bluuebunny/crossref_metadata_2025 huggingface dataset:
Late Pleistocence dynamics in central Pennsylvania (USA) – new findings on periglacial slope deposits, pedology and chronology
Authors: Hirsch Florian , Raab Thomas , Drohan Patrick , Bonhage Alexander
Published: March 2020

Pleistocene dynamics are usually associated with the formation of characteristic landforms such as moraines, dunes, or kettle holes. However, cold climate processes can also shape the landscape but not result in such prominent relief features. This is especially true for slope deposits that have been formed in periglacial regions through geli-solifluction and/or cryoturbation.  While the terms used to refer to such slope deposits may differ with the disciplines of soil science and/or geomorphology, such features are often still recognized by practicing scientists. In the US, geli-solifluction and/or cryoturbation features are subsumed with a very general term ‘colluvium’ whereas in Europe a more sophisticated number of terms is used separating sediments which formed under cold climate processes from sediments which formed due to anthropogenic induced soil erosion. Our study focuses on the stratigraphy of late Quaternary deposits and the soil formation in the northern Appalachians. The study area wasn’t glaciated during the Wisconsin glaciation; hence no MIS 5 or younger glacial deposits are reported.

To advance a common terminology between geoscientist, we examined pedons representative of Holocene and periglacial dynamics that reflect the strong role that solifluction played in pre and MIS 5landscape dynamics. Especially on foot slopes and toe slopes pedon stratigraphy is characterized by a several meter-thick par-autochthonous deposits that are rich in clasts. Clasts in deposits are aligned with the slope direction and are imbricated; on back slopes par-autochthonous deposits are also present but more shallow. Stratigraphy and OSL chronology strongly suggests that during the late Pleistocene several phases of morphodynamics shaped the landscape via solifluction followed by an eolian input of silt to the soils/sediments. Geochemistry reflects the multi-layer character of the soil profiles showing clear differences between the bedrock and deposits above. Elevated values of manganese in the surface soil indicate the importance of plant litter biocylcing during the Holocene. Hence on a landscape scale, the distribution of soils and the pedogenesis is strongly related to the par-autochthonous character of the substrate rather than the bedrock.
Parameterization of multifractal cascade models based on their breakdown coefficients
Authors: Aguilar Flores César , Carsteanu Alin Andrei
Published: March 2020

Breakdown coefficients of multifractal cascades have been shown, in various contexts, to be ergodic in their (marginal) probability distribution functions, however the necessary connection between the cascading process (or a tracer thereof, such as rainfall) and the breakdown coefficients of the measure generated by the cascade, was missing. This work presents a method of parameterization of certain types of multiplicative cascades, using the breakdown coefficients of the measures they generate. The method is based on asymptotic properties of the probability distributions of the breakdown coefficients in “dressed” cascades, as compared with the respective distributions of the cascading weights. An application to rainfall intensity time series is presented.
Detection of Crude Oil Contamination in St-Lawrence Estuary Sediments Using n-Alkanes and PAHs Diagnostic and Isotopic Ratios
Authors: Dupont Léticia , Imfeld Anic , Ouellet Alexandre , Gélinas Yves
Published: March 2020

Excessive consumption of petroleum and crude oil for energy purposes has resulted in the contamination of many natural systems and waterways. However, determining the presence and level of contamination has been difficult due to the presence of naturally occurring hydrocarbons and to the complexity of the molecular fingerprint of petroleum and crude oils. Naturally occurring straight-chain n-alkanes and polycyclic aromatic hydrocarbons (PAHs) in sediments are both commonly used to determine organic matter sources through diagnostic and isotope ratios, and these ratios are affected by the presence of petroleum and crude oil. As such, they offer a potential avenue for determining whether crude oil contaminants are present in natural systems. The purpose of this project was to determine whether diagnostic ratios of n-alkanes and of PAHs as well as compound-specific isotope ratios of n-alkanes (∂2Halk and ∂13Calk) could be used to detect crude oil or petroleum contamination, and at what level of contamination the difference becomes significant. This was accomplished by separating the aliphatic and aromatic fractions of the natural and crude oil hydrocarbons by column chromatography, spiking natural sediment hydrocarbons with crude oil hydrocarbons at different levels, and analyzing the samples by GC-MS (Gas Chromatography-Mass Spectrometry) and by GC-IRMS (Isotope-Ratio Mass Spectrometry). The isotopic ratios and the hydrocarbon concentrations were determined by external standard calibration, and the diagnostic ratios were then calculated from the concentrations. Both ratios were then evaluated for their efficiency in detecting the presence of crude oil contamination.
Effect of tectonic loading on continental rifting: Imaging, quantification and linkage of deep-seated flow and surface deformation
Authors: Schmid Timothy , Schreurs Guido , Adam Jürgen , Hollis David
Published: March 2020

