bluuebunny/crossref_metadata_2025 huggingface dataset:
Management Practices Influenced Corn Grain Yield and Soil Chemical Properties
Authors: Mikha Maysoon , Schlegel Alan
Published: March 2020

Land sustainability could be influenced by management decisions, soil nutrients content, and soil erosion potential. This study evaluates the management that consist on two sources of nitrogen (cattle beef manure, M; and synthetic fertilizer, F) and two levels of residue removal (0% and 80%) on corn yield and soil chemical properties in a no-tillage irrigated field. The study was initiated in 2011 in Tribune, Kansas where the nitrogen treatments and residue removal were organized in randomized strip design with four replications. After Seven years of annual M addition, corn yield and soil chemical properties significantly increased compared with synthetic fertilizer. Annual residue removal at 80% level greatly reduced soil chemical properties measured especially STN, SOC, and soil P availability for subsequent crops. Residue removal at 80% show a potential to decrease soil EC compared with 0% removal, but the EC reduction was not significant. The data generated from this study shows that soil nutrients content was reduced with removing the residue even in irrigated and well fertilized field unless organic amendment was accompanied the residue removal practice.
Interhemispheric conjugacy of transpolar arcs
Authors: Kullen Anita , Thor Simon , Cai Lei
Published: March 2020

Most models predict that transpolar arcs (TPAs) occur simultaneously in both hemispheres. Conjugate TPAs are expected to appear in the northern and southern hemisphere on opposite oval sides. However, several observational studies have shown that this is not always the cases. It has been suggested that IMF Bx and/or the Earth dipole tilt may be responsible for non-conjugate TPAs. During strongly negative IMF Bx and/or positive Earth dipole tilt a TPA is expected to occur only in the northern hemisphere (for positive Bx and/or negative dipole tilt only in the southern hemisphere).

In the present work we revisit this question by investigating three previously published and one new TPA dataset regarding the influence of IMF Bx and Earth dipole tilt on interhemispheric TPA occurrence. The results show, the Earth dipole tilt has no statistical effect on TPA conjugacy while IMF Bx may have a small influence. However, this influence is much smaller than previously reported, when normalizing the IMF Bx distribution during TPAs with the average IMF Bx distribution in the solar wind during the time period covered by the respective dataset.

In the second part of this study we present results from the new TPA dataset, which is based on three months of SUSSI DMSP images. Arc location and IMF conditions during conjugate and non-conjugate TPAs are discussed in detail and possible reasons for non-conjugate TPA events are discussed.
The use of radiative transfer modeling to compare normalized radiances from different instruments
Authors: Seftor Colin , Jaross Glen , Moy Leslie , Kramarova Natalya , Yang Eun-su
Published: March 2020

Measured sun-normalized radiances (S-NRs) from both the Ozone Mapping and Profiler Suite (OMPS) Nadir Mapper (NM) and Nadir Profiler (NP) on the Suomi National Polar-orbiting Partnership (SNPP) satellite have been validated to the 2% level through, in part, comparisons with radiative transfer code calculations using co-located ozone profile retrievals inputs from the Microwave Limb Sounder (MLS) on the Aura satellite. To minimize the effects of clouds and aerosols, only low reflectivity and low aerosol scenes were used. We will describe the details of the comparison technique, including how low reflectivity / low aerosol scenes were determined.  We will also show results where we extend our study to compare measured S-NRs from the OMPS nadir sensors with those from both the Ozone Monitoring Instrument (OMI) on Aura sensor and, if available, the Version 2 dataset from the TROPOMI sensor on the Sentinel 5 Precursor (S5P) satellite.
Fossil plant remains preserved as charcoal within proximal ejecta blankets of impact craters reveal the influence of asteroid collisions with the Earth’s surface
Authors: Losiak Anna , Belcher Claire , Buchner Elmar
Published: March 2020

Impact craters are formed when an asteroid strikes the surface with the hyper-velocity (usually higher than ~1km/s). The kinetic energy of the impactor is released as an explosion, a crater is formed, and target material is deposited outside, forming a proximal and later distal ejecta blanket. This consists of rocks, the surface soil layer and numerous plants remains (Cassidy et al. 1965, Khryanina 1981, Herd et al. 2008), including remains of trees directly killed by the asteroid (Losiak et al. 2016, Losiak et. Al. 2020). We have found a number of charcoals that we suggest are related to the formation of the following confirmed impact craters: Kaali Main, Kaali 2/8 (Estonia, Losiak et al. 2016), Morasko (Poland, Szokaluk et al. 2019), Whitecourt (Canada, Herd et al. 2008) and Ries crater (Buchner and Schmieder 2009). Three of these locations represent small (30-100 m in diameter) impact craters developed primarily in unconsolidated materials such as glacial tills and fluvioglacial sands. Whereas, Ries is a much larger and older crater: it is 24 km in diameter and 14.5 Ma old.

