatially small interactions and help to further develop parameterizations also for the application in regional and global models.},
  language  = {en}
}
@phdthesis{Alexoudi2023,
  author    = {Alexoudi, Xanthippi},
  title     = {Clarifying the discrepant results in the characterization of exoplanetary atmospheres},
  doi       = {10.25932/publishup-60565},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-605659},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xvi, 125},
  year      = {2023},
  abstract  = {Planets outside our solar system, so-called "exoplanets", can be detected with different methods, and currently more than 5000 exoplanets have been confirmed, according to NASA Exoplanet Archive. One major highlight of the studies on exoplanets in the past twenty years is the characterization of their atmospheres usingtransmission spectroscopy as the exoplanet transits. However, this characterization is a challenging process and sometimes there are reported discrepancies in the literature regarding the atmosphere of the same exoplanet. One potential reason for the observed atmospheric inconsistencies is called impact parameter degeneracy, and it is highly driven by the limb darkening effect of the host star. A brief introductionto those topics in presented in chapter 1, while the motivation and objectives of thiswork are described in chapter 2.The first goal is to clarify the origin of the transmission spectrum, which is anindicator of an exoplanet's atmosphere; whether it is real or influenced by the impactparameter degeneracy. A second goal is to determine whether photometry from space using the Transiting Exoplanet Survey Satellite (TESS), could improve on the major parameters, which are responsible for the aforementioned degeneracy, of known exoplanetary systems. Three individual projects were conducted in order toaddress those goals. The three manuscripts are presented, in short, in the manuscriptoverview in chapter 3.More specifically, in chapter 4, the first manuscript is presented, which is an ex-tended investigation on the impact parameter degeneracy and its application onsynthetic transmission spectra. Evidently, the limb darkening of the host star isan important driver for this effect. It keeps the degeneracy persisting through different groups of exoplanets, based on the uncertainty of their impact parameter and on the type of their host star. The second goal, was addressed in the second and third manuscripts (chapter 5 and chapter 6 respectively). Using observationsfrom the TESS mission, two samples of exoplanets were studied; 10 transiting inflated hot-Jupiters and 43 transiting grazing systems. Potentially, the refinement or confirmation of their major system parameters' measurements can assist in solving current or future discrepancies regarding their atmospheric characterization.In chapter 7 the conclusions of this work are discussed, while in chapter 8 itis proposed how TESS's measurements can be able to discern between erroneousinterpretations of transmission spectra, especially on systems where the impact parameter degeneracy is likely not applicable.},
  language  = {en}
}
@phdthesis{Riebold2023,
  author    = {Riebold, Johannes},
  title     = {On the linkage between future Arctic sea ice retreat, the large-scale atmospheric circulation and temperature extremes over Europe},
  doi       = {10.25932/publishup-60488},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-604883},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xi, 126},
  year      = {2023},
  abstract  = {Extreme weather and climate events are one of the greatest dangers for present-day society. Therefore, it is important to provide reliable statements on what changes in extreme events can be expected along with future global climate change. However, the projected overall response to future climate change is generally a result of a complex interplay between individual physical mechanisms originated within the different climate subsystems. Hence, a profound understanding of these individual contributions is required in order to provide meaningful assessments of future changes in extreme events. One aspect of climate change is the recently observed phenomenon of Arctic Amplification and the related dramatic Arctic sea