bluuebunny/crossref_metadata_2025 huggingface dataset:
Digitization of historical wind speed observations at the Swedish Meteorological and Hydrological Institute
Authors: Engström Erik , Azorin-Molina Cesar , Wern Lennart , Hellström Sverker , Sturm Christophe , Joelsson Magnus , Zhang Gangfeng , Minola Lorenzo , Chen Deliang
Published: March 2020

This contribution presents the first work package (WP1) of the project “Assessing centennial wind speed variability from a historical weather data rescue project in Sweden”, funded by FORMAS – A Swedish Research Council for Sustainable Development (ref. 2019-00509); previously reported in EGU2019-17792-1. Under a warming climate, one of the major uncertainties on the causes driving the climate variability of winds over land (i.e., the “stilling” phenomenon and the recent “recovery” since the 2010s) is mainly due to short availability (i.e. since the 1960s) and low quality of observed wind records as stated by the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC).

In this study we present the first steps of a joint initiative between the Swedish Meteorological and Hydrological Institute (SMHI) and the University of Gothenburg aimed at filling the key gap of short availability and low quality of wind datasets, and improve the limited knowledge on the causes driving wind speed variability in a changing climate across Sweden. The aim of the WP1 is to rescue historical wind speed series available in the old weather archives at SMHI for the 1920s-1930s. 13 stations with daily wind speed data (in meters per second) during the period 1925-1938 have been selected for digitization; i.e., spanning back our records 2 decades more. To get wind observations from paper to screen we will follow the “Guidelines on Best Practices for Climate Data Rescue” of the World Meteorological Organization. Our protocol will consist on (i) designing a template for digitization; (ii) digitizing papers by an imaging process based on scanning and photographs; and (iii) typing numbers of wind speed data into the template. WP2 will ensure the quality and homogeneity of wind speed series rescued.
Waveform Energy Focusing Tomography for Passive Sources
Authors: Hu Yueqiao , Li Junlun , Zhang Haijiang
Published: March 2020

Full waveform inversion (FWI) is one of the most attractive geophysical inversion methods that reconstruct models with higher quality by exploiting the information of full wave-field. Despite its high resolution and successful practical applications, there still exist several obstacles to the successful application of FWI for passive earthquake sources, such as the high non-linearity for model convergence and demand for accurate source information, such as the moment tensor, the source time function, etc. To alleviate the requirement for a priori source information in waveform inversion, we propose a new method called Waveform Energy Focusing Tomography (WEFT), which backpropagates the observed wavefield from the receivers, not the data residuals like in conventional FWI, and tries to maximize the back-propagated wavefield energy around the source location over a short period around the origin time. Therefore, there is no need to provide the focal mechanism and source time function in advance. To better reconstruct the passive sources, the least-squares moment tensor migration approach is used, and the Hessian matrix is approximated using either analytic expression or raytracing. Since waveform fitting is superseded by simpler energy maximization, the nonlinearity of WEFT is weaker than that of FWI, and even less-accurate initial velocity model can be used. These advantages of WEFT make it more practical  for challenging earthquake data, especially for local small magnitude earthquakes where both velocity model and earthquake source information are unknown.
3D printing the world: developing geophysical teaching materials and outreach packages
Authors: Koelemeijer Paula , Winterbourne Jeff , Toussaint Renaud , Zaroli Christophe
Published: March 2020

3D-printing techniques allow us to visualise geophysical concepts that are difficult to grasp, making them perfect for incorporation into teaching and outreach packages. Abstract models, often represented as 2D coloured maps, become more tactile when represented as 3D physical objects. In addition, new questions tend to be asked and different features noticed when handling such objects, while they also make outreach and education more inclusive to the visually impaired.

Some of our most effective models are simply exaggerated planetary topography in 3D, including Earth, Mars and the Moon. The resulting globes provide a powerful way to explain the importance of plate tectonics in shaping a planet and linking surface features to deeper dynamic processes. In addition, we have developed a simple method for portraying abstract global models by 3D printing globes of surface topography, representing the parameter of interest as additional, exaggerated long-wavelength topography. This workflow has been applied to models of dynamic topography, the geoid and seismic tomography. In analogy to Russian nesting dolls, the resulting “seismic matryoshkas” have multiple layers that can be removed by the audience to explore the structures present deep within our planet and learn about the ongoing dynamic processes.

While these 3D objects are easily printed on a cheap (<300 GBP, 400USD) desktop 3D-printer, the printing times still prohibit large-scale production. To ensure that there is sufficient material in a teaching setting, we have therefore also developed complementary paper equivalents. By projecting the coloured maps onto a dodecahedron, we developed cut-out-and-fold models to be handed out in a classroom setting to complement the 3D printed globes used for demonstration purposes. Together with animations, suggested questions and instructor “cheat-sheets”, these materials form a complete teaching and outreach package that is both interactive and inclusive.
Subseasonal forecasts for humanitarian decision-making in Kenya: understanding forecast skill and the latest results from the S2S ForPAc real-time pilot study.
Authors: MacLeod Dave , Kilavi Mary , Mwangi Emmah , Otieno George , Graham Richard , Todd Martin
Published: March 2020

In 2018 the long rains season in Kenya (March-May) was the wettest ever recorded. The country experienced several multi-day heavy rainfall episodes, leading to dam collapse, land and mudslides. 186 people died due to flooding and 300,000 were left displaced. 

