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The water vapor distribution in the upper troposphere–lower stratosphere (UTLS) region has a strong impact on the atmospheric radiation budget. Transport and mixing processes on different scales mainly determine the water vapor concentration in the UTLS. Here, we investigate the effect of mountain waves on the vertical transport and mixing of water vapor. For this purpose we analyze measurements of water vapor and meteorological parameters recorded by the DLR Falcon and NSF/NCAR Gulfstream V research aircraft taken during the Deep Propagating Gravity Wave Experiment (DEEPWAVE) in New Zealand. By combining different methods, we develop a new approach to quantify location, direction and irreversibility of the water vapor transport during a strong mountain wave event on 4 July 2014. A large positive vertical water vapor flux is detected above the Southern Alps extending from the troposphere to the stratosphere in the altitude range between 7.7 and 13.0 km. Wavelet analysis for the 8.9 km altitude level shows that the enhanced upward water vapor transport above the mountains is caused by mountain waves with horizontal wavelengths between 22 and 60 km. A downward transport of water vapor with 22 km wavelength is observed in the lee-side of the mountain ridge. While it is a priori not clear whether the observed fluxes are irreversible, low Richardson numbers derived from dropsonde data indicate enhanced turbulence in the tropopause region related to the mountain wave event. Together with the analysis of the water vapor to ozone correlation, we find indications for vertical transport followed by irreversible mixing of water vapor. For our case study, we further estimate greater than 1 W m−2 radiative forcing by the increased water vapor concentrations in the UTLS above the Southern Alps of New Zealand, resulting from mountain waves relative to unperturbed conditions. Hence, mountain waves have a great potential to affect the water vapor distribution in the UTLS. Our regional study may motivate further investigations of the global effects of mountain waves on the UTLS water vapor distributions and its radiative effects.

This case study of a warm conveyor belt (WCB) event that was probed on a research flight during the THORPEX (The Observing-System Research and Predictability Experiment) Pacific Asian Regional Campaign (T-PARC) field experiment in 2008, investigates the sensitivity of the forecast of the WCB, the associated cyclone and the downstream waveguide to the moisture content in the inflow region of the WCB. By assimilating water vapour profiles of a differential absorption lidar (DIAL) into the European Centre for Medium Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS), the inflow moisture in the analysis fields is adjusted and humidity is reduced in a broad region around the flight track. The initial reduction of moisture in the WCB inflow affects the latent heat release along the WCB, as well as the potential vorticity (PV) production at lower levels. This change led to a substantially lower outflow height of the forecasted WCB. Further, the height of the tropopause was reduced up to 20 hPa, which caused a change in the jet stream wind speeds of up to 15% downstream. Although the impact on the developing surface cyclone was small, improvements of the PV structure as well as of the kinetic energy could be identified.

Diese Arbeit beschreibt die Entwicklung des flugzeuggetragenen Atmosphärischen Ionisations-Massenspektrometers AIMS-H2O zur Messung von Wasserdampf in der oberen Troposphäre und unteren Stratosphäre (UTLS) und erste Flugzeugmessungen mit dem Instrument. Wasserdampf ist das wichtigste Treibhausgas in der Atmosphäre und die bestehenden Unsicherheiten in dessen Messung limitieren das Verständnis seines Einflusses auf die Dynamik und die Strahlungseigenschaften in der UTLS. Das Messprinzip von AIMS-H2O basiert auf der Ionisation von Luft in einer neuartigen Gasentladungsquelle und dem anschließenden Nachweis von H3O+(H2O)n-Ionen (n=1,2). Um die erforderliche hohe Genauigkeit zu erzielen, wird AIMS-H2O mit einem neu entwickelten Kalibrationsmodul im Flug kalibriert. Das Instrument kam auf dem Forschungsflugzeug Falcon während CONCERT 2011 erstmals zum Einsatz. Anhand zweier Fallstudien konnte sowohl die Eignung von AIMS-H2O zur Messung sehr niedriger stratosphärischer Feuchten als auch für Messung in Kondensstreifen und Zirren gezeigt werden. In jungen Kondensstreifen zeigen die Messungen, dass die hohe Konzentration der Eispartikel zu einer schnellen Relaxation der relativen Feuchte in Richtung Sättigung führt. In Zukunft wird AIMS-H2O auf HALO für die Messung von Wasserdampf bei ML-CIRRUS und weiteren Kampagnen eingesetzt.

