bluuebunny/crossref_metadata_2025 huggingface dataset:
Icelandia
Authors: Foulger Gillian , Gernigon Laurent , Geoffroy Laurent
Published: March 2021

The NE Atlantic formed by complex, piecemeal breakup of Pangea in an environment of structural complexity. North of the present-day latitude of Iceland the ocean opened by southward propagation of the Aegir ridge. South of the present-day latitude of Iceland breakup occurred along the proto-Reykjanes ridge which formed laterally offset by ~ 100 km from the Aegir ridge to the north. Neither of these new breakup axes were able to propagate across the east-westerly striking Caledonian frontal thrust region which formed a strong barrier ~ 400 km wide. As a result, while sea-floor spreading widened the NE Atlantic, the Caledonian front region could only keep pace by diffuse stretching of the continental crust, which formed the aseismic Greenland-Iceland-Faroe ridge. The magmatic rate there was similar to that of the ridges to the north and south and so the stretched continental crust is now blanketed by thick mafic flows and intrusions. The NE Atlantic also contains a magma-inflated microcontinent – the Jan Mayen Microplate Complex, and an unknown but probably large amount of stretched continental crust blanketed by seaward-dipping reflectors in the passive margins of Norway and Greenland. The NE Atlantic thus contains voluminous continental crust in diverse forms and settings. If even a small portion of the sunken continental material contiguous with the Greenland-Iceland-Faroe ridge is included the area exceeds a million square kilometers, an arbitrary threshold suggested to designate a sunken continent. We have called this region Icelandia. The conditions and processes that funneled large quantities of continental crust into the NE Atlantic ocean are common elsewhere. This includes much of the North and South Atlantic oceans including both the seaboards and the deep oceans. Nor are such processes and outcomes confined to oceans bordered by passive margins. They are also found around the Pacific rims where subduction is in progress. Indeed, these conditions and processes likely are generic to essentially all the world's oceans and are potentially also informed by observations from intracontinental extensional regions and land-locked seas.
Austral Summer Droughts and their Driving Mechanisms in Observations and Present-day Climate Simulations across Malawi
Authors: Likoya Emmanuel , Birch Cathryn , Chapman Sarah , Dougill Andrew
Published: March 2021

The societal relevance of droughts in Africa underscores the need for improved understanding of the atmospheric processes that drive them. This study examined drought characteristics across Malawi, and the associated atmospheric circulation patterns, in observations, reanalysis and global climate models. Droughts were identified using the Standardised Precipitation and Evapotranspiration Index (SPEI) for the period 1965 to 2018. Atmospheric circulation patterns during droughts were examined and the main moisture fluxes into Malawi were identified. Despite differences in the frequency, and events being asynchronous at times, droughts exhibited characteristics that were statistically similar between northern and southern Malawi. Droughts in both regions were associated with anomalous circulation that typically worked to diminish moisture advection and thus convection. Differences in the structure of the anomalies were indicative of differences in mechanisms associated with droughts in the north and south of Malawi. Three main moisture flux pathways were identified, and categorized as northeasterly, southeasterly, and northwesterly, each with a unique correlation structure with precipitation and global SSTs. Positive and negative biases of varying magnitudes were noted for drought and rainfall characteristics across the range of CMIP5 models. Such biases can be attributed to biases in moisture fluxes whose variability was found to be a key driver of summer precipitation variability across Malawi. Despite biases in moisture fluxes and their influence on precipitation biases, the majority of models exhibited moisture flux-precipitation correlations consistent with observations and reanalysis. Results from the study highlight the extent to which climate models are reliable in simulating droughts and therefore of value in developing narratives of climate variability essential for long-term development planning.
Economic optimisation of soil testing on commercial farms: space, time and variables
Authors: Takahashi Taro
Published: March 2021

A holistic evaluation of agricultural systems requires mechanistic understanding of physical, chemical and biological interactions both aboveground and belowground, yet obtaining this information on commercial farms is a challenging task. In order to support practical decision making by commercial producers, it is therefore necessary to identify system-wide performance indicators that are observable presently and cost-effectively. Data acquired through commercial soil testing satisfy these conditions; however, the relationship between the density of information — thus the cost of testing — and the value of information as a guideline for on-farm managerial changes is not well-understood.

