bluuebunny/crossref_metadata_2025 huggingface dataset:
Natural hazard impacts on infrastructure in Russian regions
Authors: Petrova Elena
Published: March 2020

Infrastructure is considered as the fundamental facilities and systems serving a country or other area to ensuring the functioning of its economy. The term infrastructure refers to public and private facilities and systems such as transport (including roads, railways, bridges, tunnels, ports, airports, etc.), water supply, sewers, electrical grids, and telecommunication lines. Throughout the area of Russia, almost all of the listed infrastructure facilities are exposed to the undesirable impacts of adverse natural processes and phenomena, as well as natural hazards of various origins such as geophysical, hydro-meteorological, and others. Adverse impacts of natural hazards may trigger accidents and failures; disrupt the normal operation of infrastructure facilities. In their turn, these negative consequences of natural hazard impacts on the infrastructure cause multiple social problems. Using the information collected by the author in the database of technological and natural-technological accidents, contributions of natural factors to accidents and failures in the infrastructure facilities are assessed. Database includes more than 21 thousand events from 1992 to 2019. Among all the identified types of natural hazards, the largest contributions to accidents and infrastructure disruptions have hydro-meteorological hazards such as heavy snowfalls and rains, floods, and ice phenomena. Electrical grids are the most vulnerable to adverse impacts of natural hazards. Regional differences in the risk of accidents and infrastructure disruptions between Russian federal regions were found. All the federal regions were grouped by their risk levels of accidents and infrastructure disruptions. The resulting maps were created and analyzed.
Roughness evaluation on a splay of the active fault system responsible of the massive 2016 seismic sequence of Central Apennines (Italy)
Authors: Corradetti Amerigo , Tavani Stefano , Zambrano Miller , Tondi Emanuele , Seers Thomas
Published: March 2020

Fault roughness is a general term used to indicate dimension and distribution of fault asperities. Due to the role that fault asperities play on slip dynamics and frictional behavior during the seismic cycle, fault roughness constitutes a key element to understand earthquakes nucleation. Since it is not possible to recover fault roughness from seismogenic sources, faults at surface are generally used as analogues. However, those faults are in most cases subject to weathering and their roughness can lose seismogenic representativeness. Active faults episodically expose “fresh” fault zones constituting the best targets for seismogenic roughness evaluations.

Here we present the study conducted on a splay of the Mt. Vettore fault system in the Central Apennines (Italy), along a vertical transect that includes both a weathered and a freshly exposed portion of the fault. The latter was exposed after the dramatic Mw 6.5 shock that hit the area on the 30th of October 2016. We produced a high detailed model of a part of the fault by means of structure from motion-multiview stereo (SfM-MVS) photogrammetry to assess its roughness parameters and to determine how these are affected by weathering. 

Our results show that weathering increases the value of the fractal parameters. Accordingly, we conclude that using high resolution point clouds it is possible to recognize patches of fault having similar exposition time to weathering. 
Geometrical Scaling Relations of Drainage Basins During Basin Evolution
Authors: Havusha Kobi , Goren Liran , Nativ Ron
Published: March 2020

Fluvial drainage systems are organized in drainage basins, whose boundaries are defined by water divides. The network of divides determines the geometry of the basins and the distribution of drainage area along flow. Drainage basins obey global geometric-geomorphic scaling relationships. These include Hack’s law that predicts the relation between channel length (L) and drainage area (A): L = c∗Ah  where c and h are referred to as Hack’s coefficient and exponent, respectively. These parameters have a relatively narrow range of 1.1 ≤ c ≤ 2.7 and 0.45 ≤ h ≤ 0.6. Additionally, the distance between basin outlets (S) has been shown to scale linearly with the distance between the main divide and the mountain front (W) and is expressed by the ratio: R = W ⁄ S , where R is within the range of 1.91 ≤ R ≤ 2.23. When the tectonic and climatic conditions change through time, drainage basins can change their geometry. It is not clear, however, if and how the global scaling relations evolve when basins change their shape and size. This gap in our understanding specifically relates to the links between geomorphic processes and surface forms. A promising approach to study fluvial landscape evolution is by using physical laboratory-scale models. These models provide a unique opportunity to study the details of drainage network evolution and geometrical changes by constraining climate and uplift and by maintaining the lithological parameters constant and uniform. In the current study, we utilize DULAB (Differential Uplift LAndscape-evolution Box), an experimental apparatus that simulates mountainous landscape evolution, to study the evolution of basin geometrical scaling relations. Our experimental scheme consists of two distinct settings: (1) uniform uplift, with basins that grow by incising backward towards an uplifting and shrinking plateau, and (2) differential uplift, where the main drainage divide migrates towards the higher uplift rate side, and the drainage basins adjust accordingly. During the experiments, precipitation is held constant, and we document the landscape geometry in predefined time intervals by applying a “Structure from Motion” algorithm on a series of photos. Experimental results show that while basins drastically change their size and shape, they tend to maintain the globally observed geometrical scaling relations. Hack’s parameters are computed to be c = 2.29 ± 0.08  and h = 0.51 ± 0.02 and the spacing ratio, R is R = 2.95 ± 0.4. This is achieved as only a subset of basins grow towards the migrating divide, while other basins maintain their former geometry or shrink. Additionally, processes of reorganization, such as basins merging close to their outlets and inter-basin divide migration, assist in maintaining the geometrical scaling relations.
The Contribution of Anthropogenic Energy Use to Urban Heat Island: Combining Energy Consumption Data with Satellite Observation of Land Surface Temperature
Authors: Yu Zhou , Li Qi , Sun Ting , Hu Leiqiu
Published: March 2020

