bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of carbon to nitrogen ratios on amounts and composition of Bacillus subtilis biofilms
Authors: Cortes Osorio Natalia , Endrika Robert , Kalbitz Karsten , Vogel Cordula
Published: March 2020

In natural environments, bacteria can be found as multicellular communities exhibiting a high degree of structure, denominated biofilms. Biofilms are composed of microbial cells, often of multiple species, embedded within a matrix of extracellular polymeric substances (EPS). The exact composition, physical and chemical properties, and amounts of these components varies depending on their growth conditions. However, it remains unclear how nutrient availability drives the allocation into cell growth or EPS production, especially under conditions found in soils. Here we aimed to evaluate the effect of various C/N ratios on Bacillus subtilis biofilm growth (spatial expansion and structure) and their EPS composition. We hypothesized that the largest biofilm development and highest EPS production by Bacillus subtilis would be caused by a nutrient imbalance reflected in C/N ratios, especially high C availability. Biofilms were grown on membranes on MSgg agar plates with C/N ratios of 1:1, 10:1, 25:1 and 100:1. Several methods from macroscopic observations over EPS extraction and determination up to various microscopic visualisation techniques were used. The radial expansion of the biofilm was measured, followed by EPS extraction to quantify EPS-proteins and EPS-polysaccharides. Hydrated biofilm samples were studied regarding their biofilm structures by scanning electron microscopy (SEM) within the environmental mode at approximately 97% humidity. Fixed, dehydrated and embedded samples were used to evaluate the biofilm height and internal structure with SEM in high vacuum mode. Low C/N ratio (1:1) resulted in the smallest biofilms in terms of radial expansion and biofilm height, with densely packed layers of cells and low amounts of EPS. Our first results revealed that the highest biofilm productions were observed at C/N ratio of 10:1 and 25:1. The microscopic approaches indicated that biofilms growing at C/N ratios of 100:1 produced the highest amount of EPS. Furthermore, changes in the microscopical features of the biofilms were detected with different structures along the biofilm regions affected by the nutrient conditions. These results suggest that the C/N ratio has a large impact on the biofilm development and structure, with different allocations into microbial cells and EPS. Overall, the results obtained until now allowed us to accept the initial hypothesis, indicating that higher C/N ratios induce a higher EPS production. This suggests that environments containing a high ratio between carbon and the limiting nutrient, often nitrogen, may favour polysaccharide production, probably because energy from the carbon excess is used for polysaccharide biosynthesis.
Improving The Municipal Solid Waste Management Plan Of The Municipality Of Nemocón (Colombia)
Authors: Vargas Terranova Camilo Andrés , Rodrigo Ilarri Javier
Published: March 2020

IMPROVING THE MUNICIPAL SOLID WASTE MANAGEMENT PLAN OF THE MUNICIPALITY OF NEMOCÓN (COLOMBIA)

CAMILO-ANDRÉS VARGAS-TERRANOVA(1) and JAVIER RODRIGO-ILARRI(2)

(1)Universidad de La Salle, Bogotá, Colombia (cvterranova@unisalle.edu.co)

(2)Instituto de Ingeniería del Agua y del Medio Ambiente (IIAMA), Universitat Politècnica de València, Spain (jrodrigo@upv.es)

 

ABSTRACT

The municipality of Nemocón (Colombia) located 45 km from Bogotá generates 810.3 t/year of municipal solid waste (MSW). Despite the Colombian national legal requirements, Nemocón Solid Waste Management Plan (SWMP) shows important deficiencies in the waste management system, especially concerning the final destination of waste.

During 2019 a set of activities have been performed in the town as an initial response to these needs with the participation of the community and local authorities. First, the design of the waste collection routes was analyzed and improved. Two routes were designed, supported by compacting vehicles with an average time of 3 hours (80 km per route) and 3 routes per week each. Besides, two shorter routes were designed for the collection of recyclable waste, supported by hand-drawn vehicles, with operating times of 6 hours (8-10 km per route) and daily routes.

With the support of students from the University of La Salle and the donation of an abandoned building, a Classification and Use Station (CUS) was implemented to strengthen the management of such recyclable waste. The CUS was provided with personal protection elements to improve their condition as managers of minor routes and the preliminary treatment of waste in the CUS, for later sale to wholesalers external managers.

Finally, a tax system was designed to finance the operation of the CUS (2500-2800 Euros/month) and promote greater separation volumes in the midterm, based on an adjustment to the normal payment made by the users for the service of waste collection and management. This system took into account the different types of users (commercial, industrial, residential and official), local socioeconomic scale and national economic variables. The increased rate varies between 1 and 1.5% for all users in the first year of increase.
Chemostratigraphy of Triassic successions on the southern Barents Sea Shelf – preliminary results from XRF Core Scanning.
Authors: Kvendbø Hegstad Sigrun Maret , Ahokas Juha , Forwick Matthias , Grundvåg Sten-Andreas
Published: March 2020

The Barents Sea Shelf on the north-western corner of the Eurasian plate has a complex geological history, comprising large-scale processes controlled by plate movements, climatic variations and changing depositional environments. During the last decades, as the search for hydrocarbons within the area gained increased interest, Triassic sequences have been the target of comprehensive investigations. In our project, we test the potential of improving the correlation of Triassic strata using X-ray fluorescence (XRF) core scanning of siliciclastic drill cores.