Here we use dynamically scaled analogue experiments to investigate the influence of tectonic loading on continental rifting. Analogue models consist of a two-layer brittle-viscous set up overlying a foam base, which expands homogeneously when extension is being applied perpendicular to the rift axis trend. A layer of quartz sand on top of a viscous silicone/corundum sand mixture layer is used as an analogue for an upper brittle crust and a ductile lower part of the crust, respectively. An additional package of sand on one part of the model simulates tectonic loading.

The aim of this work is to investigate in detail dynamic rift propagation in such a setting by means of a fully quantitative monitoring of surface and internal deformation, focusing on rift propagation velocity, growth rate and orientation. The evolution of the surface topography (DEM) and deformation (3D displacement field) is monitored and quantified using 3D Digital Image Correlation (3D stereo DIC). Furthermore, we apply an automated fault segment tracer on the surface deformation data to characterize rift evolution. Model internal deformation is investigated by digital volume correlation (DVC) techniques applied on X-ray computed tomography data of the time-series experiment volumes. With the use of such techniques we are able to visualize, quantify and link deep-seated internal flow and surface deformation over time.

Preliminary results from these experiments suggest that rift propagation in our analogue models is directly influenced by load-induced deep-seated deformation resulting in a horizontal lower-crustal flow opposing rift propagation.
Sensitivity of global gross primary production to environmental drivers
Authors: Cai Wenjia , Prentice Iain Colin
Published: March 2020

Terrestrial Gross Primary Production (GPP), the total amount of carbon taken up by terrestrial plants, is one of the largest fluxes in the global carbon cycle – and a key process governing the capacity of terrestrial ecosystems to partly offset continuing anthropogenic CO2 emissions. Accurate simulation of land carbon uptake and its response to environmental change is therefore essential for reliable future projections of the terrestrial carbon sink. However, there are still large uncertainties in the sensitivity of global GPP to environmental drivers. Here we use a recently developed and extensively tested generic model of GPP (the ‘P-model’), which uses satellite-derived green vegetation cover as an input, to simulate (a) trends in site-level GPP, as observed at eddy-covariance flux sites; (b) trends in global GPP, for comparison with independent geophysical estimates; and (c) quantitative spatial patterns of the sensitivity of grid-based GPP to green vegetation cover, vapour pressure deficit, temperature, solar radiation, soil moisture and atmospheric CO2.
A new framework to quantify carbon cycle perturbations using trace metal isotopes
Authors: Adloff Markus , Greene Sarah E. , Monteiro Fanny M. , Ridgwell Andy
Published: March 2020

