bluuebunny/crossref_metadata_2025 huggingface dataset:
Propagation and growth mechanisms for convectively coupled equatorial Kelvin waves
Authors: Matthews Adrian
Published: March 2021

Convectively coupled equatorial Kelvin waves (CCKWs) are tropical weather systems that bring high impact weather and flooding, particularly in the Maritime Continent. They are a key component of the tropical climate system through scale interactions with other phenomena such as the Madden--Julian oscillation (MJO). CCKWs share many key features with theoretical, dry, linear equatorial Kelvin waves, such as a predominantly zonal component of their horizontal wind anomalies, and eastward propagation. Here, a vorticity budget for CCKWs is constructed using reanalysis data, to identify the basic mechanisms of eastward propagation and the observed growth. The budget is closed, with a small residual. Vortex stretching, from the divergence of the Kelvin wave acting on planetary vorticity (the -f D term), is the sole mechanism by which the vorticity structure of a theoretical Kelvin wave propagates eastward. This term is also the key mechanism for the eastward propagation of CCKWs, but its different phasing also leads to growth of the CCKW. However, unlike in the theoretical wave, other vorticity source terms also play a role in the propagation and growth of CCKWs. In particular, vortex stretching from the divergence of the CCKW acting on its own relative vorticity (the -ζ D term) is actually the largest source term, and this contributes mainly to the growth of the CCKW, as well as to eastward propagation. Horizontal vorticity advection (and to a lesser extent, vertical advection), counters the vortex stretching, and acts to retard the growth of the CCKW. The tilting of horizontal vorticity into the vertical also plays a role. However, the meridional advection of planetary vorticity (the -β v term, the main mechanism for westward propagation of Rossby waves), is negligible. The sum of the source terms in this complex vorticity budget leads to eastward propagation and growth of the CCKWs. The implications for numerical weather prediction, forecasting and climate simulations are discussed.
The weak volcanic response in climate models related to low-frequency Pacific variability
Authors: Graffino Giorgio , Gregory Jonathan
Published: March 2021

Volcanic eruptions are among the most important naturally occurring cause of climate variability. Their effect can outlive the residence time of the volcanic aerosol in the stratosphere, due to the intervention of the ocean as heat reservoir. Coupled models exhibit deficiencies and uncertainties in their response to volcanic forcing as well as multiannual variability. We have investigated a possible link by analysing experiments included in the fifth and sixth phases of the Coupled Model Intercomparison Project (CMIP), along with several ad-hoc model simulations, in comparison with observational reanalyses and reconstructions. We introduce a novel technique to analyse the delayed response of sea surface temperature (SST) and mean sea level pressure (MSLP) in the Pacific Ocean to large volcanic eruptions, complemented with with an empirical orthogonal function analysis. Our study shows that coupled models are not able to reproduce the observed SST response to volcanic forcing, which has the shape of the cold phase of the Interdecadal Pacific Oscillation (IPO), and that their MSLP response is too weak. On the other hand, the observed MSLP response is reproduced by atmosphere-only simulations forced with realistic 20th-century SST.
The evolution of feathers
Authors: Benton Michael
Published: March 2021

Feathers are a diagnostic character of birds, and yet new fossils show they likely originated more than 100 million years before the first birds. In fact, feathers probably occurred in all dinosaur groups, and in their cousins, the pterosaurs, as we showed in 2019. This finding confirms current knowledge of the genomic regulation of feather development. Our work stems from ten years of collaboration with Chinese colleagues, during which we set ourselves the task of understanding fossil feathers. Our first discovery was to answer the question, ‘Will we ever know the colour of dinosaurs?’. In 2010, we were able to announce the first objective evidence for colour in a dinosaur. Using ultrastructural studies of fossil feathers, we identified melanosomes for the first time in dinosaur feathers, and these demonstrated that Sinosauropteryx had ginger and white rings down its tail. Studies of other dinosaurs identified patterns of black, white, grey, brown, and ginger. This is part of a new wave in Palaeobiology where we apply objective approaches to provide testable hypotheses, once thought impossible in the historical sciences.

 

Benton, M.J., Dhouailly, D., Jiang, B.Y., and McNamara, M. 2019. The early origin of feathers. Trends in Ecology & Evolution 34, 856-869 (doi: 10.1016/j.tree.2019.04.018).

https://dinocolour.blogs.bristol.ac.uk/

https://dinosaurs.blogs.bristol.ac.uk/
Distinguishing Closed Circulations from the Satellite Maps of the Dynamic Topography
Authors: Tarakanov Roman
Published: March 2021

An algorithm for distinguishing closed multicore circulations from digital maps of dynamic topography (DT) is described. The algorithm is based on the expansion of circulations over the area from their cores (local maxima/minima of the DT) until the DT thresholds corresponding to these cores are reached. The algorithm is performed in several iterations until the points belonging to the closed circulations are completely exhausted. The algorithm is an exact numerical solution of the problem of determining the value of the DT for a closed loop, the most distant from the core of circulation. The algorithm takes into account the problems of nesting circulations of different signs into each other, the possible intersecting of circulations with different signs on the numerical grid, and the possible existence of islands or floating ice inside the circulations. A method is described for merging smaller DT maps to larger maps with the circulations distinguished from the smaller maps.
Flood Seasonality in the Congo River Basin 
Authors: Gode Bola Bosongo , Jeff Neal , Raphael Tshimanga , Lauwrence Hawker , Mark A Trigg , Vincent Lukanda Mwamba , Paul Paul Bates
Published: March 2021