The Kenya Meteorological Department issued several advisories during the season that warned of heavy rainfall events a few days before their occurrence. Ahead of this no warnings were given.

However subseasonal forecasts gave strong indications of the heaviest rainfall episodes, several weeks in advance. With this extra lead time, preparedness actions may have been taken in order to reduce flood risk and save lives. 

To this end, the ForPAc project (Toward Forecast-Based Preparedness Action) has been working in partnerships across Kenya and the UK to evaluate and build trust in subseasonal forecasts, and explore preparedness actions which could be taken in response. Most recently ForPAc has been granted access to real-time subseasonal data as part of phase two of the S2S pilot.

In this presentation we will first show analysis of the S2S hindcasts over East Africa, demonstrating the relatively high levels of subseasonal forecast skill and linking this to a strong MJO teleconnection that models capture relatively well.

In the second part we will describe work with stakeholders to co-design forecast products derived from the S2S data, concluding with a report on the forecasts for the ongoing 2020 long rains season and an evaluation of the way in which these have influenced disaster preparedness.
Linking hydrological signatures to hydrological processes and catchment attributes: a flexible approach applied to baseflow signatures
Authors: Gnann Sebastian , Howden Nicholas , Woods Ross , McMillan Hilary
Published: March 2020

Hydrological signatures aim at extracting information about certain aspects of hydrological behaviour. They can be used to quantify hydrological similarity, to explore catchment functioning and to evaluate hydrological models. Relating hydrological signatures to hydrological processes is, however, still a challenge and many signatures remain poorly understood.

We propose a flexible approach for linking hydrological signatures to hydrological processes, which might help to improve our understanding and hence the usefulness of certain hydrological signatures. As a first step, we should build a perceptual model describing the hydrological process of interest. We should then try to find or create relevant – and ideally widely available – catchment attributes that target the process of interest, and hence have the potential to explain the signature in a process-based way. We should control for climate by either incorporating it into our perceptual model or by analysing sub-climates individually, to disentangle the influences of forcing and catchment form. Lastly, simple conceptual models might be a useful tool to systematically explore the controlling factors (parameters, forcing) of a signature. Focusing on hydrological processes and explaining hydrological signatures in a process-based way will make hydrological signatures more meaningful, useful and robust.

The proposed approach is tested on signatures related to baseflow and groundwater processes, such as the baseflow index. Baseflow generation has been studied extensively, and while many regional studies could identify landscape controls on baseflow generation (e.g. soils and geology), continental or global studies have resulted in a less clear picture, partially because of the masking influence of climate at these scales. Furthermore, the relationship between controls, such as climate and catchment form, and baseflow response has often been only described statistically (e.g. by means of regression-type approaches).  A mechanistic theory based on widely available catchment attributes (e.g. soils, geology, topography) would thus be a major step towards improved understanding and transferability.
Emerging pressure on mangrove forest environments as a result of shrimp farming expansion - A remote sensing based analyses for an exemplary coastal site at the Pacific coast in South America
Authors: Ottinger Marco , Bachofer Felix , Uereyen Soner , Huth Juliane
Published: March 2020

Given the growing world population and rising demand for fish and seafood, aquaculture is becoming the main source of aquatic food in human consumption and a primary protein source for millions of people. Since 1990, the world aquaculture production increased from 13 to over 80 million tonnes and is currently valued at USD 231 billion. The cultivation of shrimp species in land-based ponds is one of the fastest growing food production economies and became an important industry in coastal regions, generates income and employment and contributes to food security. Shrimp farms are mainly found in low-lying coastal regions such as estuaries, bays and river deltas along the shorelines of Asia and America. Shrimp farming expanded rapidly in recent years and led to environmental degradation and conversion of valuable wetlands such as mangroves and other coastal forests. The loss of mangroves poses a major threat to coastal ecosystems and population, as mangroves provide valuable flood and coastal protection, as well as risk reduction benefits with regard to global climate change induced effects.

