bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving the identifiability of Transient Storage Model parameters to explore process information in solutes breakthrough curve
Authors: Bonanno Enrico , Blöschl Günter , Klaus Julian
Published: March 2022

Transient storage models (TSM) are a valuable tool for investigating the distribution and transport of solutes, nutrients, and pollutants in the stream corridor. The application of TSM is fundamental for understanding the continuous exchange of water between the active stream channel and dead zones, in-stream sediments, and the adjacent groundwater. Despite the large amount of studies, TSM applications are often limited by the lack of information on parameters certainty. Among the available studies, only few addressed sensitivity of TSM parameters and found poor parameter identifiability and substantial model uncertainty, which make the current interpretation of TSM results rather challenging. This issue raises the question if and when TSM parameters are actually meaningful. Addressing identifiability of TSM parameters is pivotal, since uncertainty in parameter estimation and their interpretation limit linking specific physical processes to model parameters.

Here, we apply a step-sampling approach that combines global identifiability analysis with dynamic identifiability analysis to evaluate model sensitivity and uncertainty in a set of tracer breakthrough experiments in a headwater stream reach. Our results demonstrate that limitations in parameter identifiability often found in several TSM studies can be related to: (i) the assumption velocity = velocitypeak; (ii) the large parameter range used for the parameters sampling; and (iii) the relatively low number of sampled parameter sets. While it is generally assumed that advection-dispersion parameters act on the solute arrival time, and that transient-storage parameters control the tail of the breakthrough curve (BTC), our study brings new insights on the role of TSM parameters in controlling the solute transport in streams. The proposed step-sampling approach allowed us to clearly reduce uncertainty of parameters in TSM highlighting the importance of TSM parameters in certain sections of the BTC, where they are usually assumed to be negligible. By targeting the identifiability range of transient-storage parameters on the tail of the BTC, the applied step-sampling approach bears significant potential for substantially increasing TSM parameters identifiability, and for advancing our understanding of hydrological processes involved in solute transport in streams.
Mid-Holocene climate at mid-latitudes: modelling the impact of the Green Sahara
Authors: Gaetani Marco , Messori Gabriele , Alvarez Castro M. Carmen , Zhang Qiong , Pausata Francesco S.R.
Published: March 2022

During the mid-Holocene (6,000 years ago) the Northern Hemisphere experienced a reinforcement of the monsoonal regime, which led to the so-called “African Humid Period” (AHP) and to the greening of the Sahara region. Paleoclimate archives also show a gradual cooling of north-eastern Atlantic and the warming of the western subtropical Atlantic, eastern Mediterranean and northern Red Sea during the Holocene. These changes were likely accompanied by a positive-to-negative transition of the AO/NAO phase from mid-late Holocene into the pre-industrial period, leading to climate impacts in North America, Europe, the Mediterranean and Siberia.

However, inconsistencies still exist between proxies and model simulations of the Holocene climate. To explain the limitations of climate models, several studies pointed out the role of the vegetation feedback at tropical and higher latitudes. The objective of this study is to investigate the impact of the Green Sahara on the Northern Hemispheric mid-latitude atmospheric circulation and associated climate variability during the African Humid Period. To this aim, vegetated Sahara with reduced dust emission is prescribed into a coupled ocean-atmosphere model (the Green Sahara experiment).

Model simulations show a sizable impact on the main circulation features in the Northern Hemisphere when the Green Sahara is prescribed, especially during boreal summer, when the African monsoon develops. This study provides a first constraint on the Green Sahara influence on northern mid-latitudes, indicating new opportunities for understanding mid-Holocene climate anomalies in North America and Eurasia. However, inconsistencies between proxies and model simulations still persist in the Green Sahara experiment, indicating that more accurate simulations of the MH climate modifications are needed (e.g. prescribing realistic vegetation at mid and high latitudes, considering seasonal cycle in vegetation cover).
The structure of waves during Geostrophic Adjustment on the mid-latitude β-plane
Authors: Yacoby Itamar , Paldor Nathan , Gildor Hezi
Published: March 2022

