Improving performance of bucket-type hydrological models in high latitudes with multi-model combination methods: Can we wring water from a stone?

Multi-model combination (averaging) methods (MMCMs) are used to improve the accuracy of hydrological (precipitation-runoff) outputs in simulation or forecasting/prediction modes. In this paper, we examined if the application of MMCMs can improve model performance in reproducing distributions of hydrological signatures, such as annual maxima or minima of varying durations. To this end, ten MMCMs were applied to 29 bucket-type models to simulate runoff in 50 high-latitude catchments. The MMCMs were evaluated by comparing the resulting simulated flows to the reference (i.e., best-performing) individual model, considering various commonly used performance indicators, as well as model performance in reproducing the distributions of signatures. Additionally, we analysed whether (1) the selection of the candidate models, or (2) targeting specific signatures, such as annual maxima or minima, can improve performance of the model combinations. The results suggest that the application of MMCMs can improve accuracy of runoff simulations in terms of traditional performance indicators, but fails to improve performance in reproducing the distributions of signatures. Neither excluding poor-performing models nor applying the MMCMs with the targeted signatures, improves this aspect of model performance. These findings clearly reveal the need for further research aiming at enhancing model performance in reproducing the distributions of hydrological signatures, which is essential for climate-change impact studies

Uni- and multivariate bias adjustment of climate model simulations in Nordic catchments: Effects on hydrological signatures relevant for water resources management in a changing climate

Hydrological climate-change-impact studies depend on climatic variables simulated by climate models. Due to parametrization and numerous simplifications, however, climate-model outputs come with systematic biases compared to the observations. In the past decade, several methods of different complexity and dimensionality for adjustment of such biases were introduced, but their benefits for impact studies and accurate streamflow projections are still debated. In this paper, we evaluated the ability of two state-of-the-art, advanced multivariate bias-adjustment methods to accurately reproduce 16 hydrological signatures, and compared their performance against two parsimonious univariate bias-adjustment methods based on a multi-criteria performance evaluation. The results indicated that all bias-adjustment methods considerably reduced biases and increased the consistency of simulated hydrological signatures. The added value of multivariate methods in maintaining dependence structures between precipitation and temperature was not systematically reflected in the resulting hydrological signatures, as they were generally outperformed by univariate methods. The benefits of multivariate methods only emerged for low-flow signatures in snowmelt-driven catchments. Based on these findings, we identified the most suitable bias-adjustment methods for water-resources management in Nordic regions under a changing climate, and provided practical guidelines for the selection of bias-adjustment methods given specific research targets and hydroclimatic regimes

Topography and Time Shape Mire Morphometry and Large-Scale Mire Distribution Patterns in the Northern Boreal Landscape

Peatlands are major terrestrial soil carbon stores, and open mires in boreal landscapes hold a considerable fraction of the global peat carbon. Despite decades of study, large-scale spatiotemporal analyses of mire arrangement have been scarce, which has limited our ability to scale-up mire properties, such as carbon accumulation to the landscape level. Here, we use a land-uplift mire chronosequence in northern Sweden spanning 9,000 years to quantify controls on mire distribution patterns. Our objectives include assessing changes in the spatial arrangement of mires with land surface age, and understanding modifications by upland hydrotopography. Characterizing over 3,000 mires along a 30 km transect, we found that the time since land emergence from the sea was the dominant control over mire coverage, especially for the establishment of large mire complexes. Mires at the youngest end of the chronosequence were small with heterogenous morphometry (shape, slope, and catchment-to-mire areal ratios), while mires on the oldest surfaces were variable in size, but included larger mires with more complex shapes and smaller catchment-to-mire ratios. In general, complex topography fragmented mires by constraining the lateral expansion, resulting in a greater number of mires, but reduced total mire area regardless of landscape age. Mires in this study area occurred on slopes up to 4%, indicating a hydrological boundary to peatland expansion under local climatic conditions. The consistency in mire responses to spatiotemporal controls illustrates how temporal limitation in peat initiation and accumulation, and topographic constraints to mire expansion together have shaped present day mire distribution patterns

