ALBERT

Description: The methane oxidation potential of active layer profiles of permafrost soils from the Lena Delta, Siberia, was studied with regard to its respond to temperature, and abundance and distribution of type I and type II methanotrophs. Our results indicate vertical shifts within the optimal methane oxidation temperature and within the distribution of type I and type II methanotrophs. In the upper active layer, maximum methane oxidation potentials were detected at 21°C. Deep active layer zones that are constantly exposed to temperatures below 2°C showed a maximum potential to oxidize methane at 4°C. Our results indicate a dominance of psychrophilic methanotrophs close to the permafrost table. Type I methanotrophs dominated throughout the active layer profiles but their number strongly fluctuated with depth. In contrast, type II methanotrophs were constantly abundant through the whole active layer and displaced type I methanotrophs close to the permafrost table. No correlation between in situ temperatures and the distribution of type I and type II methanotrophs was found. However, the distribution of type I and type II methanotrophs correlated significantly with in situ methane concentrations. Beside vertical fluctuations, the abundance of methane oxidizers also fluctuated according to different geomorphic units. Similar methanotroph cell counts were detected in samples of a flood plain and a polygon rim, whereas cell counts in samples of a polygon centre were up to 100 times lower.

Description: On 24 March 2007, an extraordinary dust plume was observed in the Central European troposphere. Satellite observations revealed its origins in a dust storm in Southern Ukraine, where large amounts of soil were resuspended from dried-out farmlands at wind gusts up to 30 m s?1. Along the pathway of the plume, maximum particulate matter (PM10) mass concentrations between 200 and 1400 ?g m?3 occurred in Slovakia, the Czech Republic, Poland, and Germany. Over Germany, the dust plume was characterised by a volume extinction coefficient up to 400 Mm?1 and a particle optical depth of 0.71 at wavelength 0.532 ?m. In-situ size distribution measurements as well as the wavelength dependence of light extinction from lidar and Sun photometer measurements confirmed the presence of a coarse particle mode with diameters around 2?3 ?m. Chemical particle analyses suggested a fraction of 75% crustal material in daily average PM10 and up to 85% in the coarser fraction PM10?2.5. Based on the particle characteristics as well as a lack of increased CO and CO2 levels, a significant impact of biomass burning was ruled out. The reasons for the high particle concentrations in the dust plume were twofold: First, dust was transported very rapidly into Central Europe in a boundary layer jet under dry conditions. Second, the dust plume was confined to a relatively stable boundary layer of 1.4?1.8 km height, and could therefore neither expand nor dilute efficiently. Our findings illustrate the capacity of combined in situ and remote sensing measurements to characterise large-scale dust plumes with a variety of aerosol parameters. Although such plumes from Southern Eurasia seem to occur rather infrequently in Central Europe, its unexpected features highlights the need to improve the description of dust emission, transport and transformation processes needs, particularly when facing the possible effects of further anthropogenic desertification and climate change.

Description: The quality of the retrieved temperature-versus-pressure (or T(p)) profiles is described for the middle atmosphere for the publicly available Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) Version 1.07 (V1.07) data set. The primary sources of systematic error for the SABER results below about 70 km are (1) errors in the measured radiances, (2) biases in the forward model, and (3) uncertainties in the corrections for ozone and in the determination of the reference pressure for the retrieved profiles. Comparisons with other correlative data sets indicate that SABER T(p) is too high by 1-3 K in the lower stratosphere but then too low by 1 K near the stratopause and by 2 K in the middle mesosphere. There is little difference between the local thermodynamic equilibrium (LTE) algorithm results below about 70 km from V1.07 and V1.06, but there are substantial improvements/differences for the non-LTE results of V1.07 for the upper mesosphere and lower thermosphere (UMLT) region. In particular, the V1.07 algorithm uses monthly, diurnally averaged CO2 profiles versus latitude from the Whole Atmosphere Community Climate Model. This change has improved the consistency of the character of the tides in its kinetic temperature (T(sub k)). The T(sub k) profiles agree with UMLT values obtained from ground-based measurements of column-averaged OH and O2 emissions and of the Na lidar returns, at least within their mutual uncertainties. SABER T(sub k) values obtained near the mesopause with its daytime algorithm also agree well with the falling sphere climatology at high northern latitudes in summer. It is concluded that the SABER data set can be the basis for improved, diurnal-to-interannual-scale temperatures for the middle atmosphere and especially for its UMLT region.

Description: In dieser Arbeit wird der Einfluss der bewölkten Atmosphäre auf die solaren Einstrahlung am Boden untersucht. Die zugrundeliegenden Messkampagnen wurden im Rahmen einer interdisziplinären Zusammenarbeit des Leibniz - Instituts für Meereswissenschaften (IFM-GEOMAR) mit dem Institut für Medizinische Klimatologie der Universität Kiel in den Sommern 2004 und 2005 auf der Nordseeinsel Sylt durchgeführt. Dabei wurde der Wolkenkamera-Prototyp des IFM-GEOMAR zur Erfassung der Wolken verwendet. Zur Bestimmung der Güte der Bedeckungsgradbestimmungen aus den Kamerbildern wurden Vergleiche mit synoptischen Beobachtungen des Deutschen Wetterdienstes DWD vom nahegelegenen Flughafen Sylt angestellt, sowie für die Kampagne 2005 mit einem neuen Verfahren, dem APCADA-Algorithmus nach Dürr und Philipona (2004). Die Übereinstimmung der aus den Kamerabildern resultierenden Bedeckungsrade mit den synoptischen Beobachtungen beträgt 72(85) % innerhalb ± 1(2) Achtel. Verglichen mit den Beobachtungen unterschätzt APCADA die Bedeckungsgrade in 47 % aller Fälle mit Übereinstimmung von 60(74) % innerhalb ± 1(2) Achtel. Für Fälle ohne hohe Wolken, die APCADA nicht erkennen kann, erreicht APCADA deutlich bessere Übereinstimmungen mit 73(90) % innerhalb ± 1(2) Achtel. Diese Ergebnisse sind etwas schlechter als die Resultate von Dürr und Philipona (2004). Insgesamt ergeben also die Bedeckungsgrade aus den Kamerabildern, zumindest tagsüber, die bessere Wolkenklimatologie. Dank der zeitlich hochaufgelösten Strahlungsmessungen konnten Strahlungserhöhungen im Sichtbaren von maximal 522 W/m2 gegenüber der theoretischen Referenzstrahlung bei wolkenfreiem Himmel festgestellt werden, der zur Zeit größte international veröffentlichte Wert. Erhöhungen 〉 400 W/m2 treten, wie Fallstudien zeigen, bei recht unterschiedlichen Bedeckungssituationen auf. Die Dauer solcher Erhöhungen ist abhängig von deren Stärke und beträgt maximal 20 Sekunden für Erhöhungen 〉 400 W/m2 und 140 Sekunden für Erhöhungen 〉 200 W/m2. Selbst über längere Zeiträume (1h) gemittelt ergeben sich noch Erhöhungen von 50 W/m2. Im hautwirksamen UV-Bereich (Er-UV) treten zeitgleich Erhöhungen auf, maximal wurden 32 mW/m2 gemessen. Die relative Erhöhungen sind indess deutlich geringer als im Sichtbaren, maximal 59 % gegenüber 82 %. Diese Werte treten aber fast nur bei tiefstehender Sonne auf, wo die Gefahr für die menschliche Haut (Sonnenbrand) gering ist. Im Mittel wurden die stärksten Erhöhungen sowohl im Sichtbaren als auch im Er-UV-Bereich bei fast komplett bedecktem Himmel, mit Altocumuluswolken nahe der Sonnenscheibe erreicht, sowie bei tiefstehenden Cumuluswolken (z.B. Estupinan et al., 1996). Abschließende Strahlungstransportrechnungen für bewölkte 3D-Atmosphären mit dem am IFM-GEOMAR entwickelten Modell GRIMALDI bestätigen die beobachtete Wellenlängenabhängigkeit der relativen Strahlungserhöhungen (siehe auch Lovengreen et al., 2005) und stimmen zumindest im Sichtbaren relativ gut mit den Messungen überein. Zudem wird deutlich, dass diffuse Streuung bei allen untersuchten Wellenlängen einen erkennbar stärkeren Anteil an Strahlungserhöhungen hat, als Reflexion an Wolkenseiten, was die Messergebnisse bereits vermuten ließen.

Description: A major stratospheric sudden warming (SSW) in January 2009 was the strongest and most prolonged on record. Aura Microwave Limb Sounder (MLS) observations are used to provide an overview of dynamics and transport during the 2009 SSW, and to compare with the intense, long-lasting SSW in January 2006. The Arctic polar vortex split during the 2009 SSW, whereas the 2006 SSW was a vortex displacement event. Winds reversed to easterly more rapidly and reverted to westerly more slowly in 2009 than in 2006. More mixing of trace gases out of the vortex during the decay of the vortex fragments, and less before the fulfillment of major SSW criteria, was seen in 2009 than in 2006; persistent well-defined fragments of vortex and anticyclone air were more prevalent in 2009. The 2009 SSW had a more profound impact on the lower stratosphere than any previously observed SSW, with no significant recovery of the vortex in that region. The stratopause breakdown and subsequent reformation at very high altitude, accompanied by enhanced descent into a rapidly strengthening upper stratospheric vortex, were similar in 2009 and 2006. Many differences between 2006 and 2009 appear to be related to the different character of the SSWs in the two years.

Description: A major stratospheric sudden warming (SSW) in January 2009 was the strongest and most prolonged on record. Aura Microwave Limb Sounder (MLS) observations are used to provide an overview of dynamics and transport during the 2009 SSW, and to compare with the intense, long-lasting SSW in January 2006. The Arctic polar vortex split during the 2009 SSW, whereas the 2006 SSW was a vortex displacement event. Winds reversed to easterly more rapidly and reverted to westerly more slowly in 2009 than in 2006. More mixing of trace gases out of the vortex during the decay of the vortex fragments, and less before the fulfillment of major SSW criteria, was seen in 2009 than in 2006; persistent well-defined fragments of vortex and anticyclone air were more prevalent in 2009. The 2009 SSW had a more profound impact on the lower stratosphere than any previously observed SSW, with no significant recovery of the vortex in that region. The stratopause breakdown and subsequent reformation at very high altitude, accompanied by enhanced descent into a rapidly strengthening upper stratospheric vortex, were similar in 2009 and 2006. Many differences between 2006 and 2009 appear to be related to the different character of the SSWs in the two years.

Description: BASEWECS is a contribution to the German Climate Research Program DEKLIM. The project started in May 2001 and lasted until December 2004. BASEWECS aimed at the investigation of the influence of the Baltic Sea and its annual ice coverage on the water and energy budget of the BALTEX area

Description: Deep-sea whale falls create sulfidic habits Supporting chemoautotrophic communities, but microbial processes underlying the formation Of Such habitats remain poorly evaluated. Microbial degradation processes (sulfate reduction, methanogenesis) and biogeochemical gradients were studied in a whale-fall habitat created by a 30 t whale carcass deployed at 1675 m depth for 6 to 7 yr on the California margin. A variety of measurements were conducted including photomosaicking, microsensor measurements, radio-tracer incubations and geochemical analyses. Sediments were Studied at different distances (0 to 9 in) from the whale fall. Highest microbial activities and steepest vertical geochemical gradients were found within 0.5 m of the whale fall, revealing ex situ sulfate reduction and in vitro methanogenesis rates of up to 717 and 99 mmol m(-2) d(-1), respectively. In sediments containing whale biomass, methanogenesis was equivalent to 20 to 30%, of sulfate reduction. During in vitro sediment studies, sulfide and methane were produced within days to weeks after addition of whale biomass, indicating that chemosynthesis is promoted at early stages of the whale fall. Total sulfide production from sediments within 0.5 m of the whale fall was 2.1 +/- 3 and 1.5 +/- 2.1 mol d(-1) in Years 6 and 7, respectively, of which similar to 200 mmol d(-1) were available as free sulfide. Sulfate reduction in bones was much lower, accounting for a total availability of similar to 10 mmol sulfide d(-1). Over periods of at least 7 yr, whale falls can create sulfidic conditions similar to other chemosynthetic habitats Such as cold seeps and hydrothermal vents.

