bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation of River Morphology Change due to Reservoir Desiltitation Operation
Authors: Huang Cheng-Chia
Published: February 2023

The formulation of the reservoir desiltitation strategy has been addressed as an essential issue worldwide because the water resources crisis has become serious in recent years. The sediment-releasing operation using the current sluice gates or the bypass tunnel during flooding events can slow down the reservoir deposition and keep the storage capacity. However, the variation of downstream river morphology inevitably affected the channel stability due to the reservoir sediment-releasing operation. The sediment transportation downstream of the reservoir needs to be further investigated to determine the potential risk. This study adopted a calibrated two-dimensional numerical model, SRH-2D, to investigate the river morphology in the Tamshui River in northern Taiwan, East Asia. Three different typhoon events, Typhoon Hinnamnor, Soudelor, and Aere were considered slight, moderate, and severe scenarios. In addition, the original operation, sediment releasing, and bypass joint operation could be represented as the lowest, medium, and highest sediment released rate situation. The simulation shows the erosion and deposition location of different typhoon events and reservoir operations to highlight the potential disaster hotspot. As a result, this research can be a reference to reservoir management to adjust the operation principle to obtain the balance between reservoir storage capacity and downstream river stability.
A Network-Based Model for Simulating Regional Transformation Driven by University-Enterprise Collaboration
Authors: Feng Wenhan , Li Bayi
Published: February 2023

Knowledge creation is essential to encourage regional development especially for areas in regional transition. The positive impact of university-enterprise cooperation on the process has been extensively discussed in previous studies, but a comprehensive picture of the mechanism has not been fully described, such as how academic researches promote practical projects. Modeling this complex nature has been dealt and required by both academia and planner. Toward this target, we propose an empirically founded agent-based model to demonstrate the collaborative network. It uses the literature and patents created in each project as a basis for measuring regional knowledge production and innovation. Based on the analysis of the observed data, a conceptual model of network-based university-enterprise cooperation was constructed with the help of NetLogo. It will simulate the whole process from academic research to industrial practice to explore the driving mechanism of universities for regional knowledge production and innovation. The collaborative network of practice projects is constructed from the partnership data of every project recorded within the REVIERa platform, where each node in the network was classified into fields of research. Knowledge was quantified by metrics such as the quantity and quality of literature. Based on the various characteristics of nodes, networks and their path dependencies, the birth of innovative projects will be simulated and the impact of interdisciplinary on regional transformation will be quantified in the model. The model is based on the real world data and corroborated with it to capture the mechanism and characteristics of this complex process, showing its value to boost the scientific regional planning in the future.
Seasonal variation of aerosol iron solubility in coarse and fine particles at an inland city in northwestern China
Authors: Tang Mingjin , Zhang Huanhuan , Li Rui
Published: February 2023

This work investigated seasonal variation of aerosol iron (Fe) solubility for coarse (>1 μm) and fine (<1 μm) particles at Xi’an, a megacity in northwestern China impacted by anthropogenic emission and desert dust. Total Fe concentrations were lowest in summer and similar in other seasons for coarse particles, while lowest in summer and highest in spring for fine particles; for comparison, dissolved Fe concentrations were higher in autumn and winter than spring and summer for coarse particles, while highest in winter and lowest in spring and summer for fine particles. Desert dust aerosol was always the major source of total Fe for both coarse and fine particles in all the four seasons, but it may not be the dominant source for dissolved Fe. Fe solubility was lowest in spring for both coarse and fine particles, and highest in winter for coarse particles and in autumn for fine particles. In general aerosol Fe solubility was found to be higher in air masses originating from local and nearby regions than those arriving from desert regions after long-distance transport. Compared to coarse particles, Fe solubility was similar for fine particles in spring but significantly higher in the other three seasons, and at a given aerosol pH range Fe solubility was always higher in fine particles. Aerosol Fe solubility was well correlated with relative abundance of aerosol acidic species, implying aerosol Fe solubility enhancement by acid processing; moreover, such correlations were better for coarse particles than fine particles in all the four seasons. Fe solubility was found to increase with relative humidity and acid acidity for both coarse and fine particles at Xi’an, underscoring the importance of aerosol liquid water and aerosol acidity in regulating Fe solubility via chemical processing.
Application of Advanced Wflow_sbm Model with the CMIP6 climate projection for flood prediction in the data-scarce: Lake-Tana Basin, Ethiopia
Authors: Alaminie Addis , Amarnath Giriraj , Padhee Suman , Ghosh Surajit , Tilahun Seifu , Mekonnen Muluneh , Assefa Getachew , Seid Abdulkarim , Zimale Fasikaw , Jury Mark
Published: February 2023