Information on flood seasonality is required in many practical applications of hydrology and water resources management. However, an understanding of flood seasonality and how flood frequencies may have changed over time has not been established for the Congo Basin. The main objective of this study is therefore to identify flood seasonality and change in frequency the Congo Basin (CB). The analysis based on six major drainage areas of the CB, where we used a Peaks Over Threshold (POT) flood time-series with three peaks per year. The relative frequency method is applied to identify flood seasons, and then a cluster analysis is performed to classify flood into type based on monthly frequency. The directional statistics method is used to determine the mean day of flood and the flood variability measure. To identify flood frequency changes, the analysis of variance was applied to test the difference between two flood frequency time series blocks before and after the change point year. Results show that four gauging stations exhibit a unimodal flood seasonality distribution while two gauging stations have bimodal flood seasonality distribution, and two significant flood rich months are observed in all studied gauging stations.  The cluster analysis results in four spatially flood types with distinct seasonality characteristics. Mean flood dates show that the time interval between adjacent flood events in the south and south-east is shorter compared to time interval between flood events in the north and north-west. It is observed that, in almost all gauging stations, there is strong flood seasonality, and the geographical location of a watershed is indicative of its flood pattern. Most of significant decreasing frequencies are found in the southern part of the Congo Basin. There are no significant changes in flood frequency identified in the northern and eastern part of the Basin. However, flood frequencies have been increasing in the centre and western part of the Basin. This study suggest that, exploring flood generating factors and the drivers of change can provide insights for understanding the influence of these factors on floods as climate models projected changes in extreme precipitation and aridity in the future.  

 

 
What do we want to learn from spatial data?  Asking the right questions – challenges in radon mapping
Authors: Bossew Peter , Petermann Eric
Published: March 2021

Exposure to indoor radon is recognized as a health hazard, which is why regulation aimed to its reduction has been developed. One important tool of radon (Rn) policy are Rn maps. They serve (1) for visualizing the geographical distribution of the hazard and (2) as data base for regionalized legal measures, i.e. action which should be appropriate for the Rn situation at a place.

(1) has as objective information of stakeholders (the public, administrations, legislators, Rn professionals) about magnitude and location of the problem;

(2) Objective is decision support for identification of regions in which certain measures should be applied, to comply with Rn regulation.

These two objectives correspond to asking different questions and imply different maps, in general. For visualizing, isopleth or choropleth maps are usually considered adequate, the latter for assigning hazard scores to geographical units such as municipalities. On the other hand, identification of areas where certain action applies, amounts to classification of areas according to the necessity of that action.

While sharing certain steps, these two type of maps entail different technical challenges. They basically origin in the high spatial variability of the Rn hazard, usually quantified by indoor Rn concentration in buildings, its probability to exceed a threshold, or the collective hazard (i.e. sum over affected persons). Due to the multitude and different nature of physical control factors, the scale of variability extends from small-scale local to continental.

Level maps (objective 1) raises the question of resolution (a) wanted by the stakeholders and (b) achievable with data; this acts back to data acquisition, i.e. Rn surveying. Resolution is related to the appearance of maps in terms of roughness and noise. For class maps (objective 2), the critical question is, in addition, reliability of defining an area as target of certain action, in terms of sensitivity and specificity (or likewise of 1st and 2nd kind error probabilities) of a decision.

In this presentation, we shall give real-world examples of the objectives and resulting Rn maps. Further we shall describe estimation methodology suited to create maps that comply with the quality targets addressed above.

 
Restoration of landscape scars in former military areas: vegetation recovery in relation to fine-scale environmental heterogeneity
Authors: Valkó Orsolya , Borza Sándor , Godó Laura , Lukács Katalin , Kiss Réka , Kelemen András , Miglécz Tamás , Tóth Ágnes , Deák Balázs
Published: March 2021

In a large-scale restoration project, we studied the spontaneous vegetation development after the elimination of landscape scars in a former military training area in Hortobágy National Park, Central Hungary. After the removal of approximately 40,000 unexploded ordnances the bomb-craters have been soil-filled, leaving large unvegetated surfaces on a total area of 4,000 hectares in 2017. These research settings provided a unique opportunity to study the effects of environmental heterogeneity on vegetation recovery in a study system, where soil salt content and micro-topography are the major drivers of vegetation patterns. Due to the mixing of soil layers, there were patches with extremely high salt content on the recovering surfaces and several red-listed halophyte plant species, established from the seed bank already in the first year after restoration. We found that the diversity of plant species was the largest in the first year. We detected a significant increase in the vegetation cover and the cover of perennial species from the first year to the second. In the subsequent years the recovery of the vegetation continued but slowed down from the second to the third year. By eliminating landscape scars, the restoration project was successful in increasing the area of alkaline grasslands at the landscape scale and providing grazing lands for local farmers.
Prioritising ecosystem opportunities and threats of floating solar photovoltaics
Authors: Exley Giles , Hernandez Rebecca R. , Page Trevor , Chipps Michael , Gambro Stefano , Hersey Matt , Lake Richard , Zoannou Kali-Stella , Armstrong Alona
Published: March 2021