Description: About 24 % of the land surface in the northern hemisphere are underlayed by permafrost in various states. Permafrost aggradation occurs under special environmental conditions with overall low annual precipitation rates and very low mean annual temperatures. Because the general permafrost occurrence is mainly driven by large-scale climatic conditions, the distribution of permafrost deposits can be considered as an important climate indicator. The region with the most extensive continuous permafrost is Siberia. In northeast Siberia, the ice- and organic-rich permafrost deposits of the Ice Complex are widely distributed. These deposits consist mostly of silty to fine-grained sandy sediments that were accumulated during the Late Pleistocene in an extensive plain on the then subaerial Laptev Sea shelf. One important precondition for the Ice Complex sedimentation was, that the Laptev Sea shelf was not glaciated during the Late Pleistocene, resulting in a mostly continuous accumulation of permafrost sediments for at least this period. This shelf landscape became inundated and eroded in large parts by the Holocene marine transgression after the Last Glacial Maximum. Remnants of this landscape are preserved only in the present day coastal areas. Because the Ice Complex deposits contain a wide variety of palaeo-environmental proxies, it is an excellent palaeo-climate archive for the Late Quaternary in the region. Furthermore, the ice-rich Ice Complex deposits are sensible to climatic change, i.e. climate warming. Because of the large-scale climatic changes at the transition from the Pleistocene to the Holocene, the Ice Complex was subject to extensive thermokarst processes since the Early Holocene. Permafrost deposits are not only an environmental indicator, but also an important climate factor. Tundra wetlands, which have developed in environments with aggrading permafrost, are considered a net sink for carbon, as organic matter is stored in peat or is syn-sedimentary frozen with permafrost aggradation. Contrary, the Holocene thermokarst development resulted in permafrost degradation and thus the release of formerly stored organic carbon. Modern tundra wetlands are also considered an important source for the climate-driving gas methane, originating mainly from microbial activity in the seasonal active layer. Most scenarios for future global climate development predict a strong warming trend especially in the Arctic. Consequently, for the understanding of how permafrost deposits will react and contribute to such scenarios, it is necessary to investigate and evaluate ice-rich permafrost deposits like the widespread Ice Complex as climate indicator and climate factor during the Late Quaternary. Such investigations are a pre-condition for the precise modelling of future developments in permafrost distribution and the influence of permafrost degradation on global climate. The focus of this work, which was conducted within the frame of the multi-disciplinary joint German-Russian research projects "Laptev Sea 2000" (1998-2002) and "Dynamics of Permafrost" (2003-2005), was twofold. First, the possibilities of using remote sensing and terrain modelling techniques for the observation of periglacial landscapes in Northeast Siberia in their present state was evaluated and applied to key sites in the Laptev Sea coastal lowlands. The key sites were situated in the eastern Laptev Sea (Bykovsky Peninsula and Khorogor Valley) and the western Laptev Sea (Cape Mamontovy Klyk region). For this task, techniques using CORONA satellite imagery, Landsat-7 satellite imagery, and digital elevation models were developed for the mapping of periglacial structures, which are especially indicative of permafrost degradation. The major goals were to quantify the extent of permafrost degradation structures and their distribution in the investigated key areas, and to establish techniques, which can be used also for the investigation of other regions with thermokarst occurrence. Geographical information systems were employed for the mapping, the spatial analysis, and the enhancement of classification results by rule-based stratification. The results from the key sites show, that thermokarst, and related processes and structures, completely re-shaped the former accumulation plain to a strongly degraded landscape, which is characterised by extensive deep depressions and erosional remnants of the Late Pleistocene surface. As a results of this rapid process, which in large parts happened within a short period during the Early Holocene, the hydrological and sedimentological regime was completely changed on a large scale. These events resulted also in a release of large amounts of organic carbon. Thermokarst is now the major component in the modern periglacial landscapes in terms of spatial extent, but also in its influence on hydrology, sedimentation and the development of vegetation assemblages. Second, the possibilities of using remote sensing and terrain modelling as a supplementary tool for palaeo-environmental reconstructions in the investigated regions were explored. For this task additionally a comprehensive cryolithological field database was developed for the Bykovsky Peninsula and the Khorogor Valley, which contains previously published data from boreholes, outcrops sections, subsurface samples, and subsurface samples, as well as additional own field data. The period covered by this database is mainly the Late Pleistocene and the Holocene, but also the basal deposits of the sedimentary sequence, interpreted as Pliocene to Early Pleistocene, are contained. Remote sensing was applied for the observation of periglacial strucures, which then were successfully related to distinct landscape development stages or time intervals in the investigation area. Terrain modelling was used for providing a general context of the landscape development. Finally, a scheme was developed describing mainly the Late Quaternary landscape evolution in this area. A major finding was the possibility of connecting periglacial surface structures to distinct landscape development stages, and thus use them as additional palaeo-environmental indicator together with other proxies for area-related palaeo-environmental reconstructions. In the landscape evolution scheme, i.e. of the genesis of the Late Pleistocene Ice Complex and the Holocene thermokarst development, some new aspects are presented in terms of sediment source and general sedimentation conditions. This findings apply also for other sites in the Laptev Sea region.

Description: In the framework of the European Project STAR the Mobile Aerosol Raman Lidar (MARL) of the Alfred Wegener Institute (AWI) was operated in Paramaribo, Suriname (5.8°N, 55.2°W), and carried out extensive observations of tropical cirrus clouds during the local dry season from 28 September 2004 to 16 November 2004. The coverage with ice clouds was very high with 81% in the upper troposphere (above 12 km). The frequency of occurrence of subvisual clouds was found to be clearly enhanced compared to similar observations performed with the same instrument at a station in the midlatitudes. The extinction-to-backscatter ratio of thin tropical cirrus is with 26 ± 7 sr significantly higher than that of midlatitude cirrus (16 ± 9 sr). Subvisual cirrus clouds often occur in the tropical tropopause layer (TTL) above an upper tropospheric inversion. Our observations show that the ice-forming ability of the TTL is very high. The transport of air in this layer was investigated by means of a newly developed trajectory model. We found that the occurrence of clouds is highly correlated with the temperature and humidity history of the corresponding air parcel. Air that experienced a temperature minimum before the measurement took place was generally cloud free, while air that was at its temperature minimum during the observation and thus was saturated contained ice. We also detected extremely thin cloud layers slightly above the temperature minimum in subsaturated air. The solid particles of such clouds are likely to consist of nitric acid trihydrate (NAT) rather than ice.

Description: During the European heat wave summer 2003 with predominant high pressure conditions we performed a detailed study of upper tropospheric humidity and ice particles which yielded striking results concerning the occurrence of ice supersaturated regions (ISSR), cirrus, and contrails. Our study is based on lidar observations and meteorological data obtained at Lindenberg/Germany (52.2° N, 14.1° E) as well as the analysis of the European centre for medium range weather forecast (ECMWF). Cirrus clouds were detected in 55% of the lidar profiles and a large fraction of them were subvisible (optical depth 〈0.03). Thin ice clouds were particularly ubiquitous in high pressure systems. The radiosonde data showed that the upper troposphere was very often supersaturated with respect to ice. Relating the radiosonde profiles to concurrent lidar observations reveals that the ISSRs almost always contained ice particles. Persistent contrails observed with a camera were frequently embedded in these thin or subvisible cirrus clouds. The ECMWF cloud parametrisation reproduces the observed cirrus clouds consistently and a close correlation between the ice water path in the model and the measured optical depth of cirrus is demonstrated.

Description: A number of field-campaigns in the tropics have been conducted in recent years with two different LIDAR systems at Paramaribo (5.8° N, 55.2° W), Suriname. The lidars detect particles in the atmosphere with high vertical and temporal resolution and are capable of detecting extremely thin cloud layers which frequently occur in the tropical tropopause layer (TTL). Radiosonde as well as operational ECMWF analysis showed that equatorial Kelvin waves propagated in the TTL and greatly modulated its temperature structure. We found a clear correlation between the temperature anomalies introduced by these waves and the occurrence of thin cirrus in the TTL. In particular we found that extremely thin ice clouds form regularly where cold anomalies shift the tropopause to high altitudes. These findings suggest an influence of Kelvin wave activity on the dehydration in the TTL and thus on the global stratospheric water vapour concentration.

Description: Biogeochemical properties of the winterly upper water column between Madeira and Azores

Description: How warm, wet, and stormy will the next decade be? This question and how to answer it – decadal climate prediction – is currently generating a large amount of interest in the research community. The interest stems from the growing awareness that climate varies naturally on decadal time scales, both regionally and globally, with large socio-economic consequences, and has the potential to temporarily offset or exacerbate anthropogenic global warming. The aim here is to discuss the current status of decadal prediction and highlight areas where the stratosphere may play an important role.

Description: Es existieren eine Reihe von Beobachtungs- und Modellstudien, die ein Signal von El Niño/ Southern Oscillation (ENSO) in der Stratosphäre zeigen. Der Einfluss von ENSO auf das Europäische Klima wird immer stärker diskutiert. In der vorliegenden Arbeit wird der Einfluss von ENSO auf die extratropische Nordhemisphäre im Winter mit Hilfe des allgemeinen Zirkulationsmodells ECHAM5 untersucht. Dabei wird speziell auf die Rolle der Stratosphäre mit Analysen von zwei unterschiedlich hohen vertikalen Auflösungen des ECHAM5-Modells eingegangen. Dafür werden die durch Meeresoberflächentemperaturen angetriebenen Simulationen zwei verschiedener Modellversionen des ECHAM5 analysiert. Unter Nutzung des 19-Schichten ("niedriges Rand") Modells (L19), mit einem Modelloberrad in 10 hPa (ca. 30 km Höhe), werden 6 Läufe ausgewertet, die eine Periode von 1900 bis 1998 abdecken. Ein Ensemble aus 5 Läufen steht mit dem L39-Schichten ("hohes Rand") Modell (0.01 hPa, ~80 km Höhe) für den Zeitraum 1950 bis 2005 zur Verfügung. Beide Modellversionen besitzen eine horizontale Auflösung von T31 (3,75° x 3,75°). Die Anomaliemuster in der Troposphäre zeigen eine weitgehende übereinstimmung zu früheren Arbeiten. In den Anomalien für El Niño Ereignisse ist der beobachtete warme und schwache stratosphärische Polarwirbel, aufgrund erhöhter planetarischer Wellenaktivität feststellbar. Es wird gezeigt, dass die Unterschiede im stratosphärischen Signal für die ENSO-Warm- und Kaltphase mit einer unterschiedlichen Wellenanregung- und ausbreitung für die beide ENSO-Phasen erklärt werden kann. Damit wird ein annähernd umgekehrtes Signal mit einer Verstärkung und Abkühlung des Polarwirbels für La Niña Ereignisse gezeigt. Die beobachtete saisonale Entwicklung der Anomalien in der Stratosphäre werden vom L39-Modell mit einem Monat Verzögerung simuliert. Signifikante Telekonnektionsmuster in der Stratosphäre, die mit den Beobachtungen übereinstimmen, werden nur für die L39-Modellversion gefunden. Mit der Abschwächung und der Erwärmung kommt es zu häufigeren Major Warmings. Das damit verbundene Abwärtswandern der positiven Anomalie konnte für den Mitt- und Spätwinter simuliert werden. Neueste, aus Beobachtungen gewonnene Resultate zeigen während eines El Ni\~nos ein Signal am Boden im Nordeuropäischen Raum, welches der negativen NAO-Phase entspricht. übereinstimmend mit der Entwicklung der Anomalien über die Höhe, zeigt sich ein Wechsel der Muster im Mitt- bis Spätwinter am Boden. Die negative NAO-Phase wird für ERA40 im Mitt- und für L39 im Spätwinter festgestellt. Der Vergleich von unterschiedlichen Modellversionen untereinander und mit Beobachtungen, kann unser Verständnis der ablaufenden atmosphärischen Prozesse verbessern. Ebenso ist eine Schätzung möglich, ob Telekonnektion durch die Stratosphäre eine Quelle zur Verbesserung der saisonalen Vorhersage für den nordeuropäischen Winter sein kann.