Abstract:  Flood-attributed damages to infrastructure and public safety are expected to escalate in the future due to climate change, land use change, and associated hydrologic changes. In recent years, the reliability of flood forecasts has increased due to the availability of meteorological and hydrological data and advancements in flood prediction science. However, there is limited effort to apply emerging advanced hydrological models for flood prediction in poorly gauged watersheds. The overall objective of this study is to demonstrate applicability of climate model products to generate reliable flood predictions for data-limited and flood-prone areas. In this study, the most recent high-resolution climate models of the Coupled Model Intercomparison Project Phase 6 (CMIP6) were evaluated to assess the impacts of projected climate change on the flood-prone areas of the Lake Tana basin, Ethiopia. The ensemble means of the top five CMIP6 climate model forcing data were used to calibrate and validate a free open-source, spatially distributed hydrological model known as Wflow_sbm. Model-independent multi-algorithm optimization and parameter estimation tool is implemented for calibration and validation of Wflow. In terms of simulating runoff and flood events, application of Wflow_sbm to the Lake Tana basin provided promising results. This study serves as a major step towards the development and implementation of climate model product-driven hydrological model to assess flooding damages of future climate projections within the poorly gauged Lake Tana basin.
Impact of climate change on the bioclimatic suitability of different Portuguese grape varieties in Europe
Authors: Adão Filipe , C. Campos João , A. Santos João , C. Malheiro Aureliano , Fraga Hélder
Published: February 2023

Viniculture has a long tradition in southern Europe and is an important socioeconomic sector in many countries. Temperate climates allow for this activity, as moderate temperatures and precipitation are key to the proper phenological development of grape vines. However, the onset of climate change has led to increasingly higher temperatures and changing precipitation regimes during the growing season in the last decades. According to the latest report by the Intergovernmental Panel on Climate Change, a continuation of the observed changes is expected in the coming decades, independently of the radiative forcing scenarios that are considered. Wine quality has already been affected in some regions, but the long-term sustainability of wine growing itself is now in question. To better understand what the future could look like, the bioclimatic suitability of Portugal, Spain, France, and Italy for twelve Portuguese grape varieties was modeled using the R BIOMOD2 platform. Ensemble correlative models were made using the current locations of the grape varieties in Portugal and the bioclimatic indexes "Huglin Index", "Cool Night Index", "Growing Season Precipitation Index", and "Temperature Range during Ripening Index" as predictive variables. The indices were calculated with Copernicus’s E-OBS dataset for the recent past (1989-2005) and the EURO-CORDEX datasets for the future (2051-2080), considering the Representative Concentration Pathways 4.5 and 8.5. The models obtained high scores in the evaluation of their predictive performance (ROC > 0.9) and allowed for the identification of the most suitable regions for the different grape varieties across the study area. A clear shift in bioclimatic suitability towards the north was observed, namely towards the north of Spain and France, and in some cases, also towards regions with higher elevation. These shifts were mainly due to the projected overall rise in thermal accumulation and lower precipitation in the southern regions, which is corroborated by the evaluation of the contribution of each of the indexes to the models. Thus, the long-term sustainability of the wine industry in Europe will most likely require measures of adaptation that mitigate the effects caused by the change in these two atmospheric factors.
Modeling of wind conditions in Warsaw
Authors: Strzyzewski Tomasz , Jaczewski Adam
Published: February 2023

Airflow is one of the most important weather parameters in a city. It is important for the air quality, the city's heat balance, pedestrian comfort and the safety of high-rise buildings. Local flow at the scale of streets and districts is difficult or impossible to capture in regional weather models. Computational Fluid Dynamic models are the solution. In this paper, the OpenFoam model was used to model wind direction and speed in specific meteorological situations. The results were compared with measurement stations in Warsaw, and the model was improved on their basis. An averaged Navier Stokes turbulence model was used under steady-stable flow conditions. The Darcy-Forchheimer model was used to take vegetation into account. The poster presents the first results of analyzes related to the spatial distribution of wind direction and speed, delineates areas at risk of low air quality and compares it with the results from measuring stations. In addition to the basic model, a model containing ground thermals was also created to study the extent and intensity of the urban heat island and to study the phenomenon of smog during temperature inversion in selected meteorological conditions. A comparative analysis of both models was made. The first results show that it is possible quite accurately to map airflow in a city. It also indicates that some existing ventilation channels of the city have been blocked or limited due to new investments. The most important ventilation channel is the Vistula valley, which is 500-600 m wide in Warsaw. However, due to the terrain, its most important role is not fulfilled during prevailing westerly winds, and then the air quality decreases, especially at low wind speeds. In most cases, the northern districts are also generally better ventilated (spatial distribution of buildings, higher wind speeds) than the southern districts, but this is not always visible when assessing air quality. The immediate vicinity also influences the aspects of mechanical ventilation of the city and the way buildings are heated. Districts that theoretically should have better conditions for air exchange are often areas of single-family houses and independent boiler rooms. The city centre, despite tighter development, is heated by the municipal heating plant, and they are not direct emitters of pollution. Another aspect is vehicle traffic. In the city centre, more vehicle traffic is another pollutant emitter. For this reason, pollutants specific to heating and traffic were analysed separately. The general problem in high-resolution city-scale modelling is the use of adequate computational power. This initially precludes using CFD models in meteorological nowcasting and short-term modelling.
High-resolution hail detection: probability of occurrence and size of hailstones based on weather radar data
Authors: Specht Krystian , Szturc Jan , Jurczyk Anna
Published: February 2023