XRF core scanning is a frequently used method on soft sediment cores, e.g. within marine geology and palaeo-climate studies. However, the applicability of this method on drill cores from exploration wells from the hydrocarbon industry has not been tested so far. We use this method to establish geochemical stratigraphic parameters, as well as to contribute to the identification of provenances, reconstruct palaeo-envrionments, and support the correlation of drill cores. This provides a novel, fast, inexpensive, and non-destructive method to be applied in hydrocarbon exploration, as well as in studies of lithified siliciclastic sediments in general.

Triassic intervals from 24 shallow drill cores from the southern Barents Sea (Finnmark Platform, Nordkapp Basin, Svalis Dome, Maud Basin and Bjarmeland Platform) provide the basis for this study. The cores have previously been comprehensively studied and described by IKU (the Norwegian Continental Shelf Institute; today SINTEF Petroleum Research), and studies of provenance and palaeo-environment have also been performed (e.g. Vigran et al., 1986). This data makes it possible to compare the geochemical units established in this study with other stratigraphic information.

We present preliminary results of establishing geochemical units from XRF core scanning, and the use of these for correlation within known stratigraphic frameworks and between geographic areas, as well as to increase the understanding of changes in provenance and palaeo-environments within these successions in the Barents Sea.

References:
Vigran, J.O., G. Elvebakk, T.L. Leith, T. Bugge, V. Fjerdingstad, R.M. Goll, R. Konieczny, and A. Mørk. 1986. 'Dia-Structure Shallow Drilling 1986. Main data report. IKU Rep. No. 21.3420.00/04/86, 242 pp'.

 
UAV-based classification of tree-browsing intensity in open woodlands
Authors: Marzolff Irene , Stephan Robin , Kirchhoff Mario , Seeger Manuel , Aït Hssaïne Ali , Ries Johannes B.
Published: March 2020

In semi-arid to arid South-west Morocco, the endemic argan tree (Argania spinosa) forms open woodlands that are the basis of a traditional agroforestry system involving rain-fed agriculture, pasturing of goats, sheep and camels, and oil production. Due to the high grazing pressure, the trees show various morphological traits and growth forms that are strongly related to browsing intensity. The overall appearance of Argania spinosa ranges from trees with a large, round crown and single trunk, over multi-stem, umbrella-shaped and hourglass-shaped trees to heavily condensed cone-shaped cushions.

30 test sites of 1 ha each in argan woodlands of different degradation stages were surveyed with an unmanned aerial vehicle (UAV) and RGB optical camera using a dedicated flight scheme for capturing full 3D tree shape at approx. 1 cm resolution. Structure-from-Motion (SfM)-photogrammetric processing yielded dense 3D point clouds as well as ultra-high resolution (1.5 cm) digital surface models (DSMs), terrain models (DTMs), crown-height models (CHMs) and orthophoto mosaics. Tree height and crown size were extracted from the CHMs, and 3D point-cloud characteristics (point density, profile shape/layer structure) and canopy structures were analysed within a geographical information system (GIS). Using field-based reference data on tree architecture and browsing features of 2494 trees, we were able to assign characteristic combinations of the GIS-derived structural parameters to three browsing-intensity classes and thus classify each argan tree via the architectural shape captured in its UAV-based 3D point cloud. We found that the majority of argan trees at the study sites are characterised by high browsing intensities. The small percentage of trees in the minimum browsing class are mostly inaccessible to grazing livestock. We conclude that UAV-based remote sensing has a high potential for mapping structural indicators of tree degradation by herbivore browsing in open woodland environments.
The GEWEX High Mountain Activities and Its Relevance to the Andean Region
Authors: van Oevelen Peter
Published: March 2020

The importance of high mountain regions for global energy and water exchanges research is paramount and yet at the same time they are one of the lesser understood and under-observed regions in the world. The Global Energy and Water Exchanges (GEWEX) Core Project  as part of the World Climate Research Programme has as one of its foci high mountain regions. In particular, it aims to develop a global network of researchers that work in these regions. The Andean region is of particular interest as it has specific climate and weather related challenges unique to this region. We will present how this new initiative for Regional Hydroclimate Project in the Andes fits in the overall suite of activities of GEWEX, how it relates in particular to other regional hydroclimate projects and how it can contribute to a better understanding of the geophysical processes in high mountain environments.
MMS observations of wave activity in the particle foreshock bubble foreshock region
Authors: Wang Mengmeng , Shi Quanqi
Published: March 2020