Floating solar photovoltaic installations are an emerging form of solar energy deployed on varying types of water bodies globally. Deployments have proliferated in recent years, particularly in land-scarce areas, as the drive to decarbonise the energy-mix intensifies. However, the potential ecosystem opportunities and trade-offs of floating solar photovoltaic installations remain unclear, often acting as a barrier to deployment. Exploiting floating solar photovoltaic knowledge systems, we synthesise evidence and insight from scientists and industry stakeholders, through a systematic review, international survey and workshop, to evaluate potential opportunities and threats to ecosystems. We found that reduced evaporation is the greatest perceived opportunity of floating solar, while detrimental chemical impacts, such as anoxia and internal nutrient loading, are perceived as the greatest threat. Using this knowledge, we assessed the overarching sustainability of floating solar, using the United Nations Sustainable Development Goals (SDGs) as a framework. We identified that floating solar photovoltaic installations may impact on eight of the seventeen SDGs. Given the need to rapidly develop understanding, in light of the anticipated growth rates, we prioritise the knowledge gaps and improvements critical to ensuring floating solar photovoltaic installations minimise ecosystem threats and maximise opportunities, safeguarding overall sustainability.
East Asian orogenic collapse caused by oblique subduction and reduced boundary force
Authors: Allen Mark , Song Shuguang , Jean-Arthur Olive Jean-Arthur , Chu Yang , Wang Chao
Published: March 2021

East Asia experienced compressional deformation in the early Mesozoic, across the South China Block, North China Craton (NCC) and the part of the Central Asian Orogenic Belt to the north of the NCC. Deformation and magmatism resulted from Triassic collisions that accreted the continental blocks, and also Izanagi (Paleo-Pacific) Plate subduction from the east. We suggest that there was a single East Asian orogenic plateau by the Middle Jurassic, from NE Russia to SW China, with a length of ~4000 km. The causes and timings of the destruction of this plateau are unclear, especially loss of the lower lithosphere of the NCC. Here, we synthesize evidence for late Mesozoic and early Cenozoic crustal thinning via extension and denudation, to quantify the previous crustal thickness. We find that there was a ~50 km thick crust by the Middle Jurassic across much of the area between NE Asia and SW China, which has since undergone ~30% thinning. A force balance indicates that the buoyancy force produced by the gravitational potential energy of this thick crust drove extension from the latest Jurassic - Early Cretaceous (~145 Ma), when a rapid switch from orthogonal to oblique subduction at the Asia-Izanagi plate margin reduced the compressive boundary force by ~30%. Mantle lithosphere thinning of the NCC exceeds crustal thinning by a factor of ~2; extensional collapse cannot be the only cause of cratonic destruction, but played a major role, and potentially triggered mantle instability. Early Cretaceous extension was accompanied by a flare-up in volcanism along East Asia, which we speculate contributed to the Cretaceous hothouse climate.
Astronomical tuning of the Aptian Stage
Authors: Gambacorta Gabriele , Bottini Cinzia , Faucher Giulia , Grippo Alessandro , Weissert Helmut , Erba Elisabetta
Published: March 2021

We present a new astronomical tuning for the Aptian stage, based on the combined record of the Piobbico Core (Umbria-Marche Basin, central Italy - this study) and the Cismon Core (Belluno Basin, northwestern Italy - Malinverno et al., 2010).  Integrated bio-chemostratigraphy is available for both cores, granting their chronostratigraphic characterization and highest correlability.

A continuous high-resolution greyscale log of the Piobbico Core, obtained after full reprocessing of core photos, was used as input for the cyclostratigraphic analysis. Evolutionary spectral analysis reveals unstable frequencies throughout the record, indicative of uneven sedimentation rates ranging from about 2 to about 9 m/My. Reconstructed sedimentation rate model is based on the optimal fit of the long-eccentricity ~405-kyr-cycle. Changes in accumulation rate were further validated by applying the evolutionary coefficient analysis of the stratigraphic series, with the main components of the La2010a astronomical solution used as targets. Estimated variations in sedimentation rate well reflect the major lithofacies variations, from marlstone-dominated to marly limestone-dominated intervals, and the relative changes in biogenic components along the succession.

Results of the cyclostratigraphic analysis indicate that orbital forcing controlled the depositional patterns. Visual variations in the greyscale log, further supported by spectral analysis, highlight an evident cyclicity related to long- and short-eccentricity orbital periodicities. The combined short- and long-eccentricity amplitude envelope of the tuned record shows significant long-term modulations in the short eccentricity bands. Frequencies related to precession index fit as well with the La2010a astronomical model. The calibration with the theoretical astronomical solution allowed to define a consistent age model for the studied succession.