The HAIL application was developed and implemented in the Institute of Meteorology and Water Management – National Research Institute (IMGW) as a component of the MeteoWarn system of detection and forecasting of dangerous weather phenomena. The application contains two algorithms: (i) hail detection and probability estimation; (ii) estimation of the maximum hail size that occurs in the event.The probability of hail is determined using own hail detection algorithm based on fuzzy logic using the following weather radar products: the differential reflectivity (ZDR) and the exceedance of 0°C isotherm for echo top 40, 45, 50 dBZ (EHT40, EHT45, EHT50). Threshold have been introduced for the parameters to prevent false hail detection, above which hail is possible to occur. Additionally some other radar parameters: maximum reflectivity (CMAX), vertically integrated liquid water (VIL), constant altitude plan position indicator (CAPPI) on 4 km, and EHT are checked. The maximum hail size is calculated from the parameters: VIL, EHT50, and isotherm 0°C.The developed algorithms were verified by observations in meteorological stations staffed by trained observers. The stations are limited to specific locations, but they are the most reliable and precise source of data about weather phenomena. Verification data for calibration are observations from synoptic stations and for hail size additionally observations from the European Severe Weather Database (ESWD). The results of the verification show good enough reliabilities of the two HAIL products. Validation based on the contingency table provided the following results: the probability of detection (POD) is 0.99, the false alarm ratio (FAR) is 0.02, and the critical success index (CSI) is 0.98. POD of no hail is 0.39, FAR is 0.38, and CSI is 0.31.
Cost-Potential Curves of Onshore Wind Energy: the Role of Disamenity Costs
Authors: Ruhnau Oliver , Eicke Anselm , Sgarlato Raffaele , Tröndle Tim , Hirth Lion
Published: February 2023

Numerical optimization models are used to develop scenarios of the future energy system. Usually, they optimize the energy mix subject to engineering costs such as equipment and fuel. For onshore wind energy, some of these models use cost-potential curves that indicate how much electricity can be generated at what cost. These curves are upward sloping mainly because windy sites are occupied first and further expanding wind energy means deploying less favorable resources. Meanwhile, real-world wind energy expansion is curbed by local resistance, regulatory constraints, and legal challenges. This presumably reflects the perceived adverse effect that onshore wind energy has on the local human population, as well as other negative external effects. These disamenity costs are at the core of this paper. We provide a comprehensive and consistent set of cost-potential curves of wind energy for all European countries that include disamenity costs, and which can be used in energy system modeling. We combine existing valuation of disamenity costs from the literature that describe the costs as a function of the distance between turbine and households with gridded population data, granular geospatial data of wind speeds, and additional land-use constraints to calculate such curves. We find that disamenity costs are not a game changer: for most countries and assumptions, the marginal levelized cost of onshore wind energy increase by 0.2–12.5 €/MWh.
Transpiration response to atmospheric drying vs. to soil drying: underlying physical and physiological mechanisms and related plant traits
Authors: Köhler Tina , Wankmüller Fabian Joscha Pascal , Sadok Walid , Carminati Andrea
Published: February 2023

Plant water use during drought depends on atmospheric demand and soil water supply. Typically, transpiration response to drought is evaluated in two types of experiments: either exposure to a stepwise increase in vapor pressure deficit (VPD), or exposure to soil drying over the course of weeks. Surprisingly however, the extent of similarities and differences of the underlying mechanisms remains poorly documented. This hampers progress towards breeding for well-adapted crops targeting environments with high VPD, high risk of soil moisture deficit, or both. We present an extensive review of the two experimental approaches and use a soil-plant hydraulic model to simulate transpiration responses to both environmental drivers. Existing experimental results lead to contradicting results regarding the role of the plant hydraulic conductance for the transpiration response to atmospheric drying vs. to soil drying: a high plant hydraulic conductance triggers an earlier transpiration decline (i.e. in wetter soil conditions) during soil drying; but enables plants to sustain transpiration at high VPD. A hydraulic framework hypothesizing that transpiration responds to a decline in soil-plant conductance helps to explain the contradiction. At high VPD, water potential gradients mainly develop within the plant, and thus it is the plant hydraulic conductance that limits the water flow during atmospheric drying. During soil drying, the gradients develop in the soil, and thus the soil hydraulic conductivity controls the flow. The plant hydraulic conductance is expected to impact the plant’s sensitivity to the development of water potential gradients around the roots that occurs during soil drying. Thus, stomatal closure and hence transpiration response is related to a drop in hydraulic conductivities in both scenarios but the relevant hydraulic traits differ between the two environmental changes in a predictable way. Such a finding could better guide breeding efforts targeting adaptation to specific drought regimes.
Understanding the variability and stability of hydrological components under vegetation restoration in watersheds on the Chinese Loess Plateau in past 50 years
Authors: Zhang Xiaoping , Yi Haijie , Xue Fan , Bruijnzeel Leendert Adrian , Cheng Zhuo , Liu Baoyuan , Li Yangyang
Published: February 2023

