Local Regime Research Articles

Two-stage crust-mantle interactions from oceanic subduction to post-collisional extension in the northern margin of the North China Craton: Insights from Paleozoic to Mesozoic magmatism

The northern margin of the North China Craton experienced prolonged tectono-magmatic evolution during the late Paleozoic−early Mesozoic in response to the southward subduction and closure of the Paleo-Asian Ocean. However, details about the subduction process and the timing of the tectonic transition from subduction to post-collision are still poorly constrained. Here, we identify two-stage crust-mantle interactions in the Wulashan area and report new geochronology, geochemistry, and Sr-Nd-Pb-Hf isotopic data for magmatic rocks that record such processes following the subduction and closure of the Paleo-Asian Ocean. The early Carboniferous Xiguanjing pluton features a bimodal suite of gabbro (ca. 333 Ma) and syenogranite (ca. 331 Ma). The gabbros have arc-like geochemical affinities, with low Nb/La (0.31−0.40) and La/Ba (0.04−0.09) ratios, and variable Rb/Y (1.22−2.94) ratios, as well as enriched, mantle-like Sr-Nd-Pb (87Sr/86Sri = 0.7046−0.7047; εNd(t) = −3.8 to −3.5; 206Pb/204Pbi = 17.078−17.141) and enriched to depleted Hf (εHf(t) = −4.5 to +6.2) isotopic values. Such geochemical signatures indicate that they were derived from partial melting of the subcontinental lithospheric mantle that was metasomatized by slab-derived fluids, with minor involvement of asthenospheric components. In contrast, the contemporaneous syenogranites are characterized by lower negative εNd(t) (−13.5 to −12.1) and εHf(t) values (−16.3 to −8.2), which suggests that they were formed by partial melting of the lower crust. Late Triassic Shadegai and Xishadegai plutons are mainly composed of enclave-bearing syenogranite, and both mafic microgranular enclaves and syenogranites crystallized at ca. 233−231 Ma. The mafic microgranular enclaves have geochemical features similar to those of the early Carboniferous gabbros, and also have moderately enriched isotopic compositions (εNd(t) = −9.7 to −8.4; εHf(t) = −9.2 to −0.3), which suggests that they originated from interaction between mantle-derived magma and overlying crust-derived magma, with minor additions of asthenospheric melts in their sources. Field and petrological observations, coupled with the similar ages of the host granites and mafic microgranular enclaves, suggest a magmatic mingling process. Isotopic mixing models suggest that minor amounts (∼10%−20%) of lower crustal materials were mixed during the formation of the mafic microgranular enclaves. The host syenogranites display calc-alkaline to alkalic and metaluminous to weakly peraluminous compositions, and negative εNd(t) (−15.0 to −12.1) and εHf(t) values (−16.4 to −9.8), which indicates that they were mainly derived from partial melting of the lower crust and experienced the injection of deep mantle-derived magmas. Our new data, along with previously published data for magmatic rocks in the northern margin of the North China Craton, suggest that the early Carboniferous bimodal intrusive rocks formed in a localized back-arc extensional regime that was probably triggered by slab rollback of the Paleo-Asian Ocean. However, the Late Triassic plutons formed in a post-collisional extensional regime in response to slab breakoff or lithospheric delamination. Temporal variations of Nd-Hf isotopes for the magmatism in the northern margin of the North China Craton suggest that tectonic switching from advancing to retreating subduction to post-collisional extension occurred during the late Paleozoic to early Mesozoic. We propose that a tectonic transition from subduction to post-collisional extension may have occurred during the Early−Middle Triassic, marking the final closure of the Paleo-Asian Ocean, which most likely took place at ca. 250−235 Ma.

Scaling laws of failure dynamics on complex networks

AbstractThe topology of the network of load transmitting connections plays an essential role in the cascading failure dynamics of complex systems driven by the redistribution of load after local breakdown events. In particular, as the network structure is gradually tuned from regular to completely random a transition occurs from the localized to mean field behavior of failure spreading. Based on finite size scaling in the fiber bundle model of failure phenomena, here we demonstrate that outside the localized regime, the load bearing capacity and damage tolerance on the macro-scale, and the statistics of clusters of failed nodes on the micro-scale obey scaling laws with exponents which depend on the topology of the load transmission network and on the degree of disorder of the strength of nodes. Most notably, we show that the spatial structure of damage governs the emergence of the localized to mean field transition: as the network gets gradually randomized failed clusters formed on locally regular patches merge through long range links generating a percolation like transition which reduces the load concentration on the network. The results may help to design network structures with an improved robustness against cascading failure.

