bluuebunny/crossref_metadata_2025 huggingface dataset:
The Global Distribution and Trajectory of Aquaculture Ponds
Authors: Xu Yang , Feng Lian
Published: February 2023

The developments of global aquaculture ponds provide valuable socio-economic benefits in the Anthropocene epoch, also cause potential environmental and ecological impacts. However, the extent and trajectory of aquaculture ponds over the past 37 years remain unknown on a global scale. Our study maps the global distribution of aquaculture ponds over 9 periods (1984-1994, 1995-2000, and every 3 years from 2001 to 2021) based on a deep-learning method and Landsat observations. The total area of global aquaculture ponds expands from 10043.3 km2 to 18779.70 km2 and showed a slowing growth rate. Asia fishpond area accounts for up to 82% of the world's area. The extent of aquaculture ponds in Asia and South America have doubled in size since 1984. China, Vietnam, and Indonesia- the three countries with the largest fishpond area- exhibited the largest fishponds area at 2004-2006. Our study provides a critical basis for assessing spatial-temporal trajectory and potential influences of aquaculture ponds.
Comparison of Stratospheric Gravity Waves in a High-resolution General Circulation Model with 3-D Satellite Observations
Authors: Okui Haruka , Wright Corwin , Hindley Neil , Sato Kaoru
Published: February 2023

Recently, high-resolution satellite instruments and general circulation models (GCMs) which resolve gravity waves explicitly are becoming available. However, because of their small temporal and spatial scales, the entire spectral range of gravity waves cannot be fully detected by global observations or simulated by a GCM. To enhance our understanding of the characteristics of gravity waves in the middle atmosphere, quantitative comparison between observed and model-simulated gravity waves is of great importance. The aim of this study is to make a quantitative comparison between gravity waves observed by the Atmospheric Infrared Sounder (AIRS) on NASA’s Aqua satellite and those simulated by a gravity-wave permitting GCM, named JAGUAR. As a nadir-viewing satellite instrument, AIRS has relatively high horizontal resolution varying from ~13.5 km to ~41 km and coarse vertical resolution of 7–20 km over the altitude range of 15–60 km. JAGUAR is a hydrostatic spectral GCM with a T639 triangular truncation. This model contains 340 layers from the ground to the model top of ~150 km with a constant log-pressure height interval of 300 m. We first applied a vertical filter simulating the observational filter of AIRS to the output data of hindcast simulations in the 2018/19 boreal winter performed with JAGUAR. Then, the filtered model data were resampled as AIRS observational granules. Gravity waves were extracted by subtracting a fourth-order polynomial fit in the cross-track direction of a granule, whose data length is 1780 km. A three-dimensional Stockwell transform was utilized to examine the amplitudes and wavelengths of dominant waves. Stratospheric gravity waves in the model results are compared with those in AIRS observations. It was shown that amplitude, zonal momentum flux, and meridional momentum flux of the gravity waves are in good agreement between the JAGUAR and AIRS data. These results support the validity of studies on gravity waves and their roles in the middle atmosphere by using the JAGUAR model. Peaks of gravity-wave amplitudes are observed along the winter eastward jet and summer westward jet. The peaks located in the former region got weaker, and the latter got stronger as the stratospheric sudden warming in January 2019 progressed. Compared to waves in the model data without the vertical filter applied, dominant waves in the filtered model data are half the amplitude in the regions where strong gravity waves are observed. This difference is most remarkable in eastern Eurasia, where the vertical wavelengths of dominant waves are relatively short. This fact implies the importance of careful consideration on the underestimation of wave amplitudes due to AIRS observational filter especially where waves having short vertical wavelengths are likely dominant.
How compound can a compound event be? Mapping the compoundness of the Gloria storm
Authors: Aguilera Vidal Maria , Jimenez Jose A , Llasat Montserrat , Castan Salvador , Llasat Carmen
Published: February 2023