The theory of the transition from an unbalanced initial state to a geostrophically balanced state, referred to as geostrophic adjustment, is a fundamental theory in geophysical fluid dynamics. The theory originated in the 1930s on the f-plane and since then the theory was barely advanced to the β-plane. The present study partially fills the gap by extending the geostrophic adjustment theory to the β-plane in the case of resting fluid with a step-like initial height distribution η0. In the presentation, we focus on the one-dimensional adjustment theory in a zonally-invariant, finite, meridional domain of width L where η0 = η0(y). By solving the linearized rotating shallow water equations numerically, the effect of β on the adjustment process is examined primarily from the wave perspective while the spatial structure of the geostrophic steady-state will be addressed only briefly. The gradient of η0(y) is aligned perpendicular to the domain walls in our zonally-invariant set-up which implies that the geostrophic state only represents the time-averaged solution over many wave periods rather than a steady-state that is reached by the system at long times. We found that: (i) the effect of β on the geostrophic state is significant only for b = cot(φ0)Rd/R ≥ 0.5 (where Rd is the radius of deformation, R is Earth's radius and φ0 is the central latitude of the domain). (ii) In wide domains the effect of β on the waves is significant even for small b (e.g. b=0.005). EOF analysis demonstrates that for b=0.005 and in narrow domains (e.g. L = 4Rd) harmonic wave theory provides an accurate approximation for the waves, while in wide domains (e.g. L = 60Rd) accurate approximations are provided by the trapped wave theory. Preliminary results derived in the two-dimensional case, where η0 = η0(x) is symmetric, imply that the results outlined in item (ii) above hold in this case too. 
Paleo-ENSO influence on African environmentsand early modern humans
Authors: Kaboth-Bahr Stefanie , Gosling William D. , Vogelsang Ralf , Bahr André , Scerri Eleanor M. L. , Asrat Asfawossen , Cohen Andrew S. , Düsing Walter , Foerster Verena , Lamb Henry F. , Maslin Mark A. , Roberts Helen M. , Schäbitz Frank , Trauth Martin H.
Published: March 2022

In this study, we synthesize terrestrial and marine proxy records, spanning the past 620,000 years, to decipher pan-African climate variability and its drivers and potential linkages to hominin evolution. We find a tight correlation between moisture availability across Africa to El Niño Southern Ocean oscillation (ENSO) variability, a manifestation of the Walker Circulation, that was most likely driven by changes in Earth’s eccentricity. Our results demonstrate that low-latitude insolation was a prominent driver of pan-African climate change during the Middle to Late Pleistocene. We argue that these low-latitude climate processes governed the dispersion and evolution of vegetation as well as mammals in eastern and western Africa by increasing resource-rich and stable ecotonal settings thought to have been important to early modern humans.
Structures and geodynamics of the Mongolian tract of the Central AsianOrogenic Belt constrained by potential field analyses
Authors: Guy Alexandra , Schulmann Karel , Soejono Igor , Holzrichter Nils , Lexa Ondrej , Munschy Marc
Published: March 2022

A multidisciplinary approach integrating potential field analysis with geological and geochemical data provides new insights into the understanding of the crustal structure and evolution of the Mongolian collage. Magnetic and gravity data demonstrate the inconsistency between the geologically defined terranes and the geophysical domains in the southwestern part of the Mongolian collage. The combination of potential field analysis and modelling with whole rock geochemistry and isotopic mapping of Carboniferous–Permian granitoids indicates the presence of a homogeneous lower crust composed of a felsic to intermediate juvenile material beneath geophysically heterogeneous upper crust. This feature is interpreted as a result of a trench-directed lower crustal emplacement of an arc type crust underplating deformed Paleozoic oceanic crust. The potential field data also confirmed the occurrence of two orthogonal late Devonian and Permian–Triassic deformation upper crustal fabrics at the scale of the southwestern Mongolian collage. The prominent magnetic highs correspond to the tectono-metamorphic domains and magmatic provinces. The gravity anomalies highlight a periodicity of the signal correlating with alternating Permian–Triassic high and low strain zones, forming a zone of major deformation wrapping around the hinge of Mongolian orocline. The geometry and kinematics of dextral and sinistral transpressive faults are explained to result from the reactivation of Permian–Triassic deformation zones in the Cenozoic stress field.
The Southern Ocean during the ice ages: A slumped pycnocline from reduced wind-driven upwelling?
Authors: Fripiat Francois , Sigman Daniel , Ai Xuyuan , Studer Anja , Kemeny Preston , Hain Mathis , Wang Xingchen , Ren Haojia , Haug Gerald , Martinez-Garcia Alfredo
Published: March 2022

The Southern Ocean is recognized as a potential cause of the lower atmospheric concentration of CO2 during ice ages, but the mechanism is debated. In the ice age Antarctic Zone, biogeochemical paleoproxy data suggest a reduction in the exchange of nutrients (and thus water and carbon) between the surface and the deep ocean. We report simple calculations with those data indicating that the decline in the supply of nutrients during peak glacials was extreme, >50% of the interglacial rate. Weaker wind-driven upwelling is a prime candidate for such a large decline, and new, complementary aspects of this mechanism are identified here. First, reduced upwelling would have resulted in a “slumping” of the pycnocline into the AZ. Second, it would have allowed diapycnal mixing to “mine” nutrients out of the upper water column, possibly causing an even greater slumping of the vertical nutrient gradient (or “nutricline”). These mechanisms would have reduced shallow subsurface nutrient concentrations, decreasing wintertime resupply of nutrients to the surface mixed layer, beyond the reduction in upwelling alone. They would have complemented two changes previously proposed to accompany a decline in upwelling: (1) halocline strengthening and (2) reduced isopycnal mixing in the deep ocean. Together, the above changes would have encouraged declines in the nutrient content and/or the formation rate of new deep water in the AZ, enhancing CO2 storage in the deep ocean.
The peculiar nature of thermal diffusion coefficients in karst terrains and their control on cave temperatures
Authors: Domínguez-Villar David , Krklec Kristina , Sierro Francisco J.
Published: March 2022

Temperature in the inner section of most caves (i.e., away from well ventilated entrance sections) is controlled by external air temperature transferred underground by heat conduction. The key parameter that controls heat conduction is the thermal diffusion coefficient, that is specific for different materials. Although thermal diffusion coefficients can be calculated for specific carbonate rocks, the underground karst is not composed exclusively of bedrock since dissolution creates large pores and conduits filled with air and water that greatly impact thermal diffusion coefficients.  