Energy consumption, such as building energy use and traffic, is one of the key sources of anthropogenic heat flux in cities (QF), which influences the urban climate. Different methods have been proposed to quantify QF, such as using the inventory data and satellite observations of the land surface temperature. In this study, we develop an analysis framework based on urban surface energy balance and inverse calculation of the expected change of thermodynamic state as a result of different sources of energy consumption. This framework enables us to link the energy consumption data with remotely sensed land surface temperature (LST). Thus, the contribution of different sources of anthropogenic energy consumption to the urban land surface temperature can be readily quantified. We apply this method to ECOSTRESS LST, traffic volume and building energy consumption for cities in the US. We show that the exhaust heat from traffic and building energy use contributes differently to the surface urban heat island effect: the contributions differ in cities with different background climates, urban morphologies and green area fractions. Overall, the combined model-observation framework demonstrates potential in quantifying the impact of two major anthropogenic heating sources on urban climate, in particular with increasingly available high-quality urban energy-use data and fine-resolution satellite observations.  
Wildfires in Fennoscandia under changing climate and forest cover
Authors: Aalto Juha , Backman Leif , Virtanen Timo , Partanen Tero , Lehtonen Ilari , Kolstela Joonas , Aalto Tuula , Vanha-Majamaa Ilkka , Shorokhova Ekaterina , Kokki Esa , Lindberg Henrik , Tolppi Reijo , Venäläinen Ari
Published: March 2020

In recent years, large forest fires in Fennoscandia have shown that wildfires can have a strong impact on society also in northern Europe. In the future, meteorological conditions are expected to become increasingly favorable for wildfires due to climate change. An important aspect in fire management are the national forest management strategies that play a crucial role in controlling e.g. fuel availability in forests, and further areal coverage of burned area. In addition, the effectiveness of rescue services is crucial. Thus, the development of fire risk prediction and fire detection systems, as well as, modeling of spread of fires and emissions of harmful ingredients, such as black carbon are urgently required to improve the societies preparedness to the increasing thread. In this presentation we synthetize the current state-of-the-art understanding of wildfires in Fennoscandia from a wide range of key perspectives: historical fire regimes, monitoring using in-situ and remote-sensing technologies, integrated modeling (e.g. climate models, spatial fire propagation models forced with operational weather forecast model) and fire suppression. In addition, we assess the amount of black carbon emissions released from recent wildfires in Fennoscandia. These results will help northern societies to tackle against the negative impacts of climate change and to support the development of efficient mitigation strategies. In the upcoming decades the effective management of wildfires is especially relevant, as wildfires greatly affect regional carbon budgets and mitigation efforts. 
A glaciotectonic complex at the Vastyanskiy Kon’ outcrop, NE European Russia: subglacial or proglacial deformations?
Authors: Zastrozhnov Andrey , Zastrozhnov Dmitry
Published: March 2020

The Vastyanskiy Kon’ (VK) outcrop is the largest exposure of Quaternary sediments in the northeastern European part of the Russian Federation. The VK consists of Eemian to Weichselian marine and continental sediments that were deformed within a glaciotectonic complex of terminal moraine of the advancing Late Weichselian Kara Sea Ice Sheet. However, a few aspects of the stratigraphy and dynamic evolution of the VK glaciotectonic complex remain unresolved and ambiguous.

A particular debate concerns the structural position and age of the so-called “lower diamicton” (LD), a till-like unit, which generally occurs within the central part of the VK section. Two models on the development of the LD unit have been previously proposed. According to the first model, the LD is situated in its original stratigraphic position and reflects possible earlier Early/Middle Weichselian glaciation and is later deformed by Late Weichselian proglacial glaciotectonism. The second model suggests that the LD unit is a result of an injection of the overlying Late Weichselian lodgement till into underlying sandy units.

In our study, we performed a detailed tracing of stratigraphic units and structures utilizing classic surface mapping and 3D photogrammetric methods to access previously understudied parts of the VK. Our observations show that the architecture of the VK glaciotectonic complex represents an imbricate fan and partly support the model where the LD likely represents a till flow unit sourced from the overlying lodgement till under subglacial deformation mode. Finally, we conclude there is no evidence for postulated Early/Middle Weichselian glaciation in the study area.
Update of lake cover for NWP modelling
Authors: Choulga Margarita , Boussetta Souhail , Kourzeneva Ekaterina , Balsamo Gianpaolo
Published: March 2020

Lakes modify the structure of the atmospheric boundary layer. They can intensify winter snowstorms, increase/decrease surface temperature and amount of precipitation. At European Centre for Medium-Range Weather Forecasts (ECMWF) lake parametrization was introduced in 2015. Inland water bodies (lakes, reservoirs, rivers and coastal waters) are simulated by the Fresh-water Lake model FLake, which was chosen to be included in the
Integrated Forecasting System (IFS) for its intermediate complexity, particularly adapted for numerical weather prediction and climate applications.