Here we present the results from a set of experiments that reproduce the process of formation of charcoals within the proximal ejecta blankets of small impacts. Firstly, charring experiments were achieved using the iCone Calorimeter that recreated a range of heating possibilities that might results from small impact cratering processes. The iCone allows samples to be heated, with or without ignition at a range of radiant heat fluxes for given durations; these heat fluxes can be static or transient, both of which may be relevant to different impact formation mechanisms. Secondly, we buried leaves and fragments of different woods in heated sand over a range of temperatures durations and cooling regimes to assess the potential for relatively cool ejecta to cause transformations of organic material to char in situ. All the chars created in the experiments were analysed via reflectance microscopy and compared with the charcoal that have been produced by modern wildfires. Our aim being to better understand the environmental effects of differently sized impact craters, but also to study the mode of preservation of plants killed during such extraterrestrial impact events.

Buchner & Schmieder 2009. MAPS44:1051–1060.

Cassidy et al. 1965. Science149:1055-1064.

Herd et al. 2008. Geology36:955–958.

Hudspith et al. 2010. PPP291:40–51.

Khryanina 1981Int. Geology Rev.23:1-10.

Losiak et al. 2016. MAPS51:681–695.

Losiak et al. 2020. MAPSaccepted.

Scott 2010 PPP291:11–39.

Sztokaluk et al. MAPS54:1478-1494. 
Mapping Air Pollution eMissions (MAPM)
Authors: Kremser Stefanie , Mikaloff-Fletcher Sara , Nathan Brian , Dale Ethan , Tradowsky Jordis , Bird Leroy , Bodeker Greg , Lin Dongqi , Coulson Guy , Katurji Marwan , Olivares Gustavo , Mallett Tim , Revell Laura , Longley Ian
Published: March 2020

The growth of megacities from global urbanization has degraded urban air quality sufficient to impede economic growth and create a public health hazard. Emissions of particulate matter, photochemically reactive gases, and long-lived greenhouse gases, contribute to the urban environmental footprint with concomitant economic and social costs. Mitigation actions rely critically on knowing where these emissions occur. In response to this challenge, our team has developed a new method, MAPM (Mapping Air Pollution eMissions), to generate near real-time surface emissions maps of particulate matter pollution. Surface particulate matter (PM 2.5) emission maps will be derived from atmospheric measurements of particulate matter using an inverse model in conjunction with a state-of-the-art mesoscale atmospheric model.

The MAPM methodology is validated and refined using particulate matter measurements made during a field campaign that took place in Christchurch, New Zealand from June to September 2019. Key questions that MAPM aims to answer include:

How do uncertainties on the PM 2.5 measurements affect the quality of the emissions maps we extract from our inverse model.

How do uncertainties in the meteorological data affect the quality of the emissions maps we extract from our inverse model.

How does the spatial and temporal resolution of the air pollution concentration measurements affect the uncertainties in the retrieved pollution emissions maps?

Here we will not only present the measurements made during the winter field campaign but also present the first derived PM 2.5 emissions maps for the city of Christchurch.
A novel method to quantify exchangeable hydrogen fraction in organic matter
Authors: Gudasz Cristian , Soto David X. , Sparrman Tobias , Karlsson Jan
Published: March 2020

Stable isotope measurements of nonexchangeable hydrogen (δ2Hn) of bulk organic matter has emerged as a tool, with a wide range of applications in biology, biogeochemistry and forensics. However, reproducible and precise measurements of δ2Hn between laboratories and methods are still challenging. One of the largest impediments to obtain accurate isotope ratios is to use reference materials of similar exchangeable hydrogen fraction (fx) to the matrix of interest. The organic matter has typically three pools of hydrogen (H): (i) the adsorbed water, which can be minimized by extensive drying, (ii) the carbon bound H (the fraction of interest), which is non-exchangeable and cannot be removed and (iii) the non-carbon bound H, (i.e. N-, COO-, O-, and S-bound H) that cannot be removed but can be readily exchanged with the environmental moisture. Quantification of fx based on dual water vapor isotope exchange and Isotope Ratio Mass Spectrometry (IRMS) have shown large variability in fx between studies for the same organic matter type such as keratin. High variability in fx between samples and standards can translate into a large impact on the measured isotopic values. Here we used a novel approach to independently quantify fx in 21 natural organic material sources with minimal sample manipulation based on 1H-2H exchange experiments and quantified through proton based liquid-state nuclear magnetic resonance (1H-NMR) spectroscopy. The experiments were carried out at room temperature by immersing separate solid powdered samples in deuterated dimethylsulfoxide (background) and deuterium oxide (2H source) followed by the quantification of the water generated in the supernatant fraction through 1H-NMR using glucose as reference. At the same time, samples were analyzed through the most recent procedure of dual water vapor isotope equilibration method using online drying and equilibration in a UniPrep carousel. We discuss these findings and suggest that the proposed 1H-NMR method of quantifying fx is an independent and novel approach that can contribute to a better understanding of H exchangeability in a wider range of organic materials, critical for accurate measurement of the δ2Hn.
The South Adriatic observatory: towards a multidisciplinary seafloor and water column research infrastructure
Authors: Langone Leonardo , Brunetti Fabio , Conese Ilaria , Giordano Patrizia , Miserocchi Stefano , Siena Giuseppe , Ursella Laura , Cardin Vanessa
Published: March 2020

Continuous measurements are essential to assess the interannual variability of the thermohaline circulation, water masses properties and transports, and biochemical contents. The need for high-frequency sampling to resolve events and rapid processes (on different time scale) and the long-sustained measurements of multiple interrelated variables from the sea surface to the seafloor is provided by Southern Adriatic Node. It is formed by the observatory E2M3A located in the area of the Southern Adriatic Pit (Eastern Mediterranean) at 41°32'N, 18°04'E together with a system of moorings positioned along the Bari Canyon (mooring BB lat. 41°20.49’N long. 17°11.64’E at 605 m depth; mooring FF lat 41°48.35’N long 17°02.29’E at 751 m depth) and the open-slope. The Canyon is generally assumed to play an important role in dense water sinking and sediment transfer to the deep Southern Adriatic basin.