The tuned greyscale log of the Piobbico Core (this study) was merged with the tuned FMI resistivity log of the Cismon Core (Malinverno et al., 2010) in order to obtain a composite record covering the entire Aptian time interval and determine the duration of the Aptian time interval.  In addition, by anchoring the results of the cyclostratigraphy to the U-Pb absolute age of 113.1 ± 0.3 Ma for the Aptian/Albian boundary, we provide a new estimate for the age of the Barremian/Aptian boundary, currently placed at the base of the M0r polarity Chron. The ~405 ky-tuned Piobbico and Cismon merged record indicates a duration of 9.77 My for the Aptian, and an age of 122.87 ± 0.3 Ma for the Barremian/Aptian boundary.
Observational Simulation of Extreme Weather Conditions and Aviation Meteorology Applications
Authors: Gultepe Ismail , Agelin-Chaab Martin , elfstrom Gary , Komar John , Hangan Horia , Heymsfield Andrew
Published: March 2021

Observations and prediction of extreme weather (Wx) conditions are important for land, air and sea or water transportation applications. These conditions adversely affect the economic and social life of people.  Extreme Wx conditions for aviation operations for example, include, gust (Ug), wind (Uh), and turbulence (U’), low visibility (Vis), fog and frost, and icing as well as heavy precipitation. These conditions can be studied either in the natural atmosphere or in the laboratory. There have been several aircraft and balloon based in-situ studies related to extreme Wx conditions affecting aviation operations.  However, studying extreme Wx conditions from aircraft observations is limited due to safety and sampling issues, instrument uncertainties, and even the possibility of the aircraft producing its own physical and dynamical effects. Remote sensing-based techniques (e.g., retrieval techniques) for studying extreme Wx conditions usually represent a volume that cannot characterize the important scales, and also represents indirect observations. Therefore, climatic wind tunnel simulations of atmospheric processes together with field observations can help us to better evaluate the interactions among microphysical and dynamical processes affecting extreme Wx conditions e.g., cold air temperatures (Ta) and low/high relative humidity with respect to water (RHw). The Climatic Wind Tunnel (CWT) in the Automotive Centre of Excellence (ACE) at the Ontario Tech University has a large semi-open jet test chamber with a flow area of 7-13 m2 that can precisely control Ta down to -40ºC, and Uh up to 250 km hr-1.  Ice and liquid phases of particle size distributions n the CWT are measured with optical probes such as GCIP, CDP, BCP, FMD, and LPM probes (Gultepe et al 2019, PAAG). The ACE CWT employs several modes of generating sprays, including a spray nozzle array suspended in its settling chamber and fed by heated pressurized de-ionized water to create supercooled droplets, a snow gun also located in the settling chamber, and a spray rig at the nozzle exit, to create a wide range of particle sizes from a few µm up to mm size range to create extreme Wx conditions. These set-ups, together with a range of cold Ta and RHw, plus a wide range of Uh, enabled simulation of severe Wx conditions, including icing, Vis, strong Uh and U’, ice fog and frost, freezing fog, heavy snow, and blizzard conditions. Overall, the results from the CWT simulations supported by the Ontario Tech University AViation MEteorological Supersite (AVMES) observations will be summarized for the aviation operations representing cold environments.
Deformation, earthquakes and tsunamis along thickly sedimented subduction: Arakan segment of the Sunda Arc
Authors: McHugh Cecilia , Seeber Leonardo , Steckler Michael , Akhter Syed Humayun , Dubin Nickolas
Published: March 2021

Incoming sediment thickness and composition are primary factors in the morphology and shallow structure of subduction boundaries. Sediment thickness in the Indian Ocean increases SE to NW along the Sunda arc. From <1km along Java to >15km where the boundary encounters the Ganges-Brahmaputra Delta (GBD). Here the accretionary prism broadens to the NW to >300 km wide. It is dominated by shallow-water to non-marine sediment. This segment also features a broad shallow megathrust overlain by linear anticlines rooted in splay faults. It is entirely above sea level and blind in its frontal part. This GBD segment transitions to a more familiar subduction structure and morphology along the submerged Arakan segment to the SE. The SE portion of this segment is characterized by larger splay faults that expose deep-water sediment with mud diapirism forming volcanoes and circular synclines. With increasing sediment input, the NW portion of the Arakan segment encroaches onto the GBD shelf. Both the SE and NW portions of the Arakan segment ruptured in the Mw>8.5 1762 tsunamigenic earthquake according to field and modeling evidence.

Uplifted coral reefs and marine terraces along the Myanmar and Bangladesh coasts document a >500 km rupture in 1762. The uplift, ranging from 6 m to 2 m from south to north, has been linked to rupture on the megathrust and on shallow splays. Tsunami deposits are traced for ~10 km along the St. Martin’s Island anticline and for >40 km along the Teknaf peninsula. Microfossils and mollusk assemblages in these deposits are consistently of shallow water affinity and date the tsunami to 1762. This deposit covers only a small fraction of the inferred megathrust rupture. If it is representative of the total tsunami distribution, a local anticline may have been the main source. Evidence from live coral microatolls show uplift on St. Martin’s Island continuing 250 years after the earthquake. This motion could stem from continued anelastic deformation of the anticline updip of the rupture. More widely distributed evidence from sediment and corals could address questions about megathrust and splay behavior in 1762 and after. Plans include multichannel seismic surveying, high resolution subbottom profiling and 40 m long piston coring to compare the SE to NW shelf portions to the Arakan segment along the Myanmar and Bangladesh coasts. More generally, we aim to better understand subduction and geohazards along thickly sedimented systems.
 Embracing equity and cultivating inclusion
Authors: Razavi Saman
Published: March 2021

This presentation first provides an overview of a recent opinion piece by the author published in University Affairs, titled “Celebrate diversity, embrace equity and cultivate inclusion”, and then reviews anonymously some of the feedbacks the author received from the community. A main message is that diversity is easy to define and measure, and thus manage, but equity and inclusion are not and require much greater effort. We need to be innovative in this effort, as inclusion and equity, unlike diversity, are essentially qualitative, possibly with social perceptions that vary over time.