Reconstructing the environmental consequences of large carbon additions in the past has the potential to improve our understanding and prediction of how the Earth system will respond to human carbon emissions. However, uncertainties over the scale and timing of external carbon additions during past carbon emission events limit quantitative knowledge gained from the geological record. The metals Sr, Os, Li and Ca are essential proxies for changes in volcanic activity and terrestrial weathering rates, and thus for major causes of pre-industrial carbon emission and sequestration, because their isotopic compositions in old continental crust and Earth’s mantle differ significantly. So far, box models and equilibrium-state equations have been the only method to quantitatively relate weathering-derived and magmatic input fluxes to trace metal concentrations and isotopic ratios preserved in ancient sediments. This approach results most commonly in a first order estimate of emitted carbon or weathering changes, but it does not account for the effect of climate feedbacks on metal sources and sinks and associated variations in the residence time of these metals in the ocean. Particularly during fast carbon emissions (e.g. Cenozoic hyperthermals, Oceanic Anoxic Events), the processes which added isotopically traceable metals to the oceans also enchained environmental changes which would have affected metal cycles and residence times, resulting in significant alterations of the recorded isotopic excursion in marine sediments. To disentangle the signals of causes and consequences of environmental change recorded by trace metal isotopes, we simulated various coupled carbon and metal cycle perturbations in the 3D Earth system model of intermediate complexity cGENIE, now containing the first representation of isotope-enabled trace metal dynamics. Here, we present a resulting extended framework to reconstruct metal and carbon fluxes from the geological trace metal record during periods of environmental change.
Data Systems to Enable Open Science: The Joint ESA-NASA Multi-Mission Algorithm and Analysis Platform’s Data Ecosystem
Authors: Bugbee Kaylin , Kaulfus Aaron , Barciauskas Aimee , Maskey Manil , Ramachandran Rahul , Ton That Dai-Hai , Lynnes Chris , Virts Katrina , Markert Kel , Whitehurst Amanda
Published: March 2020

The scientific method within the Earth sciences is rapidly evolving. Ever increasing volumes require new methods for processing and understanding data while an almost 60 year Earth observation record makes more data-intensive retrospective analyses possible. These new methods of data analysis are made possible by technological innovations and interdisciplinary scientific collaborations. While scientists are beginning to adopt new technologies and collaborations to more effectively conduct data-intensive research, both the data information infrastructure and the supporting data stewardship model have been slow to change. Standard data products are generated at a processing system which are then ingested into local archives. These local archive centers then provide metadata to a centralized repository for search and discovery. Each step in the data process occurs independently and on different siloed components. Similarly, the data stewardship process has a well-established but narrow view of data publication that may be too constrained for an ever-changing data environment. To overcome these obstacles, a new approach is needed for both the data information infrastructure and stewardship models. The data ecosystem approach offers a solution to these challenges by placing an emphasis on the relationships between data, technologies and people. In this presentation, we present the Joint ESA-NASA Multi-Mission Algorithm and Analysis Platform’s (MAAP) data system as a forward-looking ecosystem solution. We will present the components needed to support the MAAP data ecosystem along with the key capabilities the MAAP data ecosystem supports. These capabilities include the ability for users to share data and software within the MAAP, the creation of analysis optimized data services, and the creation of an aggregated catalog for data discovery. We will also explore our data stewardship efforts within this new type of data system which includes developing a data management plan and a level of service plan.
New water fractions, transit time distributions, and solute concentrations at Plynlimon, Wales.
Authors: Knapp Julia , Kirchner James
Published: March 2020

Transit time distributions estimated from stable water isotopes (deuterium and oxygen-18) are frequently used to assess transport and storage of water in catchments. We analyzed 2.25 years of 7‑hourly and 4.5 years of weekly measurements of stable water isotopes in precipitation and streamwater at the Plynlimon catchments in Wales, UK using the ensemble hydrograph separation technique. We thereby quantified new water fractions – the average contribution of recent precipitation to streamflow – in the different subcatchments, and determined transit time distributions as the contribution of precipitation to streamflow over a range of lag times.

We found that on average only 3 % of streamwater was made up of precipitation that fell within the last 7 hours, and 13-15 % of streamwater was made up of precipitation that fell within the previous week. However, these new water fractions increased with discharge, indicating that more recent precipitation reached the stream when the catchment was wet, and the contributions of recent precipitation to streamflow were highest during large events. This dependence of new water fractions on water fluxes was also reflected in their seasonal variations, with lower new water fractions and more damped catchment transit time distributions in the drier spring and summer compared to fall and winter.