The dense waters of North Adriatic origin flow southwards, mostly intermittently, along the Adriatic shelf and sink into the basin, both along the open slope and, more markedly, through the canyon of Bari. Thus, the basin due to its morphology, is considered as a reservoir that collects these waters together with those formed in-situ by open deep water formation (DWF) processes, exiting the Adriatic as the ADW that feeds the thermohaline circulation of the Eastern Mediterranean.

Signals of transport through the canyon to the deep pit layer are evident, in particular environmental conditions as for winter 2012, from the physical and biogeochemical data measured simultaneously at high frequency by the various system components (E2M3A and BB and FF moorings). From BB’s mooring data after this event until 2018 do not show us very significant events but are episodes of lower intensity that are not clearly identified in the E2M3A time series.

The intrusion of very dense waters of North Adriatic origin (cascading) evidenced at the E2M3A, occurred in late march 2014, January 2015 and winter 2016 is remarked from salinity homogenization at the 900 -1000 m depth. This has most likely contributed to enhance the lithogenic material fluxes at the bottom trap.  However, this intrusion has not been clearly detected by BB mooring but might have sunk across the open-slope.

 

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Disaster prevention education through learning about past heavy rainfall and debris flow damage
Authors: Shogo Banshoya
Published: March 2020

This study is an introduction to disaster prevention education for high school students, which aims to raise disaster prevention awareness by learning about disasters that occurred in the past. We live in Hiroshima, Japan. There are many fan-shaped regions in this area, and when heavy rain falls due to the rainy season or typhoons, it is easy for debris flow disasters to occur. The most recent damage was caused by a heavy rain in July 2018. On July 7, 2018, 250 to 300 mm of rain fell in one day. As a result, debris flow damage occurred, greatly affecting the students’ life. Debris flow damage is said to occur repeatedly in the same place. Therefore, I think that learning from the past damage will help students learn about future disaster prevention. 

My students have studied the following 1 and 2 since April 2019. And we worked with graduate student and a professor at Hiroshima University.

1: Case study of debris flow damage caused by a typhoon (Makurazaki-typhoon) that occurred in 1945.

A huge typhoon occurred in September 1945, causing heavy rainfall and a debris flow disaster. Then our area was very confused. (Because, just after the war, only one month had passed since the atomic bomb was dropped). Therefore, details of the debris flow damage caused by the typhoon are not known.

So, we analyzed the aerial photographs taken after the disaster and clarified the extent of the damage. We examined the Kirikushi district in Etajima City, Hiroshima Prefecture, Japan as a case area.

 

2: Case study of debris flow damage through fieldwork.

We went to the area we studied in 1. We talked with people who were once affected by debris flow damage in 1945.  As a result, we were able to clarify the situation immediately after the occurrence of debris flow.  And we also asked about the debris flow damage in 2018 and compared the two damages.
A New 3D Descriptor for Irregularly Shaped Suspended Sediment Aggregates
Authors: Wheatland Jonathan , Spencer Kate , Grieve Stuart , Gu Chuan , Carr Simon , Manning Andrew , Bushby Andrew , Botto Lorenzo
Published: March 2020

Within coastal and estuarine environments suspended cohesive sediments that are often closely associated with carbon, nutrients, pathogens and pollutants form aggregates commonly known as ‘flocs’. Understanding the settling dynamics and eventual fate of flocculated sediment is therefore a major issue for the management of aquatic environments. Several factors have been reported to influence the hydrodynamic behaviour of flocs, including size, shape, density and porosity. Recent evidence suggests that of these shape exerts the greatest influence on settling rates. Yet means of characterising shape have been limited to easy to measure quantities such as fractal dimension and circularity measured in 2-dimensions (2D) that fail to capture the highly complex, irregular geometries of sediment flocs. However, recent improvements in sampling methods, 3D imaging capabilities and data processing software enable for the first time the characterisation of flocs based on their 3D morphology.

This study compares the morphologies of natural and artificial flocs generated under different environmental conditions. By employing a novel apparatus for the capture, immobilisation and handling of delicate floc samples, 3D X-ray micro-computed tomography (X-ray µCT) scans are successfully obtained and used to derive accurate volumetric reconstructions of tens of thousands of individual flocs. Using these datasets we compare different methods for describing shape, and test these for their ability to predict floc settling behaviours.
Forest structure and vegetation dynamics as a driver of global carbon uptake
Authors: Poulter Ben , Calle Leo , Pugh Thomas , McDowell Nathan , Ciais Philippe , Besnard Simon , Carvalhais Nuno , Neigh Christopher , Montensano Paul
Published: March 2020