Foreshock bubbles (FBs) are kinetic transient phenomena formed due to the interaction between IMF discontinuities and backstreaming energetic ions in Earth’s foreshock region. FBs can be driven by both rotational discontinuities and tangential discontinuities and are typically observed under higher solar wind speed conditions. They play important roles in the solar wind-magnetosphere coupling because of very large dynamic pressure variations associated with them. The trailing edge of an FB is usually a fast shock which forms due to the expansion of the thermal plasma in the core. Using data from Magnetospheric Multiscale (MMS) mission, we investigate an FB structure with a particle foreshock region upstream its trailing edge. Distinct wave activity is observed in the particle foreshock region and wave analysis shows that the waves with periods of a few seconds may be generated by shock-reflected ion instabilities. The ions reflected at FB shock are observed and the acceleration mechanism needs to be analyzed.
Prospects for the APPLICATE Project on advanced prediction in the Arctic and beyond
Authors: Bojovic Dragana , Cristini Luisa ,   APPLICATE Consortium
Published: March 2020

The effects of a changing climate are manifesting rapidly, particularly in the Arctic region, and these changes are potentially influencing weather and climate in the mid-latitudes. To understand the scope of these changes and their impacts, it is fundamental to have a better understanding of these processes and work on enhancing weather and climate predictions. It is with this motivation that a European consortium of scientists set out to advance our capability to predict the weather and climate in the Arctic and beyond in the framework of the EU-funded H2020 project APPLICATE. The project started in 2016 with a budget of 8M€ with the objective of improving the representation of key processes in coupled atmosphere-sea ice-ocean models, delivering enhanced numerical weather forecasts, seasonal to interannual climate predictions and centennial climate projections. The project put particular emphasis on the linkages between the Arctic and mid-latitudes, which are explored through a coordinated multi-model approach using coupled atmosphere-ocean models. APPLICATE is contributing to the design of the future Arctic observing system to improve our capacity to reanalyse the climate system and enhance models’ predicting skills, establishing collaborations with other programmes (e.g., within the EU-Polar Cluster). The project has also strong stakeholder engagement and training components, which see the dissemination of the scientific results as a priority and aim to enhance the communication scope of the project and add to knowledge co-production. 

In this presentation, we will give an overview of APPLICATE activities as part of our effort to understand changes in the Arctic and their far-reaching impacts for both environment and communities. We will summarise the main achievements of the project since the start in November 2016 and outline the work of the various task teams until the end of the project. The results achieved so far demonstrate a vibrant engagement of young researchers in the field of climate science and the important role the project plays in developing these scientists.
Changes in the temperature sensitivity of surface ozone production: a case-study based on long-term observations in Austria
Authors: Mayer Monika , Staehle Christoph , Schmidt Christian , Rieder Harald E.
Published: March 2020

As the production of ozone in surface air is determined by ambient temperature and by the prevalent chemical regime, a very different temperature dependence of ozone production emerges for NOx and VOC limited regions. In this study we evaluated the temperature sensitivity of ozone production for rural, suburban as well as urban sites in Austria on seasonal basis. The analysis is based on observational data from Austrian monitoring networks for the time period spanning 1990 – 2018. Surface ozone, nitrogen oxides (NOx), daily sums of global radiation and minimum daily temperature are used as covariates in our study. The observed NOx to VOC ratio at individual sites is variable over time due to changes in precursor emissions and/or the variability of meteorological parameters such as mixing layer height. At the site level we relate the temperature sensitivity of ozone production to the daily mean NOx mixing ratio and the daily minimum temperature. This information allows us to determine the impact of past/future temperature changes on surface ozone  abundance in the context of reductions of NOx emissions and changing methane backgrounds.
Slowing down the overturning – Insights from conceptual modelling on a stably stratified Mediterranean Sea during the Messinian Salinity Crisis
Authors: Ebner Ronja , Meijer Paul
Published: March 2020

Although the Mediterranean is known for its equable climate, this does not apply on geological timescales. At the end of the Miocene, salinity of the Mediterranean Sea exceeded gypsum and halite saturation, leading to the youngest known salt giant to form in a relatively short time span. This event is called the Messinian Salinity Crisis. Insight into the exact circumstances leading to this extreme situation would increase our understanding of today’s system and how it would react to climatic changes. Some of the theories rely on a drastic change in circulation, leading to a stably stratified water column at high salinities. It is yet to be determined how realistic these ideas are.

Conceptual box models can help to find answers to this. In a previous study it was already shown that a decrease in the rate of deep water formation in the margins can lead to a stratified water column. Here we used a predefined value for the overturning. In contrast, in the present study, the circulation, including the exchange through the strait of Gibraltar, is dynamically driven by density differences. By modelling stratification for various assumptions regarding the efficiency of the strait of Gibraltar, evaporation and the connectivity of the margins, this set-up ables us to get in-depth insights regarding the system in general, and the influence of climate and bathymetry on the circulation, specifically.