In this research, we use image segmentation for temporal features derived from space-borne, high-resolution synthetic aperture radar (SAR) data to extract shrimp farming ponds in coastal mangrove forest areas in Ecuador, South America. An automatic object-based image processing approach aims for the detection of rectangular shaped pond objects utilizing per-pixel median images calculated from C-band Sentinel-1 and L-band ALOS-Palsar SAR time series data. An open source connected component segmentation algorithm was used to extract and locate rectangular shrimp farms in coastal areas based on backscatter intensity and shape features. This study illustrates the opportunities by earth observation for area-wide assessments of shrimp farming activities in mangrove areas to gain more knowledge on land use dynamics with regard to global change and food security. Earth observation can effectively support the planning and management of aquaculture practices and support stakeholders, politicians, and conservationists in implementing appropriate measures in order to protect coastal environments and foster sustainable development in the coastal zone.
2D to 3D high-resolution seismic data conversion: imaging a shallow water metal bearing mine tailings deposit in Portmán Bay, Spain
Authors: Soldevila Emma , Carbonell Ramon , Amblas David , Canals Miquel
Published: March 2020

High-resolution (HR) 3D seismic acquisition is expensive and often not available due to a variety of reasons. This work builds an optimized workflow to convert a dense 2D HR seismic grid into a 3D seismic volume. The task has been developed within a broader project, NUREIEVA, which aims at characterizing a metal-rich onshore and shallow marine mine tailings deposit in Portmán Bay, Murcia, Spain, which developed from 1957 to 1990. Hence, in the framework of the NUREIEVA project a very dense set of 2D HR seismic lines was acquired. The geophysical equipment used to capture the submarine extent, thickness and internal structure of the mine tailings deposit was a hull-mounted Kongsberg TOPAS PS18 single-channel parametric source. The seismic grid thus acquired consisted of 1309 2D lines, with an approximate distance between lines of 10 m, covering an area of 7.45 km2. The parametric source yielded a vertical resolution of 15 cm, which is very high if compared with conventional seismic reflection data.

 

In order to visualize the internal architecture of the mine tailings deposit in all directions, it is desirable to convert the dense 2D network of lines into a full 3D data volume. Such a data volume is intended to assist reaching faster deposit delimitation and more accurate volumetric calculations. For this purpose, a new optimized 2D to 3D conversion processing flow including a 3D interpolation scheme has been designed. Given the specific characteristics of the input data, a number of challenges had to be addressed, namely: (i) a very high vertical resolution that differs by at least two orders of magnitude from the horizontal resolution; (ii) a large data volume (2 TB), which involves extensive computing time; (iii) the heterogeneity in the acquisition parameters. Because of this, the lines had to be processed previously to the 3D interpolation to homogenize the imaging characteristics and signal content. This new methodology can be now applied for obtaining a 3D volume to any case where a single channel dense 2D seismic grid is available. Furthermore, the new methodology, duly adapted to each particular scenario, represents a low cost alternative to conventional HR 3D seismic and could prevent further seismic shooting in areas when 2D data is already available.
Fluid geochemistry as useful tool for the recognition of the Lago Exsnia-Viscosa (Rome-Italy) as natural heritage
Authors: Procesi Monia , Cinti Daniele , Cabassi Jacopo , Capecchiacci Francesco , Pizzino Luca , Caracausi Antonio , Fazi Stefano , Casentini Barbara
Published: March 2020

Lago Exsnia-Viscosa is located in the eastern part of Rome, on the left bank of Tiber river, close to the historical centre of the city and in a highly urbanized area. The lake takes its name from the factory of artificial silk, the SNIA Viscosa, active there from 1923 to 1954. The industrial plant, located close to the Marranella ditch, used its water for the production processes, also after its channelled and covered. The Marranella ditch was named also Acqua Bullicante (in English “Bubbling water”). It is supposed that the ditch was hosted along a fault where bubbling waters and diffuse degassing from soil were recognized. These manifestations were dominated in CO2 but due to the intensive post-war (Second World War) building expansion, no trace remain. These phenomena are typically recognizable in volcanic areas characterized by active hydrothermalis, such as the neighbour volcanic district of Alban Hills. The proximity of this volcanic district to Rome and the fact that it cannot be considered extinct have moved our motivation to study the Lake Exsnia-Viscosa to investigate on possible degassing phenomena in the city centre. The lake appeared in the ‘90s, after illegal excavations (deep up to 10-13 meters) to build unlawfully a shopping center. This caused a leakage of groundwater and the emergence of a small lake (about 7,000 m2 large, around 7 meters deep). Due to the citizen protests, the works were immediately blocked and the whole area was expropriated and closed. The site, has remained closed, from ‘90s to today, favouring re-naturalization processes, new ecological systems and forbidding anthropogenic transformations. Currently, it represents a precious green area for the city, but is still in danger of being threatened by speculation. For this reason, the citizen is fighting for its recognition as natural heritage supported by cultural and professional associations. In this framework, our study, moved at the beginning to investigate on degassing phenomena, proved to be an important step in the process of recognition of the site as natural heritage. The lake has been used by us as an open-air laboratory collecting water along a vertical profile from the lake surface to the maximum depth, for a geochemical and microbial characterization of the groundwaters. Currently, the results are supporting the community and the local administration in order to make this green site a protected area to donate to their citizens.
Global catalog of NOx point sources derived from the divergence of the NO2 flux
Authors: Beirle Steffen , Borger Christian , Dörner Steffen , Wagner Thomas
Published: March 2020

Satellite observations of NO2 provide valuable information on the location and strength of NOx emissions, but spatial resolution is limited by horizontal transport and smearing of temporal averages due to changing wind fields. The divergence (spatial derivative) of the mean horizontal flux, however, is highly sensitive for point sources like power plant exhaust stacks.