ice decline, which is expected to continue over the next decades. The question to what extent Arctic sea ice loss is able to affect atmospheric dynamics and extreme events over mid-latitudes has received a lot of attention over recent years and still remains a highly debated topic. In this respect, the objective of this thesis is to contribute to a better understanding on the impact of future Arctic sea ice retreat on European temperature extremes and large-scale atmospheric dynamics. The outcomes are based on model data from the atmospheric general circulation model ECHAM6. Two different sea ice sensitivity simulations from the Polar Amplification Intercomparison Project are employed and contrasted to a present day reference experiment: one experiment with prescribed future sea ice loss over the entire Arctic, as well as another one with sea ice reductions only locally prescribed over the Barents-Kara Sea.\% prescribed over the entire Arctic, as well as only locally over the Barent/Karasea with a present day reference experiment. The first part of the thesis focuses on how future Arctic sea ice reductions affect large-scale atmospheric dynamics over the Northern Hemisphere in terms of occurrence frequency changes of five preferred Euro-Atlantic circulation regimes. When compared to circulation regimes computed from ERA5 it shows that ECHAM6 is able to realistically simulate the regime structures. Both ECHAM6 sea ice sensitivity experiments exhibit similar regime frequency changes. Consistent with tendencies found in ERA5, a more frequent occurrence of a Scandinavian blocking pattern in midwinter is for instance detected under future sea ice conditions in the sensitivity experiments. Changes in occurrence frequencies of circulation regimes in summer season are however barely detected. After identifying suitable regime storylines for the occurrence of European temperature extremes in winter, the previously detected regime frequency changes are used to quantify dynamically and thermodynamically driven contributions to sea ice-induced changes in European winter temperature extremes. It is for instance shown how the preferred occurrence of a Scandinavian blocking regime under low sea ice conditions dynamically contributes to more frequent midwinter cold extreme occurrences over Central Europe. In addition, a reduced occurrence frequency of a Atlantic trough regime is linked to reduced winter warm extremes over Mid-Europe. Furthermore, it is demonstrated how the overall thermodynamical warming effect due to sea ice loss can result in less (more) frequent winter cold (warm) extremes, and consequently counteracts the dynamically induced changes. Compared to winter season, circulation regimes in summer are less suitable as storylines for the occurrence of summer heat extremes. Therefore, an approach based on circulation analogues is employed in order to quantify thermodyamically and dynamically driven contributions to sea ice-induced changes of summer heat extremes over three different European sectors. Reduced occurrences of blockings over Western Russia are detected in the ECHAM6 sea ice sensitivity experiments; however, arguing for dynamically and thermodynamically induced contributions to changes in summer heat extremes remains rather challenging.},
  language  = {en}
}
@article{Bose2021,
  author    = {Bose, K{\"a}the von},
  title     = {Umweltf{\"u}rsorge im Krankenhaus},
  series = {NTM : Zeitschrift f{\"u}r Geschichte der Wissenschaften, Technik und Medizin},
  volume    = {29},
  journal   = {NTM : Zeitschrift f{\"u}r Geschichte der Wissenschaften, Technik und Medizin},
  number    = {1},
  publisher = {Birkh{\"a}user},
  address   = {Basel ; Berlin},
  issn      = {0036-6978},
  doi       = {10.1007/s00048-020-00289-x},
  pages     = {113 -- 141},
  year      = {2021},