From a risk management perspective, compound events are very relevant because they can significantly increase the intensity and/or the spatial and temporal extension of the impact. Thus, depending on their magnitude, they may overwhelm the capability of emergency-response services to cope with “unusual” situations of major damage and respond to a large number of emergency situations throughout the region at the same time, and/or have to maintain the level of response during a relatively long period of time. When an extreme compound event occurs, its characteristics depart from the idealized conditions that are usually analyzed and, from the risk management perspective, the problem becomes highly multidimensional. This will be illustrated with the impact of the Gloria storm on the Spanish Mediterranean coast in January 2020. During five days extreme conditions (with some record breakings) of multiple hazards (wind, waves, rainfall, river discharge and surge) were recorded. In places such as the mouth of the Tordera River, they occurred simultaneously, but the most common situation was that different extreme conditions of univariate hazard occurred in remote areas of the territory, although they had to be managed simultaneously. In addition, the storm caused massive damage of various kinds, affecting transportation infrastructure, railway services, breakwaters, docks, urban services, housing, agricultural land and four fatalities in Catalonia. As a result of this, although the storm lasted about five days, the management of its impacts was much more extended, so that several months later some repairs were still being carried out. Looking to the event, the analysis of its probability of occurrence will be significantly affected by the adopted perspective. Thus, from the “physical” point of view, the analysis would range from the simplest joint probability of some hazards occurring in a given location (classical 2-drivers multivariate events) to multiple hazards over the whole territory (spatially compound with up to four concurrent hazards). From a "management" point of view, the analysis would focus on the probability of different types of damage (and their corresponding services) occurring at the same time, and on the probability of providing services in remote parts of the territory (and, consequently, dividing the available services) within a short period of time. To illustrate this possible multidimensional study plane, we will map the compoundness of the Gloria storm encompassing its induced hazards, impacts, damage and response. This work was supported by the Spanish Agency of Research in the framework of the C3RiskMed project (PID2020-113638RB-C21/ AEI / 10.13039/501100011033).
Drought-impacted communities in social-ecological systems: exploration of different system states in Northeast Brazil.
Authors: Kchouk Sarra , Melsen Lieke , Cavalcante Louise , Ribeiro Neto Germano , Walker David , Sonsol Gondim Ruben , van Oel Pieter
Published: February 2023

Our research applies ‘Social-Ecological Systems (SESs)’ concepts to analyse why and how events happening across spatial, jurisdictional and time scales and levels influence drought and their impacts in rural communities. To trace the evolution of drought and their impacts on the livelihood system, we conducted a drought diagnosis in the rural community of Riacho da Cruz in the Banabuiú basin in the semi-arid Northeast of Brazil. We analyse how the livelihood of this community reacts differently to drought events and why impacts of previous drought events either contribute to the adaptation of the livelihood system or its collapse. The SES theory helped us posit that it is the collective capacity of stakeholders (nested across the levels of the different spatial, temporal and decision scales of drought management) to manage their drought resilience, that determines whether the considered system adapts, collapses or shifts into a new stable state, in response to drought. Monitoring these factors that influence drought resilience can help us build drought (impact) indices that account for the spatial-temporal complexities of drought.
Evaluating remedies for numerical mixing in a ¼° global NEMO configuration
Authors: Megann Alex
Published: February 2023

Numerical mixing in fixed-coordinate ocean models such as NEMO is known to arise from several sources, including truncation errors in the advection scheme, leakage of the isoneutral explicit mixing into the dianeutral direction, and excessive entrainment of overflow waters, and this spurious mixing has been associated with significant drifts and biases in model simulations. We present results from an ensemble of ¼° forced NEMO simulations in which we investigate the sensitivity of the numerical mixing to various selections of numerical schemes and parameter settings in the model, including the z~ filtered ALE vertical coordinate, increased viscosity, changes in the order of tracer advection and the choice of isoneutral mixing schemes. We also discuss the sensitivity of numerical mixing to the choice of surface forcing product.
“Fusion network with attention for landslide detection. Application to Bijie landslide open dataset”
Authors: Lissak Candide , Corpetti Thomas , Letard Mathilde
Published: February 2023

Remote sensing techniques are now widely spread for the early detection of ground deformation, implementation of warning systems in case of imminent landslide triggering, and medium- and long-term slope instability monitoring. The large breadth of data available to the scientific community, associated with processing techniques improved as the data volume was increasing, has led to noticeable developments in the field of remote sensing data processing, using machine learning algorithms and more particularly deep neural networks.
 
This arsenal of data and techniques is necessary for the present scientific challenges the community of researchers on landslides still have to meet. As landslides can be complex, for risk management and disaster mitigation strategies, it is necessary to have a precise idea of their location, shape, and size to be studied and monitored. The challenge aims to automate landslide detection and mapping, especially through learning methods. Machine learning methods based on Deep Neural Networks have recently been employed for landslide studies and provide promising efficient results for landslide detection [1].
 
In this study, we propose an original neural network for landslide detection. More precisely, we exploit a fusion network [1] dealing with optical images on the one hand and Digital Elevation Models on the other hand. To improve the results, attention layers [3] (able to stabilize the training and more precise results) as well as mix up techniques [4] (able to generalize more efficiently) are exploited.
The model was trained and tested on the open Bijie landslide dataset.
 