This model brings us one step closer to an understanding of the circumstances of this extreme state of the Mediterranean Sea
Frontal accretionary wedge structure from seismic reflection imaging in the Lesser Antilles, Guadeloupe-Antigua sector
Authors: Li Lianjun , Carton Hélène , Feuillet Nathalie , Bénâtre Gaëlle , Pan Yaocen
Published: March 2020

The Lesser Antilles Subduction Zone (LASZ), forming the plate boundary between North and South American plates and the Caribbean plate, has not produced any recent large instrumentally recorded thrust earthquake. The 1843 earthquake event (~Mw 8.5) located offshore Guadeloupe is possibly subduction thrust related. Previous studies in the north-central LASZ based on active source seismic data have examined the overall configuration of the forearc domain, especially the geometry of the backstop and effect of subducted oceanic ridges. However, the detailed architecture of the accretionary wedge is still poorly known, as are wedge structures like splay faults that may host slip during future megathrust ruptures. In this study, we use selected re-processed deep multichannel seismic (MCS) profiles from the SISMANTILLES surveys (2001, 2007) and higher-resolution MCS profiles from the CASEIS survey (2016) complemented by a bathymetric data compilation. Analysis of this combined dataset yields a more comprehensive characterization of the accretionary wedge offshore Guadeloupe and reveals features that had not been previously described in this area.

The time-domain seismic data processing sequences was performed on selected MCS profiles from the SISMANTILLES surveys (profiles H, I and K) to mitigate the strong background noises and the ringy effect from the single-bubble air-gun source. The reprocessed images clearly show the presence of arcward-dipping splay faults extending from décollement to the seafloor. The most prominent one roughly delineates a boundary between the more topographically elevated inner wedge and the less-elevated frontal domain of the accretionary wedge. We estimate an along-strike (N-S) extent of ~168 km for the identified splay faults, between 16°12′N and 17°21′N; their northward continuation is then disturbed by the subducting Barracuda Ridge. In the vicinity of the northern flank of the Barracuda Ridge, landward of the deformation front, we observe a duplex-type structure above the décollement. Its geometry is reminiscent of the initial stage of the development of underplating duplexes as observed in analog models. We suggest that the evolution of such underplating basal duplex may result from the increase in friction due to the subduction of Barracuda Ridge and the increase in sedimentary loading on its northern flank. This observation highlights the complex role played by the Barracuda Ridge on the shaping and deformation of the frontal prism.
The Role of Data Systems to Enable Open Science
Authors: Ramachandran Rahul , Bugbee Kaylin , Murphy Kevin
Published: March 2020

Open science is a concept that represents a fundamental change in scientific culture. This change is characterized by openness, where research objects and results are shared as soon as possible, and connectivity to a wider audience. Understanding about what Open Science actually means  differs from various stakeholders.

Thoughts on Open Science fall into four distinct viewpoints. The first viewpoint strives to make science accessible to a larger community by focusing on allowing non-scientists to participate in the research process through citizen science project and by more effectively communicating research results to the broader public. The second viewpoint considers providing equitable knowledge access to everyone by not only considering access to journal publications but also to other objects in the research process such as data and code. The third viewpoint focuses on making both the research process and the communication of results more efficient. There are two aspects to this component which can be described as social and technical components. The social component is driven by the need to tackle complex problems that require collaboration and a team approach to science while the technical component focuses on creating tools, services and especially scientific platforms to make the scientific process more efficient. Lastly, the fourth viewpoint strives to develop new metrics to measure scientific contributions that go beyond the current metrics derived solely from scientific publications and to consider contributions from other research objects such as data, code or knowledge sharing through blogs and other social media communication mechanisms. 

Technological change is a factor in all four of these viewpoints on Open Science. New capabilities in compute, storage, methodologies, publication and sharing enable technologists to better serve as the primary drivers for Open Science by providing more efficient technological solutions. Sharing knowledge, information and other research objects such as data and code has become easier with new modalities of sharing available to researchers. In addition, technology is enabling the democratization of science at two levels. First, researchers are no longer constrained by lack of infrastructure resources needed to tackle difficult problems. Second, the Citizen Science projects now involve the public at different steps of the scientific process from collecting the data to analysis.

