Klimaänderungsszenarien für den Oberlauf der Großen Mühl

In dieser Diplomarbeit werden unterschiedliche Klimaänderungsszenarien für den Oberlauf der Großen Mühl bezüglich hydrologischer Parameter wie Abfluss, Schneeakkumulation und Schmelze aber auch Verdunstung und Trockenphasen untersucht. Die Transformation der meteorologischen Größen Niederschlag und Temperatur in Abflusswerte erfolgt mit Hilfe eines konzeptionellen Niederschlags-Abfluss Modells auf Tageswertbasis. Für die Kalibrierung des Modells werden Zeitreihen von 1961-1990 dreier Niederschlags- und einer Temperaturstation herangezogen. Als Input für die Szenarienanalysen werden Zeitreihen der Temperatur und des Niederschlag aus dem regionalen Klimamodell ECHAM5/REMO verwendet für die Zeitspanne von 2071-2100. Drei Szenarien werden untersucht, A1B (realistisch hinsichtlich Treibhausgasemmissionen), A2 (pessimistisch) und B1 (optimistisch), sowie der Kontrolllauf des Modells welcher das Klima von 1950-2000 nachbildet. Die Güte des Klimamodells wird mittels dieses Kontrolllaufes überprüft, als Referenzzeitraum dient die Klimanormalperiode von 1961-1990, wobei der Gebietsniederschlag und die Temperatur aus Modellierung und Stationsdaten verglichen werden. Die systematischen Abweichungen zwischen Modell und Messung wird über einen monatlichen Korrekturfaktor, angewandt für die Tageswerte, ausgeglichen um realistische Abflusscharakteristika zu erreichen. In den drei Szenarien kommt es generell zu einem Anstieg der Regenmengen, vor allem im Winter und Frühjahr, und zu erhöhten Temperaturen generell. Dies wirkt sich auf den Abfluss mit höheren Durchflussmengen im Winter aus. Die Schneeakkumulation sinkt aufgrund höherer Temperaturen und der Abflusseintrag aus Schmelzabfluss sinkt. Phasen mit Trockenperioden nehmen in A2 und B1 nicht extrem zu, in A1B ist jedoch ein Trend zu sehr trockenen Sommern mit Phasen mit hohem Anteil an Niederwasserabfluss in den darauffolgenden Herbstmonaten zu erkennen.In this diploma thesis different climate change scenarios for the headwaters of the Große Mühl are investigated concerning hydrological parameters like discharge, snow accumulation, snow melt as well as evaporation and droughts. The transformation of meteorological data into values of discharge is carried out by a conceptual rainfall-runoff model on a daily basis. The calibration is based on time series from 1961-1990 of three rainfall and one temperature gauging station. For the scenario analyses time series of temperature and precipitation from the regional climate model ECHAM5/REMO are used for the period from 2071-2100. Three scenarios were investigated; A1B (realistic concerning greenhouse gas emissions), A2 (pessimistic) and B1 (optimistic), as well as the control run of the model. The performance of the climate model is verified with the control run for the normal period from 1961-1990 were rainfall and temperature of the climate model is compared to the data of the gauging stations. The systematic bias between model and observations is corrected by a monthly factor, applied on the daily. The three Scenarios show an increase in precipitation, especially in winter and spring and an increase in temperature all year round, which means higher discharge in wintertime. Snow accumulation is decreasing because of higher temperatures and the contribution of snowmelt to discharge decreases as well. Dry periods are just slightly increasing in scenarios A2 and B1. On the contrary A1B shows a trend to very dry summers with phases of high proportions of low flow in the following months in autumn

Testing spontaneous localization theories with matter-wave interferometry

We propose to test the theory of continuous spontaneous localization (CSL) in an all-optical time-domain Talbot-Lau interferometer for clusters with masses exceeding 1000000 amu. By assessing the relevant environmental decoherence mechanisms, as well as the growing size of the particles relative to the grating fringes, we argue that it will be feasible to test the quantum superposition principle in a mass range excluded by recent estimates of the CSL effect.Comment: 4 pages, 3 figures; corresponds to published versio