Using high-resolution soil data from the North Wyke Farm Platform in the UK as a case exemplar, this solicited talk discusses theoretical and computational frameworks to quantify the value of an information package defined by soil testing strategies. A bootstrapping experiment revealed that the information value is often a concave function of the spatial sampling frequency, indicating that “half-hearted” soil data are unlikely to be able to inform optimal farm management. On the other hand, a high degree of serial correlation as well as atemporal inter-variable correlation resulted in some measurements identified as being redundant, as the incremental value of additional information was often found to be small and occasionally negative. Given the time and budgetary constraints, therefore, it is suggested that more effort should be spent on snapshot spatial sampling of a small number of variables, rather than continuous spot sampling of a large number of variables.
A new Holocene record from a far-field site in the Indian Ocean to constrain Holocene sea level.
Authors: Richards Geoff , Majewski Jedrzej , Tan Christabel , Tan Fangyi , Li Tanghua , Shaw Timothy , Horton Benjamin
Published: March 2021

Reconstructions of relative sea level (RSL) during the Holocene provide important constraints for Glacial Isostatic Adjustment (GIA) models, determining Earth rheology, estimating ice-equivalent meltwater input, and fingerprinting sources of ice mass loss. In far-field regions such as the Indian Ocean, RSL is characterized by rapid rise during the early Holocene driven primarily by deglaciation of northern hemisphere ice sheets. This cumulated to a characteristic mid-Holocene highstand before falling towards present driven by hydro-isostatic processes. Reconstructions of RSL utilize proxy sea-level indicators to produce sea-level index points (SLIPs) that position RSL in time and space with an associated temporal and vertical uncertainty.

Here we present a standardized RSL database with a full consideration of uncertainty from the Maldives to investigate regional variations in the characteristics of the mid Holocene highstand, and to constrain the eustatic contribution to RSL change during the mid and late Holocene.

We produce new SLIPs from a mangrove forest in Kelaa, part of the Haa Alif Atoll in the northern area of the Maldives. We subsampled for mangrove macro fossils suitable for radiocarbon dating and obtained 5 dates with calibrated ages ranging between 630 – 1340 years BP. These new SLIPs show RSL was between 0.07m – -0.14m during this period.
Model Informed Data Collection in Coupled Human-Water Systems: An Exploratory Application of a Hydrological and Agent-Based Model
Authors: Mohajer Behshad , Yu David , Janssen Marco , Garcia Margaret
Published: March 2021

Hydrological systems in the Anthropocene have shown substantial shifts from their natural processes due to human modifications. Consequently, deploying coupled human-water modeling is a critical tool to analyze observed changes. However, the development of socio-hydrological models often requires extensive qualitative data collection in the field and analysis. Despite the advances in developing inter-disciplinary methodologies in utilizing qualitative data for coupled human-water modeling, there is a need to identify influential parameters in these systems to inform data collection. Here, we present an exploratory socio-hydrological model to systemically investigate the feedback system of public infrastructure providers, resource users, and the dynamics of water scarcity at the catchment scale to inform data collection and analysis in the field. Specifically, we propose a novel socio-hydrological model by employing and integrating a top-down hydrological model and an extension of Aqua.MORE Model (an Agent-Based Model designed to simulate dynamics of water supply and demand). Specifically, we model alternate behavioral theories of human decision-making to represent the agents’ behavior. Then, we perform sensitivity analysis techniques to identify key socio-economic and behavioral parameters affecting emergence patterns in a stylized human-dominated catchment. We apply the proposed methodology to the Lake Mendocino Watershed in Northern California, US. The results will potentially point which parameters are influential and how they could be mapped to a particular interview or survey question. This study will help us to identify features of decision-making behavior for inclusion in fieldwork, that be might be overlooked in the absence of the proposed modeling. We anticipate that the proposed approach also contributes to the current Panta Rhei Research Initiative of the International Association of Hydrological Sciences (IAHS) which aims at improving the interpretation of the hydrological processes governing the socio-hydrological systems by focusing on their changing dynamics in connection with rapidly changing human systems.
Development of a high-resolution prior for inverse modelling of New York City methane emissions
Authors: Pitt Joseph , Lopez-Coto Israel , Hajny Kris , Tomlin Jay , Kaeser Robert , Jayarathne Thilina , Stirm Brian , Floerchinger Cody , Loughner Chris , Commane Róisín , Gately Conor , Hutyra Lucy , Gurney Kevin , Roest Geoffrey , Liang Jianming , Karion Anna , Whetstone James , Shepson Paul
Published: March 2021