In a previous study, point source emissions have been identified and quantified exemplarily for Riyadh, South Africa, and Germany with a detection limit of about 0.11 kg/s down to 0.03 kg/s for ideal conditions, based on TROPOMI NO2 columns and ECMWF wind fields (Beirle et al., Science Advances, 2019).

Here we extend this study and derive a global catalog of NOx emissions from point sources. The specific challenges for e.g. high latitudes (longer NOx lifetime) or coastlines (potentially persistent diurnal wind patterns) are investigated.
Satellite Altimetry over River Basins - Beyond Water Heights
Authors: Berry Philippa , Benveniste Jerome
Published: March 2020

The unique contribution of satellite radar altimetry to river monitoring is well understood, with ‘ altimeter virtual gauge’ heights increasingly ingested into river basin models. However, altimeters gather a wealth of additional information. Waveform shapes reflect underlying topographic variation, surface composition and roughness, and distribution of surface water within the footprint. Backscatter measurements allow soil surface moisture under the satellite track to be determined, using DRy EArth ModelS (DREAMS) crafted from multi-mission altimeter data and ground truth. Initially developed over desert areas, DREAMs are now being built over river basins to extend the scope of altimeter soil moisture measurement.

This paper investigates  the potential contribution of these additional data to river basin analysis and modelling. 
The following key questions are addressed. 
1) How useful are the data encoded in complex waveform shapes? 
2) Can altimeter soil moisture estimates contribute to modelling in river basins?
A series of example river basins were chosen in different topographic and climate situations, including the Amazon, Orinoco, Nile, Niger and Congo basins, and wetlands including the Okavango delta.This paper presents outcomes from analysis of multi-mission altimetry, with ERS-1/2, Envisat, Topex, Jason-1/2, Cryosat-2 and Sentinel-3A/B, plus a database of over 86,000 river and lake timeseries.

The analysis outcomes demonstrate the value of altimeter soil surface moisture estimates, both as co-temporal and co-spatial data with inland water height measurements, and as an independent validation dataset to assess soil moisture estimates derived from other remote sensing techniques. The precise backscatter cross-calibration of altimeters on successive missions allows derivation of long soil moisture time series. The ability of nadir-pointing altimeters to penetrate vegetation canopy gives a unique perspective in rainforest areas, with information on underlying water height and extent as well as surface soil moisture. Waveform shape classification allows diverse information to be gleaned, particularly at the higher pulse repetition frequencies of the new generation of SAR Altimeters. In conclusion, satellite radar altimeters collect a wealth of information over river basins; this valuable resource is not yet fully exploited.
Quantification of peatland-mediated feedbacks to the climate system
Authors: Chaudhary Nitin , Zhang Wenxin , Schurgers Guy , Page Susan , Westermann Sebastian
Published: March 2020

Peatlands are important carbon reserves in the terrestrial ecosystem and cover 3% of the terrestrial land surface. Peatlands have stored around 350-500 Petagrams [1015] of carbon over the last thousands of years, comprising around 30% of the present-day soil organic carbon pool. Peatlands share many characteristics with upland mineral soils and non-peat wetland ecosystems. However, they constitute a unique ecosystem type with many special characteristics, such as a shallow water table depth, carbon-rich soils, a unique vegetation cover, spatial heterogeneity, anaerobic biogeochemistry and permafrost in the high latitude regions (>45°N). The recent changes in climate and land-use patterns have disturbed the Earth’s climate-carbon cycle equilibrium. These changes trigger some potentially important land-surface feedbacks, which will further modify the Earth’s climate. The ongoing changes in peatland carbon balance as a result of climate warming have the potential for strong positive and negative feedbacks to climate, but these impacts are poorly constrained. To assess the importance of these feedbacks, the interactions between the peatland carbon cycle and climate should be taken into account. However, the absence of peatlands in current Earth system models limits our understanding of the peatland-mediated feedbacks at different scales. LPJ-GUESS peatland-vegetation model showed a reasonable demonstration of capturing the right carbon accumulation rates and permafrost dynamics at different spatial and temporal scales and will be further improved and employed to quantify the hypothesized peatland-mediated feedbacks when coupled with regional/global climate models.
Detecting and using Milankovic cycles in borehole logging data: Comparing methods and application to Lake Ohrid
Authors: Wonik Thomas , Ulfers Arne , Sinnesael Matthias , Li Mingsong , Zeeden Christian
Published: March 2020

Borehole logging data are not yet systematically assessed using cyclostratigraphic methods. In order to obtain a reliable understanding of (long) borehole logging datasets, and especially data from complex settings, a good understanding of the potential and specifics of relevant (time/depth) evolutive methods in cyclostratigraphy are an essential prerequisite. Therefore, we test a suite of evolutive cyclostratigraphic methods using several artificial datasets consisting of modelled Milankovic signals and noise.

Aim of this work is the comparison of different cyclostratigraphic methods for an understanding of which methods are suitable for Quaternary lake records, also for a good understanding of ICDP logging data. Once artificial datasets are discussed, we apply these methods to real data. A discussion of the possible issues and potential of especially uncommon methods gives insight in further potential of cyclostratigraphy.