This presentations investigates the four described viewpoints on Open Science from the perspective of any large organization involved in scientific data stewardship and management. The presentation will list possible technological strategies that organizations may adopt to further align with all aspects of the Open Science movement. 
Using cave data for improving the reliability of karst groundwater flow models
Authors: Parise Mario , Liso Isabella Serena
Published: March 2020

Rock masses are typically anisotropic and heterogeneous, due to presence of sin-sedimentary discontinuities as bedding planes and of post-depositional features such as joints and faults. When compared to soil mechanics, therefore, a greater complexity of the simulation models for rock masses derives, which is further increased when dealing with carbonate rock masses. Beside the aforementioned types of discontinuities, other features are produced by karst processes; these latter are able to create highly complex networks of voids and conduits, with passages of variable size, which may reach dimensions enterable by man. These features definitely represent the larger discontinuity families within carbonate rock masses, in terms of size, frequency, and pervasiveness, and significantly control the flow of water.

The peculiar characteristics of karst require dedicated approaches to take into the due account the presence of its typical landforms (voids, conduit/caves of variable size, swallow holes, etc.), and their variable functionality as well. Ignoring karst features in the analysis and characterization of carbonate rock masses, any approach followed, or model implemented, will inevitably result in too great uncertainties (if not errors), and in incorrect information to the engineers.

What stated above is true also as regards the study of water flow in fractured carbonate rock masses, that cannot be initiated without considering the stratigraphic and structural discontinuity families. To implement flow models scholars typically start from traditional structural-geological surveys, characterization of rock masses through the classical geomechanical approaches, and elaboration of outcrop pictures elaborated by means of image process softwares. The statistical outcomes are then used as parameters in mathematical models, where also the hydrogeological boundary conditions need to be defined.

A significant step forward in this approach is the use of data directly collected underground, through surveys within the cave systems. The data so collected can be used with a two-fold goal: first, to add a view from the inside of the karst underground landscapes to what is generally observed only at the surface; second, to validate the models, when these are initially implemented only with surface data.

Plan maps of explored cave systems may be useful to determine in first approximation the main direction of development of the karst processes. Reliable maps of caves are nowadays available, that can be used to extract the main direction of karstification, as well as the average size of the explored karst conduits and passages. All these informations are precious underground-truth data that are definitely worth to be included in hydrogeological models aimed at improving them and their reliability as well.

 
Deep Learning for Precipitation Estimation from Satellite and Rain Gauges Measurements
Authors: Moraux Arthur , Dewitte Steven , Cornelis Bruno , Munteanu Adrian
Published: March 2020

In the coming years, Artificial Intelligence (AI), for which Deep Learning (DL) is an essential component, is expected to transform society in a way that is compared to the introduction of electricity or the introduction of the internet. The high expectations are founded on the many impressive results of recent DL studies for AI tasks (e.g. computer vision, text translation, image or text generation...). Also for weather and climate observations, a large potential for AI application exists.

We present the results of the recent paper [Moraux et al, 2019], which is one of the first demonstrations of the application of cutting edge deep learning techniques to a practical weather observation problem. We developed a multiscale encoder-decoder convolutional neural network using the three most relevant SEVIRI/MSG spectral images at 8.7, 10.8 and 12.0 micron and in situ rain gauge measurements as input. The network is trained to reproduce precipitation measured by rain gauges in Belgium, the Netherlands and Germany. Precipitating pixels are detected with a POD of 0.75 and a FAR of 0.3. Instantaneous precipitation rate is estimated with a RMSE of 1.6 mm/h.

 

Reference:

[Moraux et al, 2019] Moraux, A.; Dewitte, S.; Cornelis, B.; Munteanu, A. Deep Learning for Precipitation Estimation from Satellite and Rain Gauges Measurements. Remote Sens. 2019, 11, 2463.
Anoxic bottom water condition during the Deccan volcanism: Multi-proxy evidences from a shallow marine sequence in Rajahmundry, SE India
Authors: Roy Sohom , Sanyal Prasanta
Published: March 2020

Major events like global anoxic episodes and mass extinctions are often associated with the eruption of Large Igneous Provinces (LIPs) in the geological past. The Deccan Trap eruption in the end-Cretaceous period in India forms the second-largest LIP and has often been causally linked to the Cretaceous-Paleogene Boundary (K/PgB) mass extinction event. To date, however, environmental reconstructions from pre- and post-volcanic sequences (infra- and inter-trappean, respectively) have mostly been qualitative and fragmentary and as a result, the effects of volcanism on the adjacent environmental conditions are still not well understood. Here, we present evidence of bottom water anoxia as a direct consequence of the Deccan volcanism. For this work, we analyzed major and trace element abundance, total organic carbon (TOC), bulk carbon isotope composition (δ13Corg), and molecular characterization of organic matter (OM) from shallow marine trappean sediments in Rajahmundry, SE India, where the main volcanic episodes separating the infra- and inter-trappean sediments also encompass the K/PgB. The infra-trappean shows overall low TOC (<0.1%) and δ13Corg (–26.3±0.4‰) values, with relatively higher concentrations of longer-chained n-alkane homologues and detrital elements (Al, Ti, Th, K) suggesting a larger contribution from terrestrial derived OM. Across volcanism, however, there is considerable decrease in terrigenous influx, as well as lowering in Pristane/Phytane ratios (<0.6) and enrichment in redox-sensitive elements like Mo, U, V and Co. This is also accompanied by contemporaneous increases in TOC (~0.6%) and δ13Corg values (~3.9‰), suggesting that the change from oxic to sub-oxic or anoxic condition after the main volcanic episode led to increased OM burial and perturbations in the shallow marine carbon reservoir. Higher supply of micro-nutrient during this interval, as evidenced from enrichment in Ba, Fe, Ni and Zn possibly suggest that hydrothermal recycling and initial phases of eutrophication led to depletion in the bottom-water oxygen levels. Temperature increases due to CO2 degassing from volcanism may have further decreased the solubility of oxygen in the sea-waters; however, further studies from the volcanic province are required to ascertain the underlying causes and extent of perturbations and ultimately, to better constrain the complex environmental feedbacks associated with the Deccan volcanism.
3D multi-resolution mapping of Valles Marineris for better understanding of RSL formation
Authors: Tao Yu , Muller Jan-Peter , Conway Susan
Published: March 2020