The drivers for terrestrial carbon uptake remain unclear despite a clear signal that the land removes the equivalent of up to 25-30% of fossil fuel CO2 emissions each year. Recent work has confirmed sustained carbon uptake by the land that is proportional to anthropogenic emissions, meaning that the land 'sink' has strengthened over the past five decades, and with interannual variability driven by climate. Drivers responsible for sustained uptake include hypotheses related to lengthening growing season length, increasing nitrogen deposition, changes in the ratio of diffuse to direct radiation, and land-use and land cover change. More recently, land-use and land-cover change has been investigated as a driver of land carbon uptake owing to an emergence of global-scale datasets related to canopy disturbance, land use, and forest age. At the same time, land-surface models have increased their realism in terms of moving beyond 'big-leaf' model representation of ecosystems to including vertical structure and horizontal heteorogeneity via size-and-age structured approaches. This presentation will address recent work identified forest structure and vegetation dynamics as a driver for global carbon uptake and provide examples of how remote sensing observations have led to new datasets for initialization land-surface models. Compared to inventory-based approaches, land-surface models initialized with forest age show a lessor role in explaining net terrestrial carbon uptake at global scales, but at regional scales, vegetation structure is a key determinant of carbon exchange. New satellite missions improving forest structure observations are expected to reduce uncertainties and contribute substantially to ongoing land-surface model development.
Global validation of the ESA CCI+SSS products
Authors: Martin Adrien , Guimbard Sébastien , Boutin Jacqueline , Reul Nicolas , Catany Rafael
Published: March 2020

The European Space Agency (ESA) Climate Change Initiative for Sea Surface Salinity (CCI+SSS) project aims at generating long-term, improved, calibrated global SSS fields from space. The project started in mid-2018 and in its first year has produced a 9-year dataset (2010-2018) from the three available L-band radiometer satellites (SMOS: Soil Moisture and Ocean Salinity; Aquarius; SMAP: Soil Moisture Active Passive) and validated it against in situ references (Argo and ISAS: In Situ Analysis System). The dataset is available at https://catalogue.ceda.ac.uk/uuid/9ef0ebf847564c2eabe62cac4899ec41.

The comparisons with in situ ground truth indicate much better performances than the ones obtained with a single satellite data product, with global precision against in situ references of 0.16 pss and 0.10 pss in areas with low variability. There is a very good agreement between the CCI dataset and references, including long-term stability, with differences within +-0.05 pss for global ocean within [40°S-20°N]. At higher latitude, we observe seasonal oscillation of the CCI SSS difference against references. The CCI SSS products uncertainty have been validated against references and show good agreement as long as the spatial representativeness is considered in presence of strong spatial gradients in salinity.
How well is the deep Tore seamount basin ventilated?
Authors: Antón Laura , Lebreiro Susana , Nave Silvia , Skinner Luke , Michel Elizabeth , Waelbroeck Claire , Sierro Francisco
Published: March 2020

The Last Glacial Maximum (LGM) was characterized by increased carbon storage in the deep ocean, as well as extremely poorly ventilated southern-sourced deep water (AABW) compared to northern-sourced deep water (NADW).

Here we analyse benthic (Cibicidoides wellerstorfi) d13C, and compare 3 sites sitting on the deep floor at 5 km water depth: MD13-3473 in the Tore inside basin; MD03-2698 in the Iberian margin; and TN057-21 in the South Atlantic. The Tore Seamount is a geological structure 300 km off the West Iberian margin at 40°N latitude. It has a crater-like morphology with a 5500 m deep basin in its middle, where calypso core MD13-3473 was collected, confined from the open ocean by a summit rim at 2200 m water depth (wd). The only connection between the deepest Tore Seamount basin and the Atlantic circulation is a NE gateway down to 4300 mwd.

The results for the LGM show similar values around -1.0 ‰ for the South Atlantic and the Iberian margin, in other words these sites were both bathed by AABW. However, the Tore basin record exhibits values around 0 ‰, similarly to open sites in the Iberian margin at 3.5 km depth. This seems to indicate a remarkable isolation of the Tore inside basin from the Atlantic deep bottom waters influence.

Among other things, we plan to examine the residence time of the Tore basin bottom water by measuring the radiocarbon age difference between benthic and planktonic foraminifera. 

Our results confer to this enclosed environment the status of an in-situ deep ocean laboratory where to test hypotheses of past ocean circulation changes like the role of deep waters in sequestering glacial CO2. Core MD13-3473 covers 430 thousands of years, therefore 5 deglacial cycles (Spanish project “TORE5deglaciations”, CTM2017-84113-R, 2018-2020).
From individualistic behavior to full cooperation: optimal management policy design under varying cooperation levels in the Nile River basin
Authors: Trombetta Giacomo , Castelletti Andrea , Giuliani Matteo , Zaniolo Marta , Block Paul
Published: March 2020

Transboundary river basins worldwide are commonly managed by unique, institutionally independent decision makers and characterized by multiple stakeholders with conflicting interests, including distribution, co-management, and use of water resources across sectors and among countries. This competition is expected to exacerbate in the future due to climate change induced water scarcity, increasing demand, and the development of infrastructure, which is often criticized for potentially jeopardizing downstream security by affecting water supply, irrigation, and energy production. 