Recent studies have shown that methane emissions are underestimated by inventories in many US urban areas. This has important implications for climate change mitigation policy at the city, state and national level. Uncertainty in both the spatial distribution and sectoral allocation of urban emissions can limit the ability of policy makers to develop well-targeted emission reductions strategies. Top-down emission estimates based on atmospheric greenhouse gas measurements can help to improve inventories and better inform policy decisions.

This presentation builds on previous work estimating methane emissions from New York City and the wider urban area based on measurements taken during nine research flights. We used an ensemble of dispersion model runs in a Bayesian inverse modelling framework to derive posterior emission estimates. Prior emissions were taken from three coarse-resolution inventories based on spatially disaggregated national totals. The most recent version of EDGAR (v5) and the gridded EPA inventory both required upscaling by more than a factor of two to be consistent with our measurements.

Here, we construct a high-resolution methane emission prior using a combination of spatial proxies and reported emissions for various sectors. We present preliminary results evaluating the ability of this new prior to represent the magnitude and spatial distribution of emissions, through comparison with both the measured data and results obtained using coarser resolution inventories.
An efficient method for automatic slope unit delineation from a huge region
Authors: Wu Pengfei , Liu Jintao
Published: March 2021

Slope units have great potential for hydrological and geomorphological studies, especially for landslide susceptibility modelling. Digital Elevation Models are widely used to delineate slope units by connecting drainage and divide lines. However, it is difficult to estimate reasonable scale thresholds for drainage and divide lines, which limits the application of slope units. Most existing methods for slope unit delineation determine the scales manually. Recently, several automatic methods have been proposed, but these methods encounter the problem of low computing efficiency for large-scale region. In this study, a new efficient method is presented for automatic slope unit delineation. Similar to an existing method, our method divides the region into several sub-basins and delineate slope units for every sub-basin independently. Within a sub-basin, grid cells are classified into massive units, and neighboring units are merged according to several strategies when aspect homogeneity can be satisfied. The new method is tested in Yarlung Tsangpo Basin, southeastern Tibetan Plateau. This basin has a large area of nearly 250 000 km2, and can be divided into nearly 340 000 slope units within 3 hours using a general personal computers. The rationality of our method is proved by both visual and quantitative assessments.
Advances and next steps exploring the role of groundwater storage in watershed variability across spatial scales
Authors: Condon Laura
Published: March 2021

Groundwater is  by far the largest unfrozen freshwater resource on the planet. Yet it is often excluded or greatly simplified in global and  continental scale models.   It’s well established that feedbacks between groundwater depth, surface runoff and land energy fluxes can influence watershed dynamics. However, we still don’t understand the large scale implications of these exchanges in evolving systems.  Advances in continental scale integrated hydrologic modeling increasingly allow us to explore these interactions across spatial scales. With large scale models we can start to quantify the total impact that groundwater surface water exchanges have on the water balance as a whole, as well as watershed dynamics.  Here I will explore the buffering effect that groundwater can have on both human and natural water stressors across the US and the physical drivers of these connections.  I will also explore the impacts of long term trends on the stability of groundwater surface water exchanges. These results demonstrate the importance of the subsurface for future hydrologic predictions, and the potential gains from improved groundwater representations large scale simulations.  While there have been great advances in large scale groundwater modeling in recent years, there is still significant need for continued community model development and intercomparison.
Evaluating soil erosion and sediment deposition rates by  137Cs fingerprinting technique at different karst hillslope positions  in Yunnan Province, southwest China
Authors: Li Yanqing , Yu yang , Lan funing , Liu peng
Published: March 2021