In order to eliminate outdated lake location error it was decided to upgrade lake cover field in the IFS model with Global Surface Water Explorer (GSWE) data. Techniques used to adapt GSWE for the use of global NWP modelling and first results that used upgraded lake field will be presented.
The detection of ionospheric trough with GNSS measurements.
Authors: Sieradzki Rafal , Paziewski Jacek
Published: March 2020

The main ionospheric trough represents a large scale depletion of plasma density elongated in longitude, which is typically observed at the boundary between high- and mid-latitude ionosphere. The trough is characterized  by a steep density gradient in a poleward direction and gradual on the equatorward site. According to the recent studies it begins in the late afternoon, moves equatorward during the night hours and rapidly retreats to higher latitudes at a dawn. Due to the dynamic of auroral oval, this ionospheric feature exhibits a high temporal variability and shifts equatorward during the geomagnetic activity. In this work we demonstrate the initial assessment of the ionospheric trough detection performed with GNSS-based relative STEC values. The basis of this indicator are time series of  geometry-free combination with removed background variations. The separation of these low-term effects is realized with a polynomial fitting applied to the particular arcs of data. Such processed data have an accuracy of phase measurements and provide an epoch-wise information on enhancement/depletion of plasma density. In order to evaluate the applicability of the proposed approach for the trough detection, we have analyzed the state of the ionosphere during different geomagnetic conditions. In our investigations we have used the data from several tens of stations located in the northern hemisphere, what makes possible to provide the comprehensive view of this ionospheric phenomenon. The results have confirmed that the network-derived relative STEC values can be successfully used for the monitoring ionospheric trough. Its signature is more pronounced for expanded auroral oval during increased geomagnetic activity and reach in such case a few TEC units.     
Investigating Granger causality with state-space representation of time series: a case study of the total water storage anomaly over Australia
Authors: Douch Karim , Saemian Peyman , Sneeuw Nico
Published: March 2020

Originating from econometrics, the concept of Granger causality (GC) has been widely used in a variety of fields, including climate sciences, to infer directional dependencies between stochastic variables.  Going one step further than the simple detection of lag-correlations, GC evaluates the directed interaction of a variable Y on a variable X by quantifying the improvement of prediction of future values of X when past values of Y are considered or omitted. Although not prescribed initially as such, GC is routinely computed from an estimated vector autoregressive model of the data of interest X, with and without the exogenous variable Y. However, such a modelling is somewhat restrictive and not suitable for filtered, sampled and noisy time series which may contain a moving-average component, impairing at the same time the quality of the GC estimator. Conversely, state-space representation offers a much more general framework for linear time series modelling.

In this study, we use Granger causality in the framework of a state-space modelling of time series to infer the presence of causal influences of the sea surface temperature (SST) and the 500hPa geopotential height on the Terrestrial Water Storage Anomaly (TWSA) over Australia[PS1] . A first and critical step is to reduce the high-dimension of the spatio-temporal data to a size compatible with classical state-space modelling algorithms. To do that we extract a limited number of leading modes of variability from the geophysical fields. Next, the state-space models of the extracted modes are identified using subspace-based methods. Then, the Granger causality of every mode of SST (resp. 500hPa geopotential height) on TWSA is estimated. Finally, we discuss the capability of the presented method to detect real directional dependencies in the light of current knowledge on Australia’s rainfall climatology and compare it to the results obtained with the classical vector autoregressive models.
Yield Determinants and Prediction for California’s Almond Orchards Based on Machine Learning Analytics
Authors: Jin Yufang , Chen Bin , Lampinen Bruce , Brown Patrick
Published: March 2020