The Nile River basin is an emblematic transboundary basin, encompassing 11 countries and home to one-third of the African population. The largest fraction of Nile River streamflow originates in Ethiopia and is conveyed into the system via the Blue Nile. However, the larger water users have historically been downstream, in particular Egypt, where the High Aswan Dam (HAD) constitutes the backbone of Egyptian electricity supply and enables the irrigation of vast agricultural districts. This geographic disparity between water origination and consumption provides both the potential for conflict and the rationale for cooperation. Currently, the ongoing construction of the soon-to-be largest dam in Africa, the Grand Ethiopian Renaissance Dam (GERD) on the Blue Nile, is highly debated given concerns rising from how it will affect water supply and power generation in downstream countries. However, GERD may represent a response to the frequent regional power shortages, foster economic development, and represents a unique opportunity for cooperation between riparian countries from which all parties can benefit.

In this work we explore how varying levels of cooperation among the riparian countries, from individualistic behavior to full cooperation, might impact hydropower production and irrigated agriculture in the Nile River basin. We use an Evolutionary Multi-Objective Direct Policy Search approach to design optimal operation of a three-dimensional reservoir system, including GERD (Ethiopia), HAD (Egypt), and Merowe Dam (Sudan), under historical hydro-climatic conditions and under different cooperation levels, assuming the capacity of re-optimization of the High Aswan Dam and the Merowe Dam. Expected results may illustrate the benefits of implementing a centralized rather than an individualistic strategy, highlighting the value of full information exchange and of basin-wide cooperation.
Two-decade of monitoring spatio-temporal variation of surface albedo over a large saline lake
Authors: Sima Somayeh , Darzi َAmir
Published: March 2020

Saline lakes play a crucial role in regulating the regional climate, supporting unique biodiversity, and providing a diverse range of economic benefits. However, as a result of growing water withdrawals for human use, most of the large saline lakes worldwide are desiccating at a substantial rate. Water level decline and salinity rise affect physico-chemical characteristics of saline lakes including surface albedo. Water surface albedo impacts lake color and evaporation. Here, we investigate spatio-temporal variation of surface albedo over Lake Urmia, in northwest Iran, using the MODerate Resolution Imaging Spectroradiometer (MODIS) albedo product (MCD43D) from 2000 to 2019. Satellite-derived shortwave albedos were validated against in-situ surface albedo data measured at an online net-radiometer station on the lake. We identified two spatial patterns through Lake Urmia: 1) a decreasing trend from the outer shallow zones toward the deep inner parts, and 2) a higher mean albedo of the south arm compared to the north arm in summer. Moreover, the lake albedo varies seasonally with lake level and reaches its peak between September and October. This is mainly due to an increased concentration of total suspended solids (TSS) and phytoplankton (Duanalliea spp.) growth, which accounts for the lake red color between mid-spring and early autumn. Results also revealed that concurrent with the lake level drop since 2000, both lake-averaged surface albedo and its seasonal variation have constantly increased. The increased lake albedo affects net absorbed radiation by the lake and limits lake evaporation. Consequently, we emphasize that for large saline lakes which experience significant areal fluctuations seasonally, the use of a constant albedo to estimate lake evaporation and heat budget is inadequate. Instead, satellite-derived albedo maps encompassing the effect of lake depth, TSS, and phytoplankton growth can be used with confidence. Our findings can contribute to enhanced water, energy, and salt balance models for saline lakes by better estimation of their surface albedo. 

Keywords: Surface albedo, Lake Urmia, MODIS, Water level, Phytoplankton
Internal solitons on the Black Sea shelf: observation of waves of record amplitudes
Authors: Serebryany Andrey , Bondur Valeriy , Zamshin Viktor
Published: March 2020

When conducting work in the fall of 2015 on the Black Sea northeast shelf, we recorded internal waves, the unusualness of which attracts special attention for the following reasons. For the first time in 40 years of internal waves observations in the Black Sea, such high waves with amplitudes of 14–16 m were measured. The generation of these anomalous waves was connected with a cold atmospheric front passing over the sea. It was the first experimental evidence in the sea of such mechanism for internal waves generation. The observed internal waves had a clear seen character of nonlinear soliton-like waves.

We met the train of internal solitons during a sub-satellite survey conducted in the sea from a motor yacht equipped with ADCP “Rio Grande 600 kHz” in the waters near Cape Tolsty. The train was found at a point of the sea with a depth of 33 m and then was recorded on seven multidirectional tacks oriented normal to the coast. It moved across the shelf to the coast along the bottom thermocline, while the bottom currents accompanying it had a northwestern coastal orientation. The train included four waves of a soliton-like shape with sharpened crests and flattened troughs. Their lengths were 100-110 m, heights up to 14-16 m, vertical velocities in orbital currents reached 0.15-0.20 m/s. Another property of nonlinear waves was also expressed - the amplitude ranking of waves in the train. Traced on successive tacks for 2.5 hours, internal waves had preserved the soliton-like shape and as well the strong vertical component in their orbital currents. Despite the fact that the train was moving along the bottom thermocline, the effect of internal waves was sufficient to appear on satellite radar images of the sea surface of the study area. The performed processing of satellite images confirmed the wave parameters measured by contact methods.  An interesting fact of a long accompaniment of internal solitons by a school of fish was discovered. Fishes were concentrated in areas where internal waves carried the components of fish food supply to the surface from the bottom layers. The work was partially supported by RFBR grant 19- 05-00715.
Monitoring and modelling drainage network dynamics of a Mediterranean catchment
Authors: Senatore Alfonso , Liotti Alessio , Micieli Massimo , Durighetto Nicola , Botter Gianluca , Mendicino Giuseppe
Published: March 2020