We studied a 5-year temperature record of the entrance of Los Pilones Cave, in central Spain. The cave entrance is a sub-horizontal and meandering crawlway that limits the advection even in winter, making this cave ideal to study thermal conduction processes. Cave temperature was recorded along the 30 m section from the entrance by 10 TINITAG thermistors and external temperature was measured at ground and 2 m elevation levels. The thickness of bedrock cover above the cave was measured with a DISTO2 laser meter equipped with compass and clinometer providing uncertainties <0.05m.

The bedrock cover above the ceiling of the cave ranges from 8 to 15 m and all cave temperature records show annual thermal oscillations with different amplitudes and lag times in relation to the external annual thermal cycles. Cave temperature measurements support that heat conduction is the main heat transfer mechanism controlling cave temperature variability. Thermometers located under a thicker bedrock cover record less thermal amplitude of the annual signal and enhanced delays. The thermal diffusion coefficient was calculated from averaging the results from the thermal anomaly recorded at different depths and the lag time recorded at different depths. The dispersion of regression analyses (r2>0.9) is large compared to analyses performed on non-karst bedrocks, supporting the existence of local heterogeneities in the underground karst. We also noticed that the lag times of individual loggers changed during the studied period (interannual variability), which can be attributed to variable ratios of water saturation in the local porosity. Therefore, when reporting the thermal diffusion coefficient of karst terrains, their triphasic nature (i.e., rock, water and air) should be considered. So, the average thermal diffusion coefficient of a specific cave could vary in space or time beyond calculated uncertainties depending variable hydrological conditions.

Acknowledgements:

The project leading to this research has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No.101030314.
What locals want: (mapping) citizen preferences and priorities for an alpine river landscape
Authors: Scaini Chiara , Stritih Ana , Brouillet Constance , Scaini Anna
Published: March 2022

Sustainable river management frameworks are based on the connection between citizens and nature. So far, though, the relationship between rivers and local populations has played a marginal role in river management. We present a blueprint questionnaire to characterize the perception of cultural ecosystem services and flood risk by locals, and how preferences change across the river landscape. We investigate how locals value the river and whether their preferences are affected by characteristics such as place of residence, age, frequency of visits and relation to the river. The approach is tested on the Tagliamento river, the last major free-flowing river in the Alps, which is characterized by debates on flood protection, flood management and ecological conservation. The questionnaire was filled in by more than 4000 respondents, demonstrating huge interest and willingness to contribute with their opinion on this topic. A participatory map of favorite places shows that most of the river is valued/appreciated by locals, with a high preference for the landscape of the braided middle course. River conservation is the main priority for most respondents across different stakeholder groups, highlighting the need for nature-based solutions in flood-risk management and demonstrating the mismatch between management choices and citizens´ values and priorities. Land-use planning is identified as a factor that can increase flood risk. The results highlight the necessity to tackle conservation, risk management and land-use planning together in order to develop risk-oriented river management strategies. More generally, this work points out that any river intervention should be pondered carefully accounting for its environmental impact also in terms of loss of cultural ecosystem services.
Intergenerational inequities in exposure to climate extremes
Authors: Thiery Wim ,   The kids aren't alright team
Published: March 2022

Under continued global warming, extreme events such as heatwaves will continue to rise in frequency, intensity, duration, and spatial extent over the next decades. Younger generations are therefore expected to face more such events across their lifetimes compared to older generations. This raises important questions about solidarity and fairness across generations that have fueled a surge of climate protests led by young people in recent years, and that underpin questions of intergenerational equity raised in recent climate litigation. However, the standard scientific paradigm is to assess climate change in discrete time windows or at discrete levels of warming, a “period” approach that inhibits quantification of how much more extreme events a particular generation will experience over its lifetime compared to another. By developing a “cohort” perspective to quantify changes in lifetime exposure to climate extremes and compare across generations, we estimate that children born in 2020 will experience a two to sevenfold increase in extreme events, particularly heatwaves, under current climate policy pledges. Our results highlight a severe threat to the safety of young generations and call for drastic emission reductions to safeguard their future.