Keywords: Remote sensing for landslide monitoring and detection, landslide detection, deep neural networks, attention
 
[1] Ji, S., Yu, D., Shen, C., Li, W., & Xu, Q. (2020). Landslide detection from an open satellite imagery and digital elevation model dataset using attention-boosted convolutional neural networks. Landslides, 17(6), 1337-1352.
[2] Song, W., Li, S., Fang, L., & Lu, T. (2018). Hyperspectral image classification with deep feature fusion network. IEEE Transactions on Geoscience and Remote Sensing, 56(6), 3173-3184.
[3] Niu, Z., Zhong, G., & Yu, H. (2021). A review on the attention mechanism of deep learning. Neurocomputing, 452, 48-62.
[4] Thulasidasan, S., Chennupati, G., Bilmes, J. A., Bhattacharya, T., & Michalak, S. (2019). On mixup training: Improved calibration and predictive uncertainty for deep neural networks. Advances in Neural Information Processing Systems, 32.
Optimal coring locations for high resolution climate reconstructions from the East Antarctic Plateau
Authors: Laepple Thomas , Dallmayr Remi , Hörhold Maria , Hirsch Nora , Jansen Daniela , Behrens Melanie , Münch Thomas , Freitag Johannes
Published: February 2023

Oxygen isotopes of snow, firn, and ice cores provide valuable information on past climate variations. Yet, multiple processes, such as stratigraphic noise and the advection of spatial isotope variations linked to topographic anomalies create non-climatic variations (‘noise’) in the ice-core record and limit the quality of high-resolution climate reconstructions. All of these processes are site specific and vary depending on the environmental conditions at and around the ice-core location.  In the last years, based on field studies, numerical experiments and theoretical considerations, we improved our quantitative understanding of these noise generating processes and their dependency on the depositional conditions. Building on this work, we here ask the question how the potential quality of ice-core based climate reconstructions depends on the drilling site location.  Making use of digital elevation models,  ice flow-velocity maps and statistical relationships between the surface topography, accumulation anomalies,  isotopic anomalies and stratigraphic noise, we predict the site and time-scale dependent noise contribution to ice-core records of the last millennium. The created maps provide a step towards choosing optimal ice coring and  sampling locations for high-resolution climate reconstructions from Antarctic ice-cores and provide testable predictions for the quality of future ice-core records.
A Roadmap to Strengthen Geoscience Education for Sustainable Development in Kenya
Authors: Williams Rebecca , Raji Munira , Gill Joel , Olaka Lydia , Omuombo Christine , Odhiambo Cavince , Oluoch Joseph , Ochola Samuel , Kawino Dinah , Dowey Natasha , Haemmerli Hannah , Pozzi Laura , Hurman Gareth , James Honor
Published: February 2023

Meeting the targets of the 17 United Nations (UN) Sustainable Development Goals (SDGs) requires contributions from geoscientists. Like most countries, Kenya is faced with the triple dimensional challenge of balancing economic, social and environmental sustainability. Through implementation of its ‘Vision 2030’ strategy, Kenya aims to transform into a high-functioning, industrialised middle-income country, providing a high quality of life to all its citizens by 2030. The country’s constitution harmonises with Vision 2030 and entitles every Kenyan to a clean and secure environment. This background provides an integrated roadmap entrenched in the SDGs. Kenya has also committed to implementing the African Union Agenda 2063 and the East African Community (EAC) Vision 2050, both aiming to build a more prosperous Africa. Eradicating extreme poverty, waste management, disaster preparedness, ensuring affordable, clean and sustainable energy, improving access to clean water, promoting sustainable consumption and production, environmental sustainability, building resilience to climate change impacts and managing Kenya's natural resources are some of the key elements of these policies. Here, we highlight the importance of geoscience education in accelerating the critical goals of Kenya’s Vision 2030 and the SDGs. We synthesise key policy documents to explore sustainable development priorities at the national and county level in the context of geoscience in Kenya and explore the relevant geoscience training and skills needed to help address these priorities. We demonstrate that geoscience will continue to be instrumental for achievement of the SDGs and overall performance on socio-economic development in Kenya. Baseline assessments of the geoscience courses available, including training and description of modules offered in Kenya's higher institutions, were compiled and analysed. The extent of the existing geoscience workforce and future workforce required to deliver on Kenya's Vision 2030 and the SDGs was identified through online surveys, focus group discussions, and interviews. We mapped the future needs against the training available and existing current workforce capacity to conduct a skills gap analysis. We identify a number of needs, including (1) to embed sustainability concepts into geoscience curriculum; (2) to expand provision of specialist postgraduate courses (e.g. MSc); (3) to strengthen access to field-based training in both undergraduate and postgraduate degrees; (4) to increase the number of trained geoscientists; (5) improved communication between geoscientists and policymakers. We conclude with a roadmap to address these gaps, embedding good practice from the UN Technology Facilitation Mechanism, and include transferable insights for other national settings.
Proposal of UAV-Lidar and photogrammetry-based modeling for assessing soil loss using nature-based solutions as countermeasure in urban areas in DRC
Authors: Raïmat Carles , Van Eghoff Christian , Campos Ana , Corroyer Laurent , Mora-Castro Sergio , Saborío Javier , Vega Arabela
Published: February 2023