  abstract  = {Den Boden putzen, das Bett abziehen, einen Blumenstrauß arrangieren - Bem{\"u}hungen um Sauberkeit sowie eine angenehme Raumatmosph{\"a}re obliegen im Krankenhaus meist weiblichen* Pflegerinnen, Reinigungskr{\"a}ften und Hauswirtschafterinnen. Im Klinikalltag vermischen sich Anforderungen an hygienische Sauberkeit unter Prozessen der {\"O}konomisierung mit Logiken des Marketings sowie mit affektiv-emotionalen Bed{\"u}rfnissen der Akteur_innen dieser R{\"a}ume. Obwohl die Maßst{\"a}be klinischer Hygiene auf medizinischem Wissen basieren, sind die Arbeitsteilung sowie Anspr{\"u}che an Sauberkeit auf verschiedenen Hierarchieebenen zugleich von vergeschlechtlichten und teils rassifizierten Vorstellungen durchdrungen, die {\"u}ber den klinischen Kontext hinausweisen. Dies legt schon eine Besch{\"a}ftigung mit der Geschichte der Bakteriologie nahe: Die Logik und Sprache der Infektionsabwehr ist in Wissenschaft und Alltag auch verwoben mit sozialen Differenzmarkierungen. Unter R{\"u}ckgriff auf die Ergebnisse einer Ethnografie zu Sauberkeit und Reinigungsarbeiten im Krankenhaus, die wissensgeschichtlich fundiert werden, wird in dem Beitrag die Frage nach der (feminisierten) Sorge f{\"u}r die Umwelt mit der Frage nach der Atmosph{\"a}re klinischer R{\"a}ume verkn{\"u}pft. Auf welche Weise und mit welchen Effekten verschr{\"a}nken sich wissenschaftlich-medizinisches Hygienewissen mit einem allt{\"a}glichen, jedoch historisierbaren Wissen {\"u}ber sch{\"o}ne und angenehme Sauberkeit, das immer noch weiblich konnotiert ist?},
  language  = {de}
}
@phdthesis{Dahlke2020,
  author    = {Dahlke, Sandro},
  title     = {Rapid climate changes in the arctic region of Svalbard},
  doi       = {10.25932/publishup-44554},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-445542},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xv, 123},
  year      = {2020},
  abstract  = {Over the last decades, the Arctic regions of the earth have warmed at a rate 2-3 times faster than the global average- a phenomenon called Arctic Amplification. A complex, non-linear interplay of physical processes and unique pecularities in the Arctic climate system is responsible for this, but the relative role of individual processes remains to be debated. This thesis focuses on the climate change and related processes on Svalbard, an archipelago in the North Atlantic sector of the Arctic, which is shown to be a "hotspot" for the amplified recent warming during winter. In this highly dynamical region, both oceanic and atmospheric large-scale transports of heat and moisture interfere with spatially inhomogenous surface conditions, and the corresponding energy exchange strongly shapes the atmospheric boundary layer. In the first part, Pan-Svalbard gradients in the surface air temperature (SAT) and sea ice extent (SIE) in the fjords are quantified and characterized. This analysis is based on observational data from meteorological stations, operational sea ice charts, and hydrographic observations from the adjacent ocean, which cover the 1980-2016 period. It is revealed that typical estimates of SIE during late winter range from 40-50\% (80-90\%) in the western (eastern) parts of Svalbard. However, strong SAT warming during winter of the order of 2-3K per decade dictates excessive ice loss, leaving fjords in the western parts essentially ice-free in recent winters. It is further demostrated that warm water currents on the west coast of Svalbard, as well as meridional winds contribute to regional differences in the SIE evolution. In particular, the proximity to warm water masses of the West Spitsbergen Current can explain 20-37\% of SIE variability in fjords on west Svalbard, while meridional winds and associated ice drift may regionally explain 20-50\% of SIE variability in the north and northeast. Strong SAT warming has overruled these impacts in recent years, though. In the next part of the analysis, the contribution of large-scale atmospheric circulation changes to the Svalbard temperature development over the last 20 years is investigated. A study employing kinematic air-back trajectories for Ny-{\AA}lesund reveals a shift in the source regions of lower-troposheric air over time for both the winter and the summer season. In winter, air in the recent decade is more often of lower-latitude Atlantic origin, and less frequent of Arctic origin. This affects heat- and moisture advection towards Svalbard, potentially manipulating clouds and longwave downward radiation in that region. A closer investigation indicates that this shift during winter is associated with a strengthened Ural blocking high and Icelandic low, and contributes about 25\% to the observed winter warming on Svalbard over the last 20 