 

Thiery, W., Lange, S., Rogelj, J., Schleussner, C.-F., Gudmundsson, L., Seneviratne, S.I., Frieler, K., Emanuel, K., Geiger, T., Bresch, D.N., Zhao, F., Willner, S.N., Büchner, M., Volkholz, J., Andrijevic, M., Bauer, N., Chang, J., Ciais, P., Dury, M., François, L., Grillakis, M., Gosling, S.N., Hanasaki, N., Hickler, T., Huber, V., Ito, A., Jägermeyr, J., Khabarov, N., Koutroulis, A., Liu, W., Lutz, W., Mengel, M., Müller, C., Ostberg, S., Reyer, C.P.O., Stacke, T., Wada, Y., 2021, Intergenerational inequities in exposure to climate extremes, Science, 374(6564), 158-160.
High Arctic freshwaters as emitters of greenhouse gases
Authors: Valiente Nicolas , Popp Andrea L. , Dörsch Peter , Fontaine Laurent , Hessen Dag O. , Kjær Sigrid Trier , Sundal Anja , Eiler Alexander
Published: March 2022

Climate change is causing temperatures in the Arctic to rise faster than in any other region of the world. This rapid warming leads, among other effects, to the massive loss of ice masses, development of thermokarst features when permafrost thaws, intensification of the hydrological cycle, and increasing loads of nutrients and organic carbon to surface waters. Freshwaters are highly sensitive to these changes, which affect microbial community composition and diversity. Therefore, these ecosystems are good sentinels to study processes in primary ecological succession related to ecosystem processes such as productivity and greenhouse gas (GHG) emissions. With this study, we aim to contribute to a deeper understanding of the linkages between biogeochemistry and hydrology in High Arctic freshwaters. To this end, we sampled various water sources (e.g., lakes and streams) in two High Arctic catchments (Bayelva and Lovénbreen, in Svalbard in July 2021) for the analysis of GHGs (CH4, CO2, N2O), noble gases (radon-222, argon-40), major ions, stable water isotopes (δD and δ18O) and nutrients (organic C, organic -P and organic -N). We used Ar-corrected gas saturation of each GHG as a proxy of net metabolic changes, while tracers such as stable water isotopes help to disentangle water source contributions. Our first results show that lakes and streams were oversaturated in CO2 as well as N2O but slightly undersaturated in O2, suggesting higher respiration activity than primary production. Our data also indicate a  strong oversaturation in CH4 in lakes, but not in streams. Moreover, we used microbial mineralization of organic matter as a proxy for GHG production. We found similar concentrations of total organic C and N in both lakes and streams and significantly higher concentrations of total P in streams than in lakes. This work furthers our knowledge of the current state of High Arctic freshwaters and helps to predict future effects of climate change impacts on GHG evasion.
The local climate adaptation potential of reforestation, and how it changes during heat waves
Authors: Novick Kimberly
Published: March 2022

Managed alterations to ecosystems designed to increase carbon sequestration or reduce greenhouse gas emissions – so-called “natural” or “nature-based” climate solutions like reforestation and cover cropping - have growing public and private support. Despite this enthusiasm, the realizable benefits of these strategies, and unintended consequences to be avoided, are not well understood. In particular, land cover and management changes designed to affect carbon cycles will also impact water and energy cycles in ways that may or may not be climatically beneficial, but we lack systematic frameworks for assessing and valuing these “biophysical impacts.” Moreover, most of the existing observation-driven work on the topic has been limited to impacts on surface temperature; we still know relatively little about when and where modifications to surface temperature extend to the near-surface air temperature, which is arguably the more relevant target for climate adaptation. In this talk, I will describe a new approach for leveraging flux tower observations to understand the duality of surface and air temperature responses to land cover change. Then, using Eastern US reforestation as a case study, I will apply the approach together with analysis of remote sensing and meteorological data to demonstrate that over annual time scales, reforestation substantially lowers both surface and air temperature, due to canopy structural effects that enhance both sensible heat flux and latent heat flux. However, during heat waves when cooling benefits are most needed, divergent responses of sensible and latent heat fluxes between forested and non-forested ecosystems may reduce the local climate adaptation potential of reforestation.
Deep learning for ensemble forecasting
Authors: Brecht Rüdiger , Bihlo Alexander
Published: March 2022

Ensemble prediction systems are an invaluable tool for weather prediction. Practically, ensemble predictions are obtained by running several perturbed numerical simulations. However, these systems are associated with a high computational cost and often involve statistical post-processing steps to improve their qualities.

Here we propose to use a deep-learning-based algorithm to learn the statistical properties of a given ensemble prediction system, such that this system will not be needed to simulate future ensemble forecasts. This way, the high computational costs of the ensemble prediction system can be avoided while still obtaining the statistical properties from a single deterministic forecast. We show preliminary results where we demonstrate the ensemble prediction properties for a shallow water unstable jet simulation on the sphere. 
Geoethics literacy: Values clarification as an initial step into geoethical issues
Authors: Crookall David , Promduangsri Pariphat
Published: March 2022

Ethics are built on values.  Values underly ethics.  How are they related?  Can we talk about ethics without reference to values?  Do values necessarily imply ethics?  Do they form a unit, as in ‘ethical values’?  Are values and ethics driven by beliefs, or should values remain unchanged despite changing beliefs?  Those are some of the questions that people will ask when confronted with the idea of ethics in life and in the geosciences.  Values include honesty, compassion, nature, learning, quality, patience, truth, respect, individualism, creativity, wealth, justice, fame, humour, harmony, power, peace and beauty.  How are these related to ethics?  How are they related to geoethics?  Often an ethical dilemma stems from two or more underlying value conflicts, such as individual identity and social value.