Mass movements due to soil erosion, intense rains and water runoff in sandy soils represent a major socio-ecological problem in the Democratic Republic of Congo (DRC). Kinshasa, Kananga and other urban areas in DRC are currently challenged by severe forms of land degradation.Natural resources are being exploited at high rates due to unplanned human settling pressed by migration and population growth. Consequently, demanding energy, forestry, agricultural goods and services that undermine tropical forests, savannas and monsoon forests, which are fragile and high value ecosystems.The effects of forest lost are exacerbated by growing urban areas with drainage mismanagement in anarchic urban environments due to concentrated and disorganized flow. Rain events between 2019 and 2022 have compromised or destroyed basic structure such as railroads and main streets, considered key lifelines that have already caused human, environmental and infrastructural losses.Reliable rain data records are scarce or inexistent; however, intense, heavy, punctual rain events can be identified throughout the dry and rainy season. No particular erosive effect can be attributed to these events without consistent Intensity-duration-frequency (IDF) data. On the other hand, slope instability has been well documented through satellite imagery and demonstrated exponential growth since 2010. Aero transported Lidar, photogrammetry and cloud point technique have been used to map urban growth, vegetation cover and soil management practices in four study sites, in between seasons.Hence, this study proposes to systemize a methodology that assesses soil degradation and stability risks; evaluating the effectiveness of NBS to reduce soil erodibility through the combination of agroecological solutions, engineering risk management in urban and peri-urban environments facing climate change challenges. This is a project currently under research and execution by the Government of DRC with the support of the World Bank.   
Carbon stock of the Gemenc forest (Hungary)
Authors: Horváth Adrienn , Szász Dániel , Balázs Pál , Végh Péter , Bidló András
Published: February 2023

We made our investigation in the Gemenc forest, which is situated beside the Danube river near the southern border of Hungary. Mainly the Danube and in the last decades, watercourse management played a significant role in landscape evolution. Most of the area is on the saved side today, so it doesn’t get flooded. The Danube usually brings calcium carbonate to this area with its sediment. The flooded areas are built from fine sediment materials. Meadow soils rich in calcium carbonate are characteristic, and the forests of this land grow healthy here (assuming that are high-quality forest types). Farther away from the river, higher plains have sand with humus soils and Chernozem soils.Forest ecosystems of this area are probably one of the most important members of the continental vegetation that stores carbon. Because of their size, they take huge part of the global carbon cycle. The amount of carbon stored in the soil – similar to the carbon stored in wood- and the consequences of human activities on this carbon are less known in Hungary. The reason for this is the small amount of information we have about this topic. During our examinations, we visited six Quercus petraea and Robinia pseudoacacia forests and measured the carbon stock of those forest soil besides the determination of water holding capacity. The humus content of the examined soil samples varied between 0.7 and 6.9 %. Since the study areas are no longer or rarely affected by flooding, the highest organic matter content was found in the topsoil layer for each sample. SOM content gradually decreased with depth. The effect of flooding is clearly shown by the fact that we found organic matter in the samples even in the layer below 100 cm, and in several cases, we found buried humus levels. Accordingly, the organic carbon stock of these soils may be higher than average. However, the decreasing number of floods endangers the vitality of forest stands. With less flooding, decreasing groundwater level, and an increase in the temperature at night, dew formation becomes more limited, and evaporation increases. These changes also affect the decomposition processes taking place in the soil, the circulation of nutrients, and soil respiration. Increasing temperature, the speed of decomposition, and the intensity of soil respiration increase, which can further increase the decrease in the soil's C pool.This article was made in frame of the project TKP2021-NKTA-43 which has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme.
Responses of European forest fluxes to the 2022 heatwave and drought recorded by ICOS Eddy-covariance stations
Authors: Joetzjer Emilie , Lafont Sebastien , Loubet Benjamin , Destouet Gabriel , Jacotot Adrien , Cuntz Matthias , Ciais Philippe , Fu Zheng , Herig-Coimbra Pedro , Domec Jean-Christophe , Lousteau Denis
Published: February 2023

In 2022, Europe experienced a widespread severe summer edaphic drought and heat event, as well as abnormally hot autumn temperatures. By contrasting year 2022 with previous ones and using high-frequency Eddy-covariance and meteorological monitoring from 16 ecosystem ICOS forest stations across Europe, we(i) characterized the impact on carbon uptake and evapotranspiration rates, and (ii) disentangled the effects of soil water deficit from effects of atmospheric dryness on the forest fluxes.Reduction of observed CO2 uptake and evapotranspiration varied across Europe relative to drought intensity. Scandinavian forests were minimally affected in 2022, unlike the 2018 drought. On the contrary, several sites in southern Europe became a carbon source during the 2022 drought. Specifically, in southern France, some sites experienced a reduction of GPP of up to 70% relative to 2015-2021. Using artificial neural networks to analyze the responses of forests' CO2 uptake to soil water content and atmospheric dryness, showed the very high vapor pressure deficit experienced in 2022 was the major driver of the ecosystem responses in southern France this particular year.  
Protracted continental subduction, indentation and collisional boundary migration coupled with adjacent oceanic slab-rollback and slab detachment in large-scale buoyancy-driven 3D whole-mantle scale numerical models of subduction-and-collision.
Authors: Laik Arijit , Schellart Wouter , Strak Vincent
Published: February 2023