Empirical evidence indicates that the active part of the drainage networks, i.e. that characterized by flowing water, is not static but, conversely, it experiences significant expansion/contraction dynamics produced by the interactions between hydrological and climatic variability, morphological features and soil properties in the contributing catchment. The expansion and contraction dynamics of the "wet" component of the river network can be identified in a wide range of climatic conditions, particularly in the headwaters. In these areas, the observed river network dynamics largely depend on the capacity of the upstream drainage area to concentrate surface runoff in channelized sites.

The study presents a research activity carried out in the framework of the European project "DyNET: Dynamical River Networks" (http://www.erc-dynet.it/), specifically aimed at analysing in detail the processes and agents overseeing changes in form and in the length of river networks in a Mediterranean environment. The contribution describes the first results achieved in the southernmost of the basins under investigation in the DyNET project, namely the Turbolo creek catchment (Calabria, Southern Italy). Bi-weekly surveys were conducted in two sub-catchments having a total area of more than 1 km2, both during the recession (contraction) and reactivation (expansion) phases of the drainage network. The empirical data were used for the validation of a statistical model of the wet network dynamics, designed to estimate the total length of the active network over time. This length was distributed spatially on the river network in an objective way by defining a two-way relationship between active stream length and the Topographic Wetness Index (TWI). The modelling of the network contraction and expansion dynamics was possible using a few meteorological and hydrological variables. The combined use of information on the overall length of the network and the TWI led to a reasonably good representation of the drainage network dynamics over space and time.
Wave-particle interaction in the Io flux tube
Authors: Janser Sascha , Saur Joachim , Szalay Jamey , Clark George
Published: March 2020

Observations by the JUNO spacecraft revealed energetic, bidirectional particle populations with broadband energy distributions in the high-latitude region of Jupiter. These measurements indicate that an acceleration mechanism of stochastic nature plays a dominant role for the generation of the intense main auroral oval. In our current work, we investigate the heating of an energetic upward proton population recently observed by JUNO in the Io flux tube wake near Jupiter. We try to infer on the relevant physical acceleration process by considering a resonant as well as a non-resonant wave-particle interaction mechanism, both based on Alfven waves. We focus on necessary temporal scales to drive these mechanisms efficiently and also on the released wave energy by means of the transported Poynting flux along the flux tube.
Insights for the Future of Arctic Sea Ice from the CMIP6 lig127k Experiment
Authors: Brady Esther C. , Otto-Bliesner Bette L. , Kageyama Masa ,   PMIP4 and QUIGS team
Published: March 2020

New to CMIP6 is the Tier 1 lig127k experiment, designed to address the climate responses to stronger orbital forcing than the midHolocene experiment, using the same state-of-the-art models and following a common experimental protocol. We present a multi-model ensemble of 17 climate models, all of which (except for two) have also completed the CMIP6 DECK experiments, looking at the lig127k Arctic’s responses across models and the relationships with each model’s Equilibrium Climate Sensitivity (ECS), preindustrial sea ice thickness and 127ka temperature anomalies.

Boreal insolation anomalies at 127 ka enhance the seasonal cycle of Arctic sea ice, though with notable differences among the models. The consensus from the lig127k sea ice distributions is a reduced minimum (August-September) summer sea ice extent in the Arctic as compared to the piControl simulations. Sea ice remains above 15% concentrations over the central Arctic Ocean in all but one of the lig127k simulations. More than half of the models simulate a retreat of the Arctic minimum ice edge similar to the average of the last 2 decades. The lig127k minimum Arctic sea ice area anomalies show a strong negative correlation with the Arctic (60-90°N) annual surface temperature anomalies but only a weak correlation with the corresponding June-July-August (JJA) temperature anomalies. Memory in the ocean and cryosphere provide feedbacks to maintain larger positive temperature anomalies, December-January-February (DJF) and annually, in the Arctic than in JJA. The models contributing to the lig127k ensemble have an ECS varying from 2.1 to 5.3°C. There is a notable relationship between the ECS and simulation of lig127k minimum Arctic sea ice area.  With very limited Arctic sea ice proxies for 127 ka, and with evolving interpretation of the relationships of these proxies with sea ice coverage, it is still difficult to rule out the high or low values of ECS from the proxy data.
Improving global chemical weather forecast with modern online-coupled models for the U.S. Next Generation Global Prediction System (NGGPS)
Authors: Montuoro Raffaele , Grell Georg , Zhang Li , McKeen Stuart , Frost Gregory , Ahmadov Ravan , Henderson Judy , McQueen Jeff , Pan Li , Bhattacharjee Partha , Kain Jack , Baker Barry , Stajner Ivanka , Wang Jun , DeLuca Cecelia , Pleim Jon , Wong David
Published: March 2020