 

References:

Razavi, S., (2020), Celebrate diversity, embrace equity and cultivate inclusion, University Affairs, In My Opinion (Accessible at https://www.universityaffairs.ca/opinion/in-my-opinion/celebrate-diversity-embrace-equity-and-cultivate-inclusion/).
Combined impact of Climate change and Land use on water quality in the mid-21st century: A modelling study for a highly industrialized stretch of Ganga River
Authors: Santy Sneha , Mujumdar Pradeep , Bala Govindasamy
Published: March 2021

High industrial discharge, excessive agricultural activities, untreated sewage disposal make the Kanpur region one of the most contaminated stretches of the Ganga river. This study analyses water quality for the combined future climate change and land use land cover scenarios for mid-century for a 238km long Kanpur stretch of Ganga river. Climate change projections from 21 General Circulation Models for the scenarios of RCP 4.5 and RCP 8.5 are considered and Land use Land Cover (LULC) projections are made with QGIS software. Streamflow and water temperature are modelled using the HEC-HMS model and a Water-Air temperature regression model, respectively. Water quality analysis is simulated using the QUAL2K model in terms of nine water quality parameters, dissolved oxygen, biochemical oxygen demand (BOD), ammonia nitrogen, nitrate nitrogen, total nitrogen, organic phosphorus, inorganic phosphorus, total phosphorus and faecal coliform. Climate change impact alone is projected to result in degraded water quality in the future. Combined climate change and LULC change may further degrade water quality, especially at the study area's critical locations. Our study will provide guidance to policymakers to safeguard the Ganga river from further pollution.
A Community Perspective on Research Software in the Hydrological Sciences 
Authors: Reinecke Robert , Trautmann Tim , Wagener Thorsten , Schüler Katja
Published: March 2021

Software development has become an integral part of the earth system sciences as models and data processing get more sophisticated. Paradoxically, it poses a threat to scientific progress as the pillar of science, reproducibility, is seldomly reached. Software code tends to be either poorly written and documented or not shared at all; proper software licenses are rarely attributed. This is especially worrisome as scientific results have potential controversial implications for stakeholders and policymakers and may influence the public opinion for a long time. 

In recent years, progress towards open science has led to more publishers demanding access to data and source code alongside peer-reviewed manuscripts. Still, recent studies find that results in hydrology can rarely be reproduced. 

In this talk, we present first results of a poll conducted in spring 2021 among the hydrological science community. Therein, we strive to investigate the causes for that lack of reproducibility. We take a peek behind the curtain and unveil how the community develops and maintains complex code and what that entails for reproducibility. Our survey includes background knowledge, community opinion, and behaviour practices regarding reproducible software development.  

We postulate that this lack of reproducibility might be rooted in insufficient reward within the scientific community, insecurity regarding proper licencing of software and other parts of the research compendium as well as scientists’ unawareness about how to make software available in a way that allows for proper attribution of their work. We question putative causes such as unclear guidelines of research institutions or that software has been developed over decades by researchers' cohorts without a proper software engineering process and transparent licensing. 

To this end, we also summarize solutions like the adaption of modern project management methods from the computer engineering community that will eventually reduce costs while increasing the reproducibility of scientific research. 
Perceptions among students and young scholars of drivers endangering the Baltic Sea.
Authors: von Storch Hans
Published: March 2021

In a series of ad-hoc surveys, students and young scholars from various institutions in the Baltic Sea region are asked about their perceptions about the reality and seriousness of climate change, and how these compare to other pressures on the Baltic Sea. The same questionnaire, albeit adopted to the different nationalities, have been run in Sweden, Denmark, Poland and Germany, among students with different backgrounds, such as oceanography, geography, environmental sciences and chemistry. The surveys were done in 2019, 2020 and 2021. While the individual surveys at the different institutes can not be considered representative, the ensemble of the so far 7 surveys provides a consistent summary of what is common understanding, and which issues may be considered less uniformly.

Climate, eutrophication and disposal of waste are listed most often as serious issues, while overfishing and tourism less often, and the construction of bridges and pipelines are least often chosen as serious issue. Climate issues are mostly not considered a scientific issue but a public/political issue, and climate science is mostly tasked with “motivate people to act on climate change” or “determine solutions to climate change” but less so with “define the climate problems and attribute cause of climate change”.
Increasing microbial carbon use efficiency with nitrogen addition resulting from plant-mineral interaction
Authors: Feng Xuehui , Hu Jie , Yang Yuanhe , Chen Leiyi
Published: March 2021