Lake Ohrid is a tectonic lake located on the border of North Macedonia and Albania. With 1.36 Ma, it is considered Europe’s oldest lake and an important link between Mediterranean climate and African monsoon systems (Wagner et al. 2019). In 2013, an ICDP drilling campaign recovered 2100 m of sediments from four sites (Wagner et al. 2014).

Datasets from geophysical downhole logging provided by the Leibniz Institute for Applied Geophysics are used in a cyclostratigraphic analysis, which provides further insight into the sedimentation history of Lake Ohrid. Here we present initial results from the full succession in this sedimentary archive.

 

References:

Wagner, B., Wilke, T., Krastel, S., Zanchetta, G., Sulpizio, R., Reicherter, K., Leng, M. J., Grazhdani, A., Trajanovski, S., Francke, A., Lindhorst, K., Levkov, Z., Cvetkoska, A., Reed, J. M., Zhang, X., Lacey, J. H., Wonik, T., Baumgarten, H., and Vogel, H.: The SCOPSCO drilling project recovers more than 1.2 million years of history from Lake Ohrid. Sci. Dril., 17, 19–29, doi:10.5194/sd-17-19-2014 (2014).

Wagner, B., Vogel, H., Francke, A. et al.  Mediterranean winter rainfall in phase with African monsoons during the past 1.36 million years. Nature, 573, 256–260 (2019).
The partitioning of the inner and outer solar system by a structured protoplanetary disk
Authors: Brasser Ramon , Mojzsis Stephen
Published: March 2020

Mass-independent isotopic anomalies in planets and meteorites define two cosmochemically distinct regions: the carbonaceous and non-carbonaceous meteorites, implying that the non-carbonaceous (terrestrial) and carbonaceous (jovian) reservoirs were kept separate during and after planet formation. The iron meteorites show a similar dichotomy.

The formation of Jupiter is widely invoked to explain this compositional dichotomy by acting as an effective barrier between the two reservoirs. Jupiter’s solid kernel possibly grew to ~20 Mearth in ~1 Myr from the accretion of sub meter-sized objects (termed “pebbles”), followed by slower accretion via planetesimals. Subsequent gas envelope contraction is thought to have led to Jupiter’s formation as a gas giant.

We show using dynamical simulations that the growth of Jupiter from pebble accretion is not fast enough to be responsible for the inferred separation of the terrestrial and jovian reservoirs. We propose instead that the dichotomy was caused by a pressure maximum in the disk near Jupiter’s location, which created a ringed structure such as those detected by the Atacama Large Millimeter/submillimeter Array(ALMA). One or multiple such long-lived pressure maxima almost completely prevented pebbles from the jovian region reaching the terrestrial zone, maintaining a compositional partition between the two regions. We thus suggest that our young solar system’s protoplanetary disk developed at least one and likely multiple rings, which potentially triggered the formation of the giant planets [1].

[1] Brasser, R. and Mojzsis, S.J. (2020) Nature Astronomy doi: 10.1038/s41550-019-0978-6
Numerical Modeling of Heavy Metal Pollution in the Rivers
Authors: khalilzadeh poshtegal maryam , Noury Mojtaba , mirbagheri seyed ahmad
Published: March 2020

Abstract: Based on the deep studies of existing mathematical models, a mathematical model that expresses the dynamic of transport and transformation of heavy metals in the rivers has been presented. In this model, the basic principles of chemistry in the environment, hydraulic and fluid transfer dynamics have been used as well as recent studies of researchers. The effects of sediment on the transfer and evolution of heavy metals pollution can be investigated by the proposed models. For example, the evolution and transport of heavy metal pollutants in a steady state flow containing sediment are studied using the present model. The results of theoretical analysis and calculations show that transport and transformation of heavy metal pollution in sediment laden flows, not only have common characteristics of general pollutant but also have features of transport and transformation induced by the movement of sediments.

Keywords: Numerical Simulation; Heavy Metal; Pollution; Sediment; Finite Difference Method.
Biogeomorphological research frontiers: from ant mounds to Mars
Authors: Viles Heather
Published: March 2020

Biogeomorphology is a vibrant area of scientific research which focuses on the two-way interrelationships between ecological and geomorphological processes across a wide range of temporal and spatial scales. Whilst ecological influences on geomorphology were often perceived in the past as a rather niche topic, most geomorphologists now  consider the ecological dimension as being crucial to the evolution and behaviour of geomorphological systems. However, there is still much to be done to explore the intersections between ecology and geomorphology. It is now timely to investigate what frontier research in biogeomorphology might look like over the coming years. This paper explores some characteristics of frontier research (addressing scientific controversies, focusing on hard-to-answer questions, employing atypical methods and concepts, being paradigm-challenging, and having a high risk of failure) in the context of tomorrow’s biogeomorphology. As examples, the paper addresses current progress in research on the geomorphological contributions of ants on Earth, and microbial biosignatures on Mars.
Investigating the role of Iberia and its interplay with the Newfoundland and Irish offshore margins using plate reconstructions
Authors: King Michael , Welford Kim , Peace Alexander
Published: March 2020