In karst environments, soil erosion is a  prominent environmental issue that can cause many other problems. Researching the erosion and deposition rates at the hillslope scale in small watersheds is important for designing efficient soil and water conservation measures for the small watersheds even the large scale areas. In our research, the closed watershed, a representative depression in karst gabin basin, located in the Yunnan province, Southwest China, was selected to assess the soil erosion and sediment mobilisation at different hillslope positions using the 137Cs tracing technique. The results showed that the soil erosion rates in the shoulders, backslopes and footslopes were 0.87, 0.35 and 0.49 cm a-1, respectively, meanwhile the soil sediment rate in depression bottom was 2.68 cm a-1. The average annual soil erosion modulus of the complete hillslope was 632 t km-2a-1, which confirmed the serious gradation according to karst soil erosion standards. The sediment delivery ratio would summarize 0.82 in the whole catchment according to the square of hillslope and depression bottom. To identify which factor could play the most important role in influencing the estimations using 137Cs, a linear correlation and Principal Component Analysis were conducted. The results showed 137Cs concentration of different soil depth at different hillslope positions were significantly correlated with soil organic matter (SOM) and total nitrogen (TN) (P<0.05). As the typical karst geomorphological types, these findings are expected to provide data support for the whole watershed soil erosion management and ecological restoration in  fragile karst ecosystem.
Using Deep Machine Learning to Understand Green Space Popularity, Activities, Functionality, and Design Implications: a comparison of Chicago and Stockholm
Authors: Chen Si , Deal Brian
Published: March 2021

Green spaces have a significant effect on urban living environments, providing shared natural areas and entertainment spaces among other benefits. Investigating their popularity and functionality is valuable for supporting green space design and guiding land use development around public green spaces. Conventional methods used to extract use and functionality information on public green spaces have typically relied on questionnaires and in-site observations, both resource and time consuming processes. These approaches can also be context dependent and produce less transferable data across regions. This study utilizes deep machine learning techniques to mine social media text and image data to produce useful information on public green space popularity, activities, functionality and design.  Convolutional neural networks (CNN), an advanced machine learning technique, is used to analyze large scale data sets (Yelp and publicly accessible images) of public green spaces in Chicago, Illinois, US. The coupling of the two types of data enables the extraction of a rich and comprehensive analytical frame for understanding how green spaces are used and how they might be improved. The technique also utilizes a complex transfer learning process to pretrain the model and allow its quick adaptation to other regions around the world. The process will be replicated in Stockholm, Sweden. We use the analysis generated to compare open spaces in the 2 cities. The process has the potential to substantially improve nature based strategies on green space development and design.
Warm thermal structures in subduction zones lead to ample dehydration at the depths of deep slow slip and tremor and resultant transformations in viscous rheology 
Authors: Condit Cailey , Guevara Victor , French Melodie , Holt Adam , Delph Jonathan
Published: March 2021

Feedbacks amongst petrologic and mechanical processes along the subduction plate boundary play a central role influencing slip behaviors and deformation styles. Metamorphic reactions, resultant fluid production, deformation mechanisms, and strength are strongly temperature dependent, making the thermal structure of these zones a key control on slip behaviors.

 