Significant progress has been made within the last couple of years towards developing online coupled systems aimed at providing more accurate descriptions of atmospheric chemistry processes to improve performance of global aerosol and air quality forecasts. Operating within the U.S. National Weather Service (NWS) research-to-operation initiative to implement the fully-coupled Next Generation Global Prediction System (NGGPS), cooperative development efforts have delivered two integrated online global prediction systems for aerosols (GEFS-Aerosols) and air quality (FV3GFS-AQM). These systems include recent advances in aerosol convective transport and wet deposition processes introduced into the SAS scheme of the National Center for Environmental Prediction’s (NCEP) latest Global Forecast System (GFS) based on the Finite-Volume cubed-sphere dynamical core (FV3). GEFS-Aerosols is slated to become the new control member of the NWS Global Ensemble Forecast System (GEFS). The model features an online-coupled version of the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model with a biomass-burning, plume-rise model and recent advances from NOAA Earth System Research Laboratory (ESRL), along with a state-of-the-art FENGSHA dust scheme from NOAA Air Resource Laboratory (ARL). FV3GFS-AQM incorporates a coupled, single-column adaptation of the U.S. Environmental Protection Agency’s (EPA) Community Multiscale Air Quality (CMAQ) model to improve NOAA’s current National Air Quality Forecast Capability (NAQFC). Both coupled systems’ design and development benefited from the use of the National Unified Operational Prediction Capability (NUOPC) Layer, which provided a common model architecture for interoperable, coupled model components within the framework of NOAA’s Environmental Modeling System (NEMS). Results from each of the described coupled systems will be discussed.
Constraining post-glacial temperatures of rock avalanche deposits in the Yosemite Valley with cosmogenic noble gas and luminescence paleothermometry
Authors: Brown Nathan , Tremblay Marissa , Uebner Maura , Stock Greg , Balco Greg , Shuster David
Published: March 2020

Yosemite Valley is renowned for its striking topography, with many sheer granite cliffs carved during past glaciations. At the base of these cliffs many large rock avalanche deposits can be found that were deposited since ice retreated from Yosemite Valley. Cosmogenic 10Be measurements indicate that there are at least 10 different rock avalanche deposits that range in age from 13 to ~1 ka.

In this study, we estimate the time-averaged temperatures experienced by rocks from five of these rock avalanche deposits using cosmogenic noble gas and luminescence paleothermometers. These two systems yield independent estimates of valley floor temperatures during the Holocene, information that is useful for reconstructing the local environmental conditions since deglaciation.

Cosmogenic noble gas paleothermometry utilizes the fact that cosmogenic noble gases like 3He experience thermally-activated diffusive loss at Earth surface temperatures in minerals like quartz. The concentration of cosmogenic 3He in quartz relative to a cosmogenic nuclide that does not experience diffusive loss should therefore be a function of a rock’s thermal history over the duration of its exposure to cosmic ray particles. Apparent 3He boulder exposure ages from these five rock avalanche deposits are 58 to > 98% younger than the corresponding 10Be exposure ages. Preliminary models that combine these 3He observations and sample-specific diffusion parameters indicate that effective diffusion temperatures (EDTs) recorded by 3He in quartz are similar to or higher than the modern EDT from the instrumental record.

Like with the cosmogenic 3He system, thermoluminescence (TL) paleothermometry of K-feldspars also relies upon the balance between steady signal build-up and thermally-activated loss. The difference is that TL derives from trapped electronic charge at defect sites within the feldspar crystal lattice that accumulates in response to natural background radiation. K-feldspar TL signals comprise a range of stabilities. The least stable sites will experience diffusive loss even at temperatures below 0 °C and the most stable sites will accumulate at upper crustal temperatures. By monitoring which sites are occupied and how long those sites have been accumulating charge, we estimate both the ambient temperature and the time spent at that temperature.

We compare and discuss the history of rock temperatures estimated from these two systems with implications for the post-glacial climate of Yosemite Valley.
Variability and decadal trends in the Isfjorden (Svalbard) ocean climate and circulation - an indicator for climate change in the European Arctic
Authors: Skogseth Ragnheid , Olivier Lea L. A. , Nilsen Frank , Jonassen Marius O. , Falck Eva
Published: March 2020

Isfjorden, a broad Arctic fjord in western Spitsbergen, has shown significant changes in hydrography and inflow of Atlantic Water (AW) the last decades that only recently have been observed in the Arctic Ocean north of Svalbard. Variability and trends in this fjord’s climate and circulation are therefore analysed from observational and reanalysis data during 1987 to 2017. Isfjorden experienced a shift in summer ocean structure in 2006, from AW generally in the bottom layer to AW (with increasing thickness) higher up in the water column. This shift, and a concomitant shift to less fast ice in Isfjorden are linked to positive trends in the mean sea surface temperature (SST) and volume weighted mean temperature (VT) in winter (SSTw/VTw: 0.7 ± 0.1/0.9 ± 0.3 °C 10yr-1) and summer (SSTS/VTS: 0.7 ± 0.1/0.6 ± 0.1 °C 10yr-1). The local mean air temperature shows similar trends in winter (1.9 ± 0.4 °C 10yr-1) and summer (0.7 ± 0.1 °C 10yr-1). Positive trends in volume weighted mean salinity in winter (0.21 ± 0.06 10yr-1) and summer (0.07 ± 0.05 10yr-1) suggest increased AW advection as a main reason for Isfjorden’s climate change. Local mean air temperature correlates significantly with sea ice cover, SST, and VT, revealing the fjord’s impact on the local terrestrial climate. In line with the shift in summer ocean structure, Isfjorden has changed from an Arctic type fjord dominated by Winter Deep and Winter Intermediate thermal and haline convection, to a fjord dominated by deep thermal convection of Atlantic type water (Winter Open). AW indexes for the mouth and Isfjorden proper show that AW influence has been common in winter over the last decade. Alternating occurrence of Arctic and Atlantic type water at the mouth mirrors the geostrophic control imposed by the Spitsbergen Polar Current (carrying Arctic Water) relative to the strength of the Spitsbergen Trough Current (carrying AW). During high AW impact events, Atlantic type water propagates into the fjord according to the cyclonic circulation along isobaths determined by the winter convection. This study demonstrates that Isfjorden and its ocean climate can be used as an indicator for climate change in the Arctic Ocean. The used methods may constitute a set of helpful tools for future studies also outside the Svalbard Archipelago.
Riverine Macroplastics and How to Find Them
Authors: van Emmerik Tim , Schwarz Anna
Published: March 2020