Continental collision zones form at convergent plate boundaries after negatively buoyant oceanic lithosphere subducts entirely into the Earth's mantle, whereafter collision ensues, and colliding continents are sutured together. In models of free subduction, the volume of the preceding and adjacent negatively buoyant oceanic lithosphere controls the system's driving force and dynamics. To investigate the dynamics of long-term continental subduction, indentation and collisional boundary migration and associated slab dynamics we designed large-scale numerical models of subduction-and-collision including two sets of modelled depths: whole mantle (2880 km) and upper mantle + partial lower mantle (960 km) and varying the trench parallel length ratio (1.5 - 2) of the indenting continental lithosphere (~2300 km) and adjacent oceanic lithosphere. In this contribution, we present the contrasting evolution of continental subduction and indentation coupled with adjacent oceanic slab rollback focusing on the different slab dynamics observed by varying the depth of the mantle in the models. Intriguingly, the whole mantle models show sustained continental indentation and concurrent deep continental subduction to mid-low upper mantle depths resulting in deep slab tearing at the subducted continental margin and shallow slab tearing at the trench parallel boundaries of the continental plate. In addition, the models also show continental underthrusting beneath the overriding plate and underplating of the continent, coeval with indentation and adjacent oceanic slab rollback. Together, these results provide insights into the India-Eurasia collision zone where the prolonged northward indentation of India during the last 50 Myrs and the rollback of the Sunda slab appear linked.
Land-users' perspectives on carbon farming and result-based schemes
Authors: Graversgaard Morten
Published: February 2023

An extensive body of research has shown that land management practices can increase soil organic carbon stocks on agricultural lands. This knowledge has also gained interest among policy makers, and the concept of carbon farming is increasing in attention. Recently, the EU Commission published its proposal for a regulatory framework on carbon removals, in here the European Commission will set standards for certifying carbon farming activities.Successful carbon farming presupposes that scheme design enables land users’ to effectively implement relevant carbon farming practices.  Despite these new legislative ambitions on carbon farming, key questions remain, and knowledge is needed on land-users' perceptions of strengths and weaknesses of different designs for carbon farming schemes. In this paper, we analyse 9 different partner countries in EU, that have facilitated focus groups with landowners on carbon farming and scheme design. The paper, presents and discuss the basis for designing schemes that are perceived as fair and effective by land-users. Implementing stakeholders’ preferences in scheme design is important for land-users’ support and uptake of such schemes.
The first tree-ring reconstruction of streamflow variability over the last ~250 years in the Lower Danube
Authors: Ionita-Scholz Monica , Nagavciuc Viorica , Roibu Catalin , Mursa Andrei , Stirbu Marian-Ionut , Popa Ionel
Published: February 2023

Paleoclimate reconstructions are increasingly used to characterize climate variability and change prior to the instrumental record, in order to improve our estimates of climate extremes and to provide a baseline for climate change projections. Most of these reconstructions are focused on temperature, precipitation, and/or drought indices and, to a lesser extent, reconstruct streamflow variability. In this study, the first regional tree-ring width chronology (i.e. Quercus sp.), from the Caraorman forest (Danube Delta, Romania), was used to reconstruct the last ~250 years of annual (from November previous year to July of the current year) streamflow of the Lower Danube River. The obtained results indicate a stable and significant correlation between the tree-ring width index from the Caraorman forest and the Danube streamflow at the Ceatal Izmail hydrologic station situated in the southeastern part of Europe. Interannual streamflow variation for the analyzed period indicates 14 extremely high flow years, with streamflow greater than 8780 m3/s (1770, 1771, 1799, 1836, 1838, 1839, 1871, 1876, 1877, 1879, 1940, 1941, 1997 and 2010) and 14 extremely low flow years, with streamflow lower than 5300 m3/s (1741, 1745, 1750, 1753, 1773, 1794, 1812, 1832, 1843, 1882, 1899, 1921, 1964 and 1994). Periods characterized by pluvials in the lower Danube Delta are associated with a low-pressure system centered over Europe, positive sea surface temperature (SST) anomalies over the Atlantic Ocean, and negative SST anomalies over the Baltic, North, and Mediterranean Seas. These large-scale conditions favor the advection of moist air from the Mediterranean and the Black Sea towards the southeastern part of Romania, which in turn leads to high precipitation rates over this region. Opposite to this, low streamflow years are associated with a high-pressure system centered over Europe, characterized by a northward shift of the storm tracks and negative SST anomalies over the Atlantic Ocean, and positive SST anomalies over the Baltic, North, and Mediterranean Seas. Based on our results, we argue that the reconstruction of river streamflow data based on the tree-ring width has important scientific and practical implications for a better understanding of the streamflow variation of the past, necessary for water resource management and environmental-hydrological protection.
Comparison of relative locations methods and their accuracy for determining fault structures
Authors: Konrádová Diana , Horálek Josef , Doubravová Jana
Published: February 2023