Description: In this PhD thesis the diversity of functional bacterial genes in the nitrogen cycle was investigated with molecular methods in the lakes Plußsee and Schöhsee, and the Baltic Sea. The diversity of ammonia-oxidizing bacteria (AOB) was studied by diversity of specific 16S rDNA and amoA genes. Dominant sequences from Baltic Sea water column and Schöhsee 1 m were related to different Nitrosospira clusters. Sequences from Plußsee 7 m, Schöhsee 12 m and sediment of both lakes were clustered into a purely environmental cluster with no cultivated representatives. Two groups of amoA sequences from Baltic Sea sediment were related to environmental clusters from brackish and marine habitats. The diversity of the evolutionarily related genes for ammonia monooxygenase (AMO) and particulate methane monooxygenase (pMMO) was analyzed. A higher frequency of pmoA sequences, mainly belonging to methane oxidizing bacteria of the gamma subgroup of proteobacteria (g-MOB), was detected. Dominant amoA sequences were related to ammonia oxidizing bacteria of the beta subgroup of proteobacteria (b-AOB), no sequences related to amoA of the γ-AOB were detected. The deduced amino acid sequences of some clones from lake sediments were distantly related to PmoA from Crenothrix polyspora, a filamentous methane oxidizer with an unusual methane monooxygenase. The distribution of denitrifying bacteria was studied by the nitrite reductase genes nirK and nirS. The dominant sequences of nirK from all clone libraries belonged to two distinct phylogenetic clusters, while nirS sequences from both lakes were scattered over several clusters throughout the complete phylogenetic tree, and only few sequences from Baltic Sea overlapped. In the Baltic Sea, nirK-denitrifiers were diverse throughout the water column, while nirS-denitrifiers were dominant in the sediment and almost absent in the water column. In Plußsee the community composition was inverted: nirK-denitrifiers were more diverse in the water column and nirS-denitrifiers in the sediment. In Schöhsee nirS-denitrifiers were highly diverse in water and sediment samples. For nirK and nirS the sequences of the protein were less conserved than those of the gene while the amoA and pmoA protein were conserved, which might be an indication of a differential selection pressure.

Description: In this study the dynamics of the coupled troposphere/stratosphere system was investigated using the atmospheric circulation model MAECHAM5/ocean mixed layer coupled model. The focus was on the impact of the stratosphere on the troposphere. The January climatology of the model agrees well with the observations, especially in the extratropical region and below the uppermost model levels (where the sponging effect is strong). The dynamics that maintains the middle atmospheric circulation in MAECHAM5 is consistent with the middle atmospheric dynamics known from previous studies. The three-dimensional structure of the Northern Annular Mode (NAM) in MAECHMA5 agrees well with that observed. The NAM dominates not only the variability in but also the covariability between troposphere and stratosphere north of 20°N. A lag composite analysis based on the 50hPa NAM-Index (NAMI), a measure of the strength of the 'stratospheric mode', shows that strongly positive stratospheric NAM-phases are associated with strong anomalous westerlies in high latitudes and a temperature quadrupole between troposphere and lower mesosphere. The lower part of this quadrupole shows a dipole structure with an anomalous cold (warm) polar (mid-latitude) troposphere and stratosphere and is associated with a positive shear of the anomalous westerlies there. This dipole strengthens (weakens), together with the anomalous westerlies, in the NAM-increase (decrease) phase. The upper part of the temperature quadrupole shows a coherent dipole with an anomalous warm (cold) polar (mid-latitude) upper stratosphere and lowermost mesosphere and is associated with a negative shear of the anomalous zonal flow there. The warm pole in mesosphere and upper stratosphere strengthens and propagates downward together with anomalous easterlies, especially in the NAM-decrease phase. The dynamics during strong vortex is analyzed by computing the wave, residual Coriolis, and non-resolved (residual) forcing in the Transformed Eulerian Mean formulation (TEM). NAM temperature, zonal flow and geopotential height patterns and their downward propagation can be explained by the response of the stretching vorticity to residual Coriolis forcing changes, which are caused by the resolved and non-resolved wave forcing, and by quasigeostrophic adjustment of the troposphere to these changes. The persistence, increase, and downward propagation of the NAM-patterns is enhanced mainly by the planetary wave-vortex feedback that accelerates the westerlies within the coupled troposphere/stratosphere system. Thereby the strong vortex is strengthened further by the equatorward propagation of planetary waves and vice versa. The decrease and modulation of the strong NAM-anomalies is enhanced by two negative feedbacks that decelerate the westerlies in the upper and lower boundaries of the coupled troposphere/stratosphere system. The first feedback is a vortex-residual forcing feedback acting in upper stratosphere and lower mesosphere and can be explained by the filtering of gravity waves by the stratospheric jet. The second feedback acts near the lower boundary and is driven by both residual and planetary wave forcing. A lag composite analysis based on the 1000hPa-NAMI, a measure of the strength of the 'tropospheric mode', showed that tropospheric and stratospheric NAM are two different modes driven by two different forcings. In the tropospheric mode the tropospheric westerlies are induced by a strong internal wave forcing, which develops inside the troposphere on a synoptical time scale. This results in stronger tropospheric westerlies in the tropospheric mode. The stratosphere is also important in the tropospheric mode: It provides the upper troposphere with a low frequency westerly wind and wind shear and thus with enhanced baroclinicity that are associated with an amplification of the upper tropospheric wave, Coriolis and residual forcing. This forcing amplification leads then to an increase of the tropospheric circulation anomalies, which results in anomalous ascent and cooling in the Arctic and thus in a strong vortex that reaches its maximum 4-5 days later. The strong vortex contributes, through the stretching vorticity mechanism and the vortex-planetary waves forcing, to the persistence of both tropospheric and stratospheric westerlies and cooling. The stratospheric westerlies are much weaker in the tropospheric than in the stratospheric mode due to the much lower contribution of the planetary waves to the stratospheric wind anomalies in the tropospheric mode.

Description: The aim of this thesis is to improve the mechanistic understanding of nitrogen fixation by the marine non-heterocystous cyanobacterium Trichodesmium. This diazotroph is a major contributor to the marine nitrogen cycle and thus is important for parameterizations for nitrogen fixation in Ocean Biogeochemical Circulation Models. A wide-ranging amount of information on ecophysiological characteristics of Trichodesmium has been published and is summarized in a literature review (chapter I). This review stresses that Trichodesmium abundance in the open ocean can be limited by the nutrients iron and/or phosphorus and is constrained by the physical parameters temperature and light. Nevertheless, chapter I also identifies that the effects of temperature and light availability on diazotrophic growth of Trichodesmium were not fully understood and required further investigation. Laboratory results (chapter III) demonstrate that Trichodesmium N2 fixation is confined to water temperatures of 20 – 34 °C with an optimum range of 24 – 30 °C. These findings are of particular interest with respect to global warming, considering the important role of Trichodesmium in the marine nitrogen cycle. Combining these data with climate models (HadCM3 and GFDL R30) chapter III predicts a future decline in the fixed nitrogen input by Trichodesmium that could significantly affect marine nitrogen cycling within this century. Chapters IV and V address the role of light for diazotrophic growth of Trichodesmium. Results show that Trichodesmium is well adapted to the light regimes throughout the euphotic zone of tropical and subtropical oceans. The carbon specific growth rate increases up to an irradiance of 180 μmol quanta m-2 s-1, and is constant (0.26 d-1) thereafter up to 1100 μmol quanta m-2 s-1, where light inhibition sets in. The maximum nitrogen fixation rate measured was 350 nmol N2 fixed l-1 h-1. Chapter IV further provides a simple numerical model to describe nitrogen input into seawater by Trichodesmium as a function of light intensity. This outcome is complemented by a conceptual model of nitrogen and carbon fixation of Trichodesmium presented in Chapter V. Additionally, a reassessment of a commonly applied method to measure nitrogen fixation (Acetylene Reduction Assay) was conducted (chapter II). This method was improved by providing newly derived ethylene gas solubility coefficients that are required to accurately calculate nitrogen fixation rates. These were previously unavailable from published literature and thus the presented publication contributes to a standardization of nitrogen fixation measurements. Further methodological approaches to assess nitrogen fixation and release of fixed nitrogen by diazotrophs are provided in an outlook for future work in chapter V.

Description: The results of this study show that close boats (〈100 m) affect the behaviour of bottlenose dolphins more strongly than boats further away (〉100 m). Close boats induced a decrease of feeding, resting and social behaviour. The proportions of high-speed swimming and slow swimming increased. In the presence of close boats, dolphins were observed 6 times more frequently to leap and 3.6 times more frequently to tail-slap than under control conditions – an indication of disturbance. Dolphins responded to close boats with evasive manoeuvres similar to techniques used for avoiding predators. With more than two close boats, animals swam approx. 37% faster than without close boats. An energy consumption of 2.93 W kg-1 was calculated. This corresponds to a daily energy demand of 50.6 MJ per dolphin with 200 kg body weight. With boats at close range, the mean power requirement of dolphins was around 15.4% higher than during controls. With close boats, dolphins used a third of their energy budget to avoid boats by swimming at high speed. In the light of these findings, recommendations for dolphin-watching guidelines are given.

Description: We investigated the effect of seasonal environmental changes on the rate and distribution of anaerobic oxidation of methane (AOM) in Eckernforde Bay sediments (German Baltic Sea) and identified organisms that are likely to be involved in the process. Surface sediments were sampled during September and March. Field rates of AOM and sulfate reduction (SR) were measured with radiotracer methods. Additional parameters were determined that potentially influence AOM, i.e., temperature, salinity, methane, sulfate, and chlorophyll a. Methanogenesis as well as potential rates of AOM and aerobic oxidation of methane were measured in vitro. AOM changed seasonally within the upper 20 cm of the sediment, with rates being between 1 and 14 nmol cm(-3) d(-1). Its distribution is suggested to be controlled by oxygen and sulfate penetration, temperature, as well as methane supply, leading to a shallow AOM zone during the warm productive season and to a slightly deeper AOM zone during the cold winter season. Rising methane bubbles apparently fed AOM above the sulfate-methane transition. Methanosarcinales-related anaerobic methanotrophs (ANME-2), identified with fluorescence in situ hybridization, is suggested to mediate AOM in Eckerntorde Bay. These archaea are known also from other marine methane-rich locations. However, they were not directly associated with sulfate-reducing bacteria. AOM is possibly mediated solely by these archaea that show a mesophilic physiology according to the seasonal temperature changes in Eckernforde Bay.

Description: In late May 2005 unusual high levels of solar ultraviolet radiation were observed over central Europe. In Northern Germany the measured irradiance of erythemally effective radiation exceeded the climatological mean by more than about 20%. An extreme low ozone event for the season coincided with high solar elevation angles and high pressure induced clear sky conditions leading to the highest value of erythemal UV-radiation ever observed over this location in May since 1994. This hereafter called "ozone mini-hole" was caused by an elevation of tropopause height accompanied with a poleward advection of ozone-poor air from the tropics. The resultant increase in UV-radiation is of particular significance for human health. Dynamically induced low ozone episodes that happen in late spring can considerably enhance the solar UV-radiation in mid latitudes and therefore contribute to the UV-burden of people living in these regions.

Description: In late May 2005 unusual high levels of solar ultraviolet radiation were observed over central Europe. In Northern Germany the measured irradiance of erythemally effective radiation exceeded the climatological mean by more than about 20%. An extreme low ozone event for the season coincided with high solar elevation angles and high pressure induced clear sky conditions leading to the highest value of erythemal UV-radiation ever observed over this location in May since 1994. This hereafter called "ozone mini-hole" was caused by an elevation of tropopause height accompanied with a poleward advection of ozone-poor air from the tropics. The resultant increase in UV-radiation is of particular significance for human health. Dynamically induced low ozone episodes that happen in late spring can considerably enhance the solar UV-radiation in mid latitudes and therefore contribute to the UV-burden of people living in these regions.