The tectonic evolution of the southern North Atlantic is a subject of increasing interest due to its continental margins playing host to several world-class frontier regions for oil and gas exploration. The Newfoundland-Iberia conjugate margin pair serves as one of the best studied non-volcanic rifted conjugate margin pairs in the world, and is a topic of constant scientific debate due to its complex plate kinematic history and geological evolution.  Recent adaptability of the GPlates freely available plate tectonic reconstruction software provides an excellent tool for gaining insight into complex plate kinematic problems. The ability to account for regions of deformation, integration of various geological and geophysical datasets, and the ability to calculate temporal variations in crustal thickness, strain rates, and velocity vectors provide an optimal environment for solving crustal-scale geological and geophysical problems. Building upon previous rigid and deformable plate tectonic modelling studies, the aim of this work is to create deformable plate tectonic models of Iberia with emphasis on the West Iberian margin and the Pyrenees to assess Iberia’s evolution during the formation of the southern North Atlantic from 200 Ma to present day. A comparison of crustal thickness results calculated from GPlates models with those obtained from gravity inversion, passive and controlled source seismology, and geological field mapping, provided a good metric for investigating the plate kinematics of Iberia and assessing previous discrepancies when considering the crustal evolution of the West Iberian margin and the Pyrenees as an integrated plate kinematic system. Results from the GPlates models produced in this study also demonstrate the significance of continental fragments and their independent motion during rifting. In particular, we investigate the independent motion of the Galicia Bank and its role with respect to the deformation experienced within the Galicia Interior Basin and the role of the Ebro Block and Landes High during deformation prior to the Pyrenean Orogeny. In addition, this study highlights the importance of inherited structures with respect to the styles of deformation experienced during rifting of continental crust. Preliminary deformable plate modeling results of the West Iberian margin indicate that the independent motion of the Galicia Bank and its interplay with inherited structures is crucial for deriving the amount of deformation inferred by gravity inversion and regional seismic studies within the Galicia Interior Basin.
Modelling respiration pulses at rewetting as a stochastic process
Authors: Manzoni Stefano , Chakrawal Arjun , Fischer Thomas , Porporato Amilcare , Vico Giulia
Published: March 2020

Respiration pulses at rewetting are prominent features of soil responses to soil moisture fluctuations. These pulses are much larger compared to respiration rates under constant soil moisture, pointing to variations in water availability as drivers of the enhanced CO2 production. Moreover, the respiration pulses tend to be larger when soil moisture before rewetting is lower. Thus, both the pre-rainfall soil moisture and the variation in soil moisture control the size of the respiration pulse. While these patterns are known from empirical studies, models have struggled to capture the relations between rainfall statistical properties (frequency of occurrence and rain event depths) and the occurrence and size of respiration pulses, framing the scope of this contribution. Specifically, we ask – how are the statistical properties of respiration pulses related to rainfall statistics?

Because rainfall can be regarded as a stochastic process generating variations in soil moisture, also respiration pulses at rewetting can be modelled through a probabilistic model. Here we develop such a model based on the premises that rainfall can be described as a marked Poisson process, and that respiration pulses increase with increasing variations of soil moisture (i.e., larger pulses after larger rain events) and decreasing pre-rain soil moisture (i.e., larger pulses after a long dry period). This model provides analytical relations between the statistical properties of soil respiration (e.g., long-term mean and standard deviation) and those of rainfall, allowing to study in a probabilistic framework how respiration varies along existing climatic gradients or in response to climatic changes that affect rainfall statistics.

Results show that the long-term mean CO2 production during respiration pulses increases with increasing frequency and depth of rainfall events. However, the relative contribution of respiration pulses to the total microbial respiration decreases with rainfall frequency and depth. Similarly, also the variability of the size of respiration pulses, as measured by their standard deviation, decreases with increasing rainfall frequency and depth. As a consequence, climatic changes exacerbating rainfall intermittency – longer dry periods and more intense rain events – are predicted to increase both the relative contribution of respiration pulses to total microbial respiration and the variability of the pulse sizes.
Scaling up microbial dynamics for soil carbon cycling models
Authors: Manzoni Stefano , Chakrawal Arjun , Nunan Naoise
Published: March 2020