Agricultural productivity is subject to various stressors, including abiotic and biotic threats, many of which are exacerbated by a changing climate. The productivity of tree crops, such as almond orchards, is particularly complex. Moreover, the State of California has implemented legislatively mandated nitrogen (N) management strategies of all growers statewide to minimize nitrogen losses to the environment, and almond growers must now apply N in accordance with the estimated yield in early spring. To understand and mitigate these threats requires a collection of multi-layer large data sets, and advanced analytics is also critical to integrate these highly heterogeneous datasets to generate insights about the key constraints on the yields at tree and field scales. Here we used machine learning approaches to predict orchard-level yield and examine the determinants of almond yield variation in California’s almond orchards, based on a unique 10-year dataset of field measurements of light interception, remote sensing metrics, and almond yield, along with meteorological data. We found that overall the maximum almond yield was highly dependent on light interception, e.g., with each one percent increase in light interception resulting in an increase of 57.9 lbs/acre in the potential yield. Light interception was highest for mature sites with higher long term mean spring incoming solar radiation, and lowest for younger orchards and when March maximum temperature was lower than 19 oC. However, at any given level of light interception, actual yield often falls significantly below full yield potential, driven mostly by tree age, temperature profiles in June and winter, and summer maximum vapor pressure deficit (VPDmax). The full random forest model was found to explain 82% (±1%) of yield variation, with a RMSE of 480±9 lbs/acre. When excluding light interception from the predictors, overall orchard characteristics (such as age, location and tree density) and key meteorological variables could still explain 78% of yield variation. The model analysis also showed that warmer winter conditions often limited mature orchards from reaching maximum yield potential and higher summer VPDmax  significantly limited the yield. Our findings through the machine learning approach improved our understanding of the complex interaction between climate, canopy light interception, and almond nut production. The demonstrated relatively robust predictability of almond yield, driven by “big data”, also provides quantitative information and guidance to make informed orchard nutrient management decisions, allocate resources, determine almond price targets, and improve market planning.
Understanding cyclone variability in the Barents Sea
Authors: Madonna Erica , Hes Gabriel , Michel Clio , Li Camille , Siew Peter Yu Feng
Published: March 2020

Extratropical cyclones are a key player for the global energy budget as they transport a large amount of moisture and heat from mid- to high-latitudes. One of the main corridors for cyclones entering the Arctic from the North Atlantic is the Barents Sea, a region that has experienced the largest decrease in winter sea ice during the past decades. On the one hand, some studies showed that moisture transported by cyclones to the Arctic can lead to drastic temperature increases and sea ice melt. On the other hand, it has been suggested that the location of the sea ice edge can influence the tracks of cyclones. Therefore, it is crucial to understand what controls cyclone tracks through the Barents Sea into the Arctic to explain and potentially predict climate variability at high latitudes.

To address this question, we track cyclones from 1979 to 2018 in the ERA-Interim data set, characterizing and quantifying them depending on their genesis location and path. The focus is on cyclones entering the Barents Sea from the North Atlantic as they carry the most moisture into the Arctic. Despite a clear declining trend in sea ice in the Barents Sea, our results show neither significant changes in cyclone frequency nor in their tracks. However, we find that the large-scale flow and in particular the presence or absence of blocking in the Barents Sea influence the cyclone frequency in this region, providing a potential mechanism that controls high latitude climate variability.
PATMOS-x v6.0: Improvements to AVHRR Cloud Climate Record and Analysis of the Updated Data
Authors: Phillips Coda , Foster Michael , Heidinger Andrew
Published: March 2020

Since 1978, an Advanced Very-High-Resolution Radiometer (AVHRR) has flown onboard 17 polar-orbiting satellites. Together, they are the longest global record from a homogeneous set of satellite sensors. The Pathfinder Atmosphere’s Extended (PATMOS-x) dataset is a long-term cloud record derived from the AVHRR radiances, and suitable for climate analysis. It has demonstrated intersensor stability and has been rigorously compared with other cloud datasets.

However, the AVHRR alone has only limited spectral information, so cloud detection during nighttime or over ice is challenging. Therefore, performance degrades over regions with extreme diurnal patterns or low temperatures such as the poles, despite our interest.

The next production version of PATMOS-x will include numerous algorithmic changes as well as the use of High-resolution Infrared Radiation Sounder (HIRS) spectral channels to improve detection accuracy in previously difficult conditions. The low-resolution HIRS soundings are upsampled to match the AVHRR pixels through an edge-preserving process called “fusion”. The higher-resolution AVHRR imagery guides the upsampling and the resulting combination is spectrally consistent with the AVHRR and has a high spatial resolution.

For cloud detection, the difference between the AVHRR and HIRS 11μm and HIRS 6.7μm brightness temperatures has been added as a feature in the naive Bayesian cloud detector. The effect on cloud precision is seen especially in the Antarctic where false-positive cloud detections have decreased dramatically.

Other cloud properties can be improved with the new spectral channels. For example, the new cloud phase algorithm uses the HIRS 6.7μm to determine cloud phase and the AVHRR and HIRS 11μm-13.3μm beta ratio identifies overlapping clouds. Also, the 11μm, 12μm, and HIRS 13.3μm are used in the new cloud height algorithm.

We report on the development of this new version of the PATMOS-x cloud climate dataset, and the methods used to calibrate and homogenize the participating sensors. Finally, observed trends in the improved dataset will be examined and related to the old dataset. In particular, attention will be given to whether high-latitude analysis of climatic trends is finally possible on the new dataset.
Peculiarities of quasi-adiabatic dynamics of charged particles in current sheets with magnetic shear
Authors: Malova Helmi , Popov Victor , Grigorenko Elena
Published: March 2020