Description: The cooperative research project between Chinese and German leading marine research institutions, the Guangzhou Marine Geological Survey (GMGS) and Leibniz-Institut für Meereswissenschaften Kiel (IFM-GEOMAR) addressed the geological methane budget and environmental effects of methane emissions from gas hydrates along the passive margin of the northern South China Sea. Two areas were surveyed of which the NE area (A) was sampled in great detail, whereas area B, after an initial survey, yielded less promising results. Swath map bathymetry, ocean floor observation by continuous video survey (OFOS) and water column methane distribution pattern provided the basis for locating several sites of ongoing methane venting. Outstanding among these was a methane-derived carbonate structure in water depths of 600-900m. Vast accumulations of vent carbonate debris, pavements and edifices standing above the seafloor characterize this structure. A 30-m high edifice, named Jiu Long Methane Reef, proved to be an active cold vent site with chemosynthetic fauna and bacterial mats. At deep sites ( apprx. 3000m) in and adjacent to the Formosa Canyon methane anomalies in the bottom water and clam colonies also indicate active methane venting. Pore water and gas chemistry on gravity cores indicated rather shallow depths of the sulfate-methane-interface (SMI) and documented chloride anomalies. High methane concentrations (exceeding 10.000 μM) in sediments, which when extrapolated, suggest that saturation might be reached at about 16-24 mbsf at which depths the shallowest gas hydrates might be encountered in the area. The project results contribute directly to several major science policy missions. (1) Documentation of vast amounts of methane emmited from the passive margin of the northern South China Sea is seen as evidence for long-term climate forcing by the greenhouse gas methane. (2) The functioning and significance of deep-sea biota as modulating the greenhouse gas budget is convincingly demonstrated by the vast amounts of methane carbon fixed as authigenic carbonates. (3) Further development of TV-guided deep-sea instrumentation, and above all the retrieval of undecompressed sediments, have again been deomonstrated as high a priority topic for the future of marine science. (4) The success of the project has demonstrated how international partnerships can efficiently been implemented.

Description: Fouling communities are distributed worldwide, particularly in shallow and exposed marine systems. Due to their fast growth and their capacity to settle on artificial surfaces, these assemblages represent a suitable study system for ecologists and are therefore often used to investigate ecological models. Investigating broad scale ecological models has been of key interest since the time of the famous naturalist Charles Darwin. Two examples of well recognized macro-ecological patterns are i) the ‘latitudinal gradient of species richness’ and ii) the ‘relationship between local and regional diversity’. The first is the oldest paradigm about a large-scale ecological pattern and simply states that the tropical regions are richer in species than temperate and polar regions at higher latitudes. However, when exploring global diversity patterns, it is essential to comprehend not only the importance of differences in spatial scale for the observed patterns, but also how diversity at one scale may relate to diversity at a different scale. Indeed, several studies have shown that the number of species within small localities may increase either linearly or asymptotically with regional species richness (relationship between local and regional diversity). Exploring global diversity patterns still constitutes an important challenge for ecologists because it reflects the need to determine the current status of biodiversity. With the knowledge of today’s biodiversity, we can predict its future status and, as a consequence, be able to provide new answers to its probable response to phenomena such as climate change. In the present work, I investigate global diversity patterns in marine fouling communities, mainly by examining the previously mentioned macro-ecological patterns, i.e. the latitudinal gradient of species richness and the relationship between local and regional diversity. Previous studies investigating the local-regional diversity relationship have often assessed the number of species in a region by consulting available species lists. However, regional species pools based on such inventories may include species not susceptible to recruit into the community considered because they are restricted to different habitats and seasons. With the purpose of dealing with these difficulties, a few investigations have estimated regional richness based on local samples but confirmed a strong bias in relation to sampling effort. In order to optimize the quality of regional richness estimations, the current study develops a new statistical tool for estimating regional richness based on a limited number of replicates. Using three data-sets with a large number of replicates from different temperate shallow water habitats, I compare common richness estimators against the asymptote of the species accumulation curve, which was used as a reference for true regional richness. Subsequently and more importantly, the mis-estimation was quantified as a function of sampling effort. To complete this work, the relationship between local and regional diversity was expanded by integrating two categories of diversity (taxonomic and functional) and different successional stages at two different scales: European and global. At the European scale, the shape of the pattern was compared for different methods in assessing regional richness: species colonizing during a given period (transient regional richness) versus species colonizing during any phase of the experiment (total regional richness). At the global scale, I further examine whether the diversity of local communities is affected by parameters other than regional richness, such as number of functional groups or availability of resources. The results of this investigation support a clear influence of latitude on local species richness in marine fouling communities. In Chapter I, I show that tropical regions hold more marine fouling species when compared to areas at higher latitudes. In what concerns the regional richness assessment, I conclude that regional richness can be estimated based on a limited number of samples and that the quality of the estimation increases with sample effort. Moreover, the strength of the inevitable mis-estimation can be quantified (Chapter II). In addition, at the European scale (Chapter III), it was found that the shape of the relationship between local and regional diversity is sensitive to successional stage, the way regional richness is estimated and the dimension of diversity considered. The relevant regional richness, i.e. the regionally available colonizers, seems to vary in time and is larger when pooling all sampling events. As a consequence, the relationship between local and regional diversity is also influenced by the method in which regional richness is estimated. At a global scale (Chapter IV), the relationship between local and regional diversity in fouling assemblages is also affected by the succession process, if either taxonomic or functional diversity are considered. Local taxonomic diversity exhibits saturation at early stages of succession while saturation of local functional richness occurs later. In addition, functional groups were reported as the most influential predictor for local species richness.

Description: Die aktuelle thematische Ausrichtung der Maritimen Meteorologie trägt dem Sachverhalt Rechnung, dass der Zustand der Atmosphäre durch komplexe Wechselwirkungen mit dem Ozean, Land, Meereis und der Vegetation sowie durch den Einfluss äußerer Faktoren bestimmt wird. Zu letzteren gehören u.a. die Vulkane, die Sonne, aber auch anthropogene Faktoren wie etwa der Ausstoß von Treibhausgasen in die Atmosphäre. Die Intensität der Wechselwirkungen hängt stark von den betrachteten zeitlichen und räumlichen Skalen ab. Die Klimamodellierung unter Leitung von Mojib Latif bildet den Rahmen für die weiteren interagierenden Themenbereiche, die in der Maritimen Meteorologie bearbeitet werden. Hierzu gehören der globale und regionale Energieund Wasserkreislauf (Andreas Macke), die Analyse der Klimavariabiliät aus Modell und Beobachtung (Eberhard Ruprecht, Dietmar Dommenget) sowie die Rolle der ozeanischen Deckschicht (Dietmar Dommenget) und der mittleren Atmosphäre (Kirstin Krüger) im Wechselspiel mit Ozean und Atmosphäre. Present fields of research are based on the recognition that the current state of the atmosphere is a result of complex interactions with ocean, land surface, vegetation, and external influences such as volcanoes, the sun or anthropogenic factors, like the increasing atmospheric content of CO2, on all temporal and spatial scales. Climate modelling, headed by Mojib Latif, links all the Marine Meteorology research areas together. Andreas Macke is leading the working group of energy and water cycle, which comprises both, global and regional aspects. Climate variability is investigated on the basis of analyses and observations (Eberhard Ruprecht and Dietmar Dommenget). The role of the ocean’s mixed layer (Dietmar Dommenget) and of the middle atmosphere (Kirstin Krüger) on air-sea interaction are also subjects of research.

Description: Ziel der vorliegenden Arbeit war es, ein außerschulisches Unterrichtsprojekt (NaT-Working Meeresforschung) zu evaluieren. Durch den Unterricht in authentischen wissenschaftlichen Kontexten sollte das Interesse der Schülerinnen und Schüler sowie deren Verständnis meeresbiologischer Zusammenhänge gefördert werden. Das zugrunde gelegte Interessenkonstrukt stellt eine Zusammenfügung des Ansatzes von Hoffmann et al. (1998) und des von Krapp (1992a) dar. Als Maß für das Verständnis wurde der Grad an Strukturiertheit des Wissens angenommen (Novak, 1990; Glaser, 1991). Die Stichprobe setzte sich aus einem Biologie-Leistungskurs und einem Projektkurs zusammen, in denen jeweils ein Thema zum Ökosystem Meer fünf bzw. achteinhalb Monate lang bearbeitet wurde. Die Erhebung des Interesses erfolgte in einem Pre-Post-Test Design mit Fragebögen, deren Auswertung inferenzstatistisch durchgeführt wurde. Das Wissen wurde mit einer Concept Map Aufgabe erhoben, deren Auswertung mit quantitativen und qualitativen Methoden erfolgte. Es zeigte sich, dass mit dem gewählten Unterrichtsansatz das Interesse sowohl an Projektthemen als auch an naturwissenschaftlichen Schulfächern gefördert werden konnte. Das Interesse an Projektthemen stand in einem positiven Zusammenhang mit dem Projektklima und dem Interesse an naturwissenschaftlichen Denk- und Arbeitsweisen. In der ersten Hälfte des Projekts zeigte sich eine quantitative Wissenszunahme, die zweite Hälfte war durch eine qualitative Wissensveränderung im Sinne eines tieferen Verständnisses fachlicher Konzepte gekennzeichnet, z. B. über Nahrungsnetze des Ökosystems Ostsee.

Description: A long-term climatology of air mass transport through the tropical tropopause layer (TTL) is presented, covering the period from 1962–2005. The transport through the TTL is calculated with a Lagrangian approach using radiative heating rates as vertical velocities in an isentropic trajectory model. We demonstrate the improved performance of such an approach compared to previous studies using vertical winds from meteorological analyses. Within the upper part of the TTL, the averaged diabatic ascent is 0.5 K/day during Northern Hemisphere (NH) winters 1992–2001. Climatological maps show a cooling and strengthening of this part of the residual circulation during the 1990s and early 2000s compared to the long-term mean. Lagrangian cold point (LCP) fields show systematic differences for varying time periods and natural forcing components. The interannual variability of LCP temperature and density fields is found to be influenced by volcanic eruptions, El Niño Southern Oscillation (ENSO), Quasi-Biennial Oscillation (QBO) and the solar cycle. The coldest and driest TTL is reached during QBO easterly phase and La Niña over the western Pacific, whereas during volcanic eruptions, El Niño and QBO westerly phase it is warmer and less dry.

Description: Dissolved methane and high resolution bathymetry surveys were conducted over the Rock Garden region of Ritchie Ridge, along the Hikurangi margin, eastern New Zealand. Multibeam bathymetry reveals two prominent, northeast trending ridges, parallel to subduction along the margin, that are steep sided and extensively slumped. Elevated concentrations of methane (up to 10 nM, 10× background) within the water column are associated with a slump structure at the southern end of Eastern Rock Garden. The anomalous methane concentrations were detected by a methane sensor (METS) attached to a conductivity‐temperature‐depth‐optical backscatter device (CTDO) and are associated with elevated light scattering and flare‐shaped backscatter signals revealed by the ship's echo sounder. Increased particulate matter in the water column, possibly related to the seepage and/or higher rates of erosion near slump structures, is considered to be the cause of the increased light scattering, rather than bubbles in the water column. Methane concentrations calculated from the METS are in good agreement with concentrations measured by gas chromatography in water samples collected at the same time. However, there is a c. 20 min (c. 900 m) delay in the METS signal reaching maximum CH4 concentrations. The maximum methane concentration occurs near the plateau of Eastern Rock Garden close to the edge of a slump, at 610 m below sea level (mbsl). This is close to the depth (c. 630 mbsl) where a bottom simulating reflector (BSR) pinches out at the seafloor. Fluctuating water temperatures observed in previous studies indicate that the stability zone for pure methane hydrate in the ocean varies between 630 and 710 mbsl. However, based on calculations of the geothermal gradients from BSRs, we suggest gas hydrate in the study area to be more stable than hydrate from pure methane in sea water, moving the phase boundary in the ocean upward. Small fractions of additional higher order hydrocarbon gases are the most likely cause for increased hydrate stability. Relatively high methane concentrations have been measured down to c. 1000 mbsl, most likely in response to sediment slumping caused by gas hydrate destabilisation of the sediments and/or marking seepage through the gas hydrate zone.