Elucidating the mechanisms underlying the changes in microbial physiology under anthropogenic nitrogen (N) input is of fundamental importance for understanding the carbon-N interaction under global environmental change. Carbon use efficiency (CUE), the ratio of microbial growth to assimilation, represents a critical microbial metabolic parameter that controls the fate of soil C. Despite the recognized importance of mineral protection as a driver of soil C cycling in terrestrial ecosystems, little is known on how mineral-organic association will modulate the response of microbial CUE to increasing N availability. Here, by combining a 6-year N‐manipulation experiment and 18O isotope incubation, mineral analysis and a two-pool C decomposition model, we evaluate how N-induced modification in mineral protection affect the changes in microbial growth, respiration and CUE. Our results showed that microbial CUE increased under N enrichment due to the enhanced microbial growth and decreased respiration. Such changes in microbial physiology further led to a significant decrease in CO2-C release from the slow C pool under high N input. More importantly, the disruption in mineral-organic association induced by elevated root exudates is the foremost reason for the enhanced microbial growth and CUE under high N input. Taken together, these findings provide an empirical evidence for the linkage between soil mineral protection and microbial physiology, and highlight the need to consider the plant-mineralogy-microbial interactions in Earth system models to improve the prediction of soil C fate under global N deposition.
The stock and age of pyrogenic carbon in boreal forest soils of the Mackenzie Basin, Northern Canada
Authors: Schiedung Marcus , Ascough Philippa , Bellè Severin-Luca , Abiven Samuel
Published: March 2021

Wildfires occur regularly in the boreal forests of Northern Canada and an increasing frequency and intensity due to the global climate change is projected. A by-product of these forest fires is pyrogenic carbon (PyC) as a residue of incomplete combustion. The quantity and age of PyC in boreal forest soils, however, are largely unknown although boreal soils contribute to a large extent to the global soil organic carbon (SOC) stocks. The Mackenzie River is a major export pathway for PyC between terrestrial and marine environments, with exported PyC ages on geological timescales. This indicates that soil may play an important role as an intermediate pool prior to the PyC export. We sampled eleven forest soils (with nine replicates) in the Canadian Taiga Plains and Shield within the Mackenzie River basin. Our sample sites were located in regions with soils under continuous permafrost in the Inuvik region (northern sites) and under sporadic and discontinuous permafrost in the South Slave Lake regions (southern sites). All sites were unaffected by fire for at least four decades. We used the hydrogen pyrolysis (HyPy) method to separate the PyCHyPy from the non-fire-derived SOC in the upper 0-15 cm to determine PyCHyPy stocks and performed radiocarbon dating upon both bulk soil and isolated PyCHyPy. The total SOC stocks were lower in the soil from the southern sites with on average 26 ± 20 Mg ha-1 (10-153 Mg ha-1) compared to 57 ± 29 Mg ha-1 (16-188 Mg ha-1) in the northern sites. The radiocarbon dating revealed much older PyCHyPy compared to the bulk soil SOC radiocarbon age, supporting the persistent nature of PyC and stabilization in soils. The PyCHyPy found in the soil of the southern sites, however, was much younger with ages in the range of 495-3 275 radiocarbon years BP than in the northern sites with ages on the range of 2 083-10 407 radiocarbon years BP. The larger SOC stocks and higher ages of PyCHyPy in the soils of the northern sites indicate the importance of permafrost conditions for the whole carbon cycle of boreal forests soils.
Measuring and monitoring trees and forests using a novel IoT approach
Authors: Wilkinson Matthew , Bell Michael , Baer Thomas , Xanakis Georgios
Published: March 2021

International attempts to limit greenhouse gas (GHG) concentrations, aimed at stabilizing human induced climate change, require a detailed understanding of the current and potential future role of forests to sequester carbon. Accurate, high frequency and reliable measurements are therefore vital in developing effective mitigation strategies and help to improve understanding of the other ecosystem services provided by forests which are valued by society. However, forests are typically located in remote, rural environments which can make regular access for surveyors and other forest scientists challenging and logistically difficult. In 2020, Forest Research worked in partnership with the UK government’s Department for Environment, Food and Rural Affairs (Defra) and Vodafone to explore how Internet of things (IoT) technology can be used to improve environmental and forest monitoring and to test its suitability at remote rural locations in the UK. A pilot study which ran at Forest Research’s two contrasting long-term carbon flux sites, Alice Holt (Hampshire) and Harwood (Northumberland) used IoT technology to measure and transmit high frequency growth and environmental data over the course on an entire growing season. Tree growth sensors (automated dendrometers) and a range of other environmental sensors (e.g. air temperature and  humidity, soil moisture) attached to the trees and in the soil (nine replicates per site), were connected to the Vodafone Narrowband-IoT (NB-IoT) network. Data was uploaded every 15 minutes to a Grafana based online web portal, providing researchers with near real time access to the data.  Here we present results from these two sites, details of the hardware used in these new devices and evaluation of their performance during this pilot study.
Nitrogen fixation in a diazotrophic post-bloom situation in the Baltic Sea
Authors: Reeder Christian , Löscher Carolin
Published: March 2021