The dynamics of quasi-adiabatic ions in the current sheet (CS) of the Earth's magnetotail during substorms is investigated, when CS is thinned, and the scale of the magnetic inhomogeneity is about proton gyroradius. Experimental data indicate sometimes that the shear magnetic component from the interplanetary magnetic field can penetrate within the magnetosphere and support self-consistent currents. The numerical model of CS is constructed, taking into account the normal magnetic component and shear component of three types: 1) constant profile within CS, 2) bell-shaped and 3) antisymmetric ones. Poincaré maps characterizing quasi-adiabatic dynamics of ions are studied. The jumps of quasi-adiabatic invariant of motion are calculated, and comparison is made with the case of the absent magnetic shear. It is shown that the presence of constant and bell-shaped magnetic components in the current sheet leads to the asymmetric scattering of particles in the North-South direction after their interaction with CS and corresponding differences in the structure of the phase space. It is demonstrated that the jumps of the approximate invariant Iz depend on the location of the plasma source in the Northern or Southern hemispheres.  At the same time, for configurations with anti-symmetric shear component, the particle scattering near the sheet plane is negligible, therefore in this case it is no scattering asymmetry, and the jumps of invariants of motion are smallest; they do not depend on the value of the magnetic field amplitude inside CS. Applications of these results to interpret experimental observations are discussed.
Bias correction of global high-resolution precipitation climatologies using streamflow observations from 9372 catchments
Authors: Alvarez-Garreton Camila , Beck Hylke , Wood Eric , McVicar Tim R. , Zambrano-Bigiarini Mauricio , Baez-Villanueva Oscar M. , Sheffield Justin , Karger Dirk N.
Published: March 2020

We introduce a set of global high-resolution (0.05◦) precipitation (P) climatologies corrected for bias using streamflow (Q) observations from 9372 stations worldwide. For each station, we inferred the “true” long-term P using a Budyko curve, an empirical equation relating long-term P, Q, and potential evaporation. We subsequently calculated long-term bias correction factors for three state-of-the-art P climatologies (WorldClim V2, CHELSA V1.2, and CHPclim V1), after which we used random forest regression to produce global gap-free bias correction maps for the climatologies. Monthly climatological bias correction factors were calculated by disaggregating the long-term bias correction factors based on gauge catch efficiencies. We found that all three climatologies systematically underestimate P over parts of all major mountain ranges globally, despite the explicit consideration of orography in the production of each climatology. Additionally, all climatologies underestimate P at latitudes > 60◦N, likely due to gauge under-catch. Exceptionally high long-term correction factors (> 1.5) were obtained for all three climatologies in Alaska, High Mountain Asia, and Chile — regions characterized by marked elevation gradients, sparse gauge networks, and significant snowfall. Using the bias-corrected WorldClim V2, we demonstrated that other widely used P datasets (GPCC V2015, GPCP V2.3, and MERRA-2) severely underestimate P over Chile, the Himalayas, and along the Pacific coast of North America. Mean P for the global land surface based on the bias-corrected World-Clim V2 is 862 mm yr−1 (a 9.4 % increase over the original WorldClim V2). The annual and monthly bias-corrected P climatologies have been released as the Precipitation Bias CORrection (PBCOR) dataset — downloadable via www.gloh2o.org/pbcor.
High temporal resolution 13C tracing to link xylem – phloem pathways of carbon in oak trees
Authors: Yoshikawa Akira L. , Bloemen Jasper , Ingrisch Johannes , Hartmann Henrik , Bahn Michael
Published: March 2020

Carbon (C) assimilated in the canopy of trees is transported downwards via phloem to fuel metabolic processes, such as respiration of above- and below-ground tissues.  Part of the respired CO2 can be dissolved into xylem water and transported along the trunk up to the canopy, causing a CO2 efflux which is dislocated from the site of respiration. While the individual processes of C transport in the phloem and xylem in trees have been comparatively well described, little is known on the linkage of xylem–phloem pathways of C and the potential of re-assimilation of root-respired C in the canopy.

In this study, we randomly assigned a set of five-year-old oak trees (Quercus rubra) to stem infusion of 13CO2 dissolved water (n=4) or 13CO2 canopy labeling treatment (n=3), thereby labeling xylem C flow and phloem C flow, respectively. Using high temporal resolution isotope ratio measurement by laser spectroscopy, we monitored 13C in tissue and in respiratory CO2 efflux resulting from phloem- and xylem-transported C to trace the fate of C from photosynthesis through the phloem and xylem to respiration and re-assimilation. We observed that CO2 efflux was related to both phloem and xylem transport of 13C and that a quick lateral transport of sugars occurred from phloem to xylem. Furthermore, we found evidence for re-assimilation of CO2 transported through the xylem in branches and leaf petioles. The re-assimilated 13C transported by the xylem was also found in stem tissues at various heights, 24 to 96 hours after labeling. Moreover, stem 13CO2 efflux showed a diurnal variation, suggesting a potential incorporation of recycled C into respiratory substrate at different stem heights shortly upon re-assimilation. Our results demonstrate a phloem–xylem C linkage leading to repeated coupling of assimilation and respiration, with consequences for whole tree C dynamics.
Microbial responses to the release of DOC by sea ice and glacier melting in the East Greenland System
Authors: Filella Lopez de Lamadrid Alba , Engel Anja
Published: March 2020