Landscape constraints on mire lateral expansion

Little is known about the long-term expansion of mire ecosystems, despite their importance in the globalcarbon and hydrogeochemical cycles. It has been firmly established that mires do not expand linearlyover time. Despite this, mires are often assumed to have expanded at a constant rate after initiationsimply for lack of a better understanding. There has not yet been a serious attempt to determine the rateand drivers of mire expansion at the regional, or larger spatial scales. Here we make use of a naturalchronosequence, spanning the Holocene, which is provided by the retreating coastline of NorthernSweden. By studying an isostatic rebound area we can infer mire expansion dynamics by looking at theportion of the landscape where mires become progressively scarce as the land becomes younger. Ourresults confirms that mires expanded non-linearly across the landscape and that their expansion isrelated to the availability of suitably wet areas, which, in our case, depends primarily on the hydro-edaphic properties of the landscape. Importantly, we found that mires occupied the wettest locationsin the landscape within only one to two thousand years, while it took mires three to four thousand yearsto expand into slightly drier areas. Our results imply that the lateral expansion of mires, and thus peataccumulation is a non-linear process, occurring at different rates depending, above all else, on thewetness of the landscape

Ontogeny of synaptophysin and synaptoporin in the central nervous system

The expression of the synaptic vesicle antigens synaptophysin (SY) and synaptoporin (SO) was studied in the rat striatum, which contains a nearly homogeneous population of GABAergic neurons. In situ hybridization revealed high levels of SY transcripts in the striatal anlage from embryonic day (E) 14 until birth. In contrast. SO hybridization signals were low, and no immunoreactive cell bodies were detected at these stages of development. At E 14, SY-immunoreactivity was restricted to perikarya. In later prenatal stages of development SY-immunoreactivity appeared in puncta (identified as terminals containing immunostained synaptic vesicles), fibers, thick fiber bundles and ‘patches’. In postnatal and adult animals, perikarya of striatal neurons exhibited immunoreaction for SO; ultrastructurally SO antigen was found in the Golgi apparatus and in multivesicular bodies. SO-positive boutons were rare in the striatum. In the neuropil, numerous presynaptic terminals positive for SY were observed. Our data indicate that the expression of synaptic vesicle proteins in GABAergic neurons of the striatum is developmentally regulated. Whereas SY is prevalent during embryonic development, SO is the major synaptic vesicle antigen expressed postnatally by striatal neurons which project to the globus pallidus and the substantia nigra. In contrast synapses of striatal afferents (predominantly from cortex, thalamus and substantia nigra) contain SY

Differential expression of synaptophysin and synaptoporin during pre- and postnatal development of the hippocampal network

The closely related synaptic vesicle membrane proteins synaptophysin and synaptoporin are abundant in the hippocampal formation of the adult rat. But the prenatal hippocampal formation contains only synaptophysin, which is first detected at embryonic day 17 (E17) in perikarya and axons of the pyramidal neurons. At E21 synaptophysin immunoreactivity extends into the apical dendrites of these cells and in newly formed terminals contacting these dendrites. The transient presence of synaptophysin in axons and dendrites suggests a functional involvement of synaptophysin in fibre outgrowth of developing pyramidal neurons. Synaptoporin expression parallels the formation of dentate granule cell synaptic contacts with pyramidal neurons: the amount of hippocampal synaptoporin, determined in immunoblots and by synaptoporin immunostaining of developing mossy fibre terminals, increases during the first postnatal week. Moreover, in the adult, synaptoporin is found exclusively in the mossy fibre terminals present in the hilar region of the dentate gyrus and the regio inferior of the cornu ammonis. In contrast, synaptophysin is present in all synaptic fields of the hippocampal formation, including the mossy fibre terminals, where it colocalizes with synaptoporin in the same boutons. Our data indicate that granule neuron terminals differ from all other terminals of the hippocampal formation by the presence of both synaptoporin and synaptophysin. This difference, observed in the earliest synaptic contacts in the postnatal hippocampus and persisting into adult life, suggests distinct functions of synaptoporin in these nerve terminals

Altered splicing of the BIN1 muscle-specific exon in humans and dogs with highly progressive centronuclear myopathy