It is not easy to understand the principles and dynamics of such relations.  Reading can of course help.  However, for newcomers to the area, as well as those already familiar with concepts and dilemmas, one way into this quagmire is by using a values clarification exercise or game (VCE or VCG).  A VCE can be a useful geoethics literacy tool to help people explore the complexities of the above relationships, to allow them to express their own ideas, to confront their ideas with those of others and to gain a rich understanding of the values that underly geoethics.

We have designed and used VCEs and VCGs in a variety of settings, such as:

A workshop for farmers in Costa Rica, organized by CIRAD and CATIE.

A session on sustainability in an international conference on simulation/games.

In an online conference organized by the Earth Action Hub, a global, online community dedicated to supporting one another in taking climate and environmental action.

An online workshop for the Eastern Mediterranean University (EMUNI) on the topic of blue economy values.

Our EGU Geoethics session will summarise our previous experience of this kind of methodology, indicating that it is relatively easy to implement, show some sample materials (such as values cards and debriefing forms) and outline a blueprint for such an exercise to be used for geoethics literacy.  We will also answer audience questions.
Method of isolation of soil microorganisms - destructors of biopolymers
Authors: Chupakhina Nataliia , Nikolaeva Nadezda , Nechaev Dmitriy , Medjalo Nadezda , Novichkova Anastasija , Lobanova Valerija , Chupakhina Galina
Published: March 2022

Method of isolation of soil microorganisms - destructors of biopolymers

Nataliia Chupakhina, Nadezda Nikolaeva, Dmitriy Nechaev, Nadezda Medjalo, Anastasija Novichkova, Valerija Lobanova and Galina Chupakhina

School of Life Sciences, Immanuel Kant Baltic Federal University, Universitetskaya str. 2, 236040 Kaliningrad, Russian Federation

Biological degradation of plastic by microorganisms and their enzymes is one of the ways to eliminate the waste resulting from mass production of plastic (Carr C. M., Clarke D. J., 2020).
We analyzed the soil microflora in the presence of fragments of oxo-biodegradable polyethylene with the addition of d2w. The experiment was conducted in the historical center of the city with medium-rise buildings and mass landscaping. We took soil samples at a depth of 10 cm in accordance with GOST 17.4.4.02-84. The soil was classified as heavy sandy loam with the pH of 7.4. Soil suspension (1 g of dry soil per 100 ml of sterile water) in an amount of 100 ml was distributed on solid nutrient media Nutrient dry agar, Nutrient broth with agar addition, GMF broth with agar addition (pH 7.3), sterilized in an autoclave for 20 min at 121 °C. The cultivation regime consisted of keeping the Petri dishes in a thermostat at a temperature of 37 ° C in the range from 1 to 7 days. When using dry soil, bacteria could not be isolated. We repeated the experiment using raw soil. The highest number of diverse colonies had grown on the Nutrient Dry agar medium. After the growth of a large number of microorganisms on Petri dishes, 20 non-repeating colonies of bacteria were isolated.

Next, we placed 5-7 polyethylene discs with the diameter of 7 mm on Petri dishes with 20 isolated colonies. We washed the discs with soap, soaked them in alcohol and rinsed them with autoclaved water. The bacteria were cultured in a thermostat at 37°C for 1 - 7 days. The maximum reliable biofouling of the polymer was recorded on day 7 in 50% of the cups with a double complete repetition of the experiment. 

We can conclude that in order to isolate the soil bacteria aiming to find out their destructive activity against biodegradable plastic, it is effective to use a soil from a depth of 10 cm in suspension with sterile water (1g per 100ml) and cultivate it on Nutrient dry agar (pH 7.3) at 37 ° C for 7 days.
Connected or disconnected? Spatial and temporal patterns of river-floodplain connectivity
Authors: Passalacqua Paola , Wright Kyle , Tull Nelson , Hassenruck-Gudipati Hima , Mohrig David
Published: March 2022

The boundary between a river and its floodplain is often viewed as a static feature which demarcates where the river ends and where the floodplain begins. This boundary, however, is a geomorphic transition whose spatial and temporal evolution controls the interaction of rivers and their floodplains. The transport of water, solutes, and solids across this geomorphic transition affects the functioning of rivers, floodplain sedimentation, carbon storage, and ecosystem functioning. Using examples from studies that combine remotely sensed observations, modeling, and field observations, I will discuss the exchange of fluxes across geomorphic transitions in the context of connectivity and its variability in space and time. We will analyze the role of various climate forcings as well as topography and vegetation patterns, and their effect on water connectivity and the connectivity of sediment and other materials. These connectivity patterns can be quite different from each other, suggesting that water exchanges are not always accurate proxies for sediment exchanges in river systems and their floodplains.
Towards sustainable landscapes: insights from the network and connectivity
Authors: Passalacqua Paola
Published: March 2022