Precise earthquake locations are a prerequisite for determining real fault structures. To improve the precision of the event location, a few relative locations methods are commonly used to refine event locations. Relative relocation methods reduce effects of an imperfect velocity model and errors due to arrival time measurement. We performed comparative tests of tree different relocation methods: HypoDD (HD), GrowClust (GC) and Master event (ME). We tested the efficiency and differences in the event locations using these three methods on dataset from REYKJANET seismic network operating in Iceland on Reykjanes Peninsula. All these methods provide substantially focused shapes of clusters compared to the absolute event locations but the locations of individual events differ evidently depending on the method used.We also aimed at an effect of the control parameters of HD, GC and ME on final location results and their optimization as well as computational and memory demands.
Integrating intermittent renewables via hydropower alone adversely impacts other sectors
Authors: Gonzalez Jose M. , Martínez-Ceseña Eduardo A. , Panteli Mathaios , Harou Julien J.
Published: February 2023

Large-scale integration of intermittent renewable sources in Africa, such as solar and wind, can accelerate the transition to low-carbon energy systems, which is critical to mitigate the impacts of climate change and increase electricity access. Hydropower can support this transition because its operational flexibility can be used, in a cost-effective manner, to counteract the variability and seasonality of intermittent renewables. However, using hydropower to provide energy system flexibility services can affect aquatic ecosystems and create intersectoral conflict. We use a multi-objective design framework to address this issue and demonstrate it on a national-scale case study for Ghana. This case study shows that available hydropower flexibility can be deployed to support expanding intermittent renewables by 38%. However, this would increase the sub-daily flow variability of the main national river (Volta) by up to 22 times compared to the historical baseload hydropower operation that does not support intermittent renewables. The increase in sub-daily flow variability is estimated to damage the river ecosystem and reduce national crop yield revenue by up to US$169 million per year. We propose an alternative approach that uses a diversified investment strategy, including intermittent renewables, bioenergy, and transmission network expansion in addition to existing hydropower, and show that such designs can maintain acceptable flow variability and agricultural performance while meeting future national energy service goals and reducing CO2 emissions. The proposed framework can support governments and power system planners by designing efficient diversified energy investment portfolios and highlighting their sectoral and emission trade-offs.
A new, high-resolution climatological atmospheric dataset for southern New Zealand
Authors: Kropac Elena , Mölg Thomas , Cullen Nicolas J.
Published: February 2023

The regional climate of New Zealand’s South Island is shaped by the interaction of the Southern Hemisphere westerlies with the complex orography of the Southern Alps. Due to the geographical setting of New Zealand in the south-west Pacific, the properties of the transported air masses and the regional circulation itself are strongly influenced by the surrounding oceans. Therefore, variations in sea surface temperature (SST) are reflected on a variety of spatial and temporal scales and are statistically detectable through to temperature anomalies and glacier mass balance changes in the high mountains of the Southern Alps. The relationship between SST and high-mountain climate has not yet been investigated from a process perspective, leaving the underlying physical mechanisms that transmit large-scale SST signals to local climate anomalies and glacier mass changes unknown.We used dynamical downscaling with the Weather Research and Forecasting (WRF) model laterally forced by ERA5 reanalysis data to produce a regional atmospheric modeling dataset for the South Island of New Zealand. The dataset covers the present-day, 16-year period of 2005 to 2020. The high horizontal resolution of 2 km ensures that high-mountain topography and glaciers are resolved realistically, and convection is modeled explicitly. The two-domain setup is centered on Brewster Glacier, a benchmark glacier close to the main divide of the Southern Alps, which is the focus of further process-oriented investigations. The model configuration has been optimized to provide both reasonable output and fast simulation time, allowing for expense-limited follow-up sensitivity experiments.The dataset is evaluated regionally against an extensive network of observational meteorological data from the National Institute of Water and Atmospheric Research (NIWA) and MetService New Zealand as well as against atmospheric water content from Moderate Resolution Imaging Spectroradiometer (MODIS) imagery. Locally, the model output is compared to high-mountain weather station measurements at Brewster Glacier. The model represents variability in both atmospheric water content and near-surface meteorological conditions generally well, although there are both seasonal and spatial biases that are particularly confined to high elevations. The local climate at Brewster Glacier (where landuse and topographic conditions have been optimized) is remarkably well represented on both seasonal and daily timescales.Given the fact that the Southern Hemisphere has been understudied in terms of multiscale climate and cryosphere relations, the dataset provides a unique and valuable tool for investigations of climate change and related impacts in southern New Zealand with high interdisciplinary relevance. Data from the finest-resolution model domain are available for download at daily temporal resolution from a public repository.
Identifying needs for urban greenhouse gas monitoring in Seoul using ground-based EM27/SUN measurements
Authors: Park Hayoung , Jeong Sujong
Published: February 2023