The net impact of aviation on global climate results from a combination of individual contributions (e.g. from CO2, ozone, and methane changes, contrails). The various components are usually compared in terms of their respective radiative forcing, or in terms of advanced metrics (like the global warming potential) for which radiative forcing forms the key input. However, this only leads to sensible assessments if the efficacy of the contributing forcings is similar or equal, i.e. if each effect causes the same global temperature change per unit radiative forcing. A systematic comparison of efficacies is presented for the most important component forcings (as far as their effect has established in the framework of global climate models). The results are compiled from simulations with the ECHAM4/ATTILA climate model, which has been especially prepared for investigating aviation climate impact. The climate sensitivity of CO2 is rather well defined, i.e., its value is only moderately dependent on the CO2 radiative forcing amount over a wide range of concentration changes. The efficacy of contrails is significantly lower than that of CO2, a result which appears to be robust and confirms a similar conclusion drawn from simulations with other models. For other aviation forcings (ozone, methane, stratospheric water vapour) it is less easy to establish unique efficacy values. The difficulties are caused by non-linearities in the feedbacks that make the efficacy dependent on the extent of scaling of the original forcing. Moreover, methodical and model dependencies allow only preliminary conclusions at the present stage. Deeper understanding of the feedbacks caused by non-CO2 forcings within the model framework is necessary. Independent research with other models is also highly recommended.

Eidesstattliche Erklärung Vorwort und Dankeschön Zusammenfassung 1 Ausgangsfragen und Zielsetzungen des Projekts 2 Durchgeführte Feld- und Laborarbeiten 3 Ergebnisse und Interpretation 4 Grenzen des Isotopenbilanzmodells 5 Literatur A. Seebach, S. Dietz, D. Lessmann and K. Knöller. 2008. Estimation of lake water - groundwater interactions in meromictic mining lakes by modelling isotope signatures of lake water. Isotopes in Environmental and Health Studies, 44(1): 99-110. A. Seebach, C. von Rohden, J. Ilmberger, S.M. Weise and K. Knöller. 2010. Dating problems with selected mining lakes and the adjacent groundwater body in Lusatia, Germany. Isotopes in Environmental and Health Studies (in print). A. Seebach and K. Knöller. 2010. Water Balance Studies in Remote Areas – Limits and Possibilities in Evaluating Groundwater-Lake Water Interactions by Stable Isotopes. Journal of Hydrology (submitted). Lebenslauf Literaturliste, An drei Untersuchungsstandorten in der Niederlausitz wurde versucht, der monatliche Grundwassereintrag isotopenhydrologisch (Sauerstoff-18, Deuterium) zu berechnen. Die Untersuchungen wurden an zwei meromiktischen sowie einem polymiktischen Tagebausee durchgeführt. Ziel der Untersuchungen war es, die für durchmischte Seen etablierte isotopenhydrologische Bilanzgleichung zu abzuwandeln und damit die Bilanzierung geschichteter Seen zu ermöglichen. Ein weiterer Aspekt waren Studien zur Modifizierung des Craig & Gordon Modells von 1965 (Craig und Gordon, 1965) und dessen Anpassung an Gebiete hoher Luftfeuchtigkeit. Hierzu wurden über einen Untersuchungszeitraum von 2,5 Jahren zeitlich und räumlich hochaufgelöste Proben aus Grundwasser, Seewasser, Verdunstungs-pfannen, Niederschlag und Luftfeuchte genommen und isotopisch (δ18O, D) untersucht. Ferner wurden die meteorologischen Parameter Luftfeuchte und Lufttemperatur sowie die Oberflächenwassertemperatur der untersuchten Seen aufgezeichnet. Diese Daten wurden in einem Bilanzmodell zusammengeführt. Unglücklicherweise traten während des Untersuchungszeitraumes aufgrund der unbekannten hydrogeologischen Situation unvorhersehbare Schwierigkeiten mit der Bestimmung eines lokalen Backgroundwertes für die Isotopensignaturen des Grundwassers auf. Außerdem stellten die hydrodynamischen Rahmenbedingungen an allen drei Standorten die Bilanzierung vor eine Herausforderung. So schränken starke Seespiegelschwankungen durch den begleitenden Wechsel von effluenten und influenten Strömungsbedingungen die Anwendung der Isotopenbilanz enorm ein. Des Weiteren verliefen die Verdunstungsexperimente unter den lokalen meteorologischen Bedingungen nicht zufrieden stellend, was leider erst gegen ende des Untersuchungszeitraums erkannt wurde. Die Ergebnisse dieser Studie zeigen, dass die Anwendbarkeit des Isotopenbilanzmodells bezüglich der Quantifizierung von Grundwassereintragsraten durch die lokalen hydrogeologischen Verhältnisse stark limitiert werden kann. Dennoch konnte durch die umfassenden Gelände- und Laborarbeiten neben einem nahezu lückenlosen Datensatz für die drei Untersuchungsgebiete wertvolle Erkenntnisse zur Weiterführung dieses Projektes sowie zur Umsetzung bei zukünftigen ähnlichen Untersuchungen gewonnen werden. Hierzu zählen u.a. die Entwicklung einer Methode zur direkten isotopischen Bestimmung von Wasserdampf bzw. Evaporat. Ferner konnten für die untersuchten Standorte hochaufgelöste Local Meteoric Water Lines (LMWL) und Evaporation Lines (EL) generiert werden. Darüber hinaus konnten Erkenntnisse über die heterogenen Verteilungsmuster von Isotopensignaturen im Grund- und Seewasser gewonnen werden., The application of stable isotopes is a common tool for evaluating water balances of lakes. In this paper, we present a two-year isotope data set from three study sites in Lusatia, Eastern Germany, where pit lakes have been explored: Mine lake 107 (ML107), lake Waldsee and lake Moritzteich. ML107 is part of a pit lake area in the Lusatian Lignite District near Plessa. The latter two lakes are located in the Muskau Arch Fold, which is an ice-thrust ridge of a moraine formed by the Elsterian glaciation. Aim of the investigations was to quantify monthly groundwater recharge into pit lakes. Two of the three investigated lakes are meromictic, which makes it essential to adapt existing water balance models to permanently stratified lakes. For isotope analyses, high-resolution data sets of lake water, precipitation, and groundwater were collected in addition to comprehensive meteorological records of the three study sites. Evaporation pan experiments as well as the design of a special procedure for collecting monthly average samples of lake evaporate complete the survey of the isotope water balance concerning parameters. Unfortunately, unexpected problems arose during processing the work programme. Namely, the isotope signatures of the local groundwater bodies are not uniform in none of the investigated sites. Moreover, seasonal lake water level fluctuations accompany regular changes in the hydrodynamic system; surface water infiltration into the groundwater aquifer alternates with groundwater exfiltration into the lake water body. The results of this study show that the hydro-/geological setting at the study sites in the Muskau Arch Fold is far too complex for the application of well-established water balance models in terms of quantification of groundwater recharge. Furthermore, evaporation pan experiments carried out in the framework of these investigations do not bring any satisfactory results under local meteorological conditions. Regardless of problems mentioned above, the present work introduces a nearly complete high- resolution isotope data set from three mine lakes in the Lusatian Lignite District. So the first local meteoric water and evaporation line were generated for the study areas. The novel technique for sampling lake evaporate allowed obtaining more than thirty water samples which provided (discontinuous) records of isotope signatures of lake evaporate δE. For all evaluated components of the hydrological balance (precipitation, groundwater, lake water, lake evaporate) seasonal pattern were observed. Such as, the amplitude height of the temporal variations in surface lake water isotope composition was between 2.43 ‰ (Moritzteich) and 4.43 ‰ (ML107) for oxygen-18, respectively.