The Baltic Sea is characterised as a semi-enclosed brackish Sea that has experienced increased eutrophication, hypoxia, and increased temperature over the last ~100 years making Baltic Sea one of the most severely impacted oceanic environment by climate change. Biological fixation of dinitrogen gas (N2) is an essential process to make atmospheric N2 available for marine life. This process is carried out by specialised organisms called diazotrophs and is catalysed by the energetic-consuming enzyme nitrogenase. Nitrogenases exist in three subtypes depending on their metal cofactors, (1) the most common molybdenum-dependent (Nif), (2) the vanadium-dependent (Vnf) and (3) the Iron-Iron-dependent nitrogenase (Anf). To date, the effect of climate change on those three enzyme subtypes and their potential role a future ocean is yet to be explored. The predicted ongoing oxygen loss in the ocean may limit Mo's availability and trigger a shift from the abundant Nif-type nitrogenase to Vnf or Anf and, therefore, a potential shift in the diazotrophic community. This study explored the climate change-related pressures on N2 fixation and the diazotrophic community based on nifH and vnf/anfD amplicons. At the time of sampling, we found a post-bloom high-nutrient low-chlorophyll situation. Cyanobacterial groups, Nodularia and UCYN-A, dominated the diazotrophic community and showed a horizontal where UCYN-A were the dominant fixers at 20 m. Based on alternative nitrogenases amplicons, Rhodopseudomonas was the dominating microbe in the surface water. This paper presents the first hint of active nitrogenases in surface water and further establish UCYN-A as a significant player in Baltic Sea primary production.
Comparing Higher-dimensional Velocity Models for Seismic Location Accuracy using a Consistent Travel Time Framework
Authors: Begnaud Michael , Ballard Sanford , Conley Andrea , Hammond Patrick , Young Christopher
Published: March 2021

Historically, location algorithms have relied on simple, one-dimensional (1D, with depth) velocity models for fast, seismic event locations. The speed of these 1D models made them the preferred type of velocity model for operational needs, mainly due to computational requirements. Higher-dimensional (2D-3D) seismic velocity models are becoming more readily available from the scientific community and can provide significantly more accurate event locations over 1D models. The computational requirements of these higher-dimensional models tend to make their operational use prohibitive. The benefit of a 1D model is that it is generally used as travel-time lookup tables, one for each seismic phase, with travel-time predictions pre-calculated for event distance and depth. This simple, lookup structure makes the travel-time computation extremely fast.

Comparing location accuracy for 2D and 3D seismic velocity models tends to be problematic because each model is usually determined using different inversion parameters and ray-tracing algorithms. Attempting to use a different ray-tracing algorithm than used to develop a model almost always results in poor travel-time prediction compared to the algorithm used when developing the model.

We will demonstrate that using an open-source framework (GeoTess, www.sandia.gov/geotess) that can easily store 3D travel-time data can overcome the ray-tracing algorithm hurdle. Travel-time lookup tables (one for each station and phase) can be generated using the exact ray-tracing algorithm that is preferred for a specified model. The lookup surfaces are generally applied as corrections to a simple 1D model and also include variations in event depth, as opposed to legacy source-specific station corrections (SSSCs), as well as estimates of path-specific travel-time uncertainty. Having a common travel-time framework used for a location algorithm allows individual 2D and 3D velocity models to be compared in a fair, consistent manner.
Analysis of a large, seismically-induced mass movement after the December 2018, Etna volcano (southern Italy) seismic swarm
Authors: Albano Matteo , Saroli Michele , Atzori Simone , Moro Marco , Tolomei Cristiano , Bignami Christian , Stramondo Salvatore
Published: March 2021

In the last decades, satellite monitoring techniques allowed to discover non-catastrophic slope movements triggered by earthquake shaking and involving deep blind sliding surfaces of old paleo-landslides. Understanding the triggering and attenuation mechanisms of such mass movements is crucial to assess their hazard. On December 2018, the Etna volcano (southern Italy) began a very intense eruption, accompanied by a seismic swarm with magnitudes up to 4.9. Synthetic Aperture Radar data from Sentinel-1 and ALOS-2 identified some local displacements over a hilly area to the southwest of the Etna volcano, near Paternò village. We evaluated the contribution of seismically-induced surface instabilities to the observed ground displacement by employing a multidisciplinary analysis comprising geological, geotechnical and geomorphological data, together with analytical and dynamic modelling. The results of our study allowed us to identify the geometry and kinematics of a previously unknown paleo-landslide. A pseudostatic, limit-equilibrium back-analysis of the landslide mass highlighted that the displacements detected by InSAR data were caused by the undrained seismic instability of the landslide mass, which was dormant before the volcanic eruption, under the light-to-moderate seismic shacking of the December 26, Mw 4.9 earthquake. Such a new observation allowed to identify the geometry and kinematics of a previously unknown landslide mass and confirms that earthquakes have a cumulative effect on landslides that doesn't necessarily manifest as a failure but could evolve in a catastrophic collapse after several earthquakes. Such an aspect must be adequately investigated to identify unknown quiescent landslide bodies and to prevent the effects of their potential collapse during an earthquake.
Multi-site, multi-crop measurements in the soil-vegetation-atmosphere
continuum: A comprehensive dataset from two climatically contrasting regions in South West Germany for the period 2009–2018
Authors: Weber Tobias K. D. , Ingwersen Joachim , Högy Petra , Poyda Arne , Wizemann Hans-Dieter , Demyan Michael Scott , Bohm Kristina , Eshonkulov Ravshan , Gayler Sebastian , Kremer Pascal , Laub Moritz , Nkwain Yvonne Funkiun , Troost Christian , Witte Irene , Cadisch Georg , Müller Torsten , Fangmeier Andreas , Wulfmeyer Volker , Streck Thilo
Published: March 2021