Assessing ecological restoration effects on hydrological regimes is important for watershed management, especially under semi-arid conditions.  The long-term trends of streamflow components were analyzed for three less forested watersheds (LFWs), and for two largely forested watersheds (FWs) within the Beiluo River Basin on the Chinese Loess Plateau.  Three LFWs were undergoing major vegetation restoration, in which the vegetation coverage changed from 16–23% in 1970 to 57–80% coverage in 2019. While as contrast, the two FWs has vegetation coverage from 65–68% in 1970 to 88–92% in 2019. Daily flow data for each watershed and year were normalized by rainfall to eliminate effects of non-stationary rainfall.  Mean annual streamflow totals for the ~60-year study period were 25.1–34.1 and 21.6–48.1 mm y_1 for the LFWs and FWs, respectively.  Average contributions of baseflow to total streamflow were 32–44% for the LFWs and 58–61% for the FWs. Mann-Kendall tests showed significant decreasing trends for annual streamflow and stormflow (0.23–0.54% y_1) from the LFWs throughout.  Mean streamflow from the LFWs between 2000 and 2019 decreased by 58% compared to the pre-2000 period, while the average contribution of stormflow decreased from 66% to 35% (2010s). However, winter baseflow increased with time since start of restoration.  Conversely, streamflow (components) for the FWs showed only slight fluctuations in decadal, annual and seasonal trends.  Both total streamflow and stormflow exhibited strong power relationships with vegetation coverage, illustrating a tendency towards stable flow regimes for vegetation coverage >60–70%.  Large-scale vegetation restoration has fundamentally changed amounts and temporal distribution of streamflow (components) on the Loess Plateau mainly by regulating stormflow. After 20 years of restoration, the trend and proportion of streamflow components from the LFWs approximated those of the FWs.  Since soil erosion is driven by a certain of amount and intensity of runoff, the above results imply that soil erosion and sediment transportation would reach a stability with vegetation restoration to a certain coverage in watersheds. But it is necessary to investigate the difference among regions.  These results underpin the planning of sustainable management of natural resources and socio-economic development during long term ecological restoration on the Loess Plateau.Keywords: Trends of long-term hydrological elements; Surface flow and baseflow; Vegetation restoration; Loess Plateau
Reconstruction of Mercury’s internal magnetic field beyond the octupole
Authors: Töpfer Simon , Oertel Ida , Schiron Vanita , Narita Yasuhito , Glassmeier Karl-Heinz , Heyner Daniel , Kolhey Patrick , Motschmann Uwe
Published: February 2023

The reconstruction of Mercury’s internal magnetic field enables us to take a look into the inner heart of Mercury. In view of the BepiColombo mission, Mercury’s magnetosphere is simulated using a hybrid plasma code, and themultipoles of the internal magnetic field are estimated from the virtual spacecraft data using three distinct reconstruction methods: the truncated singular value decomposition, the Tikhonov regularization and Capon’s minimum variance projection. The study shows that a precise determination of Mercury’s internal field beyond the octupole up to the dotriacontapole (fifth degree of the multipole expansion) is possible. Especially, Capon’s method provides the most accurate inversion result compared to the Tikhonov regularization and the truncated singular value decomposition.
Synchronous detection of vegetation structures in semi-terrestrial areas of the Rhine via unmanned surface vehicles and unmanned aerial vehicles and its benefits for river management
Authors: Eberhardt Benjamin , Heuner Maike , Gattung Thomas , Hoffmann Magnus , Hansen Issa , Lüthi Beat , Teege Julian , Neumann Enrico , Becker Ralf , Blankenbach Jörg
Published: February 2023

Maintenance of waterways is often a challenging task with conflicting interests between different parties. They are subject to economical stresses through the industry and transportation sector on the one hand, on the other the European Water Framework Directive dictates to ensure (or lead them back to) a chemically and ecologically “good status” (which benefits the balance between regulating, supporting, providing and cultural ecosystem services).To have a good decision base for ecological measures, local-scale high resolution temporal and spatial data is needed to make sound decisions for a sustainable river management, which extends to assess and monitor the succession of restoration areas and to document change.The objective of the project RiverCloud is the development of a data acquisition platform which enables synchronous data collection with unmanned aerial vehicles (UAV) and unmanned surface vehicles (USV). On the base of this platform different sensors can be used for a holistic data base in semiterrestrial areas of streams: e.g. acoustic doppler current profilers, multi-parameter sensors, multibeam-echosounders and a 360° camera for the USV; Sensors on the UAV consist of a bathymetric range finder and an industrial grade camera for structure from motion application to derive high-resolution point clouds and orthomosaics.Building upon this data base, a further objective is the detection of vegetation structures such as a canopy height, single trees and the balancing of aboveground biomass, as a regulating ecosystem service for carbon sequestration, from high-resolution point clouds by using open source software. The results from remote sensing data are tested against comparative data collected in the field. Workflow, results and benefits for river management will be presented. All data was collected in September 2022 along the river Rhine near Karlsruhe, Germany.
Fish starved to death by Mediterranean water-column stratification and high salinity in pre-evaporitic Messinian
Authors: Agiadi Konstantina , Vasiliev Iuliana , Butiseaca Geanina , Kontakiotis George , Thivaiou Danae , Besiou Evangelia , Zarkogiannis Stergios , Koskeridou Efterpi , Antonarakou Assimina , Mulch Andreas
Published: February 2023