What does it mean for a landscape to be sustainable? And what does sustainability mean for the people living on the landscape? As we address whether landscapes are sustainable or under which conditions sustainability can be achieved, it is important to realize that the view we get at system scale can be very different from the view at human scale. Sustainability can mean different things for the system and for the people living on it. The connector between these two views is the river network itself, which is responsible for the distribution of fluxes of water, sediment, and nutrients across the landscape. A leaky river network  connects channels and their floodplains, a fundamental property for the construction and maintenance of floodplains and delta plains. In this lecture, I will cover the analysis of landscapes across scales with particular focus on river deltas: what we learn from a system view, what happens at the local/human scale, and how the network fills the gap between these two views. I will also discuss which opportunities exist to inform delta sustainability from studies combining remote sensing, modeling, and field observations. Flux partitioning along delta networks, hot spots of change, and associated rates of change need to be quantified and this information integrated into adaptive delta management strategies for future climate scenarios.
Towards a global spectral-geomechanical database of volcanic rocks using VNIR-SWIR spectroscopy
Authors: Kereszturi Gabor , Heap Michael , Schaefer Lauren , Darmawan Herlan , Deegan Frances , Kennedy Ben , Komorowski Jean-Christophe , Rosas-Carbajal Marina , Ryan Amy , Troll Valentin , Villeneuve Marlène , Walter Thomas
Published: March 2022

Volcanoes are subject to intense fluid circulation, altering primary rock properties. The rock alteration can be due to “cold” water-driven weathering or “hot” hydrothermal fluids. Such alteration is facilitated by the efficient circulation of fluids through fractures and the connected pore-network. Fluid-driven alteration can manifest as mineral dissolution and precipitation, ultimately changing the properties of the host rock, such as strength and elasticity. Alteration-induced geomechanical changes are complex due to the large range of protolith porosity (e.g. 0.01-0.8) and permeability (e.g. 10-10 to ≤10-18 m2). For example, fresh pyroclastic rocks can initially have low strength, which can be ‘reinforced’ by mineral precipitation. In contrast, dense lava rocks can decrease their strength due to pore space enlargement and development of secondary clays, oxides, sulfides and sulfates.

This study analysed lab-tested samples from Ruapehu, Merapi, Whakaari, Chaos Crags, Ohakuri, Styrian Basin and La Soufrière de Guadeloupe volcanoes to provide new insights into the controls on geomechanical properties due to weathering and hydrothermal alteration. The volcaniclastic and lava rocks range from basaltic to rhyolitic in composition and encompass surface weathering and intermediate and advanced argillic alteration styles. The physical, geomechanical, Visible-Near Infrared (VNIR; 350-1000 nm), and Shortwave Infrared (SWIR; 1000-2500 nm) properties of the rocks were measured on core samples. Porosity, P-wave velocity, and uniaxial compressive strength ranged from 0.02-0.67, 88-5800 m/s, and 0.1-312 MPa, respectively. Partial Least Squares Regression (PLSR) was employed to successfully predict physical and mechanical properties using VNIR-SWIR spectroscopy data. The PLSR-based prediction models highlighted a handful of spectral bands around 400-600 nm, 1400 nm and 2200-2300 nm, indicating that hydrated secondary minerals were responsible for the observed geomechanical changes. The proposed method using VNIR-SWIR spectroscopy can lead to a new way of mapping physical and geomechanical properties at outcrop-scale using field spectrometers, and at volcano-scale using airborne and satellite remote sensing.
Spatial-Temporal Changes Of Vegetation Coverage In Yulin City And Its Influencing Factors During The Past Two Decades Since The Implementation Of The“Grain For Green” Program
Authors: Liu Yibin , Liu Baoyuan , Zhang Jiaqiong
Published: March 2022

    As one of the important indicators reflecting the regional ecological environment, fractional vegetation coverage is significant for regional eco-environmental protection and sustainable utilization of resources. To understand changes in the ecological environment of the ecologically fragile areas in the Loess Plateau affected by “Grain for Green” Program and its main driving forces in the past two decades, this study taking Yulin City as a typical example of the fragile ecological environment on the Loess Plateau, to analyze spatial-temporal variations of the vegetation coverage in Yulin City during the past two decades based on the pixel dichotomy model with vegetation index, using univariate linear regression methods. The dominant factors and interaction between factors influencing the interannual changes and spatial distribution of vegetation coverage are analyzed using the partial correlation analysis and geographic detector methods during the different period in “Grain for Green” Program. Results showed that: (1) The vegetation coverage in Yulin City significantly increased (S = 0.011, p < 0.01) from 2001 to 2020. The vegetation coverage during the construction periods (2001-2010) increased significantly (S = 0.013, p <0.01); while its increase in the consolidation periods (2011-2020) was relatively slow (S = 0.005, p > 0.05). (2)The spatial distribution of vegetation coverage in Yulin City decreased from east to west from 2001 to 2020. The vegetation coverage of all counties (districts) in Yulin City shows an overall increasing trend, among which the eastern part of Yulin City has a more significant growth trend. However, the proportion of area in the construction periods (82.1%) was larger than that in the consolidation periods (58.0%). (3) The cumulative area of the Grain for Green Program was the dominant factor in the construction periods, while it was rainfall in the consolidation period. (4) Soil texture, rainfall, and land use type mainly affected the spatial distribution of vegetation coverage from 2001 to 2020. Soil texture was closely related to changes in the vegetation coverage both in the construction and consolidation periods. The spatial heterogeneity of vegetation distribution and the interaction between the main influencing factors provides a scientific basis for the precise implementation of ecological restoration measures.
Rapid large-amplitude vertical motions generated by 3D subduction slab roll-back in the Valencia Trough, Western Mediterranean
Authors: Fang Penggao , Tugend Julie , Mohn Geoffroy , Kusznir Nick , Ding WeiWei
Published: March 2022