Recurring Slope Lineae (RSLs) are metre- to decametre-wide dark streaks found on steep slopes, which lengthen downslope during the warmest times of the year, fading during the cooler periods and reappearing again in the next Martian year. This behaviour has been linked to the action of liquid water, but as liquid water is thermodynamically unstable under current martian conditions this interpretation is under vigorous debate. A better understanding of the formation process of RSLs is therefore fundamental to constraining Mars’ water budget and habitability. One of the key components for studying the RSL process is accurate knowledge of the slopes and aspects.

 

The Valles Marineris (VM) area has the highest concentration of RSLs found on Mars as well as being a location where the triple point of water can be reached during the Martian summertime. This study focuses on multi-resolution 3D mapping of the whole VM area with all digital terrain models (DTMs) vertically referenced to the global standard Mars Orbiter Laser Altimeter (MOLA) surface. A multi-resolution DTM has been generated consisting of 82 Mars Express High Resolution Camera (HRSC) 50m DTMs and 1763 Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) 18m DTMs which will be presented. For 3 selected study areas (Coprates Montes, Capri Mensa, Nectaris Montes), terrain corrected and co-registered MRO High Resolution Imaging Science Experiment (HiRISE; at 0.25m), Compact Reconnaissance Imaging Spectrometer for Mars (CRISM; at 20/50m) and ExoMars Trace Gas Orbiter (TGO) Colour and Stereo Surface Imaging System (CaSSIS; at 2.5m) colour images and associated DTMs will be discussed.

 

Acknowledgements

The research leading to these results is receiving funding from the UKSA Aurora programme (2018-2021) under grant no. ST/S001891/1.
Land Surface Temperature and Miombo forest canopy phenophases: what induces leaf fall and leaf flush?
Authors: Zimba Henry , Coenders-Gerrits Miriam , Kawawa Banda , Nyambe Imasiku , Savenije Hubert , Winsemius Hessel
Published: March 2020

Miombo woodland is the most widespread tropical seasonal woodland and dry forest formation in Africa covering between 2.7 and 3.6 million km2 in eleven countries. Leaf fall and leaf flush during the dry season is a major characteristic feature of the various Miombo species. However, the question on what induces the leaf fall process is by far inconclusive. Different studies indicate either moisture or temperature or both elements as inducers for leaf fall. Knowing what induces leaf fall is important for studying the consequence of e.g., climate change on the Miombo forest. To better understand the driver of leaf fall in Miombo forest we employed a simple remote sensing and statistical analysis approach using long term averages (2009 – 2018) of Land Surface Temperature (LST) of the Miombo forest, various vegetation indices (VI), actual evaporation (Ea), and root zone soil moisture (SM). The vegetation indices (VI) included the Normalised Difference Water Index (NDWI) as indicator of vegetation water content and the Normalised Difference Vegetation Index (NDVI) as indicator of plant photosynthetic activities and leaf cover. Results showed that the NDWI, NDVI, Ea and SM begun to decline immediately following the end of the rainy season in early April while the LST remained relatively constant before it began to decline in May when leaf fall in some Miombo species begins. Hysteresis graphs revealed that vegetation water content (i.e. NDWI) responded quicker to changes in both LST and SM. Furthermore, high rates of decrease in NDWI and NDVI values were observed between July and September the same period when LST increased. This is also the same period when leaf fall intensifies in Miombo forest. Correlation analysis revealed strong season-dependent LST relationship with VI and SM with the rainy season exhibiting strong negative linear correlations (R2 = 0.77, 0.91, 0.88; for the NDWI, NDVI and SM respectively). In the dry season relatively weaker negative correlations (R2 = 0.52, 0.60, 0.55; for NDWI, NDVI and SM respectively) were observed. On the other hand SM showed strong positive linear correlations (R2 > 0.6) with NDWI and NDVI (for the rainy and dry seasons respectively). The correlations imply that in Miombo forest soil water content (i.e. SM), vegetation water content (i.e. NDWI) and the photosynthetic activities and leaf cover (i.e. NDVI) declines with increase in LST. These relationships show the possibility of land surface temperature being a major inducing element of leaf fall and changes in canopy structure in the Miombo woodland.
A more complete Rossby wave source
Authors: Wicker Wolfgang , Greatbatch Richard
Published: March 2020