Macroplastic (>0.5 cm) pollution in aquatic environments is an emerging environmental risk, as it negatively impacts ecosystems, endangers aquatic species, and causes economic damage. Rivers are known to play a crucial role in transporting land-based plastic waste into the world’s oceans. However, rivers and their ecosystems are also directly affected by plastic pollution. To better quantify global plastic pollution pathways and to effectively reduce sources and risks, a thorough understanding of riverine macroplastic sources, transport, fate and effects is crucial. In our presentation, we discuss the current scientific state on macroplastic in rivers and evaluate existing knowledge gaps. We discuss the origin and fate of riverine plastics, including processes and factors influencing macroplastic transport and its spatiotemporal variation. Moreover, we present an overview of monitoring and modeling efforts to characterize riverine plastic transport and give examples of typical values from around the world (van Emmerik & Schwarz, 2020). With our presentation, we aim to present a comprehensive overview of riverine macroplastic research to date and suggest multiple ways forward for future research.

 

References

van Emmerik, T, Schwarz, A. Plastic debris in rivers. WIREs Water. 2020; 7:e1398. https://doi.org/10.1002/wat2.1398
On brittle-ductile strain localization
Authors: Podladchikov Yury
Published: March 2020

The classification of the strain localization modes is attempted around brittle-ductile transition. The stresses are high. The are a number of suspects: earthquake-like thermal runaway (Braeck et al. 2009), stable sliding as shear heating zones oriented 45 degrees to the principal stresses (Kiss et al. 2019), brittle faults/shear bands oriented ca. 30 degrees to the maximum compressive principal stress and mode 1 fracture. The coupling to the porous fluid hydrology is accounted for.  High resolution numerical simulations are compared to classical and newly derived composite asymptotic solutions.

References

Braeck, S., Podladchikov, Y., & Medvedev, S., 2009. Spontaneous dissipation of elastic energy by self-localizing thermal runaway, Phys. Rev. E , 80, 046105, doi:10.1103/PhysRevE.80.046105.

Kiss, D., Podladchikov, Y., Duretz, T., & Schmalholz, S., 2019. Spontaneous generation of ductile

shear zones by thermal softening: Localization criterion, 1D to 3D modelling and application to the

lithosphere, Earth Planet. Sci. Lett., 519, 284–296, doi:10.1016/j.epsl.2019.05.026.
A 1300-year reconstruction of the South Pacific Convergence Zone using a Pacific-wide tree-ring network
Authors: Higgins Philippa , Palmer Jonathan , Turney Christian , Andersen Martin , Cook Edward
Published: March 2020

The South Pacific Convergence Zone (SPCZ) is the largest driver of precipitation variability over South Pacific island communities during the austral warm season influencing the severity and duration of drought and the frequency of tropical cyclones. The SPCZ is known to exhibit variability on a range of timescales, from intra-seasonal to multidecadal variations, modulated by the Interdecadal Pacific Oscillation (IPO). Despite its climatic and societal importance, determining the causes of low frequency variability in the SPCZ has been hampered by the short instrumental data record, with most comprehensive analyses since the satellite era. Here we report the first paleoclimate reconstruction of the SPCZ, allowing climate variability in the South Pacific region to be explored back to 700 CE. Our 1300-year reconstruction of the SPCZI (South Pacific Convergence Zone Index; the difference between mean sea level pressure between Apia, Samoa and Suva, Fiji) is based on a trans-Pacific network of precisely dated tree-ring proxies. Capturing SPCZ teleconnections from both sides of the Pacific has produced a robust, unbiased reconstruction with excellent reconstruction skill over the entire period. El Niño-Southern Oscillation periodicities (∼3-7 years) are pervasive throughout the SPCZI reconstruction. Multidecadal periodicities wax and wane, apparently coinciding with the timing of the Medieval Climate Anomaly (c. 1000-1200 CE) and Little Ice Age (1300-1700 CE). We discuss some of the drivers of SPCZI variability including global dimming events. Our reconstruction helps improve our understanding of past hydroclimatic behaviour in the southwest Pacific and can be used to validate general circulation model projections for Pacific Island communities in the twenty-first century.