years. Conversely, circulation changes during summer include a strengthened Greenland blocking high which leads to more frequent cold air advection from the central Arctic towards Svalbard, and less frequent air mass origins in the lower latitudes of the North Atlantic. Hence, circulation changes during winter are shown to have an amplifying effect on the recent warming on Svalbard, while summer circulation changes tend to mask warming. An observational case study using upper air soundings from the AWIPEV research station in Ny-{\AA}lesund during May-June 2017 underlines that such circulation changes during summer are associated with tropospheric anomalies in temperature, humidity and boundary layer height. In the last part of the analysis, the regional representativeness of the above described changes around Svalbard for the broader Arctic is investigated. Therefore, the terms in the diagnostic temperature equation in the Arctic-wide lower troposphere are examined for the Era-Interim atmospheric reanalysis product. Significant positive trends in diabatic heating rates, consistent with latent heat transfer to the atmosphere over regions of increasing ice melt, are found for all seasons over the Barents/Kara Seas, and in individual months in the vicinity of Svalbard. The above introduced warm (cold) advection trends during winter (summer) on Svalbard are successfully reproduced. Regarding winter, they are regionally confined to the Barents Sea and Fram Strait, between 70°-80°N, resembling a unique feature in the whole Arctic. Summer cold advection trends are confined to the area between eastern Greenland and Franz Josef Land, enclosing Svalbard.},
  language  = {en}
}
@article{Stottmeister2018,
  author    = {Stottmeister, Ulrich},
  title     = {Umweltgedanken zu Alexander von Humboldt},
  series = {HiN : Alexander von Humboldt im Netz ; International Review for Humboldtian Studies},
  volume    = {XVIII},
  journal   = {HiN : Alexander von Humboldt im Netz ; International Review for Humboldtian Studies},
  number    = {35},
  publisher = {Universit{\"a}tsverlag Potsdam},
  address   = {Potsdam},
  issn      = {1617-5239},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-419330},
  pages     = {75 -- 94},
  year      = {2018},
  abstract  = {Alexander von Humboldt hat auf der Grundlage des Wissens seiner Zeit in den Schlussfolgerungen zu seinen Messungen zu Boden, Luft und Wasser gelegentlich auch offene Fragen formuliert und Vermutungen ge{\"a}ußert. Es ist das Ziel dieses Beitrages, fr{\"u}he Ver{\"o}ffentlichungen daraufhin zu pr{\"u}fen, ob die damaligen Annahmen mit dem heutigen naturwissenschaftlichen Wissen best{\"a}tigt werden k{\"o}nnen. Nach einer Darstellung der „Umweltsituation" um 1800 folgt eine Diskussion der Anleitungen zur Beeinflussung der Bodenfruchtbarkeit und zur Ertragssteigerung. Humboldt erkannte bei seinen Untersuchungen zu methanhaltigen Grubengasen und der Erdatmosph{\"a}re einige uns heute aus der Klimadiskussion bekannte Effekte (z. B. die Rolle von Spurengasen auf die Eigenschaften von Gasmischungen, die Existenz atmosph{\"a}rischer Stoffkreisl{\"a}ufe). Weniger bekannt sind Humboldts umfassende praktische Anleitungen zum Bau des 50 km langen Entw{\"a}sserungstunnels „Meissner Erbstolln" unter geologischen, technischen, {\"o}konomischen und soziologischen Aspekten. Die zentrale Rolle von „dynamischen" Gleichgewichten wird am heutigen {\"o}kologischen Zustand des Sees von Valencia (Venezuela) erl{\"a}utert.},
  language  = {de}
}
@misc{PaesslerEtteHeydetal.2017,
  author    = {P{\"a}ßler, Ulrich and Ette, Ottmar and Heyd, Thomas and Rapisarda, Cettina and Schwarz, Ingo and Stottmeister, Ulrich and Hoppe, G{\"u}nter},
  title     = {HiN : Alexander von Humboldt im Netz},
  series = {HIN : Alexander von Humboldt im Netz ; international review for Humboldtian studies},
  volume    = {XVIII},
  journal   = {HIN : Alexander von Humboldt im Netz ; international review for Humboldtian studies},
  number    = {35},
  editor    = {Ette, Ottmar and Knobloch, Eberhard},
  publisher = {Universit{\"a}tsverlag Potsdam},
  address   = {Potsdam},
  issn      = {2568-3543},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-405028},
  pages     = {97},
  year      = {2017},