Isotopic variations in surface waters and groundwaters of an extremely arid basin and their responses to climate change

Abstract. Climate change accelerates the global water cycle. However, the relationships between climate change and hydrological processes in the alpine arid regions remain elusive. We sampled surface water and groundwater at high spatial and temporal resolutions to investigate these relationships in the Qaidam Basin, an extremely arid area in the northeastern Tibetan Plateau. Stable H–O isotopes and radioactive 3H isotopes were combined with atmospheric simulations to examine hydrological processes and their response mechanisms to climate change. Contemporary climate processes and change dominate the spatial and temporal variations of surface water isotopes, specifically the westerlies moisture transport and the local temperature and precipitation regimes. The H–O isotopic compositions in the eastern Kunlun Mountains showed a gradually depleted eastward pattern, while a reverse pattern occurred in the Qilian Mountains water system. Precipitation contributed significantly more to river discharge in the eastern basin (approximately 45 %) than in the middle and western basins (10 %–15 %). Moreover, increasing precipitation and a shrinking cryosphere caused by current climate change have accelerated basin groundwater circulation. In the eastern and southwestern Qaidam Basin, precipitation and meltwater infiltrate along preferential flow paths, such as faults, volcanic channels, and fissures, permitting rapid seasonal groundwater recharge and enhanced terrestrial water storage. However, compensating for water loss due to long-term ice and snow melt will be a challenge under projected increasing precipitation in the southwestern Qaidam Basin, and the total water storage may show a trend of increasing before decreasing. Great uncertainty about water is a potential climate change risk facing the arid Qaidam Basin.

Effects of online citizen participation on legitimacy beliefs in local government. Evidence from a comparative study of online participation platforms in three German municipalities

AbstractIn order to generate legitimacy for policies and political institutions, governments regularly involve citizens in the decision‐making process, increasingly so via the Internet. This research investigates if online participation does indeed impact positively on legitimacy beliefs of those citizens engaging with the process, and which particular aspects of the participation process, the individual participants, and the local context contribute to these changes. Our surveys of participants in almost identical online consultations in three German municipalities show that the participation process and its expected results have a sizeable effect on satisfaction with local political authorities and local regime performance. While most participants report at least slightly more positive perceptions that are mainly output‐oriented, for some engagement with the process leads not to more, but in fact to less legitimacy. We find this to be the case both for those participants who remain silent and for those who participate intensively. Our results also confirm the important role of existing individual resources and context‐related attitudes such as trust in and satisfaction with local (not national) politics. Finally, our analysis shows that online participation is able to enable constructive discussion, deliver useful results, and attract people who would not have participated offline to engage.

Air pollution trapping in the Dresden Basin from gray-zone scale urban modeling

Abstract. The microscale variability of urban air pollution is essentially driven by the interaction between meteorology and urban topography, which remains challenging to represent spatially accurately and computationally efficiently in urban dispersion models. Natural topography can additionally exert a considerable amplifying effect on urban background pollution, depending on atmospheric stability. This requires an equally important representation in models, as even subtle terrain-height variations can enforce characteristic local flow regimes. In this model study, the effects of urban and natural topography on the local winds and air pollution dispersion in the Dresden Basin in the Eastern German Elbe valley are investigated. A new, efficient urban microscale model is used within a multiscale air quality modeling framework. The simulations that consider real meteorological and emission conditions focus on two periods in late winter and early summer, respectively, as well as on black carbon (BC), a key air pollutant mainly emitted from motorized traffic. As a complement to the commonly used mass concentrations, the particle age content (age concentration) is simulated. This concept, which was originally developed to study hydrological reservoir flows in a Eulerian framework, is adapted here for the first time for atmospheric boundary-layer modeling. The approach is used to identify stagnant or recirculating orographic air flows and resulting air pollution trapping. An empirical orthogonal function (EOF) analysis is applied to the simulation results to attribute the air pollution modes to specific weather patterns and quantify their significance. Air quality monitoring data for the region are used for model evaluation. The model results show a strong sensitivity to atmospheric conditions, but generally confirm increased BC levels in Dresden due to the valley location. The horizontal variability of mass concentrations is dominated by the patterns of traffic emissions, which overlay potential orography-driven pollutant accumulations. Therefore, an assessment of the orographic impact on air pollution is usually inconclusive. However, using the age-concentration metric, which filters out direct emission effects, previously undetected spatial patterns are discovered that are largely modulated by the surface orography. The comparison with a dispersion simulation assuming spatially homogeneous emissions also proves the robustness of the orographic flow information contained in the age-concentration distribution and shows it to be a suitable metric for assessing orographic air pollution trapping. The simulation analysis indicates several air quality hotspots on the southwestern slopes of the Dresden Basin and in the southern side valley, the Döhlen Basin, depending on the prevailing wind direction.