Anthropogenic emissions of greenhouse gases from fossil fuel combustion have a significant impact on the global climate. Cities, which are home to more than half of the global population, account for over 70% of anthropogenic greenhouse gas emissions and are the major sources of air pollution that we face today. However, as much as they are big emitters, cities also have great potential to be drivers of global greenhouse gas reductions. To better manage atmospheric greenhouse gases, it is necessary to accurately monitor and quantify emissions at all spatial scales from national to urban levels. In addition to using satellites which provide global coverage with high space and time resolutions for greenhouse gas monitoring, several studies have used portable ground-based remote sensing Fourier transform infrared (FTIR) spectrometers, EM27/SUNs, to measure the column-averaged concentrations of greenhouse gases. This study analyzes the column-averaged dry air mole fractions of CO2, CH4, and CO (XCO2, XCH4, XCO) in the atmosphere over Seoul using two EM27/SUNs which is the first to be done in South Korea. Moreover, we compare our measurements with satellite measurements of the Orbiting Carbon Observatory-2 (OCO-2), Orbiting Carbon Observatory-3 (OCO-3), and Sentinel-5 Precursor TROPOspheric Monitoring Instrument (TROPOMI). Together, this study aims to analyze the three-dimensional structure of greenhouse gases in Seoul which has been difficult to do due to the absence of domestic greenhouse gas observation satellites. Furthermore, this study identifies the need for more ground-based column measurements of greenhouse gases in cities and plume areas, as well as locally adaptable methods of greenhouse gas emissions monitoring in urban areas.
Hydrologic characterization of sponge-city systems for urban trees based on monitoring and modelling
Authors: Zeiser Anna , Rath Sebastian , Strauss Peter , Weninger Thomas
Published: February 2023

Sponge-city sites for urban trees based on the model of Stockholm promise to improve the chances of trees surrounded by sealed or condensed surfaces for root growth and therefore vital tree development tremendously. The system furthermore helps to conquer the urban heat island effect, aids in stormwater management as an underground retention basin saving soil water for transpiration and hence supports the ambition to approach a (more) natural hydrologic cycle. The actual capacity of the system to fulfil these services is determined by a variety of design criteria which need to be optimized based on detailed knowledge about the hydrological functionality of the different elements of the system. The aim of several monitoring and modelling studies in Austria is to gain such knowledge to ensure a proper performance of the system in terms of tree growth and rainwater retention.First of all, the substructure construction consists of unconsolidated fine substrate flushed into the voids of edged stones that serve as load-bearing structure, assuring root-favouring pore distribution. Technical components like an inlet and surface water distribution system accompany the substrate. Further influencing parameters are e.g. properties of the existing substrate underneath, design of urban surface as well as origin and treatment of fed surface water. Based on monitoring sites in the shape of lysimeters, field scale projects in real urban settings, and laboratory experiments, modelling approaches for the hydrological functionality of the sponge-city systems are generated. Crucial system elements and target values for design properties are derived from these simulations. In the longer term, the results should serve as a supportive planning tool for engineering projects in urban environments.
On the inaccuracy of CMIP6 models in capturing the observed long-term variability of the NAO
Authors: Halifa-Marín Amar , Torres-Vázquez Miguel A. , Pravia-Sarabia Enrique , Trigo Ricardo , Vicente-Serrano Sergio M. , Turco Marco , Jerez Sonia , Jiménez-Guerrero Pedro , Montavez Juan Pedro
Published: February 2023

This study assesses how the CMIP6 simulations capture the non-stationarity of the main source of winter climate variability in the Euro-Atlantic region, the North Atlantic Oscillation (NAO), observed in the recent past.For that purpose, we characterise the NAO long-term variability in climate reanalysis, analysing their features in several 30-year periods since 1851; and we evaluate whether CMIP6 historical simulations capture all the observed NAO “types”. Although the literature sometimes assumes that the NAO pattern is stationary, three groups of NAO pattern have been proved in the reanalyses depend on the location of their Action Centres (ACs): 1) the north AC locates over Iceland and the south AC in Azores, 2) the north AC locates over Southern Greenland and the south AC in the Western Mediterranean, and 3) the north AC locates over Northern Scandinavia and the south AC in the Azores.Our main finding is that the NAO long-term variability is not accurately captured by all CMIP6 models. In particular, the overestimation of the NAO group 3 is remarkable in most simulations. This NAO group mainly represents the last decades, which the literature has addressed with much interest for its exceptional features (e.g. NAO+ strengthening and northeastward shift of its north AC), and which has been generally associated with the anthropogenic warmer climate. We also found underestimation of NAO group 2.We have also found that each NAO group could be associated with precipitation anomalies in Europe. For example, the NAO group 3 implies drier(wet) conditions in the south(north). While group 2 implies the opposite pattern of anomalies. Therefore, we have reason to suggest that the lack of accuracy of models reproducing the non-stationarity of NAO may explain some of the bias in the expected changes of winter precipitation in Europe for future scenarios.
Paradise lost: Microplastic pollution on a remote coral island, Vietnam
Authors: Mendrik Freija , Hackney Christopher , Cumming Vivien , Hung Nguyen , Hennige Sebastian , Parsons Daniel
Published: February 2023