Soils are heterogeneous at all scales and so are the biogeochemical reactions driving the cycling of carbon (C) and nutrients in soils. While the microbial processes involved in these reactions occur at the pore scale, what we observe at the soil core or pedon scale depends on how micro-scale processes are integrated in space (and time). This integration step requires accounting for the inherent patchiness of soils, but models used to describe element cycling in soils typically assume that conditions are well-mixed and that kinetics laws developed for laboratory conditions hold. Similarly, the response functions used in models to capture the effects of environmental conditions on C and nutrient fluxes neglect the contribution of spatial heterogeneities, which might alter their shape. There is therefore a need to re-evaluate model structures to test whether they can account for micro-scale heterogeneities. Alternatively, one can ask why some models are clearly successful in capturing observations despite neglecting soil heterogeneities. In this contribution, we present examples of how soil heterogeneities – in particular the spatial placement of soil microorganisms and their substrate – may affect decomposition kinetics and microbial responses to soil drying. We show that the kinetics laws used in current models are different from the kinetics obtained by integrating microbial dynamics at the micro-scale, and that respiration responses to soil drying may vary depending on soil heterogeneity. These results thus highlight structural uncertainties in current models that we propose can be assessed using existing ‘scale-aware’ methods to derive macro-scale model formulations. Model advances will need to be supported by empirical evidence bridging the gap between pore and core (or larger) scales, but can also provide new theory-based hypotheses for novel experiments.
Inference On Streamflow Predictability Using Horizontal Visibility Graph Based Networks
Authors: Ghimire Ganesh , Jadidoleslam Navid , Krajewski Witold , Tsonis Anastasios
Published: March 2020

Streamflow is a dynamical process that integrates water movement in space and time within basin boundaries. The authors characterize the dynamics associated with streamflow time series data from about seventy-one U.S. Geological Survey (USGS) stream-gauge stations in the state of Iowa. They employ a novel approach called visibility graph (VG). It uses the concept of mapping time series into complex networks to investigate the time evolutionary behavior of dynamical system. The authors focus on a simple variant of VG algorithm called horizontal visibility graph (HVG). The tracking of dynamics and hence, the predictability of streamflow processes, are carried out by extracting two key pieces of information called characteristic exponent, λ of degree distribution and global clustering coefficient, GC pertaining to HVG derived network. The authors use these two measures to identify whether streamflow process has its origin in random or chaotic processes. They show that the characterization of streamflow dynamics is sensitive to data attributes. Through a systematic and comprehensive analysis, the authors illustrate that streamflow dynamics characterization is sensitive to the normalization, and the time-scale of streamflow time-series. At daily scale, streamflow at all stations used in the analysis, reveals randomness with strong spatial scale (basin size) dependence. This has implications for predictability of streamflow and floods. The authors demonstrate that dynamics transition through potentially chaotic to randomly correlated process as the averaging time-scale increases. Finally, the temporal trends of λ and GC are statistically significant at about 40% of the total number of stations analyzed. Attributing this trend to factors such as changing climate or land use requires further research.
Moisture Source-to-Receptor Network for East Asian Summer Monsoon and the Associated Atmospheric Bridges
Authors: Cheng Tat Fan , Lu Mengqian
Published: March 2020

There has been growing interest in studying precipitation recycling and identifying relationships between moisture sources and receptors. The network built upon the relationships is crucial for the knowledge of the atmospheric water cycle, weather prediction, and adaptation to hydroclimatic disasters. This study aims to provide an interesting perspective of a Source-to-Receptor (SR) network to study the dynamics of the East Asian Summer Monsoon (EASM). By prescribing 24 sources and 6 EASM subregions, the SR network during the wet season is quantified using the two-dimensional physically-based Dynamical Recycling Model (DRM). Results reveal that in addition to oceanic sources, land sources including the often-overlooked plateau regions play an important role in supplying moisture to most EASM subregions. A seesaw relationship of the Indian Ocean/South Asia sector from April to June and the Pacific Ocean/East Asia sector from July to September is evidenced in the intraseasonal variation of the SR network for EASM subregions including South China coast and Taiwan, Yangtze River basin, South Japan and Korean Peninsula. Conversely, weaker intraseasonal variation is seen in the SR network for the Yellow River basin and North China. During heavy rainfall days, the zonal oscillation of western North Pacific Subtropical High (WNPSH) is deemed crucial to modulate the SR network through enhanced contributions from Bay of Bengal, Indochina, Indian subcontinent and Southwest China (the Philippine Sea and western North Pacific) during the positive (negative) phase. Coupled circulations such as two distinct pressure dipoles and coherent upper-level wave trains from mid-latitudes are responsible for bridging the moisture routes. Lastly, preceding winter/springtime El Niño is likely associated with the enhanced (weakened) moisture supply from the southwesterly (Pacific Ocean) sources. Longer-term variabilities such as the Pacific Decadal Oscillation is also considered influential to the SR network. We believe that the attributable atmospheric bridges and the SR network itself can offer insights to the current understanding of EASM and model simulations of the monsoon systems and the water cycles.
Energy Conversion in the Electron Stagnation Region of Magnetopause Reconnection
Authors: Burch James , Webster James , Pritchard Kristina , Genestreti Kevin , Hesse Michael , Cassak Paul , Torbert Roy , Giles Barbara , Ergun Robert , Russell Christopher , Strangeway Robert , Hwang Kyoung-Joo , Dokgo Kyunghwan , Fuselier Stephen
Published: March 2020