On the localization regime of certain random operators within Hartree–Fock theory

Localization results for a class of random Schrödinger operators within the Hartree–Fock approximation are proved in two regimes: Large disorder and weak disorder/extreme energies. A large disorder threshold λHF analogous to the threshold λAnd obtained in Schenker [Lett. Math. Phys. 105(1), 1–9 (2015)] is provided. We also show certain stability results for this large disorder threshold by giving examples of distributions for which λHF converges to λAnd, or to a number arbitrarily close to it, as the interaction strength tends to zero.

Mesoscopic Conductance Fluctuations in 2D HgTe Semimetal.

Mesoscopic conductance fluctuations were discovered in a weak localization regime of a strongly disordered two-dimensional HgTe-based semimetal. These fluctuations exist in macroscopic samples with characteristic sizes of 100 μm and exhibit anomalous dependences on the gate voltage, magnetic field, and temperature. They are absent in the regime of electron metal (at positive gate voltages) and strongly depend on the level of disorder in the system. All the experimental facts lead us to the conclusion that the origin of the fluctuations is a special collective state in which the current is conducted through the percolation network of electron resistances. We suppose that the network is formed by fluctuation potential whose amplitude is higher than the Fermi level of electrons due to their very low density.

Reversal in the drought stress response of the Scots pine forest ecosystem: Local soil water regime as a key to improving climate change resilience

In a changing climate, forest ecosystems have become increasingly vulnerable to continuously exacerbating heat and associated drought conditions. Climate stress resilience is governed by a complex interplay of global, regional, and local factors, with hydrological conditions being among the key players. We studied a Scots pine (Pinus sylvestris L.) forest ecosystem located near the southern edge of the boreal ecotone, which is particularly subjected to frequent and prolonged droughts. By comparing the dendrochronological series of pines growing in apparently contrasting hydrological conditions ranging from the waterlogged peat bog area to the dry soil at the surrounding elevations, we investigated how the soil water regime affects the climate response and drought stress resilience of the forest ecosystem. We found that in the dry land area, a significant fraction of the trees were replaced after two major climate extremes: prolonged drought and extremely low winter temperatures. The latter has also been followed by a three- to ten-fold growth reduction of the trees that survived in the next year, whereas no similar effect has been observed in the peat bog area. Multi-scale detrended partial cross-correlation analysis (DPCCA) indicated that tree-ring width (TRW) was negatively correlated with spring and summer temperatures and positively correlated with the Palmer drought severity index (PDSI) for the same year. For the elevated dry land area, the above effect extends to interannual scales, indicating that prolonged heatwaves and associated droughts are among the factors that limit tree growth. In marked contrast, in the waterlogged peat bog area, a reversed tendency was observed, with prolonged dry periods as well as warmer springs and summers over several consecutive years, leading to increasing tree growth with a one- to three-year time lag. Altogether, our results indicate that the pessimal conditions of a warming climate could become favorable through the preservation of the soil water regime.