Description: Communities of methane oxidizing bacteria in soils and sediments of siberian permafrost

Description: R/V METEOR Cruise No. 61 was divided into three different legs, which all focused on the NEAtlantic to the west of Ireland from the Porcupine Seabight towards the Rockall Bank. Legs 1 and 3 concentrated on geo-biological studies on the carbonate mounds in this region, which are covered by a unique cold water coral fauna. Leg 2 dealt with seismic investigations in order to investigate the extension processes that led to the development of the Porcupine rift basin. The foci of the individual legs were on the following themes. M61-1 was a multidisciplinary cruise addressing biological, paleo-geological and hydrographical scientific objectives in the carbonate mound provinces west of Ireland in the eastern Porcupine Seabight and on the Rockall Bank. The cruise started in Lisbon (Portugal) and ended in Cork (Ireland). M61-1 activities were embedded within the ESF-DFG MOUNDFORCE project of the EUROMARGINS Programme. Together with the succeeding M61-3 cruise, these Meteor activities document Germany´s strong scientific and logistic support for the success of this challenging programme. Investigations are also designed as a preparatory cruise for the EUproject HERMES (Hotspot Ecosystem Research on the Margins of European Seas; start April 2005). All institutions participating in M61-1 are partners in HERMES Work package 2 "Coral Reef and Carbonate Mound Systems". M 61-2 was directed at researching the earth's crust in the vicinity of the Porcupine rift basin. During this leg, seismic research has been undertaken in the Porcupine Basin west of Ireland, an area that represents a natural laboratory for the investigation of extensional processes. Firstly, both sides of a rift basin occurring in close proximity to each other could have been studied here, allowing questions about the symmetry of extension to be addressed by several east-west profiles parallel to the direction of extension. Secondly, the amount of extension increases from north to south, so a series of east-west cross sections on different latitudes has provided information on crustal structure during variable extension. The spatial changes between these sections also represent the temporal development of the rift through continued extension. In order to achieve these research goals, a series of east-west oriented wide angle reflection profiles in the Porcupine Basin has been acquired. These profiles aid in the explanation of extensional processes and their development through continued extension. They also address insufficiently explained questions about the initiation of large scale magmatism and intrusion, the onset of mantle serpentinisation and the development of detachment faults. M61-3 During this leg, the only recently discovered 'carbonate mounds' on the NWEuropean continental margin have been investigated, which represent unique geo- and ecosystems for European waters. The broad scientific interest that is directed at these mounds is reflected in three EU-projects, which until recently almost exclusively concentrated their efforts on the mounds, as well as the currently operating ESF-EUROMARGINS project MOUNDFORCE M 61-3 focused on the use of a 'Remotely Operated Vehicle' (ROV) for the investigation of the carbonate mounds. The primary tasks of Bremen's QUEST ROV were a detailed characterization of individual mound structures, selective sample collection and the retrieval of sensor systems placed at the seafloor one year before. These ROV tasks have been supplemented by hydro-acoustic measurements and conventional sediment sampling in order to work - in close collaboration with M61-1 - on the main research focuses of the MOUNDFORCE project: (a) analysis of the environmental factors that drive the development of the 'carbonate mounds', (b) surveying the benthic communities in dependence of changing environmental factors and (c) investigations to the stabilization and lithification of the mound sediments.

Description: Dynamics of the submarine permafrost regime, including distribution, thickness, and temporal evolution, was modeled for the Laptev and East Siberian Sea shelf zones. This work included simulation of the permafrost-related gas hydrate stability zone (GHSZ). Simulations were compared with field observations. Model sensitivity runs were performed using different boundary conditions, including a variety of geological conditions as well as two distinct geothermal heat flows (45 and 70 mW/m2). The heat flows used are typical for the coastal lowlands of the Laptev Sea and East Siberian Sea. Use of two different geological deposits, that is, unconsolidated Cainozoic strata and solid bedrock, resulted in the significantly different magnitudes of permafrost thickness, a result of their different physical and thermal properties. Both parameters, the thickness of the submarine permafrost on the shelf and the related development of the GHSZ, were simulated for the last four glacial-eustatic cycles (400,000 years). The results show that the most recently formed permafrost is continuous to the 60-m isobath; at the greater depths of the outer part of the shelf it changes to discontinuous and “patchy” permafrost. However, model results suggest that the entire Arctic shelf is underlain by relic permafrost in a state stable enough for gas hydrates. Permafrost, as well as the GHSZ, is currently storing probable significant greenhouse gas sources, especially methane that has formed by the decomposition of gas hydrates at greater depth. During climate cooling and associated marine regression, permafrost aggradation takes place due to the low temperatures and the direct exposure of the shelf to the atmosphere. Permafrost degradation takes place during climate warming and marine transgression. However, the temperature of transgressing seawater in contact with the former terrestrial permafrost landscape remains below zero, ranging from −0.5 to −1.8°C, meaning permafrost degradation does not immediately occur. The submerged permafrost degrades slowly, undergoing a transformation in form from ice bonded terrestrial permafrost to ice bearing submarine permafrost that does not possess a temperature gradient. Finally the thickness of ice bearing permafrost decreases from its lower boundary due to the geothermal heat flow. The modeling indicated several other features. There exists a time lag between extreme states in climatic forcing and associated extreme states of permafrost thickness. For example, permafrost continued to degrade for up to 10,000 years following a temperature decline had begun after a climate optimum. Another result showed that the dynamic of permafrost thickness and the variation of the GHSZ are similar but not identical. For example, it can be shown that in recent time permafrost degradation has taken place at the outer part of the shelf whereas the GHSZ is stable or even thickening.

Description: Additional to the interannual variability, the Pacific region experiences climate fluctuations on decadal and longer time scales. It is not clear whether Tropical Pacific decadal variability is internal to Tropical Pacific, or whether the midlatitudes exhibit independent decadal variability that affects the tropics or ENSO variability. Available observational data are insufficient to determine the true causes of Tropical Pacific decadal variability. Internal and remote forcing from subtropics are investigated in this study. This is done with state of the art global circulation models (coupled and uncoupled). The leading mode of Tropical Pacific decadal variability in the ECHAM5-MPIOM model, isolated in the tropical cells (TC) index by means of SSA, has a period of about 17 years. The associated SST spatial structure is characterized by a horseshoe-like pattern with maximum explained variance in the central-western equatorial Pacific and off the equator, therefore resembling the signature of the observed decadal climate variability in the tropical Pacific. The mechanism for decadal variability in the model involves coupled oceanatmosphere processes over the western tropical South Pacific, in the region of the SPCZ. Strong positive TCs are associated with periods of increased ENSO variability and vice versa, contributing to the decadal modulation of ENSO activity. The influence of the remote subtropical forcing was studied in more detail with tailored experiments performed with the ocean-atmosphere-sea ice coupled model ECHAM5/MPI-OM. In these sensitivity experiments, the coupled model is forced with idealized sea surface temperature anomalies (SSTA) and sea surface salinity anomalies (SSSA) in the subtropics of both hemispheres. Thus, the relative impact of the subtropical North and South Pacific Oceans on the tropical climate mean state and variability can be estimated. The largest impact on tropical mean climate and variability was simulated in the SSTA experiments. Subtropical South Pacific thermal forcing had more impact on equatorial ocean sea surface temperature than the subtropical North Pacific. In response to a 2°C warming in the subtropical South Pacific, the equatorial Pacific SST increases by +0.58°C, being about 65% larger than the change in the North Pacific experiment. The results show that the subtropics affect equatorial SST mainly through the „atmospheric bridge“ for the South Pacific experiments and through the„oceanic bridge“ for the North Pacific experiments. This explains the different timescale of the response in the two experiments. Although the tropical Pacific surface response to an enhanced warming/cooling in the subtropics is to first order linear, we found that the negative thermal forcing has a stronger impact on the equatorial thermocline. Similar sensitivity experiments conducted with the AGCM ECHAM5 showed that both air-sea interactions and ocean dynamics are crucial for the generation of simulated tropical climate response to the subtropical surface warming/cooling. We found that the statistics of ENSO exhibit significant changes in amplitude and frequency in response to a warming/cooling in the subtropical South Pacific: a 2°C subtropical South Pacific SST warming can reduce the mean ENSO standard deviation by 28%, while a 2°C subtropical South Pacific SST cooling can increase the mean ENSO standard deviation by 21%. The simulated changes in the equatorial zonal SST contrast between the eastern equatorial Pacific and the warm pool region are the main contributor to the modulation of ENSO variability in our South Pacific sensitivity experiments. The simulated intensification/weakening of the annual cycle in response to an enhanced warming/cooling in subtropical South Pacific may also lead to a weaker/stronger ENSO. The subtropical North Pacific thermal forcing did not change the statistical properties of ENSO. The main results of this study suggest that subtropical South Pacific climate variations play a dominant role in tropical Pacific decadal variability and in the decadal modulation of ENSO activity.

Description: Die Berechnung des kurzwelligen atmosphärischen Strahlungstransports in Klimamodellen basiert üblicherweise auf eindimensionalen Strahlungstransportroutinen unter Verwendung planparallel-homogener Wolken. Die vertikale Variabilität der Bewölkung wird ausschließlich über sogenannte Überlappungsannahmen in der Vertikalen berücksichtigt. Horizontale Variabilität wird nicht berücksichtigt. Diese Arbeit untersucht die Ergebnisse einer Strahlungstransportparametrisierung nach Schewski und Macke (2003) (Schewski-Parametrisierung, SP) in ECHAM5 und vergleicht diese mit den Ergebnissen der modellinternen Strahlungstransportroutinen. Die SP wurde anhand eines 3D Monte-Carlo Strahlungstransportmodells, das auf ein mesoskaliges Wolkenmodell angewendet wurde, bestimmt. Die SP berücksichtigt daher den Einfluss der dreidimensionalen Struktur der Wolken auf den Strahlungstransport (sogenannte „3D-Effekte“). Im ersten Teil werden anhand der globalen Verteilung der Differenzen zwischen SP und ECHAM5 in den atmosphärischen Transmissions-, Reflektions- und Absorptionseigenschaften systematische Unterschiede und Grenzen der SP aufgezeigt, die zu der Entwicklung einer verbesserten Version der SP führen. Anhand der verbesserten Version der SP wird im zweiten Teil gezeigt, dass die Berücksichtigung von 3D-Effekten in der SP zu einer höheren Absorption sowie zu einer geringeren Reflektion solarer Strahlung in der Atmosphäre führt. In Bezug auf die Transmission ergibt sich je nach geographischer Lage und Wolkentyp eine höhere oder geringere Transmission solarer Strahlung bei Anwendung der SP im Vergleich zu ECHAM5. Letzteres gilt auch für den zonal gemittelten Wolkenstrahlungeffekt. Trotz der unabhängigen Parametrisierung von Transmission, Reflektion und Absorption ergibt sich eine nahezu exakte Konsistenz der SP. Anhand der SP wird desweiteren eine globale kurzwellige Strahlungsbilanz aufgestellt und mit ECHAM5 sowie den Ergebnissen von Kiehl und Trenberth (1997) verglichen. Trotz der im Rahmen der Analyse gefundenen lokalen Unzulänglichkeiten der SP ergibt sich eine mit ECHAM5 und Kiehl und Trenberth (1997) vergleichbare und konsistente Strahlungsbilanz. Im letzten Teil dieser Arbeit werden Zeitserien und Tagesgänge der optischen Eigenschaften der Atmosphäre in der SP und ECHAM5 in verschiedenen Klimazonen analysiert. Insbesondere im Bereich mariner Stratocumulusbewölkung über dem Ozean zeigt sich, dass die Berücksichtigung von 3D-Effekten in der SP selbst bei einem simplenWolkentyp wie marinen Sc z.T. Unterschiede von über 100 W/m2 in den reflektierten und transmittierten Strahlungsflüssen verursacht.

Description: Air bubbles in the ocean, naturally induced by breaking waves or artificially entrained by ships, remain in the water for different periods of time. Knowledge of the factors accounting for the differences in air bubble residence time (BRT) is essential for understanding processes of air sea-gas exchange as well as for the detection of underwater ship wakes in defence applications. Reasons for the differences in BRT have been found mainly with respect to physical and chemical properties of seawater, such as temperature, salinity and gas saturation level. The impact of biological factors on the behaviour of air bubbles in seawater has not previously been investigated. It is hypothesised that phytoplankton influence BRT through the production of dissolved organic material (DOM) and oxygen. Laboratory experiments were carried out in a seawater mesocosm tank system to investigate the influence of phytoplankton growth on the BRT of artificially injected air bubbles of a wide size range (10-1000 µm diameter) using both natural phytoplankton populations from Kiel Firth and phytoplankton monocultures. BRT was determined acoustically and several phytoplankton growth-related parameters (chlorophyll concentration, dissolved inorganic nutrients, dissolved organic carbon (DOC), oxygen saturation, bacteria numbers) as well as physico-chemical parameters (surface tension and viscosity) were monitored. BRT showed statistically significant covariation with oxygen saturation and chlorophyll a concentration during phytoplankton growth periods in the tank. Increases in BRT of a factor of 〉 2 were found during the chlorophyll maxima, provided that the water was sufficiently supersaturated with oxygen (~〉110%). When the seawater was undersaturated with oxygen, BRT changed only marginally regardless of the chlorophyll a concentration. No clear relationship was evident between BRT and measurements of DOC, surface tension and viscosity. Investigations of the influence of dissolved oxygen on BRT through variation of oxygen saturation of deionised water showed that oxygen saturation alone has no apparent effect on BRT. The influence of phytoplankton on the rheological properties of an air/water interface was investigated in small scale experiments using different phytoplankton monocultures. An increase in surface shear viscosity was detected for only one of the four species of microalgae tested, Nitzschia closterium. Dependency of BRT on the combination of oxygen supersaturation and other phytoplankton growth-related parameters are discussed.