  abstract  = {Inhalt: -Ulrich P{\"a}ßler: Plantae des {\´E}tats-Unis Rediscovered Pages from Alexander von Humboldt's United States Diary -Ottmar Ette: Texto-isla y escritura archipi{\´e}lica: „Isle de Cube. Antilles en g{\´e}n{\´e}ral" de Alexander von Humboldt -Thomas Heyd: Alexander von Humboldt y la unidad de la naturaleza -Cettina Rapisarda: Lava memoriae deodati dolomieu Alexander von Humboldts Gesteinsstudien in Neapel -Ingo Schwarz: Fahndung nach geraubtem Gold und Silber - 1839 -Ulrich Stottmeister: Umweltgedanken zu Alexander von Humboldt -G{\"u}nter Hoppe: Ein Museumsdiebstahl vor 144 Jahren},
  language  = {de}
}
@phdthesis{Schmidt2014,
  author    = {Schmidt, Lukas},
  title     = {Aerosols and boundary layer structure over Arctic sea ice based on airborne lidar and dropsonde measurements},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-75076},
  school      = {Universit{\"a}t Potsdam},
  pages     = {vii, 98, xiii},
  year      = {2014},
  abstract  = {The atmosphere over the Arctic Ocean is strongly influenced by the distribution of sea ice and open water. Leads in the sea ice produce strong convective fluxes of sensible and latent heat and release aerosol particles into the atmosphere. They increase the occurrence of clouds and modify the structure and characteristics of the atmospheric boundary layer (ABL) and thereby influence the Arctic climate. In the course of this study aircraft measurements were performed over the western Arctic Ocean as part of the campaign PAMARCMIP 2012 of the Alfred Wegener Institute for Polar and Marine Research (AWI). Backscatter from aerosols and clouds within the lower troposphere and the ABL were measured with the nadir pointing Airborne Mobile Aerosol Lidar (AMALi) and dropsondes were launched to obtain profiles of meteorological variables. Furthermore, in situ measurements of aerosol properties, meteorological variables and turbulence were part of the campaign. The measurements covered a broad range of atmospheric and sea ice conditions. In this thesis, properties of the ABL over Arctic sea ice with a focus on the influence of open leads are studied based on the data from the PAMARCMIP campaign. The height of the ABL is determined by different methods that are applied to dropsonde and AMALi backscatter profiles. ABL heights are compared for different flights representing different conditions of the atmosphere and of sea ice and open water influence. The different criteria for ABL height that are applied show large variation in terms of agreement among each other, depending on the characteristics of the ABL and its history. It is shown that ABL height determination from lidar backscatter by methods commonly used under mid-latitude conditions is applicable to the Arctic ABL only under certain conditions. Aerosol or clouds within the ABL are needed as a tracer for ABL height detection from backscatter. Hence an aerosol source close to the surface is necessary, that is typically found under the present influence of open water and therefore convective conditions. However it is not always possible to distinguish residual layers from the actual ABL. Stable boundary layers are generally difficult to detect. To illustrate the complexity of the Arctic ABL and processes therein, four case studies are analyzed each of which represents a snapshot of the interplay between atmosphere and underlying sea ice or water surface. Influences of leads and open water on the aerosol and clouds within the ABL are identified and discussed. Leads are observed to cause the formation of fog and cloud layers within the ABL by humidity emission. Furthermore they decrease the stability and increase the height of the ABL and consequently facilitate entrainment of air and aerosol layers from the free troposphere.},
  language  = {en}
}
@phdthesis{Streibel2005,
  author    = {Streibel, Martin Albert Gerhard},
  title     = {Bestimmung von Ozonabbauraten {\"u}ber der Arktis und Antarktis mittels Ozonsonden- und Satellitendaten},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-6570},
  school      = {Universit{\"a}t Potsdam},
  year      = {2005},