        The Cenozoic geodynamic evolution of the Western Mediterranean is complex comprising subduction, slab roll-back, back-arc extension, collision, and lithosphere delamination. We investigate the subsidence of a regionally observed unconformity in the Valencia Trough of the Western Mediterranean, here referred to as the Miocene Unconformity, which separates Mesozoic from latest Palaeogene to Neogene sediments. The mechanisms controlling its subsidence are poorly understood.

        We show, using a dense grid of seismic reflection data, well data and 3D flexural backstripping, that the Miocene Unconformity in the SW Valencia Trough subsided by more than 1.5 km to the present day at an average rate of 90 m/Myr. The absence of Cenozoic extensional faults affecting the basement shown by seismic data indicates that this rapid subsidence is not caused by Cenozoic rifting or remaining Mesozoic post-rift thermal subsidence. Neither can this subsidence be explained by subduction dynamic subsidence or flexural loading related to the thin-skin Betic fold and thrust belt which only affects subsidence observed near the deformation front.

        We interpret the 1.5 km subsidence of the Miocene Unconformity as the collapse of a back-arc transient uplift event. Erosion during this uplift, resulting in the formation of the Miocene Unconformity, is estimated to exceed 4 km. Transient uplift was likely caused by heating of back-arc lithosphere and asthenosphere, combined with mantle dynamic uplift, both caused by segmentation of Tethyan subduction resulting in slab tear. Subsidence resulted from thermal equilibration and the removal of mantle flow dynamic support Tethyan subduction slab roll-back. We propose that our observations and interpretation of rapid back-arc km-scale uplift and collapse have global applicability for other back-arc regions experiencing subduction segmentation and slab tear during subduction slab roll-back.
Linking characteristics of debris flows to their high frequency seismic signature: insights from field measurements and model predictions
Authors: Zhang Zhen , Walter Fabian , McArdell Brian , de Haas Tjalling , Wenner Michaela , Chmiel Małgorzata , He Siming
Published: March 2022

Measuring debris-flow properties remains a significant challenge in studies of natural hazards. Recent works suggest that the seismic signals generated by debris flows can help analyze flow dynamics, but theoretical details for estimating bulk flow properties from seismic signals are not fully understood or comprehensively tested. Here, we invert basal force fluctuations on the torrent bed using high frequency seismic signals generated by 6 well-documented debris flows at Illgraben, Switzerland. Verified against independent measurements, our seismically-derived basal force fluctuations match well with the measured basal fluctuations at a force plate and correlate with the bulk flow properties, including flow depth and weight. We propose a physical model employing the multi-particle force chains and random single-particle impacts within a debris flow to simulate the generation of high frequency seismic signals. We find that the random impacts of single particles and of multi-particle force chains are active at the same time, and together they control the debris-flow’s basal force fluctuations. For different events and different positions within events, the relative contributions of single particle impacts and of multi-particle force chains dominating the basal fluctuations vary significantly and control the non-linear relation between the high-frequency seismic signal strength and the bulk flow characteristics. According to our model, fluctuating basal forces are strongly controlled by particle sizes and flow depth. Our results open new perspectives for the understanding of high frequency seismic signals generated by debris flows and the estimation of bulk flow characteristics, such as flow depth and weight.
Medium- to long-term forecast of sea surface temperature using EEMD-STEOF-LSTM hybrid model
Authors: Hao Rixu , Zhao Yuxin , Deng Xiong , Zhou Di , Yang Dequan , Jiang Xin
Published: March 2022