Description: The family Solemyidae represents ancestral protobranch bivalves with the shallow-water genus Solemya and the deep-sea genus Acharax. All known members of this family host symbiotic sulfur-oxidizing bacteria in their gill filaments. Analysis of 18S rRNA gene sequences of Acharax specimens from methane-seeps off Makran (Pakistan), Java (Indonesia), the Aleutian Trench and off the Oregon, Costa Rica, and Peru margins revealed that Solemya spp. and Acharax spp. are well-separated genetically. This supports the current systematic distinction based on morphological criteria. We found 2 clearly distinct clusters within the genus Acharax, with specimens from the Makran, Oregon and Peru (MOP) margins in one (MOP–Acharax) cluster, and those from Java, the Aleutian Trench and Costa Rica (JAC) in the other (JAC–Acharax) cluster. The separation of MOP– and JAC–Acharax clusters from each other and from Solemya (S. reidi and S. velum) is well-supported by phylogenetic calculations employing maximum likelihood and maximum parsimony. Compared to genetic distances among other protobranch groups, distances between the MOP– and JAC–Acharax clusters would justify the affiliation of these clusters to separate species. This implies that species differentiation in Acharax based on shell morphology is likely to underestimate true species diversity within this taxon. Furthermore, our results support the hypothesis that genetic separation of Solemya and Acharax is congruent with the phylogeny of their bacterial endosymbionts.

Description: The investigations carried out between 2002-2004 during several field experiments within the Op-erational radar and optical mapping in monitoring hydrodynamic, morphodynamic and environ-mental parameters for coastal management project (OROMA) aimed to improve the effectiveness of new monitoring technologies such as shipborne imaging radars in coastal waters. The coastal monitoring radar of the GKSS Research Centre, Geesthacht, Germany, is based on a Kelvin Hughes RSR 1000 X-band (9.42 GHz) VV polarized river radar and was mounted on board the research vessel Ludwig Prandtl during the experiments in the Lister Tief, a tidal inlet of the German Bight in the North Sea. The important progress realized in this investigation is the availability of calibrated X-band radar data. Another central point of the study is to demonstrate the applicability of the quasi-specular scattering theory in combination with the weak hydrodynamic interaction the-ory for the radar imaging mechanism of the sea bed. It is shown that specular point scattering con-tributes significantly to the normalized radar cross section (NRCS) modulation due to marine sand waves. According to the theory quasi-specular scattering can be applied for wind speeds Uw ≤ 8 m s-1. Measured and simulated NRCS modulations caused by flood and ebb tide oriented marine sand waves have been compared and agree fairly well

Description: We present the first complete budget of the interannual variability in Arctic springtime ozone taking into account anthropogenic chemical and natural dynamical processes. For the winters 1991/1992 to 2003/2004 the Arctic chemical ozone loss is available from observations. This work investigates the dynamical supply of ozone to the Arctic polar vortex due to mean transport processes for the same winters. The ozone supply is quantified in a vortex-averaged framework using estimates of diabatic descent over winter. We find that the interannual variability of both dynamical ozone supply and chemical ozone loss contribute, in equal shares, to the variability of the total ozone change. Moreover, together they explain nearly all of the interannual variability of Arctic springtime column ozone. Variability in planetary wave activity, characterized by the Eliassen-Palm flux at 100 hPa, contributes significantly to the variability of ozone supply, chemical ozone loss and total springtime ozone.

Description: The sensitivity of the El Ni ̃no/Southern Oscillation phenomenon (ENSO) with respect to different wind stress formulations is simulated by a hybrid coupled general circulation model (HCM). The HCM consists of a version of the MPI-OM general circulation model (GCM) coupled to a statistical atmosphere model. The design of the HCM allows mean wind stress and the anomalous sea surface temperature (SST) to wind stress coupling to be prescribed. Two main aspects are addressed: First, ENSO variability and equatorial Pacific ocean thermal structure are investigated with respect to variations in the mean background climatology, and second, improved parameterizations of the momentum flux at the ocean to atmosphere boundary in GCMs of the tropical Pacific are analyzed. To address the first aspect, the climatology of the tropical Pacific is varied via the strength of the mean wind stress and the ocean-to-atmosphere coupling. The results of the coupled model simulations show that the ENSO period decreases as the mean wind stress is increased. Furthermore, the zonal SST gradient along the equator as well as the mean thermocline depth increase with increasing mean wind stress, while the thermocline intensity is reduced. The ENSO amplitude is more sensitive to the anomalous ocean to atmosphere coupling, where a stronger coupling leads to higher amplitudes. The results are compared to recent studies with intermediate complexity models (ICMs) and to results from intercomparison studies with coupled atmosphere ocean GCMs (AOGCMs). At first view, the prediction of ENSO period from the ICM contradicts the HCM results. This is explained by the setup of the ICM, where the thermocline intensity is prescribed by a parameter, while in the HCM the thermal intensity is modelled. The AOGCMs do not exhibit relationships similar to the results of the HCM. To address the second aspect, the common bulk formula for wind stress is corrected for a moving ocean surface and improved parameterizations of the drag coefficient Cd. Sensitivity studies are carried out for various parameterizations in coupled and uncoupled mode, to give an overview of possible changes. The results of the uncoupled simulations suggest that the correction for a moving surface and the improved parameterization generally lead to reduced mean wind stress and reduced ENSO variability. The correction partly improves the equatorial east Pacific SST and thermal structure. Accounting for surface motion also reduces the variability in coupled simulations. In some experiments the system moves from a self sustained to a damped ENSO mode. The results partly sustain findings in recent sensitivity studies with the ECHAM5/MPI-OM AOGCM, which account for surface motions. The results emphasize the need for an accurate parameterization of the momentum flux also for very low wind speeds.

Description: Diese Diplom-Arbeit behandelt den Einfluss von Wolken und Meereis auf die solare und terrestrische Einstrahlung am Boden. Es werden unterschiedliche Parametrisierungen der solaren Einstrahlung auf reale Daten angewandt. Diese empirischen Daten, die unterschiedliche meteorologische Parameter beinhalten, wurden während den Polarstern Expeditionen ARK-XXIII/1 im Juni und Juli 2008 sowie ANT-XXV/2 im Dezember 2008 und Januar 2009 gewonnen. Ferner werden die Parametrisierungen mit der ebenfalls an Bord den Polarstern erzeugten Daten der letzten 14 Jahre verwendet. Es folgt ausserdem ein Vergleich der parametrisierten Flüsse mit der an Bord gemessenen solaren Einstrahlung. Vier Strahlungsparametrisierungen der kurzwelligen solaren Einstrahlung wurden ausgewählt. Drei von ihnen berechnen auf Grundlage derselben Parameter die solare kurzwellige Einstrahlung. Die Transmissivität der Atmosphäre wird aus dem Wasserdampfdruck am Boden und der Wolkenbedeckung abgeleitet \cite{Zillman72,Bennett82}. Die vierte Parametrisierung verwendet als zusätzliche Eingangsparameter die Albedo des Untergrundes und die optische Dicke der Wolken \cite{Shine84}. Es werden ausschließlich solche Tage betrachtet, die eindeutig mit einer hohen Bodenalbedo einhergehen, also Tage an denen sich das Forschungsschiff Polarstern in eisbedeckten Gewässern befand. Im wolkenfreien Fall ist eine systematische Unterschätzung der Parametrisierungen bezüglich der solaren Einstrahlung zu erkennen. Im bewölkten und im teilweise bewölkten Fall liegt der systematische Fehler bei den meisten Parametrisierungen um 100 W/m2 (ca. 20%). Unter Berücksichtigung der Bodenalbedo und der optischen Dicke der Wolken können die Fehler jedoch deutlich verringert werden. Neben den genannten werden vier weitere Parametrisierungen verwendet, die die langwellige nach unten gerichtete Strahlungsflussdichte parametrisieren. Diese hängen unterschiedlich von Temperatur, Wasserdampf und Wolkenbedeckungsgrad ab. Sowohl im bewölkten, als auch im unbewölkten Fall zeigt die Parametrisierung nach Zillman den kleinsten systematischen Fehler. Anders als die übrigen Parametrisierungen verwendet Zillman den Faktor des Bedeckungsgrades, der nichtlinear in seine Parametrisierung eingeht \cite{Zillman72}. Alle Parametrisierungen, mit Ausnahme der von Zillman, wurden speziell für Bedingungen im Meereis entwickelt. Zusätzlich zu den Parametrisierungen werden auch die Ausmaße der Strahlungserhöhungen bezüglich der solaren Einstrahlung bei einem unbewölkten Himmel während der beiden erwähnten Polarsternfahrten sowie aus den Daten, die innerhalb der letzten 14 Jahre an Bord von Polarstern gesammelt wurden, untersucht. Mit Hilfe von zeitlich hochaufgelösten Messungen, konnte während der Fahrt ANT-XXV/2 am 23.12.2008 die größte absolute Strahlungserhöhung mit 71,86% gemessen werden. Die Erhöhung erreichte mit 596 W/m2 einen Wert, der sogar über dem größten bisher veröffentlichten Wert von 537 W/m2 liegt \cite{Schade07}. %bekannte publizierte Erhöhung galt. Als Abschluß wird mit Hilfe eines Strahungstransportmodells untersucht, ob die Strahlungserhöhungen in den polaren Regionen mit Modellen vergleichbar sind. Das verwendete Modell basiert auf der Monte-Carlo-Methode, die ebenfalls kurz beschrieben wird. Die Ergebnisse machen deutlich, dass die Bodenalbedo, die optische Dicke der Wolken und auch der Sonnenstand wichtige Komponenten für die Strahlungserhöhungen sind. Eine höhere Bodenalbedo verstärkt das Rückstrahlvermögen und die Mehrfachreflexionen zwischen Boden und Wolkenunterkante. Eine größere optische Dicke der Wolken führt zu helleren Wolkenrändern, die ebenfalls die Reflexionen begünstigen. Ein tiefer Sonnenstand führt ebenso zu einer erhöhten solaren Einstrahlung, da dieselbe Menge an Strahlung auf einer größeren Fläche verteilt ist. Dadurch kann diese öfter gestreut werden und führt somit zu einer Erhöhung.

