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Bassler C.,National Park Bayerischer Wald | Muller J.,National Park Bayerischer Wald | Hothorn T.,Ludwig Maximilians University of Munich | Kneib T.,Ludwig Maximilians University of Munich | And 2 more authors.
Ecological Indicators | Year: 2010

The evidence for climate change is increasing, and global warming could lead to the extinction of some species. Here we estimated the extinction risk of six high-montane species of different taxonomic groups (fern, vascular plant, wood-inhabiting fungus, mollusk, saproxylic beetle, and bird) by modeling their occurrence under two global warming scenarios. We also assessed the cross-taxon indicator suitability of the selected species for monitoring climate change in low-mountain-range forests in southeastern Germany (Bavarian Forest National Park). We tested the influence of temperature and other habitat variables by applying semi-parametric spatial generalized linear models with binomial error. The probability of occurrence for each species under the present conditions and under two conditions of global warming was calculated. To assess the cross-taxon suitability, we tested the predictability of the final generalized linear models for each species using the measured occurrence of the other selected species and a discrimination technique. We identified temperature as the main driver for all selected high-montane species. Our statistical models predict a considerable risk of extinction of these species within the Bavarian Forest National Park as a result of global warming. Our discrimination model indicates that these species have essentially similar relationships with the environment and that five of the six species are suitable as indicators of early signs of global warming. The choice of which indicators to use should involve a consideration of the type of monitoring systems already in place. © 2009 Elsevier Ltd. All rights reserved.

Koch H.,TU Brandenburg | Wechsung F.,Potsdam Institute For Klimafolgenforschung | Grunewald U.,TU Brandenburg
Hydrologie und Wasserbewirtschaftung | Year: 2010

Dry periods with low flows are a particular challenge for water-resources managers. The quantities of water required by users at the moment must be delivered with a certain reliability. However, water supply must be continued also with sufficient reliability in future when the dry period possibly persists. The management of reservoirs must consider additional objectives that impose restrictions on reservoir operation such as flood control (vs. full impoundment) and touristic uses (vs. minimum operation level). In the planning of water-resources management the available natural yield is a key factor. The quantification of the natural yield is subject to large uncertainties. These uncertainties come from variable climate elements, such as precipitation and potential évapotranspiration. Further uncertainty is added by water management actions that are reflected in the measured discharges. Beside climate variability, climatechange effects have gained more attention in the planning of water-resources management recently. One frequently asked question is whether climate-change effects can be detected in measured river-discharge series. This paper describes the elimination of watermanagement effects from measured river-discharges ("naturalization") in the Czech part of the Elbe river basin. These naturalized discharge data are analyzed by statistical means. Moreover, such naturalized discharge data can be used in the calibration of rainfallrunoff-models.

Ilgenfritz E.-M.,Bielefeld University | Ilgenfritz E.-M.,Humboldt University of Berlin | Menz C.,Humboldt University of Berlin | Menz C.,Potsdam Institute For Klimafolgenforschung | And 3 more authors.
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

We study the Landau gauge gluon and ghost propagators of SU(3) gauge theory, employing the logarithmic definition for the lattice gluon fields and implementing the corresponding form of the Faddeev-Popov matrix. This is necessary in order to consistently compare lattice data for the bare propagators with that of higher-loop numerical stochastic perturbation theory. In this paper we provide such a comparison, and introduce what is needed for an efficient lattice study. When comparing our data for the logarithmic definition to that of the standard lattice Landau gauge we clearly see the propagators to be multiplicatively related. The data of the associated ghost-gluon coupling matches up almost completely. For the explored lattice spacings and sizes discretization artifacts, finite size, and Gribov-copy effects are small. At weak coupling and large momentum, the bare propagators and the ghost-gluon coupling are seen to be approached by those of higher-order numerical stochastic perturbation theory. © 2011 American Physical Society.

Siegismund F.,University of Hamburg | Romanova V.,University of Hamburg | Romanova V.,Potsdam Institute For Klimafolgenforschung | Kohl A.,University of Hamburg | Stammer D.,University of Hamburg
Journal of Geophysical Research: Oceans | Year: 2011

Ocean bottom pressure variability is analyzed from three monthly products available from (1) the Gravity Recovery and Climate Experiment (GRACE), (2) sterically corrected altimetry, and (3) from a forward run of the German part of the Estimating the Circulation and Climate of the Ocean (GECCO-2) model. Results lead to an approximate error estimate for each of the ocean bottom pressure (OBP) maps under the assumption of noncorrelated errors among the three products. The estimated error maps are consistent with the misfits of individual fields against OBP sensor data, with the caveat that a general underestimation of the signal strength, as a common, correlated error in all products, cannot be recovered by the method. The signal-to-noise ratio (SNR) increases in all products, when a 3 month running mean filter is applied. Using this filter, we estimate globally averaged errors of 8.6, 11.1, and 5.7 mm of equivalent water height for GRACE, nonsteric altimetry, and GECCO2, respectively. Based on resulting uncertainties, a new OBP product is being produced by merging all three data sets. When validated with bottom pressure observations this new OBP product has a 20% increased SNR compared to the best individual product (GECCO2-ref). Estimated total ocean mass variations explain a considerable part of OBP variability with a SNR above 1 in most of the ocean. In some regions the nonuniform part is weaker than the estimated error. However, most dynamic ocean models are designed to reproduce only the nonuniform, dynamic, OBP variability, but do not accurately describe total mass variability. Copyright 2011 by the American Geophysical Union.

Muller A.,Humboldt University of Berlin | Riedl M.,Humboldt University of Berlin | Penzel T.,Charite - Medical University of Berlin | Kurths J.,Humboldt University of Berlin | And 3 more authors.
Somnologie | Year: 2014

The analysis of events such as apneas, hypopneas, and various types of arousals during sleep plays a central role when diagnosing and trying to understand sleep-related disorders and possible sequelae. Often, only the occurrence of these events is regarded instead of putting them into context with other cardiovascular variables and characterizing their mutual interactions. In this article, we present two new methods that allow for such an analysis: the coordigram and the ensemble symbolic-coupling traces. Through a case study of a subject with frequent arousals, the potential of the new tools for quantifying the autonomic response to sleep disturbances is shown. Furthermore, in a reanalysis of patients suffering from obstructive sleep apnea, the diagnostic relevance of cardiorespiratory coordination for risk stratification of an emerging hypertension is demonstrated. © 2014, Springer-Verlag Berlin Heidelberg.

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