Firstly, we investigate the role of metamorphic devolatilization reactions in the production of Episodic Tremor and Slip (ETS) in warm subduction zones. Geophysical and geologic observations of ETS hosting subduction zones suggest the plate interface is fluid-rich and critically stressed, which together, suggests that this area is a zone of near lithostatic pore fluid pressure.  Fluids and high pore fluid pressures have been invoked in many models for ETS. However, whether these fluids are sourced from local dehydration reactions in particular lithologies, or via up-dip transport from greater depths remains an open question. We present thermodynamic models of the petrologic evolution of four lithologies typical of the plate interface along predicted pressure–temperature (P-T) paths for the plate boundary along Cascadia, Nankai, and Mexico which all exhibit ETS at depths between 25-65 km. Our models suggest that 1-2 wt% H2O is released at the depths of ETS along these subduction segments due to punctuated dehydration reactions within MORB, primarily through chlorite and/or lawsonite breakdown. These reactions produce sufficient in-situ fluid across this narrow P-T range to cause high pore fluid pressures. Punctuated dehydration of oceanic crust provides the dominant source of fluids at the base of the seismogenic zone in these warm subduction margins, and up-dip migration of fluids from deeper in the subduction zone is not required to produce ETS-facilitating high pore fluid pressures. These dehydration reactions not only produce metamorphic fluids at these depths, but also result in an increased strength of viscous deformation through the breakdown of weak hydrous phases (e.g., chlorite, glaucophane) and the growth of stronger minerals (e.g., garnet, omphacite, Ca-amphibole). Lastly, we present preliminary data on viscosity along warm subduction paths showing the locations of these dehydration pulses correlate with viscosity increases in mafic lithologies along the shallow forarc.
Investigating Possible Effects of Changing Hydroclimatic Persistence on Lake Cyanobacterial Harmful Algal Blooms
Authors: Oikonomou Panagiotis D. , Zia Asim , Hecht Jory S. , Clemins Patrick J. , Rizzo Donna M. , Schroth Andrew W.
Published: March 2021

Harmful Algal Blooms (HABs) are a major environmental problem worldwide. Apart from their adverse effects on aquatic habitat, and possible economic losses, they also pose a serious threat to public health. Future climatic uncertainties that include possible shifts in patterns of climatic variables are points of concern in terms of how such changes would affect the development, growth, and duration of HABs. Weather whiplash, abrupt dry-to-wet or wet-to-dry condition transitions, is one of these shifts in climatic patterns and despite its potential environmental impacts, few studies have examined the implications of such changes on lake water quality. Lake Champlain, located on the US-Canada border, has repeatedly faced cyanobacterial HABs predominately in its shallow bays. The aim of the current work is to (i) investigate potential changes in the persistence of hydroclimatic variables (precipitation and temperature) and (ii) examine their effects on cyanobacterial HABs in the lake’s shallow Missisquoi Bay. Our approach focuses on short-term persistence (STP) shifts over different timescales (daily, monthly, seasonal, and annual). STP scenarios that capture these plausible shifts are constructed using projected climate scenarios for the period 2000-2040. An Integrated Assessment Model that simulates the Missisquoi Basin’s physical processes, including watershed hydrology, management, and the Missisquoi Bay’s water quality dynamics, is utilized to run the modeled STP scenarios for each timescale. The determination of changes in STP through a scenario-based approach offers a framework to rigorously investigate the effects of persistence at different timescales on lake cyanobacterial HABs.
Modelling the impact of a GLOF scenario at Parón lake, Cordillera Blanca, Perú, using a novel multi-phase topographical and geological procedure
Authors: Villafane Gomez Hilbert , Torres Lázaro Juan C. , Caballero Bedriñana Adriana , Jara Infantes Harrinson W. , Melgarejo Romero Enver L. , Araujo Reyes Julia E. , Yarleque Christian , Harrison Stephan , Wilson Ryan , Wood Joanne L. , Glasser Neil F.
Published: March 2021