The restriction of the Mediterranean–Atlantic marine connection over the Messinian stage, which led to a salinity crisis and the deposition of the youngest salt giant on Earth, impacted the composition and structure of marine biota in unprecedented ways, but its effects on the biological functions of marine organisms remains unchartered territory. By analyzing the stable oxygen and carbon isotopic composition of the otoliths of two carefully selected fish species, a pelagic (surface) and a benthic (bottom-dwelling) one, we were able to infer not only the sea surface and bottom salinity and oxygenation conditions, but also the fishes’ metabolic response to the paleoceanographic changes in the eastern Mediterranean from 7.2 to 6.5 Ma. The high salinity and stratification of the Mediterranean water column during this interval hampered the ability of the marine fishes to grow, particularly those dwelling in the sea bottom. A first event (6.82–6.81 Ma) of high temperature and salinity induced an increase in the metabolism of fishes across the water column, meaning that they consumed and respired more. Subsequent warming, increased salinity and stratification at 6.70–6.69 Ma further intensified the environmental stress for bottom-water fishes. To cope with these extreme conditions at the sea floor, benthic fishes show increased metabolic carbon despite low food availability, which implies that fishes metabolized (i.e. consumed) their own tissue to survive. The disappearance of benthic fishes in the study area after 6.8 Ma further reinforces this conclusion. Our study promotes the importance of otoliths stable isotopic analyses as tools for reconstructing complex paleoenvironmental histories.
Antarctic Atmospheric Rivers in the Past and Future Climates
Authors: Maclennan Michelle , Winters Andrew , Shields Christine , Wille Jonathan , Baiman Rebecca , Barthelemy Léonard , Favier Vincent
Published: February 2023

Atmospheric rivers (ARs) are long, narrow bands of warm and moist air that travel poleward from the midlatitudes. While Antarctic atmospheric rivers (ARs) occur only 1-3% of the time over the ice sheet, they are a significant contributor to Antarctic surface mass balance: they contribute 10% on average, and more than 20% locally, of Antarctic precipitation each year. Here we use an Antarctic-specific AR-detection algorithm to identify ARs in MERRA-2 and ERA5 reanalyses and the Community Earth System Model version 2 (CESM2). We use this algorithm to quantify the frequency, location, and precipitation attributed to Antarctic ARs for the period 1980-2014 and use these statistics to identify CESM2 biases relative to MERRA-2 and ERA5. We then apply the AR-detection algorithm to CESM2 for the future period (2015-2100) to examine how the frequency and intensity of ARs, AR-attributed total precipitation, and year-to-year variability in AR precipitation changes in the future under the SSP370 emissions scenario. Our results quantify past and future impacts of ARs on Antarctic annual precipitation, interannual variability, and trends, and ultimately provide an early assessment of future AR-driven changes in Antarctic surface mass balance.
Irregular recurrence of surface-faulting paleoearthquakes along the Gowk fault, southeast Iran
Authors: Foroutan Mohammad , Meyer Bertrand , Sébrier Michel , Murray Andrew , Shokri Mohammad-Ali , Solaymani Azad Shahryar , Nazari Hamid , Azhandeh Faezeh , Sajedi Far Ailar , Bassiri Mojtaba
Published: February 2023

While long-averaged recurrence times of large earthquakes are documented on many slow-slipping fault zones in intracontinental settings, the variability of the return periods through multiple seismic cycles remains poorly known. Paleoseismic investigations across fault zones with the well-documented instrumental sequence of surface-breaking earthquakes are a way to tackle the problem. In this context, the Gowk fault, a 160-km-long dextral fault in central Iran, that experienced four surface-rupturing earthquakes with magnitudes ranging from Mw 5.8 to 7.0 during a 1981-1998 earthquake sequence offers a case study. The four earthquakes have ruptured a 90-km-stretch of the fault. The most recent one, the 14 March 1998 Fandoqa earthquake of Mw 6.6, produced a 23-km-long surface rupture along the northern part of the Gowk fault with a maximum right-lateral displacement of 3 m. With a Holocene slip-rate between 3.8-5.7 mm yr-1 and several recent seismic events testifying to its high level of seismicity, the Gowk fault is an appropriate target to conduct paleoseismic investigations and address the earthquake behavior of slow-slipping faults activated by a sequence of well-documented instrumental earthquakes. We excavated two neighboring trenches across the 1998 fault breaks and identified at least four Holocene event horizons that preceded the 1981-1998 earthquake sequence. The age of the faulted stratigraphic sequence is constrained by eighteen optically stimulated luminescence samples and one radiocarbon age on charcoal. The ages of the event horizons suggest an irregular seismic behavior of the Gowk fault characterized by significant variability in the return period of surface rupturing earthquakes.
Light-limited dynamics of sinking phytoplankton in a convective flow model with ice-covered waters
Authors: Berti Stefano , Tergolina Vinicius Beltram , Calzavarini Enrico , Mompean Gilmar
Published: February 2023