For reconnection at the Earth’s day side, which is asymmetric, the main energy conversion occurs on closed field lines in the electron stagnation region. Energy conversion, as measured by J⦁E, occurs where out-of-plane electric field components are embedded within larger regions of out-of-plane current, which is carried by strong electron flows in the M direction of the LMN coordinate system. Bracketing these energy conversion sites are electron jet reversals (along L and -L) and converging  electron flows (along N and -N). These electron flows are like those that surround reconnection X lines, however, in these cases they occur completely within closed field lines. The question then is what, if anything, this energy conversion has to do with local reconnection of magnetic field lines. This paper reports on a study of two events observed by MMS on December 29, 2016 and April 15, 2018. The electron inflows have velocities between 0.05 VeA and 0.1 VeA, (VeA = electron Alfvén speed), which are consistent with predicted reconnection rates. Laboratory measurements and 3D simulation results offer some clues about how reconnecting current sheets can evolve in a uniform background magnetic field.
Increase in summer monsoon rains in northeast India during ENSO periods: a multiproxy analysis
Authors: Singh Arvind , Pullabotla Kiran Kumar , Rengaswamy Ramesh
Published: March 2020

El-Niño Southern Oscillation (ENSO) affects Indian summer monsoon. Most of the worst droughts - the most recent being in 2009 - in India have been triggered by ENSO. But given the heterogeneity in rainfall patterns over India, we revisited ENSO influence on Indian summer monsoon. Our analysis based on multiple isotopic (proxy-based) and satellite data set shows significant variation in the spatiotemporal patterns of rainfall over the Indian subcontinent and adjoining oceans. We observed a weaker summer monsoon over central India and relatively stronger summer monsoon over northeast India during strong El-Niño events. Rainfall derived from isotope-enabled general circulation models reproduces weak and strong rainfall patterns during the El-Niño events over central India and northeast India, respectively. These model derived δ18Orain (oxygen isotopic composition of rainfall) variation over central India during ENSO events mimic the weaker rainfall conditions. However, significant changes in the model derived rainfall and associated δ18Orain is not observed over northeast India during ENSO events. Based on multiple data analysis, we infer that the long term variations (trends) in the Indian summer monsoon strength were controlled by the long term variation in ENSO during the last 50 years (1965 – 2013).

Since these observations were unprecedented and counterintuitive, we further verified our observations from the proxy records. Two speleothems (cave deposits) records from the central India and northeast India were analyzed for the rainfall variation and ENSO influence signatures. These paleo-proxy records showed a similar inverse relation of rainfall patterns over central India and northeast India during ENSO periods, confirming observed ENSO’s role on rainfall. Also, these proxy records showed a long-term pause in ENSO events or stronger La-Niña like conditions, which were persisted during 1625 – 1715 and favored stronger (weaker) rainfall over central India (northeast India).
assimilative capacity analysis and total maximum daily load strategy for smart water management
Authors: Chang Chia-Ling
Published: March 2020

Due to steep terrain, uneven rainfall, and high-speed streams, Taiwan's water environmental vulnerability is relatively high. Under the impact of climate change and environmental variation, Taiwan faces more and more challenges in water environmental management. Although environmental development can bring economic benefit, it can also impact the environment. Therefore, it is important to consider environmental assimilative capacity for maintaining a balance condition between environmental development and environmental protection. This study assesses the environmental assimilative capacity of several water systems in Taiwan. The total maximum daily load (TMDL) strategy considers water quality management from effluent-based control to ambient-based management to protect waterbodies based on their assimilative capacity. It is determined by a target water quality concentration and the assimilative capacity of the receiving waterbody. The concept of TMDL is similar in flood management and control. The purpose of this study is to discuss the total maximum environmental assimilative capacity of these water systems and to propose smart water management strategies for decreasing the water environmental risk and impact. Highly flexible and intelligent water management is essential for sustainable environmental development.
Critical Region Identification of Land Use/Land Cover based on typical ecosystem services - a case study of Beijing-Tianjin-Hebei Urban Agglomeration
Authors: Liu Yinglu
Published: March 2020

Contradictions between population, economic development, land and ecological environment occur frequently in the Beijing-Tianjin-Hebei urban agglomeration, forming a complex problem of "population - land - social economy - ecological environment" at a regional level. This study considers seven indicators, including LUCC and three typical ecosystem services, to recognize the critical regions. Through continuous experiments and adjustments of parameters, we finally determine the building methods of overlaying in a equal power, and quantificationally evaluate the land use dynamic degrees, land use extents, diversity of land use types, ecological land use ratio, carbon sequestration service, soil conservation and water production services, integrated identify critical areas of the Beijing-Tianjin-Hebei urban agglomeration. We aim at realizing the coordinated sustainable development of Beijing-Tianjin-Hebei region as soon as possible, and providing the basis for land planning. The results show that the critical regions of the Beijing-Tianjin-Hebei urban agglomeration are mainly distributed in the Yanshan and Taihang mountain regions and the surrounding towns. On the scale of county level, the first-level critical regions are mainly located in Beijing, Qinhuangdao and Chengde, and the second-level critical regions are mainly located in Chengde, Beijing, Qinhuangdao and Baoding.