Description: Methane is a greenhouse gas that exerts a significant influence on the radiation budget and thereby the earth’s climate. Geological sources of methane, especially submarine, are particularly relevant in this regard because they emit significant quantities of methane into the atmosphere. However, it is difficult to estimate the magnitude of the global geological source because the extent of these methane-releasing areas and the processes, which influence the methane cycle, are not yet well understood. The Black Sea is a region characterized by numerous submarine methane sources. Methane emissions in the form of methane-containing fluids or gas bubbles have been documented here at all water depths, from the shelf down to the abyss. This marginal sea features a unique hydrographic structure resulting from the inflow of freshwater from rivers and the salty waters of the Mediterranean Sea over the Bosphorus. These inputs have very different densities, and this leads to a pronounced stratification of the water column that limits vertical mixing. High biological production in the surface waters leads to an intense consumption of oxygen in the upper water column, which can not be balanced by downward ventilation of oxygenated surface waters. The pronounced redox-gradient has in turn an important influence on the biochemical cycles in the water column and leads to anoxic conditions at depths below approximately 100 m. These particular conditions make the Black Sea the largest anoxic marine basin on earth. Chapters 2 and 3 of this work (as well as the articles in the appendix) explore the questions of what influence methane emissions have at different water depths on the methane cycle of the water column and what significance these submarine emissions have as sources of atmospheric methane. To this end, the zones of methane sources along the northwest shelf and continental slope (Paleo Dnepr Area) as well as in the northeastern deep sea region (Sorokin Trough) of the Black Sea were explored throughout 2003 and 2004. The observed depths span from between 60 and 2100 m and encompass the entire biogeochemical spectrum of the water column. The methane concentrations of the water column and the overlaying atmosphere were carefully recorded, as were the carbon isotope signatures of this methane. The physical description of the water column, the microorganisms involved in the methane cycle and their methane consumption rates were additionally documented. The area affected by the emission of methane from submarine sources was ascertained through extensive sampling campaigns. The dataset was used to model the methane flux at the sea/air interface and to evaluate the influence of methane sources, present in different water depth on the marine methane emission. In addition, the exploration of this area throughout two consecutive years provides insight into the seasonal variability of the source strength of these submarine emissions. Chapter 4 serves to combine the results of this investigation with those present in the literature for the purpose of constructing a methane budget that quantifies the significant sources and sinks of methane in the Black Sea. A transport-reaction model investigates the release of methane at discrete water depths and identifies those of particular interest. Various model scenarios were used to determine to what extent sizable methane emission events, for example from mud volcano eruptions or submarine landslides, affect the methane budget of the Black Sea and the associated methane emissions at the ocean surface. The following work cannot completely address the complex methane cycle of the Black Sea and its associated processes. This work serves rather to provide new insights, discuss relevant areas and point out still unanswered questions. The increase in research on methane in the Black Sea during recent years shows that its methane cycle is of great scientific interest.

Description: This thesis shows different aspects of the distribution of adult sprat in the central Baltic Sea. The seasonal development of the horizontal distribution of sprat was investigated in 2002/2003 under the influence of a shift in the environmental regime. During the period of investigation, several inflow events of saline and well oxygenated water into the deep Basins of the Baltic Sea were observed. This includes the first major Baltic inflow (MBI) since 1993, which occurred in January/February 2003 and dramatically changed the environmental condition in the Bornholm Basin. Prior to this MBI, a ‘typical’ seasonal development of the sprat abundance in the Bornholm Sea was observed. After the MBI in 2003, relatively cold temperatures were observed in the Bornholm Basin throughout the water column. It was assumed that these unfavourable conditions lead to an avoidance migration of sprat in the more eastern areas. This was supported by an increase of the sprat abundance in the Gotland Basin. The abiotic parameters that determine the vertical distribution of sprat were investigated during several cruises, including meso-scale and small-scale investigations. Temperature and oxygen content of the water were confirmed as main driving factors for the vertical distribution of sprat, whereby the relevant thresholds were determined as 5°C and 1ml/l oxygen content. Other environmental parameters were identified to have an impact on the diel vertical migration (DVM) of sprat. Light was assumed to induce DVM of sprat, whereas the causal relationship remained unclear. Strong vertical temperature gradients can prevent DVM, if the minimum temperature, to be passed is colder than 5°C. On the other hand, cold water was crossed where the temperature gradient was relatively low. The influence of salinity and depth was found to be negligible. The results of these investigations were used to develop two models for the vertical distribution of sprat. The first model approach bases upon the calculation of the probability of occurrence, calculated for temperature and oxygen. This simple model was successfully applied to data, derived during spawning time in spring 2002, but revealed weaknesses when applied to other seasons. Furthermore, a more complex was introduced, whereas the vertical distribution of sprat was modelled as behavioural response to external stimuli. This approach was successfully applied to model the diel vertical migration of sprat. With the latter model approach a tool is delivered to include the vertical distribution into ecosystem models and is therefore an important improvement in ecosystem research in the Baltic. With regard to the consequences of the distribution patterns of Baltic sprat it was shown, that the vulnerability of key zooplankton species to predation by clupeids is highly influenced by the spatial overlap of predator and prey. Highest impact of sprat on zooplankton species was found for Pseudocalunus sp. during spring and Temora longicornis during summer.

Description: The synoptic evolution and some meteorological impacts of the European winter storm Kyrill that swept across Western, Central, and Eastern Europe between 17 and 19 January 2007 are investigated. The intensity and large storm damage associated with Kyrill is explained based on synoptic and mesoscale environmental storm features, as well as on comparisons to previous storms. Kyrill appeared on weather maps over the US state of Arkansas about four days before it hit Europe. It underwent an explosive intensification over the Western North Atlantic Ocean while crossing a very intense zonal polar jet stream. A superposition of several favourable meteorological conditions west of the British Isles caused a further deepening of the storm when it started to affect Western Europe. Evidence is provided that a favourable alignment of three polar jet streaks and a dry air intrusion over the occlusion and cold fronts were causal factors in maintaining Kyrill's low pressure very far into Eastern Europe. Kyrill, like many other strong European winter storms, was embedded in a pre-existing, anomalously wide, north-south mean sea-level pressure (MSLP) gradient field. In addition to the range of gusts that might be expected from the synoptic-scale pressure field, mesoscale features associated with convective overturning at the cold front are suggested as the likely causes for the extremely damaging peak gusts observed at many lowland stations during the passage of Kyrill's cold front. Compared to other storms, Kyrill was by far not the most intense system in terms of core pressure and circulation anomaly. However, the system moved into a pre-existing strong MSLP gradient located over Central Europe which extended into Eastern Europe. This fact is considered determinant for the anomalously large area affected by Kyrill. Additionally, considerations of windiness in climate change simulations using two state-of-the-art regional climate models driven by ECHAM5 indicate that not only Central, but also Eastern Central Europe may be affected by higher surface wind speeds at the end of the 21st century. These changes are partially associated with the increased pressure gradient over Europe which is identified in the ECHAM5 simulations. Thus, with respect to the area affected, as well as to the synoptic and mesoscale storm features, it is proposed that Kyrill may serve as an interesting study case to assess future storm impacts.

Description: Microwave Limb Sounder and Sounding of the Atmosphere with Broadband Emission Radiometry data show the polar stratopause, usually higher than and separated from that at midlatitudes, dropping from 〈55-60 to near 30 km, and cooling dramatically in January 2006 during a major stratospheric sudden warming (SSW). After a nearly isothermal period, a cool stratopause reforms near 75 km in early February, then drops to 〈55 km and warms. The stratopause is separated in longitude as well as latitude, with lowest temperatures in the transition regions between higher and lower stratopauses. Operational assimilated meteorological analyses, which are not constrained by data at stratopause altitude, do not capture a secondary temperature maximum that overlies the stratopause or the very high stratopause that reforms after the SSW; they underestimate the stratopause altitude variation during the SSW. High-quality daily satellite temperature measurements are invaluable in improving our understanding of stratopause evolution and its representation in models and assimilation systems.

Description: Microwave Limb Sounder and Sounding of the Atmosphere with Broadband Emission Radiometry data provide the first opportunity to characterize the four-dimensional stratopause evolution throughout the life-cycle of a major stratospheric sudden warming (SSW). The polar stratopause, usually higher than that at midlatitudes, dropped by 30 km and warmed during development of a major "wave 1" SSW in January 2006, with accompanying mesospheric cooling. When the polar vortex broke down, the stratopause cooled and became ill-defined, with a nearly isothermal stratosphere. After the polar vortex started to recover in the upper stratosphere/lower mesosphere (USLM), a cool stratopause reformed above 75 km, then dropped and warmed; both the mesosphere above and the stratosphere below cooled at this time. The polar stratopause remained separated from that at midlatitudes across the core of the polar night jet. In the early stages of the SSW, the strongly tilted (westward with increasing altitude) polar vortex extended into the mesosphere, and enclosed a secondary temperature maximum extending westward and slightly equatorward from the highest altitude part of the polar stratopause over the cool stratopause near the vortex edge. The temperature evolution in the USLM resulted in strongly enhanced radiative cooling in the mesosphere during the recovery from the SSW, but significantly reduced radiative cooling in the upper stratosphere. Assimilated meteorological analyses from the European Centre for Medium-Range weather Forecasts (ECMWF) and Goddard Earth Observing System Version 5.0.1 (GEOS-5), which are not constrained by data at polar stratopause altitudes and have model tops near 80 km, could not capture the secondary temperature maximum or the high stratopause after the SSW; they also misrepresent polar temperature structure during and after the stratopause breakdown, leading to large biases in their radiative heating rates. ECMWF analyses represent the stratospheric temperature structure more accurately, suggesting a better representation of vertical motion; GEOS-5 analyses more faithfully describe stratopause level wind and wave amplitudes. The high-quality satellite temperature data used here provide the first daily, global, multiannual data sets suitable for assessing and, eventually, improving representation of the USLM in models and assimilation systems.

Description: Microwave Limb Sounder and Sounding of the Atmosphere with Broadband Emission Radiometry data provide the first opportunity to characterize the four-dimensional stratopause evolution throughout the life-cycle of a major stratospheric sudden warming (SSW). The polar stratopause, usually higher than that at midlatitudes, dropped by ∼30 km and warmed during development of a major “wave 1” SSW in January 2006, with accompanying mesospheric cooling. When the polar vortex broke down, the stratopause cooled and became ill-defined, with a nearly isothermal stratosphere. After the polar vortex started to recover in the upper stratosphere/lower mesosphere (USLM), a cool stratopause reformed above 75 km, then dropped and warmed; both the mesosphere above and the stratosphere below cooled at this time. The polar stratopause remained separated from that at midlatitudes across the core of the polar night jet. In the early stages of the SSW, the strongly tilted (westward with increasing altitude) polar vortex extended into the mesosphere, and enclosed a secondary temperature maximum extending westward and slightly equatorward from the highest altitude part of the polar stratopause over the cool stratopause near the vortex edge. The temperature evolution in the USLM resulted in strongly enhanced radiative cooling in the mesosphere during the recovery from the SSW, but significantly reduced radiative cooling in the upper stratosphere. Assimilated meteorological analyses from the European Centre for Medium-Range weather Forecasts (ECMWF) and Goddard Earth Observing System Version 5.0.1 (GEOS-5), which are not constrained by data at polar stratopause altitudes and have model tops near 80 km, could not capture the secondary temperature maximum or the high stratopause after the SSW; they also misrepresent polar temperature structure during and after the stratopause breakdown, leading to large biases in their radiative heating rates. ECMWF analyses represent the stratospheric temperature structure more accurately, suggesting a better representation of vertical motion; GEOS-5 analyses more faithfully describe stratopause level wind and wave amplitudes. The high-quality satellite temperature data used here provide the first daily, global, multiannual data sets suitable for assessing and, eventually, improving representation of the USLM in models and assimilation systems.

Description: The first three Canadian Arctic Atmospheric Chemistry Experiment (ACE) Validation Campaigns at Eureka (80° N, 86° W) were during two extremes of Arctic winter variability: Stratospheric sudden warmings (SSWs) in 2004 and 2006 were among the strongest, most prolonged on record; 2005 was a record cold winter. New satellite measurements from ACE-Fourier Transform Spectrometer (ACE-FTS), Sounding of the Atmosphere using Broadband Emission Radiometry, and Aura Microwave Limb Sounder (MLS), with meteorological analyses and Eureka lidar and radiosonde temperatures, are used to detail the meteorology in these winters, to demonstrate its influence on transport and chemistry, and to provide a context for interpretation of campaign observations. During the 2004 and 2006 SSWs, the vortex broke down throughout the stratosphere, reformed quickly in the upper stratosphere, and remained weak in the middle and lower stratosphere. The stratopause reformed at very high altitude, above where it could be accurately represented in the meteorological analyses. The 2004 and 2006 Eureka campaigns were during the recovery from the SSWs, with the redeveloping vortex over Eureka. 2005 was the coldest winter on record in the lower stratosphere, but with an early final warming in mid-March. The vortex was over Eureka at the start of the 2005 campaign, but moved away as it broke up. Disparate temperature profile structure and vortex evolution resulted in much lower (higher) temperatures in the upper (lower) stratosphere in 2004 and 2006 than in 2005. Satellite temperatures agree well with Eureka radiosondes, and with lidar data up to 50–60 km. Consistent with a strong, cold upper stratospheric vortex and enhanced radiative cooling after the SSWs, MLS and ACE-FTS trace gas measurements show strongly enhanced descent in the upper stratospheric vortex during the 2004 and 2006 Eureka campaigns compared to that in 2005.