Plankton dynamics are controlled by an often subtle interplay between biological and physical processes. Among the latter, fluid transport is known to play a prominent role. Field studies have, e.g., provided evidence of the effects of turbulent-convection upwelling and downwelling motions on phytoplankton survival. Recent numerical investigations have emphasized, in addition, that relatively large-scale coherent flow features on the vertical can considerably hinder survival and thus negatively impact plankton blooms.
In nutrient-rich polar marine environments phytoplankton growth is critically limited by light availability, especially in waters that are partially covered by ice. In these conditions, the heterogeneity of the light intensity distribution, in association with a large-scale coherent fluid flow, can give rise to complex biological dynamics. In the Arctic ocean, several studies reported under-ice phytoplankton blooms that were initiated by the onset of ice melt. Nevertheless, it is still only partially known how such blooms are controlled by the interaction between different factors, such as the increase of light transmittance, leads (openings in the ice), convective mixing, and biological processes. Under-ice blooms are expected to become more common in the future, due to increasingly thinner and dynamic ice coverage, and thus more frequent lead formation. This could significantly alter primary production, and have important consequences on local marine food webs.
In this work we consider an advection-reaction-diffusion model of phytoplankton light-limited vertical dynamics in the presence of convective transport, intended as an idealized representation of nonuniformly ice-covered polar waters. Specifically, we assume that the incident light intensity at the surface is horizontally modulated by the presence of opaque obstacles, giving rise to regions of the water column that are characterized by different production regimes. We focus on the impact of advection, and more generally of the different transport processes occurring in the fluid, on the average biomass. By means of numerical simulations we show that convective motions may be harmful to under-ice blooms, in agreement with previous findings. In the present setup, such effect depends on the positions of the surface obstacles with respect to the upwelling and downwelling flow regions. We further find, however, that the sinking speed, due to the density difference between phytoplankton organisms and water, also plays an important role, which depends on how it adds to the flow. While small, the sinking speed has a measurable impact on the growth dynamics of the population and can even be critical for its survival, which may have ecological relevance, as different phytoplankton species have different densities and, hence, different settling velocities.
Sea ice kinetic energy dissipation with different yield curves
Authors: Liu Yuqing , Losch Martin , Tremblay Bruno , Ringeisen Damien
Published: February 2023

Wind imparts energy via surface stress to sea ice where it leads to internal stress and motion. The ocean also exerts a drag that slows down ice motion, but the internal stress dissipates part of the energy in convergent and shear motion (ridging). This internal dissipation is an important part of the energy balance. Floe-floe interactions within sea ice play an essential role in the kinetic energy dissipation in winter when the sea-ice is compact. In large-scale sea ice models, these interactions are parameterized by the rheology. The main goal of this work is to investigate the influence of the viscous plastic rheology, in particular the shape of the yield curve on the kinetic energy dissipation within sea ice. Different yield curves (standard ellipse, Mohr–Coulomb with an elliptic plastic potential, Truncated Ellipse Method, and teardrop) are implemented in a sea ice model with viscous-plastic rheology and a grid spacing of 4.5 km. Also, the impact of model resolution is explored for one rheological model with simulations with grid spacings of 36, 9 and 4.5 km. The results suggest that a yield curve with more shear strength leads to smaller sea ice drift, and thus, to smaller wind energy input and energy loss due to ocean drag. Furthermore, in simulations with the elliptical yield curve with tensile strength, the sea ice is thicker than in those without tensile strength. The simulations with the Teardrop yield curve and the Mohr–Coulomb yield curve have the largest frictional dissipation in shearing and ridge deformation, respectively. In summary, the impact of the different yield curve on the net energy dissipation is small, but simulations with similar yield curves have similar kinetic energy dissipation within the ice. Finally, the higher the resolution of the simulation, the more the deformation and hence the dissipation is localized along shear lines. More localization leads to smaller mean drift and hence less kinetic energy input and loss by ocean drag. Because of the smaller energy input, the net dissipation by internal stress is also reduced for higher resolution.
Impact of climate change on agro-climatic zones in Europe under different RCPs
Authors: Georgoulias Aristeidis K. , Akritidis Dimitris , Lorilla Roxanne S. , Kontoes Charalampos , Ceglar Andrej , Toreti Andrea , Zanis Prodromos
Published: February 2023