Freshwater discharge around Greenland has more than doubled during the last decade. Understanding the associated physical and biogeochemical impacts in the ocean is of great importance for future predictions of ocean circulation, productivity and feedbacks within the Earth system. In summer 2019 we performed several cross-shore sections passing through the highly variable environments and physical regimes along the east Greenland coastline. Microbial communities showed distinct latitudinal and meridional distributions. Water mass characteristics played a major role in controlling the abundances of organisms with few groups appearing in significant numbers in coastal (colder and fresher) waters. Surface polar waters rich in dissolved organic carbon (DOC) flow south in the East Greenland Current maintaining a high DOC signal in inshore waters. Further optical analyses on the DOC fraction will determine what fractions of this material originate from long scale transport out of the Arctic. Of particular interest was an enhanced production of gel particles rich in carbon in an area extending across Denmark Strait, from close to Scoresby Sund to north of Iceland. Significant concentrations (e.g. 80 µg X.G. eq. L-1) of these transparent exopolymer particles (TEP) were even found deeper than 100m, which is highly unusual. Given the role of TEP as a binding agent for sinking particles, enhancing the sinking of carbon in the water column, it is of interest to know why such a TEP hotspot arises. We hypothesize that it could be either related to circulation through the Strait or the timing of bloom dynamics in this region prior to our cruise.  Our main conclusion from preliminary data analysis is that the east Greenland coastal system is highly dynamic with mixed properties reflecting various degrees of mixing between southward flowing Polar Water and warmer Atlantic water masses.
Quantifying the role of volcanic ash supply in the oceanic iron and manganese cycles
Authors: Longman Jack , Palmer Martin , Gernon Thomas
Published: March 2020

Primary productivity in the upper ocean is a key driver of Earth’s carbon cycle. The supply of micronutrients such as iron (Fe) and manganese (Mn) to the ocean is now known to exert a controlling influence on net primary productivity. Fragmental volcanic material, or tephra, is enriched in such nutrients, highly reactive and regularly supplied to the upper ocean when eruptions occur. However, there are no existing estimates of the global magnitude of the volcanic supply of these (and associated) nutrients to the oceans. Here we present new data from ten volcanic provinces globally including the Aleutian Islands and Lesser Antilles to estimate depletion factors of both Fe and Mn in altered tephra. By comparing the concentration of altered tephra to unaltered protolithic compositions, we can estimate depletion factors, and thus the amount of each element supplied to the oceans via this method. Using a novel Monte Carlo approach, we estimate mean values of Fe and Mn to be on the order of 26.1 and 0.25 Gmol yr-1, respectively. These values are broadly comparable to riverine and atmospheric dust fluxes to the ocean, indicating that volcanism plays a major role in Fe and Mn ocean cycles.
Controls over the export flux of marine snow into the deep ocean
Authors: Le Moigne Frederic
Published: March 2020

The oceanic biological carbon pump (BCP) regulates the Earth carbon cycle by transporting part of the photosynthetically fixed CO2 into the deep ocean. Suppressing this mechanism would result in an important increase of atmospheric CO2 level. The BCP occurs mainly in the form of organic carbon particles (POC) sinking out the surface ocean. Various types of particles are produced in surface ocean. They all differ in production, sinking and decomposition rates, vertically and horizontally. The amount of POC transported to depths via these various export pathways as well as their decomposition pathways all have different ecological origins and therefore may response differently to climate change. Here I will briefly review some of the processes driving both particle export out of the euphotic zone (0-100m) as well as particles transport within the mesopelagic zone (100-1000m). In the early 2000s, strong correlations between POC and mineral (calcite an opal) fluxes observed in the deep ocean have inspired the inclusion of “ballast effect” parameterizations in carbon cycle models. These relationships were first considered as being universal. However global analysis of POC and mineral ballast fluxes showed that mineral ballasting is important in regions like the high-latitude North Atlantic but that in most places (some of which efficiently exporting) the unballasted fraction often dominates the export flux. In such regions, we later on showed that zooplankton-mediated export (presence of faecal pellets) and surface microbial abundance were important drivers of the efficiency of particles export. Similar trends were found globally by including bacteria and zooplankton abundances to a global reanalysis of the global variations of the POC export efficiency. This implies that the whole ecosystem structure, rather than just the phytoplankton community, is important in setting the strength of the biological carbon pump. Further down in the water column (mesopelagic zone), processes impacting the transport of particles are less clear. Sinking particles experience a number of biotic and abiotic transformations during their descent. These includes solubilization, remineralisation, fragmentation, ingestion/active transport, break down among others. While some potential factors such as O2 concentration and temperature have been proposed as powerful controls, globally evidences are often inconsistent. Current challenges related to the role of particles consumption by zooplankton and fishes as well as the role of particles attached prokaryotes (bacteria and archaea) in setting the efficiency of the carbon transport in the mesopelagic zone will be discussed.
Understanding the effectiveness of measures aiming to stabilize urban mega gullies in Kinshasa
Authors: Lutete Landu Eric , Ilombe Mawe Guy , Bielders Charles , Makanzu Imwangana Fils , Dewitte Olivier , Poesen Jean , Vanmaercke Matthias
Published: March 2020