A three-pillar approach to assessing climate impacts on low flows

The objective of this paper is to present a framework for assessing climate impacts on future low flows that combines different sources of information, termed pillars. To illustrate the framework three pillars are chosen: (a) extrapolation of observed low-flow trends into the future, (b) rainfall–runoff projections based on climate scenarios and (c) extrapolation of changing stochastic rainfall characteristics into the future combined with rainfall–runoff modelling. Alternative pillars could be included in the overall framework. The three pillars are combined by expert judgement based on a synoptic view of data, model outputs and process reasoning. The consistency/inconsistency between the pillars is considered an indicator of the certainty/uncertainty of the projections. The viability of the framework is illustrated for four example catchments from Austria that represent typical climate conditions in central Europe. In the Alpine region where winter low flows dominate, trend projections and climate scenarios yield consistently increasing low flows, although of different magnitudes. In the region north of the Alps, consistently small changes are projected by all methods. In the regions in the south and south-east, more pronounced and mostly decreasing trends are projected but there is disagreement in the magnitudes of the projected changes. The process reasons for the consistencies/inconsistencies are discussed. For an Alpine region such as Austria the key to understanding low flows is whether they are controlled by freezing and snowmelt processes, or by the summer moisture deficit associated with evaporation. It is argued that the three-pillar approach offers a systematic framework of combining different sources of information aimed at more robust projections than that obtained from each pillar alone

Uncertainty contributions to low-flow projections in Austria

The main objective of the paper is to understand the contributions to the uncertainty in low-flow projections resulting from hydrological model uncertainty and climate projection uncertainty. Model uncertainty is quantified by different parameterisations of a conceptual semi-distributed hydrologic model (TUWmodel) using 11 objective functions in three different decades (1976&ndash;1986, 1987&ndash;1997, 1998&ndash;2008), which allows for disentangling the effect of the objective function-related uncertainty and temporal stability of model parameters. Climate projection uncertainty is quantified by four future climate scenarios (ECHAM5-A1B, A2, B1 and HADCM3-A1B) using a delta change approach. The approach is tested for 262 basins in Austria. <br><br> The results indicate that the seasonality of the low-flow regime is an important factor affecting the performance of model calibration in the reference period and the uncertainty of <i>Q</i>₉₅ low-flow projections in the future period. In Austria, the range of simulated <i>Q</i>₉₅ in the reference period is larger in basins with a summer low-flow regime than in basins with a winter low-flow regime. The accuracy of simulated <i>Q</i>₉₅ may result in a range of up to 60 % depending on the decade used for calibration. <br><br> The low-flow projections of Q₉₅ show an increase of low flows in the Alps, typically in the range of 10–30 % and a decrease in the south-eastern part of Austria mostly in the range &minus;5 to &minus;20 % for the climate change projected for the future period 2021&ndash;2050, relative the reference period 1978&ndash;2007. The change in seasonality varies between scenarios, but there is a tendency for earlier low flows in the northern Alps and later low flows in eastern Austria. The total uncertainty of <i>Q</i>₉₅ projections is the largest in basins with a winter low-flow regime and, in some basins the range of <i>Q</i>₉₅ projections exceeds 60 %. In basins with summer low flows, the total uncertainty is mostly less than 20 %. The ANOVA assessment of the relative contribution of the three main variance components (i.e. climate scenario, decade used for model calibration and calibration variant representing different objective function) to the low-flow projection uncertainty shows that in basins with summer low flows climate scenarios contribute more than 75 % to the total projection uncertainty. In basins with a winter low-flow regime, the median contribution of climate scenario, decade and objective function is 29, 13 and 13 %, respectively. The implications of the uncertainties identified in this paper for water resource management are discussed

Concept of an ionizing time-domain matter-wave interferometer

We discuss the concept of an all-optical and ionizing matter-wave interferometer in the time domain. The proposed setup aims at testing the wave nature of highly massive clusters and molecules, and it will enable new precision experiments with a broad class of atoms, using the same laser system. The propagating particles are illuminated by three pulses of a standing ultraviolet laser beam, which detaches an electron via efficient single photon-absorption. Optical gratings may have periods as small as 80 nm, leading to wide diffraction angles for cold atoms and to compact setups even for very massive clusters. Accounting for the coherent and the incoherent parts of the particle-light interaction, we show that the combined effect of phase and amplitude modulation of the matter waves gives rise to a Talbot-Lau-like interference effect with a characteristic dependence on the pulse delay time.Comment: 25 pages, 5 figure

Colloquium: Quantum interference of clusters and molecules

We review recent progress and future prospects of matter wave interferometry with complex organic molecules and inorganic clusters. Three variants of a near-field interference effect, based on diffraction by material nanostructures, at optical phase gratings, and at ionizing laser fields are considered. We discuss the theoretical concepts underlying these experiments and the experimental challenges. This includes optimizing interferometer designs as well as understanding the role of decoherence. The high sensitivity of matter wave interference experiments to external perturbations is demonstrated to be useful for accurately measuring internal properties of delocalized nanoparticles. We conclude by investigating the prospects for probing the quantum superposition principle in the limit of high particle mass and complexity.Comment: 19 pages, 13 figures; v2: corresponds to published versio

Hydrology needed to manage droughts: the 2015 European case

Hydrology needed to manage droughts: the 2015 European cas