Morphological Modelling to Investigate the Role of External Sediment Sources and Wind and Wave-Induced Flow on Sand Bank Sustainability: An Arklow Bank Case Study

Offshore anthropogenic activities such as the installation of Offshore Renewable Energy (ORE) developments and sediment extraction for marine aggregates have been shown to disrupt current flow, wave propagation, and sediment transport pathways, leading to potential environmental instability. Due to the complexity of the interconnected sediment transport pathways in the south-western Irish Sea combined with an increase in planned anthropogenic activities, the assessment of this risk is imperative for the development of a robust marine spatial plan. Subsequently, this study uses two-dimensional morphological modelling to build upon previous studies to assess the dependency of Arklow Bank’s local sediment transport regime on external sediment sources. Additionally, scenario modelling is used to identify vulnerable areas of this offshore linear sand bank to wind and wave-forcing and to examine the nature of this impact. A sediment budget is estimated for Arklow Bank, whereby seven source and nine sink pathways are identified. New evidence to support the exchange of sediment between offshore sand banks and offshore independent sand wave fields is also provided. The areas of the bank most vulnerable to changes in external sediment sources and the addition of wind- and wave-induced flow are analogous. These high vulnerability zones (HVZs) align with regions of residual cross-flow under pure current conditions. The restriction of sediment sources off the southern extent of Arklow Bank impacts erosion and accretion patterns in the mid- and northern sections of the bank after just one lunar month of simulation. Where tidal current is the primary driver of sand bank morphodynamics, wind- and wave-induced flow is shown to temporarily alter sediment distribution patterns. Wind and wave-induced flow can both accelerate and decelerate the east-west fluctuation of the upper slopes of the bank, yet the nature of this impact is inconsistent due to the misalignment of the directionality of these two forces. The methods and new knowledge derived from this study are directly applicable to tidally-dominated environments outside the Irish Sea.

Groundwater-level fluctuation effects on petroleum hydrocarbons in vadose zones and their potential risks: Laboratory studies

Despite the role of the vadose zone protecting groundwater from contamination, the non-stationarity in this zone makes it difficult to predict the behavior of petroleum hydrocarbons (PH) therein. In laboratory soil columns with sandy and sandy loam soils, we simulated a vadose zone subjected to repeated groundwater-level fluctuation (GLF) to evaluate the behavior of PH under hydrodynamic conditions. The GLF vertically redistributed the PH, the extent of which was pronounced in the sandy soil with a high initial concentration due to the enhanced transport of the immiscible PH through the larger pores. The frequency of GLF did not show a substantial effect on the extent of PH redistribution but largely affected their attenuation. The greater GLF hindered PH volatilization by maintaining a high degree of water saturation, while the subsequent development of a local anaerobic regime inhibited biodegradation, which was more apparent in the sandy loam. Finally, a specific potential risk index was introduced to quantitatively compare the potential risk of PH contamination in different vadose zones exposed to GLF. Overall, the sandy soil contaminated with the higher total PH (TPH) concentration showed markedly higher potential risk indices (i.e., 18.4–29.0%), while the ones comprised of the sandy loam showed 0.6–4.9%, which increased under the greater number of GLF cycles.

Giant atom induced zero modes and localization in the nonreciprocal Su–Schrieffer–Heeger chain

A notable feature of non-Hermitian systems with skin effects is the sensitivity of their spectra and eigenstates to the boundary conditions. In the literature, three types of boundary conditions–periodic boundary condition, open boundary condition (OBC) and a defect in the system as a boundary, are explored. In this work we introduce the other type of boundary condition provided by a giant atom. The giant atom couples to a nonreciprocal Su–Schrieffer–Heeger (SSH) chain at two points and plays the role of defects. We study the spectrum and localization of eigenstates of the system and find that the giant atom can induce asymmetric zero modes. A remarkable feature is that bulk states might localize at the left or the right chain-atom coupling sites in weak localization regimes. This bipolar localization leads to Bloch-like states, even though translational invariance is broken. Moreover, we find that the localization is obviously weaker than the case with two small atoms or OBCs even in strong coupling regimes. These intriguing results indicate that nonlocal coupling of the giant atom to a nonreciprocal SSH chain weakens the localization of the eigenstates. We also show that the Lyapunov exponent in the long-time dynamics in real space can act as a witness of the localized bulk states.