Sea surface temperature (SST) is a vitally important variable of the global ocean, which can profoundly affect the climate and marine ecosystems. The field of forecasting oceanic variables has traditionally relied on numerical models, which effectively consider the discretization of the dynamical and physical oceanic equations. However, numerical models suffer from many limitations such as short timeliness, complex physical processes, and excessive calculation. Furthermore, existing machine learning has been proved to be able to capture spatial and temporal information independently without these limitations, but the previous research on multi-scale feature extraction and evolutionary forecast under spatiotemporal integration is still inadequate. To fill this gap, a multi-scale spatiotemporal forecast model is developed combining ensemble empirical mode decomposition (EEMD) and spatiotemporal empirical orthogonal function (STEOF) with long short-term memory (LSTM), which is referred to as EEMD-STEOF-LSTM. Specifically, the EEMD is applied for adaptive multi-scale analysis; the STEOF is adopted to decompose the spatiotemporal processes of different scales into terms of a sum of products of spatiotemporal basis functions along with corresponding coefficients, which captures the evolution of spatial and temporal processes simultaneously; and the LSTM is employed to achieve medium- to long-term forecast of STEOF-derived spatiotemporal coefficients. A case study of the daily average of SST in the South China Sea shows that the proposed hybrid EEMD-STEOF-LSTM model consistently outperforms the optimal climatic normal (OCN), STEOF, and STEOF-LSTM, which can accurately forecast the characteristics of oceanic eddies. Statistical analysis of the case study demonstrates that this model has great potential for practical applications in medium- to long-term forecast of oceanic variables.
The joint dependence of longwave feedback on surface temperature and relative humidity
Authors: McKim Brett , Jeevanjee Nadir , Vallis Geoffrey
Published: March 2022

The longwave clear-sky feedback (the dependence of outgoing longwave radiation on surface temperature) is a major determinant of the climate's stability. Various studies have suggested that the feedback is largely independent of both surface temperature and relative humidity, which implies that the climate stability is also independent of surface temperature and relative humidity. However, this uniformity seems to contradict other work which shows that the subtropics are relatively stable and the deep tropics are relatively unstable, implying the feedback must vary between the two regions. We resolve this apparent contradiction by systematically computing the feedback as a function of both surface temperature and relative humidity. Above 275 K, the feedback depends significantly on relative humidity. We then show the feedback does indeed vary in the tropics and that this difference arises from regional differences in relative humidity. Finally, we estimate the effects of clouds on the feedback with a simple model and find that although clouds have a destabilizing influence, the significant dependence on relative humidity persists. Our work gives a renewed appreciation for how the feedback can vary significantly with both surface temperature and relative humidity.
Influence of Physical-biochemical Coupling Processes on the Noctiluca scintillans and Mesodinium red tides in October 2019 in northern Yellow Sea, China
Authors: Zhang Wenjing , Dong Zhijun , Zhang Chen , Sun Xiyan , Hou Chaowei , Liu Yongliang , Wang Lei , Ma Yuanqing , Zhao Jianmin
Published: March 2022

Red tide has always been an environmental issue with global concern. A Noctiluca scintillans red tide and a Mesodinium red tide occurred successively in northern Yellow Sea, China, where is important shallow sea aquaculture base, in October 2019. The initiation of the red tides was the result of both biotic (e.g. food) and abotic factors (e.g. currents and nutrients availability). The maximum N. scintillans and Mesodiniium abundance reached 124.92 ± 236.84 × 103 cells/ L and 1157.52 ± 1294.16 × 103 cells/L respectively. The fast growth of N. scintillans was due to increasing abundance of phytoplankton after the harvest of cultured scallops. Appropriate temperatures also increased the growth of N. scintillans. Water dynamics played a key role in the formation of the red tides. The steady southward current from the Bohai Sea and northern Yellow Sea was instrumental in the accumulation of N. scintillans along the coast. The accumulation of Mesodinium was attributed to the neap tide and weak current on October 19 to 22. Water turbulence from a strengthened current on October 24 eventually destroyed the Mesodinium red tide. The red tides significantly redistributed the nutrients in the red tide patches and regulated the dominant species in phytoplankton community. Our study illuminates the influence of physical-biochemical coupling processes on red tides, and suggests that ocean dynamics such as currents and tidal factors deserve more attention when considering the ecosystem health problems of coastal zones.
Hot Plasma Effects on the Pitch-Angle Scattering of Ring Current Protons by EMIC Waves
Authors: Zhu Qi , Cao Xing , Ni Binbin , Gu Xudong , Ma Xin
Published: March 2022

Via cyclotron resonant interactions, electromagnetic ion cyclotron (EMIC) waves play an important role in the loss of ring current protons. In this study, by calculating the proton bounce-averaged pitch angle diffusion coefficients using both the cold and hot plasma dispersion relations, we investigate the hot plasma effects on the EMIC wave-induced scattering loss of ring current protons. Our results show that, for H+ band (He+ band) EMIC waves, inclusion of hot protons results in significant decrease of pitch angle diffusion coefﬁcients of ~ 10 - 60 keV (4 - 30 keV) protons, while the scattering efficiency of higher energy protons increases at low pitch angles and decreases at relatively high pitch angles. We also find that the cold plasma approximation seriously underestimates the loss timescales of protons at energies from a few keV to tens of keV but overestimate that of higher energy protons. The differences in proton loss timescales caused by hot plasmas are generally less than a factor of ~ 5 for H+ band but can exceed an order of magnitude for He+ band, showing a strong dependence on ,  and L-shell. This study conﬁrms that hot plasma effects play a crucial role in the EMIC wave driven loss of ring current protons and should be included in future modeling of ring current dynamics.