The »Radiometer for Atmospheric Measurements« is a passive microwave radiometer which measures the rotational emission lines of water vapor, ozone and chlorine monoxide. As part of the »Network for the Detection of Stratospheric Change« the RAM is situated in Ny-Ålesund at 79° North at the Spitsbergen archipelago. This location is special, because in arctic winter it mostly lies under the polar vortex which is essential for the measurement of chlorine activation and therefore the observation of ozone depletion.Since the designation of heterogenous chemistry as basic cause for the Antarctic ozone hole the observation of stratospheric chlorine monoxide is more important than ever. The RAM is the only instrument in the Arctic for long term monitoring of this crucial species. Within the scope of this work several improvements have been made on the instrument´s hard- and software. We will show measurements of stratospheric chlorine monoxide from 2000 which have been analyzed with a newly implemented retrieval software. In this context we will show measured diurnal chlorine monoxide cycles as well as the comparison to other instruments and models.As tracer for global warming and participant in catalytic ozone depletion water vapor is an important species for atmospheric physics. In the last decades stratospheric water vapor has increased noticeably in lower stratosphere which not can be explained by current theories. In this work we will present the technical realization of the new installed instrument, the water vapor retrieval software as well as some evaluated measurements.Tropospheric water vapor is also a disturbing factor to microwave measurements. In this work we have inspected several sites for their suitability as location of a newly planned 278 GHz chlorine monoxide radiometer. As result we discovered Summit in Greenland and Mérida in Venezuela as ideal places which eventually lead to the installation of two new instruments.