Evidence for nanosized magnetic clusters of Ce-ions in the archetypal heavy fermion metal CeB6

Fine details of crystal structure of archetypal CeB6 hexaboride with heavy fermions are studied at temperatures 85 and 500 K by precise X-ray diffraction technique. Small static Jahn-Teller distortions of a simple cubic lattice are observed at these temperatures, leading to emergence of (i) dynamic charge stripes along selected directions <110>, <100>, and <111> in the crystals in combination with (ii) vibrationally coupled pairs of Ce ions. Instead of a Currie-Weiss type behavior, the temperature dependence of magnetization M∼(T − TCrand)−0.8 with TCrand∼TQ∼3.3 K was deduced in a wide temperature range 5–800 K for various directions of external magnetic field, which indicates the Griffiths phase formation with nanosized clusters of magnetic ions in CeB6. Moreover, in contrast to the scenario of a single-ion Kondo lattice, when revealing the power-law behavior of the magnetic contribution ρm(T)∼T−0.4 to the resistivity in the range of 8–90 K, we conclude in favor of the regime of weak localization of charge carriers in CeB6. Fourier maps of electron density confirm the conclusion about the nanosized magnetic clusters of Ce ions in this archetypal strongly correlated electron system with unusual magnetic ground state.

Benchmarking an allocation to the foreign Sub-portfolio from a South African perspective

This paper responds to the recent (2022) change to Regulation 28 of the South African Pension Funds Act which now permits an increased allocation (raised from 30% to 45%) in foreign investments. Our primary aim is to establish a strategic (long-term) benchmark weight for the allocation to foreign assets. Our secondary aim is to assist in building intuition on potential tactical (shorter-term) foreign allocation decisions. To ensure rigour in our study, we use a novel dataset dating back to the 1930s and we utilise methodologies in recent academic literature in the mean-variance framework. Our optimisation evidence supports a strategic foreign benchmark allocation of 39% (with 61% allocated to local asset classes). We highlight that this strategic foreign benchmark of 39% (probably for the first time) enables managers to potentially take on meaningful tactical overweight foreign positions. We establish that this strategic foreign benchmark would have reduced the risk (standard deviation of returns) of the local-only optimal portfolio significantly from 10% p.a. down to 8.7% p.a. over the 92 year period analysed, whilst increasing the return by an additional 1.1% p.a. over the local-only portfolio. Lastly, we provide guidance on tactical foreign allocation decisions based on four potential local economic regimes.

Habitat associations and threat vulnerabilities of seahorses and pipefishes (Syngnathidae) in Biscayne National Park, Florida, USA

Habitat loss is a primary threat to seahorses, pipefishes, and their relatives (family Syngnathidae) globally. Conservation intervention is difficult or ineffective when species lack critical habitat information. To better understand the habitat associations of syngnathids we conducted underwater visual surveys of 79 sites in three habitat categories (Reef, Continuous, and Discontinuous Submerged Rooted Vegetation) in Biscayne National Park (BNP), a coastal Marine Protected Area (MPA) in southeastern Florida. We recorded nine syngnathid species in our surveys; presence/ absence data was analyzed alongside a suite of abiotic and biotic variables. Nonparametric statistical tests indicated that syngnathids were significantly more abundant inside Biscayne Bay and we did not detect any syngnathids at reef sites—located outside Biscayne Bay—despite reef-associated species being previously reported in BNP. Additional analyses indicated that sites where syngnathids were present were characterized by fine sediment, reduced horizontal visibility, high seagrass coverage, and low coverage of sessile benthic invertebrates and reef-associated turf algae. The most important predictor of syngnathid presence was a predominance of fine sediment—an indicator of low-velocity hydrodynamic conditions—and seagrass coverage at occupied sites was nearly double that of unoccupied sites. Variation in habitat use among the three most abundant sympatric syngnathids (Hippocampus zosterae, S yngnathus scovelli, and Syngnathus floridae) indicates niche partitioning based on salinity, local hydrodynamic regime, and seagrass coverage. Our study points to the value of protecting sheltered seagrass beds; heightened vulnerability to habitat change—driven by watershed development, impacts from fisheries, recreation and tourism, and climate change—necessitates coordinated management of land use outside of the protected area.