The rise of surface temperature due to climate change has a significant impact on the growth of different plant species, including aromatic plants, agricultural crops, fruit trees, and forests. Within the framework of the MICROSERVICES project, that aims on improving the capacity to predict the cascading effects of climate change on microbial diversity, crop-microbiome interactions and agricultural ecosystem functions, we studied the future projection of agro-climatic zones over Europe under two different IPCC Representative Concentration Pathways (RCP4.5 and RCP8.5). To this end, an ensemble of 11 bias-corrected EURO-CORDEX simulations covering the period 1981-2100 was used following the methodology of Ceglar et al. (2019)*. The agro-climatic zones were identified based on two temperature-related parameters, the Growing Season Length (GSL) and the Active Temperature Sum (ATS). The categorization into one of the 8 agro-climatic zones was implemented by applying the k-means clustering method for the reference period 1981-2010. Then, the agro-climatic zone patterns over Europe for the intermediate period 2031-2060 and the end-of-the-century period 2071-2100 were compared against that of the reference period. Our results point towards a strong northward shift of the agroclimatic zones, especially under the no-mitigation emission scenario (RCP8.5) at the end of the century. For the moderate mitigation scenario (RCP4.5), a significant shift of the agroclimatic zones is also observed for the intermediate and the end-of-the-century periods for extended areas in Europe. Our results are in line with that of Ceglar et al. (2019), who studied the migration of agro-climatic zones over Europe under the 2 oC warming level utilizing a subset of the simulations used in this study. *Ceglar et al., Earth's Future, 7, 1088-1101, https://doi.org/10.1029/2019EF001178, 2019.This research was supported by the MICROSERVICES project funded by the General Secretariat for Research and Innovation (GSRI, Greece) under the Action ERANETs 2021A [Call ID: 037KE - A/A MIS 4888] (Project Number: T12ERA5-00075) and through the 2019-2020 BiodivERsA joint call for research proposals [BiodivClim ERA-Net COFUND programme].
Balanced data assimilation with a blended numerical model
Authors: Chew Ray , Benacchio Tommaso , Hastermann Gottfried , Klein Rupert
Published: February 2023

Physical imbalances introduced by local sequential Bayesian data assimilation pose a problem for numerical weather prediction. For example, fast-mode acoustic imbalances of the order of the relevant slower dynamics destroy solution quality. We introduce a novel dynamics-driven method that suppresses imbalances arising from data assimilation. Specifically, we employ a blended numerical model with seamless access to compressible, soundproof, and hydrostatic dynamics. After careful numerical and asymptotic analysis, we introduce a one-step blending strategy to switch between model regimes within a simulation run. Upon assimilation of data, the model configuration is switched for one timestep to the limit soundproof pseudo-incompressible or hydrostatic regime. After that, the model configuration is switched back to the compressible regime for the duration of the assimilation window. The switching between model regimes is repeated for each subsequent assimilation window. Idealised experiments involving the travelling vortex, buoyancy-driven rising thermals, and internal gravity wave pulses demonstrate that our method successfully eliminates imbalances from data assimilation, yielding up to two orders-of-magnitude improvements in the analysis fields. While our studies involved eliminating acoustic and hydrostatic imbalances, this novel dynamics-driven method of achieving balanced data assimilation can be extended to eliminate other undesired imbalances, with significant prospective applications in real-world weather prediction.
Revealing the hidden Mesozoic exhumation history of the Qinling orogenic belt, Central China: insights from multiple geochronological and geochemical data of the molasse granitic gravels
Authors: Peng Heng , Wang Jianqiang , Liu Chiyang , Li Jiaoli , Jiao Xiaoqin , Zhang Liying , Zattin Massimiliano
Published: February 2023

Qinling Orogenic Belt with its Meso-Cenozoic intracontinental orogeny and uplift, is a key physiographic element that characterized the differential evolution of the geology, geography and climate in continental China (Dong et al., 2022). However, numerous thermochronological dates of the Qinling bedrocks (Dong et al., 2011; Yang et al., 2017) show that there is a wide cooling gap between Triassic and Early Cretaceous. In this study, we studied this gap by multiple geochronology and geochemistry on Lower Cretaceous molasse granitic gravel samples, with the aim to recover the hidden Mesozoic exhumation history. We report the first detailed zircon U-Pb ages, whole-rock major and trace elements and Sr-Nd-Pb isotopic data, which suggest that these clasts derive from Late Triassic I-type granites which were emplaced in a syn-collisional setting during a subduction phase. Their provenances were also determined by comparison with the geochemical fingerprint of Qinling granitic bedrocks. New zircon and apatite U-Pb, (U-Th)/He and fission-track data, as well as biotite 40Ar-39Ar, were performed on the granitic gravels dated between ca. 222 Ma to 110 Ma. Thermal history modeling, based on the multiple geochronological data, shows rapid cooling from ca. 700 °C to 200 °C during Late Triassic-Early Jurassic, then followed by a period of slow cooling from Middle Jurassic to Early Cretaceous.As a whole, our new multiple geochronological and geochemical data and the related thermal history modeling results provide new insights on the prolonged pre-Cenozoic cooling history as well as the intracontinental deformation of the Qinling, which were mostly related to Paleo-Tethyan subduction and Late Triassic North China-South China Block collision.Reference:Dong, Y., Genser, J., Neubauer, F., Zhang, G., Liu, X., Yang, Z. and Heberer, B., 2011. U-Pb and 40Ar/39Ar geochronological constraints on the exhumation history of the North Qinling terrane, China. Gondwana Research, 19(4): 881-893.Dong, Y., Sun, S., Santosh, M., Hui, B., Sun, J., Zhang, F., Cheng, B., Yang, Z., Shi, X., He, D., Yang, L., Cheng, C., Liu, X., Zhou, X., Wang, W. and Qi, N., 2022. Cross Orogenic Belts in Central China: Implications for the tectonic and paleogeographic evolution of the East Asian continental collage. Gondwana Research, 109: 18-88.Yang, Z., Shen, C., Ratschbacher, L., Enkelmann, E., Jonckheere, R., Wauschkuhn, B. and Dong, Y., 2017. Sichuan Basin and beyond: Eastward foreland growth of the Tibetan Plateau from an integration of Late Cretaceous-Cenozoic fission track and (U-Th)/He ages of the eastern Tibetan Plateau, Qinling, and Daba Shan. Journal of Geophysical Research: Solid Earth, 122(6): 4712-4740.
Quantifying braided river loss to groundwater using Active Distributed Temperature Sensing
Authors: Sai Louie Alice , Morgan Leanne , Banks Eddie , Dempsey David , Wilson Scott
Published: February 2023