Despite microplastic pollution now being ubiquitous in natural environments, there remains several unknowns in terms of which zones may act as microplastics sinks. Coral reefs are the most ecologically diverse marine ecosystem, supporting 25% of all ocean species, and have high socio-economic value, offering ecosystem services such as coastal protection and tourism. However, the average cover of tropical reefs has declined by 50-75% in nearly all global regions over the last 30-40 years due to a range of anthropogenic stressors. There is growing evidence that coral reefs can entrap plastics and that microplastic (>5 mm) pollution threatens coral physiology. However, there is a lack of understanding as to the occurrence, accumulation, spatial distribution and impacts of microplastic pollution on coral ecosystems. It is, therefore, necessary that more research is undertaken within coral reefs to understand microplastic contamination levels and ensure effective mitigation measures are in place.The islands of Con Dao, Vietnam, are 90 km from the Mekong Delta coast and are a designated national park, with a 14,000 ha marine protected area that conserves endangered wildlife and a diverse range of coral that support hundreds of fish species. Although considered pristine, Con Dao it is influenced by the Mekong River, which is one of the top contributors to marine plastic waste worldwide, posing an increasing risk to this biodiversity hotspot. Understanding the volumes and impacts of microplastic pollution in this area will allow insight into the levels of exposure and risk coral reefs in Southeast Asia, including the highly biodiverse Coral Triangle, have from increasing plastic pollution.Here, the occurrence and spatial distribution of microplastics in water and sand samples from Con Dao is presented. Reef health is also provided through photogrammetry whereby 3D reconstruction of reef sites allows analysis of coral cover and diversity, in addition to structural complexity, which is strongly correlated to reef health indicators including biodiversity, especially within tropical reef ecosystems. Potential sources of microplastics are also discussed through polymer identification by FT-IR analysis.
Future change in atmospheric synoptic variability : impact on ocean circulation and primary productivity
Authors: Duteil Olaf , Park Wonsun
Published: February 2023

Climate change impacts atmospheric properties and circulation at different time scales, ranging from daily to millenial. We specifically assess here the impact of a change in atmospheric synoptic variability (ASV) (0-1 month) on mean upper ocean properties. In a first step, we disentangle the ASV and low frequency part in atmospheric fields originating from a climate change experiment performed by the Kiel Climate Model. In a second step, we use these fields to perform a set of sensitivity experiments to the change in ASV by employing a NEMO-PISCES configuration. We show that a decrease in ASV results in a slowdown of the mean ocean circulation and a global decrease in primary productivity. Our study highlights the need for more precise quantifications of the atmospheric synoptic variability in climate models and observations.
Assessing the physical processes controlling oxygen subduction in CMIP6 models
Authors: Blackledge Benedict , Andrews Oliver , Portela Esther , Bingham Rory , Couespel Damien
Published: February 2023

Approximately half of the total loss of upper ocean oxygen over the recent past has been driven by its reduced solubility in a warming ocean. The remainder can be explained by less well constrained changes to ocean circulation, mixing and biogeochemical processes. Model based studies have shown that the choice of mixing parameterisations as well as biogeochemical factors, can introduce substantial differences in the distribution of oxygen within an individual Earth System Model (ESM).  Model Intercomparison Projects such as the latest Coupled Model Intercomparison Project Phase 6 provide an opportunity to explore processes controlling oceanic oxygen in a multi-model framework. Here we apply an oxygen transport decomposition to seven CMIP6 ESMs, using a well-established framework for the transport of tracers from the surface mixed layer into the ocean interior. We show that despite a close agreement in the oxygen concentration at the mixed-layer base, the transports to the ocean interior vary greatly between models. ESMs with similar physical ocean model components are clearly identifiable based on the spatial distribution of oxygen transport, both in the globally integrated transport terms and their inter-annual variability. Applying this decomposition to CMIP6 pre-industrial control experiments, we find the total oxygen subduction ranges between +0.6 to +1.1PMol yr-1, in agreement with an observationally based estimate. Despite broad agreement in the total magnitude of oxygen subduction, the inter-model range for individual transport terms is often large (+0.69 PMol yr-1 to -0.23 PMol yr-1 for vertical advection), implying a high degree of model uncertainty as to the physical processes controlling interior oxygen. We also characterise variability in oxygen transport terms and find that interannual variability in advective transport depends on the term and the model family. Lateral advection displays the greatest model-model difference in interannual variability, by a factor of ~6 between the most and least variable model. Mixed-layer entrainment of oxygen shows closer agreement between models, with interannual variability in this term differing by a factor of ~1.4. We recommend that future model intercomparisons including ocean biogeochemistry archive the relevant transport, production and consumption terms for key biogeochemical variables such as oxygen.