Tropical convection drives extratropical variability on subseasonal to interannual time-scales by exciting Rossby wave trains in the upper troposphere. Traditionally the relevant Rossby wave source is considered to be the sum of vortex stretching and vorticity advection by the divergent horizontal flow ( - ∇·uχ (ζ+f) - uχ·∇ (ζ+f)). Since absolute vorticity is very small at the equator, the equatorward flanks of the upper tropospheric jets have been regarded the source region of Rossby wave trains. In these considerations vertical momentum advection is neglected, although, it is an important source for westerly momentum at the equator. The curl of vertical momentum advection is the sum of vertical vorticity advection and vortex tilting ( -  ω ζp - ωx vp + ωy up). These contributions are smaller than the traditional Rossby wave source in midlatidues by about one order of magnitude but they are of similar size in the tropics.
Relaxing segmentation on the Wasatch fault zone: impact on seismic hazard
Authors: Valentini Alessandro , DuRoss Chrisopher , Field Edward , Gold Ryan , Briggs Richard , Visini Francesco , Pace Bruno
Published: March 2020

The Wasatch fault zone (WFZ) is one of the most studied normal fault systems in the world and one of the most hazardous in the United States as it has paleoseismic evidence of repeated Holocene surface-faulting earthquakes and occurs within the densely urbanized Wasatch Front region. Here, we develop an earthquake rupture forecast for the WFZ that quantifies the 50-year probability of all potentially damaging earthquakes above Mw 6.2. Our goal is to evaluate the impact that models of fault segmentation (i.e., hard limits on rupture extent) have on seismic hazard. We evaluate the long-term rate of ruptures on the WFZ, adapt standard inverse theory used in the Uniform California Earthquake Rupture Forecast 3, and implement a segmentation constraint where ruptures that cross primary structural complexities are penalized. Penalized ruptures have low rates or are removed from the inversion. We develop and test three segmentation models, including (1) a segmented model in which ruptures are confined to individual segments, (2) a penalized model where some multi-segment ruptures are allowed, and (3) an unsegmented model in which all ruptures are allowed, and none are penalized. Our results show that mean seismic hazard is highest in the segmented model because of more frequent moderate-magnitude (Mw 6.2–6.8) ruptures and lowest in the unsegmented models. We evaluate the change in hazard curves and maps from these segmentation models, test how other parameters such as slip rate and magnitude-scaling relations affect our results and conclude that segmentation exerts a primary control on seismic hazard. Our study demonstrates the need for additional geologic observations of prehistoric rupture extent as well as methods to include this information in hazard assessments.
Rising Temperatures Increase Importance of Oceanic Evaporation as a Source for Continental Precipitation
Authors: Findell Kirsten , Keys Patrick , van der Ent Ruud , Lintner Benjamin , Berg Alexis , Krasting John
Published: March 2020

Understanding vulnerabilities of continental precipitation to changing climatic conditions is of critical importance to society at large. Terrestrial precipitation is fed by moisture originating as evaporation from oceans and from recycling of water evaporated from continental sources. In this study, continental precipitation and evaporation recycling processes in the Earth system model GFDL-ESM2G are shown to be consistent with estimates from two different reanalysis products. The GFDL-ESM2G simulations of historical and future climate also show that values of continental moisture recycling ratios were systematically higher in the past and will be lower in the future.

Global mean recycling ratios decrease 2%–3% with each degree of temperature increase, indicating the increased importance of oceanic evaporation for continental precipitation. Theoretical arguments for recycling changes stem from increasing atmospheric temperatures and evaporative demand that drive increases in evaporation over oceans that are more rapid than those over land as a result of terrestrial soil moisture limitations. Simulated recycling changes are demonstrated to be consistent with these theoretical arguments. A simple prototype describing this theory effectively captures the zonal mean behavior of GFDL-ESM2G.

Key sources of terrestrial evaporation, notably the interior of the Amazon basin and parts of the Ganges-Brahmaputra and Indus River basins, may experience reductions in moisture recycling. This has implications for key sink regions of terrestrial recycled precipitation, especially in rain-fed agricultural regions where crop yields will become increasingly soil moisture limited, such as the La Plata River basin, the corn producing regions of North America, southern Africa and the Sahel.