Exploring the functional connectivity between the Kis-Balaton Water Protection System and Lake Balaton using satellite data

Lake Balaton, a shallow polymictic freshwater lake in Central Europe, became eutrophic in the 1970s. To retain the inorganic nutrients from the main tributary River Zala, a semi-artificial system called the Kis-Balaton Water Protection System (KBWPS) was constructed in the early 1980s. In 2015, the system was reconstructed and modernised, thus offering the opportunity to evaluate the effectiveness of the functional connection between the KBWPS and Lake Balaton over the past 20 years and to compare its impact before and after the reconstruction. To this end, time series data of algal biomass in Lake Balaton between 1999 and 2019 based on Landsat 7 satellite data were analysed. Over the last 20 years, the algal biomass in Lake Balaton showed an increasing trend (0.009 ± 0.011% increase per year), with territorial specificities also observed. No change was noted in the western part, while an increase was recorded in the eastern part of the lake. A significant difference in the rate of algal biomass accumulation was noticed before (annual increase of 0.008 ± 0.019%) and after (0.240 ± 0.306% per year) the KBWPS reconstruction. Given that the largest increase in algal biomass after reconstruction was observed in the outermost KBWPS basin of Lake Balaton, it appears that mesoscale environmental, water balance, or other factors affecting the lake are playing a role in this increase, rather than the KBWPS reconstruction. This research highlights the potential to study aquatic ecosystems using Earth observation techniques, and how mesoscale factors such as changes in the local climate regime or shifts in lake management can greatly impact the trophic state of a large shallow lake. Effectively identifying these factors is crucial in maintaining the proper status of aquatic ecosystems.

Phenomenology of the Prethermal Many-Body Localized Regime.

The dynamical phase diagram of interacting disordered systems has seen substantial revision over the past few years. Theory must now account for a large prethermal many-body localized regime in which thermalization is extremely slow, but not completely arrested. We derive a quantitative description of these dynamics in short-ranged one-dimensional systems using a model of successive many-body resonances. The model explains the decay timescale of mean autocorrelators, the functional form of the decay-a stretched exponential-and relates the value of the stretch exponent to the broad distribution of resonance timescales. The Jacobi method of matrix diagonalization provides numerical access to this distribution, as well as a conceptual framework for our analysis. The resonance model correctly predicts the stretch exponents for several models in the literature. Successive resonances may also underlie slow thermalization in strongly disordered systems in higher dimensions, or with long-range interactions.

“However I talk about it, my kids tell me I’m doing it wrong”: U.S. Mothers of Cisgender Children Grapple With Gender Diversity

Current literature shows that parents of trans and gender-diverse children relearn gender from their children to fulfill their parenting role. In-depth interviews with 35 mothers raising teens in a progressive region of the United States reveal that mothers of cisgender children must also relearn gender to parent successfully, and they utilize their children’s generational gender literacy to do so. Using the theory of gender as structure, I argue that, in a progressive community, transitions on the institutional and individual levels of gender created a shift on the interactional level, causing mothers who were socialized into gender as binary and stable to reconceptualize it as fluid and to adopt appropriate gendering conduct. In the new generational and local regime, accountability, thus far conceptualized in gender theory as reinforcing heteronormativity, became a tool for enforcing conscious gendering conduct. Furthermore, despite theories of gender and sexual socialization flowing from parent to child, I find that children had access to individual and institutional-level resources helping them adapt to the new gender regime. Children thus became tutors and cultural resources for their mothers, illustrating that the direction of gender socialization may depend on cultural fluency rather than family role.

Gypsum‐lined degassing holes in tumuli

AbstractSmall, circular holes, lined with a thin gypsum veneer, and closely associated with gypsum tumuli (domes), occur at Salar de Pajonales, a salt flat in the northern Andes, Chile. We propose a model in which the formation of the gypsum‐lined holes, and less commonly the formation of the tumuli itself, is controlled by the unique juxtaposition of physiographic, geologic and hydrologic conditions. On a regional scale, Salar de Pajonales is unusual compared to other salars, as it is located close to a large magmatic inflation centre (Lazufre), lies along strike of major regional structural trends, is a large ephemeral lake and contains high salt concentrations. On a basin scale, the lined holes are only present along strike of lineaments that are directly linked to the local stress regime. In turn, these lineaments control the location of degassing and subsequently the formation of the lined holes in the gypsum tumuli and, in part, the tumuli themselves.