  abstract  = {Diese Arbeit besch{\"a}ftigt sich mit der chemischen Ozonzerst{\"o}rung im arktischen und antarktischen stratosph{\"a}rischen Polarwirbel. Diese wird durch Abbauprodukte von anthropogen emittierten Fluorchlorkohlenwasserstoffen und Halonen, Chlor- und Bromradikale, verursacht. Studien in denen der gemessene und modellierte Ozonabbau verglichen wird zeigen, dass die Prozeße bekannt sind, der quantitative Verlauf allerdings nicht vollst{\"a}ndig verstanden ist. Die Prozesse, die zur Ozonzerst{\"o}rung f{\"u}hren sind in beiden Polarwirbeln {\"a}hnlich. Allerdings f{\"a}llt als Konsequenz unterschiedlicher meteorologischer Bedingungen der chemische Ozonabbau im arktischen Polarwirbel weniger drastisch aus als {\"u}ber der Antarktis. Der arktische Polarwirbel ist im Mittel st{\"a}rker dynamisch gest{\"o}rt als der antarktische und weist eine st{\"a}rkere Jahr-zu-Jahr Variabilit{\"a}t auf. Das erschwert die Messung des chemischen Ozonabbaus. Zur Trennung des chemischen Ozonabbaus von der dynamischen Umverteilung des Ozons im arktischen Polarwirbel wurde die Matchmethode entwickelt. Bei dieser Methode werden Luftpakete innerhalb des Polarwirbels mehrfach beprobt, um den chemischen Anteil der Ozon{\"a}nderung zu quantifizieren. Zur Identifizierung von doppelt beprobten Luftpaketen werden Trajektorien aus Windfeldern berechnet. K{\"o}nnen zwei Messungen im Rahmen bestimmter Qualit{\"a}tskriterien durch eine Trajektorie verbunden werden, kann die Ozondifferenz zwischen beiden Sondierungen berechnet und als chemischer Ozonabbau interpretiert werden. Eine solche Koinzidenz wird Match genannt. Der Matchmethode liegt ein statistischer Ansatz zugrunde, so dass eine Vielzahl solcher doppelt beprobter Luftmassen vorliegen muss, um gesicherte Aussagen {\"u}ber die Ozonzerst{\"o}rung gewinnen zu k{\"o}nnen. So erh{\"a}lt man die Ozonzerst{\"o}rung in einem bestimmten Zeitintervall, also Ozonabbauraten. Um die Anzahl an doppelt beprobten Luftpackten zu erh{\"o}hen wurde eine aktive Koordinierung der Ozonsondenaufstiege entwickelt. Im Rahmen dieser Arbeit wurden Matchkampagnen w{\"a}hrend des arktischen Winters 2002/2003 und zum ersten Mal w{\"a}hrend eines antarktischen Winter (2003) durchgef{\"u}hrt. Aus den gewonnenen Daten wurden Ozonabbauraten in beiden Polarwirbeln bestimmt. Diese Abbauraten dienen zum einen der Evaluierung von Modellen, erm{\"o}glichen aber auch den direkten Vergleich von Ozonabbauraten in beiden Polarwirbeln. Der Winter 2002/2003 war zu Beginn durch sehr tiefe Temperaturen in der mittleren und unteren Stratosph{\"a}re charakterisiert, so dass die Matchkampagne Ende November gestartet wurde. Ab Januar war der Polarwirbel zeitweise stark dynamisch gest{\"o}rt. Die Kampagne ging bis Mitte M{\"a}rz. F{\"u}r den H{\"o}henbereich von 400 bis 550 K potentieller Temperatur (15-23 km) konnten Ozonabbauraten und der Verlust in der Gesamts{\"a}ule berechnet werden. Die Ozonabbauraten wurden in verschiedenen Tests auf ihre Stabilit{\"a}t {\"u}berpr{\"u}ft. Der antarktische Polarwirbel war vom Beginn des Winters bis Mitte Oktober 2003 sehr kalt und stellte Ende September kurzzeitig den Rekord f{\"u}r die gr{\"o}ßte bisher aufgetretene Ozonloch-Fl{\"a}che ein. Es konnten f{\"u}r den Kampagnenzeitraum, Anfang Juni bis Anfang Oktober, Ozonabbauraten im H{\"o}henbereich von 400 bis 550 K potentieller Temperatur ermittelt werden. Der zeitliche Verlauf des Ozonabbaus war dabei auf fast allen H{\"o}henniveaus identisch. Die Zunahme des Sonnenlichtes im Polarwirbel mit der Zeit f{\"u}hrt zu einem starken Anwachsen der Ozonabbauraten. Ab Mitte September gingen die Ozonabbauraten auf Null zur{\"u}ck, da bis zu diesem Zeitpunkt das gesamte Ozon zwischen ca. 14 und 21 km zerst{\"o}rt wurde. Im letzten Teil der Arbeit wird ein neuer Algorithmus auf Basis der multivariaten Regression vorgestellt, mit dem Ozonabbauraten aus Ozonprofilen verschiedener Sensoren gleichzeitig berechnet werden k{\"o}nnen. Dabei k{\"o}nnen neben der Ozonabbaurate die systematischen Fehler zwischen den einzelnen Sensoren bestimmt werden. Dies wurde exemplarisch am antarktischen Winter 2003 f{\"u}r das 475 K potentielle Temperatur Niveau gezeigt. Neben den Ozonprofilen der Sonden wurden Daten von zwei Satellitenexperimenten verwendet. Die mit der multivariaten Matchtechnik berechneten Ozonabbauraten stimmen gut mit den Ozonabbauraten der Einzelsensor-Matchans{\"a}tze {\"u}berein.},
  subject      = {Ozon},
  language  = {de}
}