Amphiphysin 2, encoded by BIN1, is a key factor for membrane sensing and remodelling in different cell types. Homozygous BIN1 mutations in ubiquitously expressed exons are associated with autosomal recessive centronuclear myopathy (CNM), a mildly progressive muscle disorder typically showing abnormal nuclear centralization on biopsies. In addition, misregulation of BIN1 splicing partially accounts for the muscle defects in myotonic dystrophy (DM). However, the muscle-specific function of amphiphysin 2 and its pathogenicity in both muscle disorders are not well understood. In this study we identified and characterized the first mutation affecting the splicing of the muscle-specific BIN1 exon 11 in a consanguineous family with rapidly progressive and ultimately fatal centronuclear myopathy. In parallel, we discovered a mutation in the same BIN1 exon 11 acceptor splice site as the genetic cause of the canine Inherited Myopathy of Great Danes (IMGD). Analysis of RNA from patient muscle demonstrated complete skipping of exon 11 and BIN1 constructs without exon 11 were unable to promote membrane tubulation in differentiated myotubes. Comparative immunofluorescence and ultrastructural analyses of patient and canine biopsies revealed common structural defects, emphasizing the importance of amphiphysin 2 in membrane remodelling and maintenance of the skeletal muscle triad. Our data demonstrate that the alteration of the muscle-specific function of amphiphysin 2 is a common pathomechanism for centronuclear myopathy, myotonic dystrophy, and IMGD. The IMGD dog is the first faithful model for human BIN1-related CNM and represents a mammalian model available for preclinical trials of potential therapies

Understanding watershed hydrogeochemistry: 2. Synchronized hydrological and geochemical processes drive stream chemostatic behavior

This article is a companion to Bao et al. [2017], doi: 10.1002/2016WR018934.Why do solute concentrations in streams remain largely constant while discharge varies by orders of magnitude? We used a new hydrological land surface and reactive transport code, RT‐Flux‐PIHM, to understand this long‐standing puzzle. We focus on the nonreactive chloride (Cl) and reactive magnesium (Mg) in the Susquehanna Shale Hills Critical Zone Observatory (SSHCZO). Simulation results show that stream discharge comes from surface runoff (Qs), soil lateral flow (QL), and deeper groundwater (QG), with QL contributing >70%. In the summer, when high evapotranspiration dries up and disconnects most of the watershed from the stream, Cl is trapped along planar hillslopes. Successive rainfalls connect the watershed and mobilize trapped Cl, which counteracts dilution effects brought about by high water storage (Vw) and maintains chemostasis. Similarly, the synchronous response of clay dissolution rates (Mg source) to hydrological conditions, maintained largely by a relatively constant ratio between “wetted” mineral surface area Aw and Vw, controls Mg chemostatic behavior. Sensitivity analysis indicates that cation exchange plays a secondary role in determining chemostasis compared to clay dissolution, although it does store an order‐of‐magnitude more Mg on exchange sites than soil water. Model simulations indicate that dilution (concentration decrease with increasing discharge) occurs only when mass influxes from soil lateral flow are negligible (e.g., via having low clay surface area) so that stream discharge is dominated by relatively constant mass fluxes from deep groundwater that are unresponsive to surface hydrological conditions.EAR 07‐25019EAR 12‐39285EAR 13‐3172

Wege in die Ernährungszukunft der Schweiz - Leitfaden zu den grössten Hebeln und politischen Pfaden für ein nachhaltiges Ernährungssystem

Aus wissenschaftlicher Sicht ist klar: Unser Ernährungssystem ist nicht nachhaltig. Um unsere Lebens- und Wirtschaftsgrundlagen zu erhalten, braucht es eine Neuausrichtung über die gesamte Wertschöpfungskette. Diese ist gleichzeitig ein Schlüssel zur Erreichung der Agenda 2030 für nachhaltige Entwicklung. SDSN Schweiz hat das wissenschaftliche Gremium Ernährungszukunft Schweiz initiiert, um einen Wegweiser zu entwickeln. Er soll es der Schweiz erlauben, Chancen rechtzeitig anzupacken und unkontrollierbare Kostenfolgen zu vermeiden. Das wissenschaftliche Gremium hat international wegweisende Pionierarbeit geleistet. In einem interdisziplinären wissenschaftlichen Prozess wurde zum ersten Mal für ein Land ein umfassender Handlungspfad zur Neuausrichtung des Ernährungssystems im Einklang mit den Zielen für nachhaltige Entwicklung ausgearbeitet. Die beteiligten Forschenden schaffen damit eine wichtige Grundlage für die weitere politische Diskussion in der Schweiz und international