Description: The interaction of clouds with solar and terrestrial radiation is one of the most important topics of climate research. In recent years it has been recognized that only a full three-dimensional (3D) treatment of this interaction can provide answers to many climate and remote sensing problems, leading to the worldwide development of numerous 3D radiative transfer (RT) codes. The international Intercomparison of 3D Radiation Codes (I3RC), described in this paper, sprung from the natural need to compare the performance of these 3D RT codes used in a variety of current scientific work in the atmospheric sciences. I3RC supports intercomparison and development of both exact and approximate 3D methods in its effort to 1) understand and document the errors/limits of 3D algorithms and their sources; 2) provide “baseline” cases for future code development for 3D radiation; 3) promote sharing and production of 3D radiative tools; 4) derive guidelines for 3D radiative tool selection; and 5) improve atmospheric science education in 3D RT. Results from the two completed phases of I3RC have been presented in two workshops and are expected to guide improvements in both remote sensing and radiative energy budget calculations in cloudy atmospheres.

Description: The statoliths of cephalopods are calcified bio mineral structures found in the gravity receptor system in the head of cuttlefish and squid. They grow throughout the lifetime of the animal and deposit microscopically visible daily increments similar to the annual rings in tree stems. Statolith growth and composition are linked to environmental factors. Thus, the statolith reveals the biological history of each individual cephalopod. If a relationship can be established between the composition of a growth layer of the statolith and the ambient water properties, then the statolith chemistry becomes a predictor of the surrounding water chemistry and/or temperature. Provided that statolith material is not altered or resorbed after deposition, the statolith becomes a permanent archive of environmental conditions and may provide information on habitat use, timing of exposure to a pollutant, and timing of migrations. Several micro analytical state-of-the-art techniques have been applied in this thesis to investigate the spatially resolved chemical composition of cephalopod statoliths. Recent applications of these methods include mainly geological samples, which do not contain organic compounds. Therefore a considerable part of this project focussed on adjusting and optimising the respective methods to the analyses of biogenic aragonite intergrown with organic compounds. In this thesis, the influence of different environmental factors on the chemical composition of cephalopod statoliths was investigated. On the basis of laboratory experiments under controlled conditions, it is now possible to qualify the influences of salinity, temperature and diet on the concentrations of several elements in the statoliths. Analytical results indicate that the incorporation of a number of elements is influenced by environmental factors. Barium and iodine appear to be the most suitable indicators for temperature. The incorporation of strontium into cephalopod statoliths, however seems to be influenced to a greater extent by diet than by the surrounding water. This is contradictory to results from corals and fish otoliths, where strontium is a well-established indicator for both temperature and salinity. The suitability of statolith micro-chemistry for field-studies has been proven as well. Statolith trace element compositional zoning reflects very well the life history and ontogenetic habitat-shifts of the boreoatlantic armhook squid Gonatus fabricii. Further, this thesis gives valuable insights into the microstructure of statoliths and the elemental nano-scale distribution in daily increments. For the first time, the application of NanoSIMS NS50 provided distribution patterns of calcium, strontium and sodium in cephalopod statoliths with a spatial resolution of 400nm. The results of this study provide an essential basis for future investigations in the field, probably leading into further understanding of yet unknown migration patterns and spawning grounds of various cephalopod species. Applying these future approaches could establish a consolidated biological knowledge on cephalopod species and stocks, and therefore may contribute to an effective and sustainable management of this both ecologically and economically valuable resource.

Description: While the northern and central part of the South American subduction zone has been intensively studied, the southern part has attracted less attention, whichmay be due to its difficult accessibility and lower seismic activity. However, the southern part exhibits strong seismic and tsunamogenic potential with the prominent example of the Mw=9.5 May 22, 1960 Valdivia earthquake. In this study data from an amphibious seismic array (Project TIPTEQ) is presented. The network reached from the trench to the active magmatic arc incorporating the Island of Chiloé and the north-south trending Liquiñe-Ofqui fault zone (LOFZ). 364 local events were observed in an 11-month period from November 2004 until October 2005. The observed seismicity allows to constrain for the first time the current state of stress of the subducting plate and magmatic arc, as well as the local seismic velocity structure. The downgoing Benioff zone is readily identifiable as an eastward dipping plane with an inclination of ∼30◦. Main seismic activity occurred predominantly in a belt parallel to the coast of Chiloé Island in a depth range of 12–30 km, which is presumably related to the plate interface. The down-dip termination of abundant intermediate depth seismicity at approximately 70 km depth seems to be related to the young age (and high temperature) of the oceanic plate. A high-quality subset of events was inverted for a 2-D velocity model. The vp model resolves the sedimentary basins and the downgoing slab. Increased velocities below the longitudinal valley and the eastern part of Chiloé Island suggest the existence of a mantle bulge. Apart from the events in the Benioff Zone, shallow crustal events were observed mainly in different clusters along the magmatic arc. These crustal clusters of seismicity are related to the LOFZ, as well as to the volcanoes Chaitén, Michinmahuida and Corcovado. Seismic activity up to a magnitude of 3.8 Mw reveals the recent activity of the fault zone. Focal mechanisms for the events along the LOFZ were calculated using a moment tensor inversion of amplitude spectra for body waves which mostly yield strike-slip mechanisms indicating a SW-NE striking of σ1 for the LOFZ. Focal mechanism stress inversion indicates a strike-slip regime along the arc and a thrust regime in the Benioff zone. The observed deformation – which is also revealed by teleseismic observations – suggests a confirmation for the proposed northwardmovement of a forearc sliver acting as a detached continental micro-plate.

Description: CORONA images have been used for the mapping of periglacial features on the Bykovsky Peninsula and adjacent Khorogor Valley in northeast Siberia. Features, mapped and analysed within a geographical information system, include thermokarst depressions, thermo-erosional valleys, thermo-erosional cirques, thermokarst lakes, thermokarst lagoons and pingos. More than 50% of the area is strongly influenced by thermally-induced subsidence. Thermokarst in the area is probably less active today than in the early-middle Holocene.

Description: This paper describes the retrievals algorithm used to determine temperature and height from radiance measurements by the Microwave Limb Sounder on EOS Aura. MLS is a "limbscanning" instrument, meaning that it views the atmosphere along paths that do not intersect the surface - it actually looks forwards from the Aura satellite. This means that the temperature retrievals are for a "profile" of the atmosphere somewhat ahead of the satellite. Because of the need to view a finite sample of the atmosphere, the sample spans a box about 1.5km deep and several tens of kilometers in width; the optical characteristics of the atmosphere mean that the sample is representative of a tube about 200-300km long in the direction of view. The retrievals use temperature analyses from NASA's Goddard Earth Observing System, Version 5 (GEOS-5) data assimilation system as a priori states. The temperature retrievals are somewhat deperrde~zt on these a priori states, especially in the lower stratosphere. An important part of the validation of any new dataset involves comparison with other, independent datasets. A large part of this study is concerned with such comparisons, using a number of independent space-based measurements obtained using different techniques, and with meteorological analyses. The MLS temperature data are shown to have biases that vary with height, but also depend on the validation dataset. MLS data are apparently biased slightly cold relative to correlative data in the upper troposphere and slightly warm in the middle stratosphere. A warm MLS bias in the upper stratosphere may be due to a cold bias in GEOS-5 temperatures.

Description: Global satellite observations of temperature and geopotential height (GPH) from the Microwave Limb Sounder (MLS) on the EOS Aura spacecraft are discussed. The precision, resolution, and accuracy of the data produced by the MLS version 2.2 processing algorithms are quantified, and recommendations for data screening are made. Temperature precision is 1 K or better from 316 hPa to 3.16 hPa, degrading to ∼3 K at 0.001 hPa. The vertical resolution is 3 km at 31.6 hPa, degrading to 6 km at 316 hPa and to ∼13 km at 0.001 hPa. Comparisons with analyses (Goddard Earth Observing System version 5.0.1 (GEOS-5), European Centre for Medium-range Weather Forecasts (ECMWF), Met Office (MetO)) and other observations (CHAllenging Minisatellite Payload (CHAMP), Atmospheric Infrared Sounder/Advanced Microwave Sounder Unit (AIRS/AMSU), Sounding of the Atmosphere using Broadband Radiometry (SABER), Halogen Occultation Experiment (HALOE), Atmospheric Chemistry Experiment (ACE), radiosondes) indicate that MLS temperature has persistent, pressure-dependent biases which are between −2.5 K and +1 K between 316 hPa and 10 hPa. The 100-hPa MLS v2.2 GPH surface has a bias of ∼150 m relative to the GEOS-5 values. These biases are compared to modeled systematic uncertainties. GPH biases relative to correlative measurements generally increase with height owing to an overall cold bias in MLS temperature relative to correlative temperature measurements in the upper stratosphere and mesosphere.

Description: For the first time the long-term interannual and spatial variability of residence time (τ) is presented for the TTL between 360 K and 400 K potential temperature (~14 to 18 km altitude). The analysis is based on a Lagrangian approach using offline calculated diabatic heating rates as vertical velocities, covering Northern Hemisphere (NH) winters from 1962–2004. The residence time τLCP–400 K, being the duration time of air parcels in the layer between the Lagrangian Cold Point (LCP) and 400 K, varies spatially and is longer (〉50 days) over the maritime continent as the LCP is lowest there (〈370 K). Comparing three theta layers within the TTL reveals the vertical dependence of τ. We derive a mean duration time of 34 days for 360–380 K (lower TTL), 38 days for 380–400 K (upper TTL) and 70 days for 360–400 K theta layers for the 1962–2001 period. A case analysis reveals that τ is positively skewed for 360–380 K and 380–400 K during La Niña and El Niño Southern Oscillation (ENSO) neutral years. For these cases, ~60% of air parcels travel from 360 K to 380 K within 25 days. There is large interannual variability for τ varying up to ±20% from the long-term mean, with strongest variability seen in the lower part of the TTL. Statistical analysis reveals a significant anti-correlation between the residence time and the extratropical and subtropical wave driving in the lowermost stratosphere.

Description: A multiyear time series of the vortex-averaged diabatic descent for 47 Arctic winters from 1957/1958 until 2003/2004 is presented. The climatology of diabatic descent is based on trajectory calculations coupled with diabatic heating rate calculations carried out in the polar lower stratosphere of the Northern Hemisphere winters. We demonstrate the improved performance of the approach based on diabatic heating rates compared to the approach based on vertical winds from meteorological analysis. The time series of the vortex-averaged diabatic descent gives a detailed picture of intensity and altitude dependence of the stratospheric vertical transport processes during the Arctic winter. In addition to the overall vortex-averaged diabatic descent, the spatial structure of the descent is analyzed for two different Arctic winters. We demonstrate for this case study that not only the intensity but also the zonal structure of the diabatic descent depends on the meteorological conditions in the polar vortex. The climatology is characterized by very pronounced interannual variability which is linked to the variability of temperature anomalies and to the variability of Eliassen-Palm (EP)-flux anomalies, wherein strong planetary wave activity leads to strong diabatic descent and vice versa. The correlation between EP-flux and descent shows that tropospheric dynamics have a strong influence on the strength of the polar branch of the residual circulation by means of the atmospheric wave activity.

Description: We examine the relationship between three tropical and two subtropical western Indian Ocean coral oxygen isotope time series to surface air temperatures (SAT) and rainfall over India, tropical East Africa and southeast Africa. We review established relationships, provide new concepts with regard to distinct rainfall seasons, and mean annual temperatures. Tropical corals are coherent with SAT over western India and East Africa at interannual and multidecadal periodicities. The subtropical corals correlate with Southeast African SAT at periodicities of 16–30 years. The relationship between the coral records and land rainfall is more complex. Running correlations suggest varying strength of interannual teleconnections between the tropical coral oxygen isotope records and rainfall over equatorial East Africa. The relationship with rainfall over India changed in the 1970s. The subtropical oxygen isotope records are coherent with South African rainfall at interdecadal periodicities. Paleoclimatological reconstructions of land rainfall and SAT reveal that the inferred relationships generally hold during the last 350 years. Thus, the Indian Ocean corals prove invaluable for investigating land–ocean interactions during past centuries.