The Cordillera Blanca is undergoing rapid deglaciation due to climatic warming, especially since the late 20th century. This process has resulted in the formation of new glacial lakes and an increase in the volume of existing lakes, some of which pose a risk in the form of Glacier Lake Outburst Floods (GLOF); such as Parón lake in the Cordillera Blanca, which represents a significant hazard to the Caraz city and smaller populations located in the Llullán-Parón sub-basin. Here, we model a potential dam breach and GLOF generation scenario at Parón lake using a novel numerical modelling procedure that, amongst other factors, considers the geological structure of the natural dam. Overall, this procedure includes four distinct phases: (1) estimation of the potential for ice avalanche impact on Parón lake sourced from surrounding glacial cirques; (2) modelling of subsequent impulsive wave generation and propagation; (3) analysis of the hydraulic parameters of a possible breach of the natural dam, considering the non-erodible material within empirical estimations of the hydrograph where the composition of the dam is interpreted based on surface geological mapping and drill sampling carried out in the area; and (4) simulation of a potential GLOF using the FLO-2D model with input data from the previous phases. Modelling results indicate that Parón lake is most at risk from ice avalanches that originate from the adjacent Hatunraju glacier and that such events have the potential to generate impulse waves that could initiate erosion and a subsequent breach of the natural dam. Considering a worst-case ice avalanche scenario, our results indicate the potential generation of a GLOF with average peaks flow of 25,264.22 m3/s. This GLOF event would reach the urban area of the  Caraz city in around 36 - 42 minutes with now rates and flood heights fluctuating between 11.2 m/s to 22.4 m/s and 9.9 m to 19.7 m, respectively.
Assessing the impact of Sr/Ca-SST calibrations on coral-based seawater δ18O reconstructions - First results from PAGES CoralHydro2k
Authors: Walter Rachel ,   PAGES CoralHydro2k
Published: March 2021

Corals are distributed throughout the tropical oceans, making them useful for resolving climate information covering time before the satellite era when instrumental data is often scarce. Coral δ18O has been used to reconstruct changes in both sea surface temperature (SST) and hydrology, while coral Sr/Ca is thought to mainly record SST. Coral δ18O data, when used in conjunction with Sr/Ca, can therefore be used to reconstruct seawater δ18O (δ18Osw), an indicator of the local precipitation-evaporation balance as well as other surface ocean hydrological changes. Coral Sr/Ca-SST relationships are critical for reconstructing δ18Osw from paired Sr/Ca and δ18O records, but vary across existing literature. Some of this variation is due to existing natural differences between corals, but variation also stems from differences in calibration methods or SST products used to determine the Sr/Ca-SST relationship. Such methodological differences complicate the comparison of results across studies and slow efforts to create a global picture of reconstructed tropical ocean hydroclimate.

Here, we use the PAGES CoralHydro2k database - a collection of 45 paired coral Sr/Ca-δ18O records and 70 coral δ18O records - to assess different methodological choices such as SST product and regression method and develop a calibration framework to use as a set of “best practices” moving forward. We also examine the sensitivity of δ18Osw to our calibration framework and to existing δ18Osw calculation methods. The PAGES CoralHydro2k project aims to leverage its coral database and apply these best practices and insights to a global reconstruction of tropical marine hydrology over the past 200 years.
Carbon burial capacity limited by accelerated sea-level rise in coastal wetlands
Authors: Sandi Steven , Rodriguez Jose , Saco Patricia , Saintilan Neil , Riccardi Gerardo
Published: March 2021

Coastal wetland are known to be among the most efficient carbon burial environments around the worlds and given this high efficiency for carbon sequestration, wetland restoration and conservation efforts have been proposed as a way to potentially mitigate greenhouse emissions. The processes that lead to carbon sequestration can be quite complex and often depend on feedbacks between the type of vegetation in the wetlands, tidal flow regime, geomorphology and sediment availability. Coastal wetland vulnerability to submergence due to sea-level rise has been widely discussed in the current literature, and while wetlands could survive under some sea-level rise scenarios, accelerated rates of sea-level rise would most likely result in significant wetland losses. These can be less accentuated when accommodation space is available and the wetland is able to migrate inland, however, topography, physical barriers, and some anthropogenic factors can limit wetland migration thus decreasing the ability of wetlands to cope with sea-level rise. Potential losses of wetland vegetation under accelerated sea-level rise and limited capacity for wetlands to migrate inland are expected to affect the overall efficiency for carbon sequestration. We apply an eco-geomorphic model to simulate vegetation dynamics, carbon accumulation and overall change in carbon stocks for a restored mangrove-saltmarsh wetland experiencing accelerated sea-level rise under different management scenarios. Our results suggest that under accelerated sea-level rise and limited space for inland migration, vegetation might not be able to fully mature, reducing the capacity for sequestering carbon over time.