Aggregation in environmental systems – Part 2: Catchment mean transit times and young water fractions under hydrologic nonstationarity Hydrology and Earth System Sciences DOI 10.5194/hess-20-299-2016 19 January 2016 Here I show that seasonal tracer cycles yield strongly biased estimates of mean transit times in nonstationary catchments (and, by implication, in real-world catchments). However, they can be used to reliably estimate the fraction of “young” water in streamflow, meaning water that fell as precipitation less than roughly 2–3 months ago. This young water fraction varies systematically between high and low flows and may help in characterizing controls on stream chemistry. Read more
Diagnosing hydrological limitations of a land surface model: application of JULES to a deep-groundwater chalk basin Hydrology and Earth System Sciences DOI 10.5194/hess-20-143-2016 18 January 2016 This paper presents a strategy to diagnose hydrological limitations of a Land Surface Model. It includes the adaptation of the model for hydrological applications and highlights challenges faced while moving towards high resolution modelling. Read more
Topology of sustainable management of dynamical systems with desirable states: from defining planetary boundaries to safe operating spaces in the Earth system Earth System Dynamics DOI 10.5194/esd-7-21-2016 18 January 2016 The debate about a safe and just operating space for humanity and the possible pathways towards and within it requires an analysis of the inherent dynamics of the Earth system and of the options for influencing its evolution. We present and illustrate with examples a conceptual framework for performing such an analysis not in a quantitative, optimizing mode, but in a qualitative way that emphasizes the main decision dilemmas that one may face in the sustainable management of the Earth system. Read more
The Imbert Formation of northern Hispaniola: a tectono-sedimentary record of arc–continent collision and ophiolite emplacement in the northern Caribbean subduction–accretionary prism Solid Earth DOI 10.5194/se-7-11-2016 15 January 2016 New stratigraphical, structural, geochemical, and geochronological data from the northern Caribbean orogenic belt indicate that the Imbert Fm constitutes a coarsening-upward stratigraphic sequence that records the transition of the sedimentation from a pre-collisional forearc to a syn-collisional piggy-back basin in the lower-to-middle Eocene. This piggy-back basin was transported to the top of the Puerto Plata ophiolitic slab as it was emplaced onto the North America continental margin units. Read more
The assessment of a global marine ecosystem model on the basis of emergent properties and ecosystem function: a case study with ERSEM Geoscientific Model Development DOI 10.5194/gmd-9-59-2016 15 January 2016 To use models to inform policy or to forecast the impact of climate change, the model must first be shown to be a valid representation of the ecosystem. Here we show an novel method to validate a marine model using its ability to represent ecosystem function. These relationships are the community structure, the carbon to chlorophyll ratio and the stoichiometric balance of the ecosystem. These methods are powerful, valid over large spatial scales and independent of the circulation model. Read more
Committed retreat of Smith, Pope, and Kohler Glaciers over the next 30 years inferred by transient model calibration The Cryosphere DOI 10.5194/tc-9-2429-2015 21 December 2015 We calibrate a time-dependent ice model through optimal fit to transient observations of surface elevation and velocity, a novel procedure in glaciology and in particular for an ice stream with a dynamic grounding line. We show this procedure gives a level of confidence in model projections that cannot be achieved through more commonly used glaciological data assimilation methods. We show that Smith Glacier is in a state of retreat regardless of climatic forcing for the next several decades. Read more
Hidden biosphere in an oxygen-deficient Atlantic open-ocean eddy: future implications of ocean deoxygenation on primary production in the eastern tropical North Atlantic Biogeosciences DOI 10.5194/bg-12-7467-2015 21 December 2015 The waters of the tropical Atlantic Open Ocean usually contain comparably high concentrations of oxygen. Now, it became clear that there are watermasses related to eddies that are nearly anoxic. We surveyed one of those eddies and found a biosphere that largely differed from the usual biosphere present in this area with a specific community responsible for primary production and for degradation processes. Further, we found the very first indication for active nitrogen loss in the open Atlantic. Read more
Comment on “Ultra low frequency (ULF) electromagnetic anomalies associated with large earthquakes in Java Island, Indonesia by using wavelet transform and detrended fluctuation analysis” by Febriani et al. (2014) Natural Hazards and Earth System Sciences DOI 10.5194/nhess-15-2697-2015 18 December 2015 Reports of possible earthquake precursors have social responsibility. They motivate the idea that earthquakes may be predicted in the future. Thus, these papers should be convincing about the seismogenic origin of the reported precursors. We have reviewed Febriani et al. (2014). We have shown that the pre-earthquake magnetic changes they reported are not seismogenic but global-scale variations in the geomagnetic field in response to Sun–Earth interactions. Read more
Continental-scale temperature variability in PMIP3 simulations and PAGES 2k regional temperature reconstructions over the past millennium Climate of the Past DOI 10.5194/cp-11-1673-2015 16 December 2015 A comparison of model simulations and reconstructions at the continental scale over the past millennium indicates that models are in relatively good agreement with temperature reconstructions for Northern Hemisphere regions, particularly in the Arctic. This is likely due to the relatively large amplitude of the externally forced response across northern and high-latitudes regions. Conversely, models disagree strongly with the reconstructions in the Southern Hemisphere. Read more
Grain sorting in the morphological active layer of a braided river physical model Earth Surface Dynamics DOI 10.5194/esurf-3-577-2015 15 December 2015 A physical scale model of a gravel-bed braided river was used to measure vertical grain size sorting in the morphological active layer defined as the bed material between the maximum and minimum bed elevation. By normalizing active layer thickness and dividing into 10 sublayers we show that all grain sizes occur with almost equal frequency in all sublayers. Occurrence of patches and strings of coarser material relates to preservation of particular morphotextural features within the active layer. Read more