Kinshasa, the capital of the D.R. Congo, is strongly affected by urban mega gullies. There are currently hundreds of such gullies, having a total length of >100 km. Many of these gullies (typically tens of meters wide and deep) continue to expand, causing major damage to houses and other infrastructure and often claiming human casualties. To mitigate these impacts numerous efforts are being implemented. The type and scale of these measures varies widely: from large structural measures like retention ponds to local initiatives of stabilizing gully heads with waste material. Nonetheless, earlier work indicates that an estimated 50% of the existing urban gullies continue to expand, despite the implementation of such measures. As such, we currently have very limited insight into the effectiveness of these measures and the overall best strategies to prevent and mitigate urban gullies. One reason for this is that gully erosion is typically very episodic with long periods of stability, followed by sudden expansion events. As a result, understanding the dynamics of gully expansion in urban environments requires observations over sufficiently long time periods. However, most current initiatives to stabilize urban gullies happen on a rather isolated basis and are rarely evaluated afterwards.

This work aims to improve our understanding of this issue by constructing a large inventory of measures implemented to stabilize urban gullies in Kinshasa and statistically confronting these measures with observed vegetation recovery and long-term gully expansion rates (derived from high-resolution imagery over a period of >10 years). Our preliminary results (based on a dataset of > 140 urban gullies) shows that the most commonly applied measures are revegetation and reinforcement of gully heads with sandbags or household waste material (implemented in around 50% of the cases). Also retention ponds and water storage tanks are frequently implemented (around 30% of the cases). Surprisingly, our results indicate that urban gullies with higher expansion rates tend to have more measures implemented in their upstream catchment. While this seems counterintuitive, it may point to the fact that more actively retreating gullies create a larger sense of urgency and therefore instigates a higher number of (often ineffective) initiatives. More research is needed to confirm this. Furthermore, the stability of gullies seems to be strongly linked to vegetation cover in the gully. Nonetheless, it is not always clear if vegetation is the cause or the result of this stability. Overall, this study provides one of the first large scale assessments of the effectiveness of gully control measures in urban tropical environments. With this study, we hope to contribute to a better prevention and mitigation of this problem that affects many cities of the tropical Global South.
The heartbeat of a glacier: Cascading subglacial water pockets and ocean tides cause hourly to daily ice-flow variations of Priestley Glacier, Antarctica, detected with Terrestrial Radar Interferometry
Authors: Drews Reinhard , Wild Christian , Neckel Niklas , Marsh Oliver , Rack Wolfgang , Ehlers Todd A.
Published: March 2020

In Antarctica, basal melting in the ice-sheet’s interior generates subglacial water that is routed via the subglacial hydrological system towards the margins. At the grounding zone, the subglacial meltwater comes into contact with ocean water subject to tides. The mixing of the two water masses may be one reason for velocities variations on tidal timescales, providing a window into processes of basal sliding. With this goal in mind, we instrumented a flowline across the grounding zone of Priestley glacier, Antarctica, with 4 differential GNSS stations co-located with advanced phase sensitive radars (ApRES) and tiltmeters all measuring continuously over several months. Moreover, we installed a Terrestrial Radar Interferometer (TRI) overlooking the glacier from an adjacent rock outcrop. The to our knowledge first-time deployment of the TRI in Antarctica reveals a stunning picture of grounding-zone dynamics providing spatially coherent 1D flowfields every 3 hours over a time period of 10 days. This enables interpretations of velocity changes measured by GNNS in an unprecedented spatial context. We complement our on-site geophysical dataset with airborne ice-penetrating radar as well as spaceborne InSAR data using timeseries from TanDEM-X, Sentinel-1A, and the ERS satellites.

TRI and GNSS stations jointly detect tidal velocity fluctuations (> 50 % around the mean) which decay landwards with increasing distance from the grounding line. Triple differences in satellite interferometry reveal transient bull’s eye patterns far upstream of the grounding line quantifying localized surface lowering together with adjacent surface uplift. We interpret this as a result from abruptly migrating subglacial water pockets cascading over obstacles in the basal topography. The TRI also shows such bull’s eye patterns pulsating in our highly resolved time series. Moreover, all GNSS stations and the TRI detect a short-lived acceleration event (~100 % horizontal speedup over 2 hours) paired with spatially coherent surface uplift (~15 cm). Magnitude and duration of this event suggests operation of hydraulic jacking, a mechanism explaining short-lived speed-ups with pressure variations in a linked-cavity system. However, usually this is pre-conditioned to the existence of significant surface meltwater entering the subglacial hydrological system, which is not the case at our study site. Our joint observations with multiple sensors and instruments therefore  provide unique observations to further develop our understanding of basal sliding, particularly it's dependency on upstream water supply and ocean tides.
The Levaiathan gas rig struggle: environmental, political, regulatory, technological and scientific aspects.
Authors: Aharonov Einat
Published: March 2020