Analysis of data from the full-scale prototype testing of the WASP – A novel wave measuring buoy.

To assess the viability of locations for wave energy farms, and design effective coastal protection measures, knowledge of local wave regimes is required. Current regime-measuring devices are expensive, and the aim of the WASP Project is to develop a low-cost, self-powering wave-measuring device. The Wave-Activated Sensor Power Buoy (WASP) comprises a floating body with a moonpool. The relative motion of the water level in the moonpool to the buoy will pressurise and depressurise the air above the water column, which will be used to drive a bidirectional turbine in the manner of an oscillating water column, which will operate in conjunction with a generator to recharge an on-board battery pack. It has previously been demonstrated through tank testing of scale-models that a sea-state may be estimated from measurements of the pressure within the air above the water column under controlled conditions [1]. Important statistical parameters relating to the sea state, such as the significant wave height, zero-cross period et cetera. may then be estimated from the spectral moments of the wave spectrum [2].&#x0D; This paper seeks to validate the use of measurements taken of the pressure in a volume of air contained in a chamber above an oscillating water column (OWC) (which is in communication with the ocean) to estimate the sea state which induces motion of the water column.&#x0D; The WASP was deployed from March to July 2019 at the Smart Bay test facility in Galway Bay, Ireland. The ¼ Scale test site was previously characterised by B Cahill UCC 2011 [3] using data captured by the Marine Institute Datawell WaveRider buoy from 2006 to 2011. Pressure signal data recorded by the WASP at a frequency of 8Hz was processed in to 30-minutes blocks to reflect the presented data from the WaveRider buoy, from which the WASP was moored a distance of 400m from during deployment. Power Density Spectra for 6,500 thirty-minute sea states were generated and an inverse transfer function between the WASP and the WaveRider produced. This allowed for the calculation of the associated significant wave height, Hs, and zero-crossing period, Tz, from the WASP pressure data for each thirty-minute block of data. At this time, outliers and bimodal spectra were removed to simplify the analysis, and the data was binned based on Hs and Tz ranges. For each bin, average inverse transfer functions were generated. A Bretschneider Spectrum [4] was produced using the Hs and Tz values from the WaveRider data for the respective binned WASP data. An average transfer function was then generated between the Bretschneider models and the corresponding sea states for the WASP. Using this final transfer function, a scatter plot of Hs and Tz for the test site was generated and compared against the previously produced scatter plot from the initial resource characterisation of the Galway Bay Test Site in 2011 in order to determine if the WASP is capable of measuring sea-states through measurement of time series pressure signals in the volume of air above the water column in the OWC.

Hydrological regimes explain the seasonal predictability of streamflow extremes

Advances in hydrological modeling and numerical weather forecasting have allowed hydro-climate services to provide accurate impact simulations and skillful forecasts that can drive decisions at the local scale. To enhance early warnings and long-term risk reduction actions, it is imperative to better understand the hydrological extremes and explore the drivers for their predictability. Here, we investigate the seasonal forecast skill of streamflow extremes over the pan-European domain, and further attribute the discrepancy in their predictability to the local river system memory as described by the hydrological regimes. Streamflow forecasts at about 35 400 basins, generated from the E-HYPE hydrological model driven with bias-adjusted ECMWF SEAS5 meteorological forcing input, are explored. Overall the results show adequate predictability for both hydrological extremes over Europe, despite the spatial variability in skill. The skill of high streamflow extreme deteriorates faster as a function of lead time than that of low extreme, with a positive skill persisting up to 12 and 20 weeks ahead for high and low extremes, respectively. A strong link between the predictability of extremes and the underlying local hydrological regime is identified through comparative analysis, indicating that systems of analogous river memory, e.g. fast or slow response to rainfall, can similarly predict the high and low streamflow extremes. The results improve our understanding of the geographical areas and periods, where the seasonal forecasts can timely provide information on very high and low streamflow conditions, including the drivers controlling their predictability. This consequently benefits regional and national organizations to embrace seasonal prediction systems and improve the capacity to act in order to reduce disaster risk and support climate adaptation.