Globally, braided river systems are a major recharge mechanism for alluvial aquifer systems providing a significant contribution to groundwater, yet this process of surface water – groundwater (SW - GW) interaction is a gap in hydrological research. River leakage from braided rivers is the main source of groundwater recharge in the Canterbury Plains of New Zealand (Coluccio & Morgan, 2019). This study investigated surface water – groundwater interaction in the Waikirikiri Selwyn River, in the South Island of New Zealand, using Active-Distributed Temperature Sensing (A-DTS) and estimated groundwater recharge to the alluvial aquifer system, as outlined in Banks et al. (2022).The field study site is within an ephemeral losing reach of the river and contains two active channels. Braided rivers are dynamic, high-energy environments; therefore, the fibre-optic cables were installed beneath the ground to protect this infrastructure from regular flood events. Novel horizontal Directional Drilling was used to construct two, 100 m long drillholes at a depth of approximately 5 m below ground level and perpendicular to the river channel. The drillholes were completed with a hybrid fibre optic cable containing four multi-mode fibres and copper conductors. Additionally, a vertical A-DTS installation was constructed to 30 m depth adjacent to the river channel and horizontal drillhole. A series of twelve back-to-back A-DTS surveys on the horizontal and vertical A-DTS installations were conducted over 48-hrs. River stage and flow during the survey period was constant, hence steady-state groundwater recharge conditions were assumed. The localised temperature variations along the cables indicated spatial variation of preferential groundwater recharge pathways. Groundwater velocities were derived using both analytical and numerical solutions and preliminary results indicate vertical groundwater velocities exceeding 10 m/d. By calculating groundwater velocities it is possible to quantify groundwater recharge from braided rivers with high spatial and temporal resolution, which can aid in understanding the recharge process and the relationship between river stage height and groundwater recharge rates. ReferencesBanks, E. W., et al. (2022). "Active distributed temperature sensing to assess surface water–groundwater interaction and river loss in braided river systems." Journal of Hydrology 615: 128667.             Coluccio, K. and L. K. Morgan (2019). "A review of methods for measuring groundwater-surface water exchange in braided rivers." Hydrology and Earth System Sciences 23: 4397-4417.
Assessing the Pliocene–Recent erosion history of New Zealand's eastern Southern Alps using cosmogenic radionuclides, tracer techniques and grain size analyses
Authors: Oesterle Juergen , Norton Kevin , Lukens Claire , Schlunegger Fritz , Sagar Matthew , Wilcken Klaus , Wang Ningsheng
Published: February 2023

The Southern Alps / Kā Tiritiri o te Moana in Aotearoa New Zealand have attracted scientists to study the interactions between climate and tectonics for decades. It has long been argued that tectonic uplift of this orogen is approximately balanced by erosion. The prevailing westerly airflow at the latitudes of the Southern Alps has created a strong orographic effect with precipitation decreasing sharply across the orogen’s main divide. The signature of this orographic effect is apparent in erosion rates that decrease from west to east, and from the dominant types of erosional processes that operate on either side of the orogen’s main divide. Most studies quantifying erosion over geologic timescales have focussed on the wetter—but areally significantly smaller—side of the orogen. Here, we seek to quantify the Pliocene–Recent erosion history of the Southern Alps’ much larger and drier eastern side using cosmogenic radionuclides (10Be and 26Al), tracer techniques (U–Pb) and a grain size analysis on fluvial deposits in the Canterbury region that record concomitant erosion of this mountain range. Cosmogenic radionuclides provide a powerful tool to constrain catchment-scale erosion rates on timescales of 100–100,000 years, which is the temporal range at which tectonic and climatic forcings overlap and meso-scale stratigraphic architecture is created, thereby offering critical insights into the dynamics between tectonics, climate, and surface processes. Detrital grain U–Pb analysis of the fluvial deposits will be used to establish the sediment’s provenance, while a grain size analysis of the river sediments will provide insights into associated past stream dynamics. With this multi-method study, we seek to constrain both spatial patterns and catchment-scale rates of erosion of the eastern Southern Alps, as well as their changes through time and see if erosion has been affected by major climatic shifts during the Pliocene and Pleistocene epochs. Finally, this research will provide a benchmark for assessments of anthropogenically influenced erosion of the eastern Southern Alps. Preliminary results from 10Be and 26Al analyses and dating of fluvial terraces will be presented.