Abstract. We present a comprehensive, high-quality dataset characterising soil-vegetation and land-surface processes from continuous measurements conducted in two climatically contrasting study regions in South West Germany: the warmer and drier Kraichgau region with a mean temperature of 9.7 °C and annual precipitation of 890 mm, and the cooler and wetter Swabian Alp with mean temperature 7.5 °C and annual precipitation 1042 mm. In each region, measurements were conducted over a time period of nine cropping seasons from 2009 to 2018. The backbone of the investigation was formed by six eddy-covariance stations (EC) which measured fluxes of water, energy and carbon dioxide between the land surface and the atmosphere at half-hourly resolution. This resulted in a dataset containing measurements from a total of 54 site*years containing observations with a multitude of crops, as well as considerable variation in local growing season climates. The presented multi-site, multi-year data set is composed of crop-related data on phenological development stages, canopy height, leaf area index, vegetative and generative biomass and their respective carbon and nitrogen content. Time series of soil temperature and soil water content were monitored with 30-min resolution at various points in the soil profile, including ground heat fluxes. Moreover, more than 1,200 soil samples were taken to study changes of carbon and nitrogen contents. The data set was uploaded to the Pangaea database and can be accessed at https://doi.org/10.20387/bonares-a0qc-46jc (for the review process, please refer to the data availability section). One station in each region has now been set up as continuous observatories of state variables and fluxes in intensively managed agricultural fields.
Deriving Arctic 2 m air temperatures over snow and ice from
satellite surface temperature measurements
Authors: Nielsen-Englyst Pia , Høyer Jacob L. , Madsen Kristine S. , Tonboe Rasmus T. , Dybkjær Gorm , Skarpalezos Sotirios
Published: March 2021

Abstract. The Arctic region is responding heavily to climate change, and yet, the air temperature of ice covered areas in the Arctic is heavily under-sampled when it comes to in situ measurements, resulting in large uncertainties in existing weather- and reanalysis products. This paper presents a method for estimating daily mean clear sky 2 meter air temperatures (T2m) in the Arctic from satellite observations of skin temperature, using the Arctic and Antarctic ice Surface Temperatures from thermal Infrared (AASTI) satellite dataset, providing spatially detailed observations of the Arctic. The method is based on a linear regression model, which has been tuned against in situ observations to estimate daily mean T2m based on clear sky satellite ice surface skin temperatures. The daily satellite derived T2m product includes estimated uncertainties and covers clear sky snow and ice surfaces in the Arctic region during the period 2000–2009, provided on a 0.25 degree regular latitude-longitude grid. Comparisons with independent in situ measured T2m show average biases of 0.30 °C and 0.35 °C and average root mean square errors of 3.47 °C and 3.20 °C for land ice and sea ice, respectively. The associated uncertainties are verified to be very realistic for both land ice and sea ice, using in situ observations. The reconstruction provides a much better spatial coverage than the sparse in situ observations of T2m in the Arctic, is independent of numerical weather prediction model input and it therefore provides an important supplement to simulated air temperatures to be used for assimilation or global surface temperature reconstructions. A comparison between in situ T2m versus T2m derived from satellite and ERA-Interim/ERA5 estimates shows that the T2m derived from satellite observations validate similar or better than ERA-Interim/ERA5 in the Arctic.
Pengaaruh Pemberian Pupuk Bokashi Terhadap Pertumbuhan dan Produksi Tanaman Buncis (Phaseolas vulgaris L) di Desa Ubung Dengan Program SPSS
Authors: Ningkeula Edy Said
Published: March 2021

Penelitian ini dilakukan dengan menggunakan teknik Penelitian praktikum menggunakan lahan di desa Ubung Kecamatan Lilialy Kabupaten Buru. Tujuan Penelitian ini adalah untuk mengetahui pertumbuhan dan produksi tanaman Buncis (Phaseolus vulgaris L), akibat pemberian pupuk limbah kayu putih dan sistim olah tanah pada lahan kering di desa Ubung. Kegunaan Penelitian ini adalah dapat berguna sebagai basis data pertanian dan sebagai informasi bagi petani, peneliti lain, pihak-pihak yang berkepentingan serta pengembangan lebih lanjut dari produksi tanaman Buncis. Hasil dari penelitian ini, yaitu, 1) Kombinasi perlakuan dosis pupuk bokashi limbah kayu putih dengan dosis 15 ton.ha-1 dan sistim olah tanah sempurna berpengaruh terhadap pertumbuhan vegetatif tanaman buncis 2) Sedangkan perlakuan dosis pupuk 30 ton.ha-1 dan sistim olah tanah sempurna berpengaruh terhadap pertumbuhan dan perkembangan generative tanaman Buncis (Phaseolus vulgaris L.) pada lahan di desa Ubung. 3) Pemupukan yang dilakukan untuk tanaman buncis, seharusnya memperhatikan kelestarian lingkungan dengan program 4t, tepat waktu, tepat dosis, tepat lokasi dan tepat aplikasinya.