The results presented here have been published last year in Journal of Climate dx.doi.org/10.1175/JCLI-D-19-0145.1

 
The seasonal and zonal differences in the temperature, circulation and composition of the tropical upper troposphere and lower stratosphere due to the MJO
Authors: Tweedy Olga , Oman Luke , Waugh Darryn
Published: March 2020

The intraseasonal (20-90 day) variability of the tropical upper troposphere/lower stratosphere (UTLS)  is dominated by the Madden-Julian Oscillation (MJO). Previous studies showed a strong connection between the MJO and variability in the UTLS circulation and trace gases. However, seasonality of UTLS circulation and trace gas response to the MJO has received very little attention in the literature. In this study, we use observations of trace gases (ozone, carbon monoxide and water vapor) and temperature from the Microwave Limb Sounder (MLS, version 4) and meteorological fields from the Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) reanalyses to examine and explain the seasonal and zonal differences in the UTLS temperature, circulation, and trace gas anomalies associated with the MJO propagation. We find that the response of the UTLS during boreal summer months (June -September, JJAS) is different from the response during boreal winter months (November -February, NDJF). Ozone, temperature and circulation anomalies during JJAS are more zonally symmetric with a stronger Kelvin wave response than during NDJF. These differences are explained in terms of seasonal variations in vertically propagating Kelvin waves that strongly depend on the zonal structure of the climatological zonal winds. The trace gas response to the MJO is in agreement with circulation anomalies, showing strong seasonal differences. The analysis of MLS observations presented in this study may be useful for evaluation and validation of the MJO-related physical and dynamical processes in a hierarchy of models.
Cosmic Ray Neutron Sensing: Integration with land surface modelling using data assimilation for improved field-scale soil moisture estimates
Authors: Patil Amol , Fersch Benjamin , Hendricks-Franssen Harrie-Jan , Kunstmann Harald
Published: March 2020

Soil moisture is a key variable in atmospheric modelling to resolve the partitioning of net radiation into sensible and latent heat fluxes. Therefore, high resolution spatio-temporal soil moisture estimation is getting growing attention in this decade. The recent developments to observe soil moisture at field scale (170 to 250 m spatial resolution) using Cosmic Ray Neutron Sensing (CRNS) technique has created new opportunities to better resolve land surface atmospheric interactions; however, many challenges remain such as spatial resolution mismatch and estimation uncertainties. Our study couples the Noah-MP land surface model to the Data Assimilation Research Testbed (DART) for assimilating CRN intensities to update model soil moisture. For evaluation, the spatially distributed Noah-MP was set up to simulate the land surface variables at 1 km horizontal resolution for the Rott and Ammer catchments in southern Germany. The study site comprises the TERENO-preAlpine observatory with five CRNS stations and additional CRNS measurements for summer 2019 operated by our Cosmic Sense research group. We adjusted the soil parametrization in Noah-MP to allow the usage of EU soil data along with Mualem-van Genuchten soil hydraulic parameters. We use independent observations from extensive soil moisture sensor network (SoilNet) within the vicinity of CRNS sensors for validation. Our detailed synthetic and real data experiments are evaluated for the analysis of the spatio-temporal changes in updated root zone soil moisture and for implications on the energy balance component of Noah-MP. Furthermore, we present possibilities to estimate root zone soil parameters within the data assimilation framework to enhance standalone model performance.
Novel comprehensive field-based monitoring dataset of largest Siberian river particulate flux into Arctic ocean
Authors: Chalov Sergey , Kasimov Nikolay
Published: March 2020

Northern rivers transport huge quantities of water and constituents from the continents to the Arctic Ocean. Characteristics of the transport mode of chemical flow are poorly monitored, and the existing estimates of river flux are characterized by high uncertainty. Since 2018, the monitoring campaign ArcticFlux has been sampling the 4 largest Siberian rivers (Ob, Enisey, Lena and Kolyma) multiple times per year at the most downstream river crossection selected as unaffected by river mouth processes (tides, surges etc).  Using Acoustic Doppler Current Profiler (ADCP) acquisitions with sediment depth profile sampling we build a simple model to derive the bed and suspended seasonal fluxes, grain size and particulate heavy metals distributions. Study demonstrates the significance of the hydraulic control for the metal partitioning within river as well as explains spatial (inter-basin) variations in particulate flux due to local hydrology, erosion rates and catchment lithology. Using (ADCP) acquisitions with sediment depth profile sampling of the Ob, Enisey, Lena and Kolyma, we aim to build a model to derive the annual flux of the sediments and particulate flux of the selected metals.  The datasets is also used to assess the uncertainties in selected sediment quantity and quality data, including contributions from vertical and crossectional variations into fluxes estimates including requirements for sampling strategy. Based on the modeling techniques and application of erosion models for all four Arctic catchments the project will also focus on the novel quantitative assessment of bank and catchment erosion contribution into chemical flux.