The Leviathan gas rig, erected 9kms offshore Dor beach, Israel, started in Dec 2019 to treat and refine gas from the largest Israeli gas field, Levaiathan. Initially (2014), gas treatment was planned to occur on an FPSO, which is a deep-sea floating platform. But then in 2015 the gas treatment was moved, following an undocumented decision, to a static platform opposite the coastal settlements of Hof HaCarmel. This sparked the largest environmental struggle that Israel ever knew. I will present the whole story: How and why was the rig moved from sea to shore. Why were regulators sure there will be no environmental problem. Why are citizens concerned. And finally, how are scientists and academics involved, playing a role of scientific experts in the service of society.
Unrevealing tree carbon allocation beyond the stress – a case study of heat and drought impacts on Pinus sylvestris
Authors: Rehschuh Romy , Gast Andreas , Jakab Andrea-Livia , Lehmann Marco , Saurer Matthias , Gessler Arthur , Ruehr Nadine
Published: March 2020

The resistance of trees to stress events has been studied intensively, however we know little on underlying processes affecting the recovery of trees following stress release. Hence, this clearly impairs our ability to project the resilience of trees and forests to an intensification of heatwaves and drought spells.

Here we studied the legacy effects of heat and heat-drought stress on carbon (C) allocation dynamics in Scots pine. We were particularly interested in how C allocation changes post heat and heat-drought stress and how this change in allocation affects tree growth. We exposed Pinus sylvestris seedlings to increasing temperatures from 30 to 40°C within 18 days either under well-watered or drought conditions and measured stem growth, leaf water potential and above- and belowground gas exchange. Two days after stress release, we conducted a 13CO2 pulse-labelling experiment in custom build single tree cuvettes (n=18) allowing us to continuously monitor 13CO2 shoot and root gas exchange. We then chased the fate of the newly assimilated C from leaves to roots via soluble sugars, starch and cellulose.

Our results showed that Pinus sylvestris is able to recover gas exchange following heat release immediately in the well-watered trees, while drought-treated trees recovered slightly slower. We found indications for a stress compensatory response of the previously heat-treated trees, which tended to translocate recent assimilates faster compared to the control trees as identified in the dynamics of water-soluble carbon in the phloem and root 13CO2 efflux. In addition, we found larger stem growth rates in the heat-treated trees which was also reflected by a larger investment of new assimilates to cellulose. In the trees that experienced both, heat and drought stress, C allocation differed strongly from the control trees as apparent in a half as fast C translocation from leaves to root respiration and large investments of new assimilates into starch. This delayed translocation but enhanced allocation towards C storage in needle tissues was reflected in a delayed recovery of stem growth and very low detection of the 13C signal in twig, root and stem cellulose. We can conclude that heatwaves of 40°C have relatively moderate responses on C allocation post-stress, whereas hot drought stress clearly affects C allocation as indicated by a delayed C transport capacity and a preferential allocation towards C storage in needle tissues. This could indicate that C allocation following hot drought stress is affected by an impaired phloem functionality, which only slowly recovers post-stress.
Microbial necromass shaped plant traits in a warmer condition
Authors: Stelmach-Kardel Wioleta , Frąc Magdalena , Gryta Agata , S. Razavi Bahar
Published: March 2020

Among many factors controlling root exudation, root hairs proliferation and warming have strong influence on exudate release as well as microbial substrate utilization and enzyme activities. Thus, the interactions of these two factors are important but least known in the rhizosphere. Phosphorus (P) is the most important growth limiting nutrient in soils. Concerns about a depleting supply of P as fertilizer has boosted research efforts on understanding P cycling and fluxes, as a breakdown of P availability would have disastrous global consequences. Efficient P recycling in temperate ecosystems provides an excellent possibility to study all kind of biogeochemical P transformations – those mobilizing low available P species and those recycling available P – maintaining a high level of microbial biomass P in the ecosystem. Such microbial cycling has been successfully shown for individual C compounds or within compound classes. P recycling, especially within microbial communities, has not been investigated so far. Microbial necromass as a source of available C and N affect microbial P utilization. However, the mechanisms underlying this alteration of biogeochemical transformations within the P cycle are not understood. To clarify these interactions for 21 days, rhizoboxes with Maize wildtype and mutant (rth3, no root hairs) under 20 and 30 °C, with and without necromass addition were incubated. The spatial distribution of acid phosphatase was assessed with MUF-based Zymography. Phosphatase activity as well as enzyme kinetics parameters (Vmax and Km) were determined in bulk and rhizosphere soil of all treatments. 
Our result showed that necromass addition accelerated microbial activity and phosphates hotspots at high temperature ranges. Necromass had no influence on rhizosphere size but increased hotspots independent of temperature. In treatment without necromass amendment, root-hairs effects on enzyme activity and efficiency was pronounced only at elevated temperature. Necromass addition caused formation of roots with special morphology comparable to root hairs in mutant type (hairless root). This was plant strategy to compensate P limitation and acquire more P under competition with soil microbiome. Consequently, P content in plant biomass after changes of root morphology increased while MBP decreased. This, shows that microbial necromass was decomposed and used as a source of P by plant. Thus, plant by adaptation of their morphology over compete microorganisms for more efficient P uptake.