A comparison between changes in solute concentrations and new water fractions with discharge provides additional insight into the storage and release of water and solutes from the catchments. Our analysis demonstrates that changes in solute concentrations primarily reflect changes in flowpaths between dry and wet conditions, rather than changes in the fraction of recent precipitation in streamflow.
Study of heat extraction and flow process by fully coupled thermal- hydro- mechanical model
Authors: Zhou Dejian , Tatomir Alexandru , Sauter Martin
Published: March 2020

Enhanced Geothermal Systems (EGS) are widely used in the development and application of geothermal energy. They usually consist of two parallel deep boreholes, where cold water is injected into one borehole and abstracted at the second one after being heated when passing through the fractured network system. Recently, simple analytical solutions have been proposed to estimate the water pressure at the output. Nevertheless, these methods do not take into account the influences of the coupled thermal and mechanical processes. In this research study we build a fully coupled Thermal – Hydro-mechanical model (THM model) to simulate the processes of heat extraction, deformation and water flow in the nearby fractured rock formations. The influences of single thermal – hydraulic and mechanical – hydraulic effects were compared with the fully coupled and decoupled results, showing that temperature influences mostly the water pressure in the second borehole, compared with temperature. The mechanical effect alone has little influences on the water pressure. A sensitive analysis was also conducted to study which parameters affect the simulation results the most. It was shown that the initial permeability and temperature are playing the main roles in this simulation.
An overview of climate hazard impacts to the global airport system
Authors: Voskaki Asimina , Budd Thomas , Mason Keith
Published: March 2020

In recent years airports have demonstrated sensitivity to climate hazards, raising various safety, environmental and socio-economic concerns. Evidence from the literature indicates that the occurrence of climate hazard events, including sea-level rise, extreme heat, precipitation changes and convective weather, is likely to become more frequent as a result of climatic change. This, in turn, is likely to place additional stress on airports infrastructure and threatening its ability to maintain their social and economic function. While climate adaptation and hazard impacts are more established in other major sectors, in the case of airports this issue has only more recently emerged as a risk.

By examining the key challenges airports face in different geographical regions and climate zones, this study examines how climate extremes and hydrological hazards affect the airport system and, presents best practices to improve the resilience of airport infrastructure. The key objective of this contribution is to provide a better understanding of the direct and indirect impact of climate hazards and to outline some of the aspects that could be included in climate hazard risk reduction strategies in the future.
Storm Xaver over Europe in December 2013 and its energy meteorological impacts
Authors: Kettle Anthony
Published: March 2020

Storm Xaver impacted the northern Europe on 5-6 December 2013.  It developed southeast of Greenland and passed north of Scotland and across southern Norway on a trajectory that led to a cold air outbreak across the North Sea and intense convection activity in northern Europe.  Strong sustained north winds led to a high storm surge that impacted all countries bordering the North Sea.  Storm Xaver was a century scale event with certain locations around the North Sea reporting their highest ever water levels since the start of modern records.  Media reports from the time of the storm chronicle the scale of the disruptions, including many cancelled flights, interrupted rail networks, closed bridges and roads, coastal building collapses, and power blackouts across northern Europe.  Much of this was due to the strong winds, but coastal storm surge flooding was important in the UK, and it led to interrupted port operations around the North Sea.

The storm was important for energy infrastructure and particularly for wind energy infrastructure.  In the northern North Sea, petroleum platforms were evacuated and operations closed ahead of the storm as a precautionary measure.  A number of onshore wind turbines were badly damaged by high winds and lightning strikes in the UK and Germany.  Over the North Sea, wind speeds exceeded the turbine shutdown threshold of 25 m/s for an extended period of time, with economic impacts from the loss of power generation.   In the German Bight, the FINO1 offshore wind energy research platform was damaged at the 15 m level by large waves.  This was the third report of storm damage to this platform after Storm Britta in 2006 and Storm Tilo in 2007.  Researchers have highlighted the need to reassess  the design criteria for offshore wind turbines based on these kinds of extreme meteorological events.  For the offshore wind industry, an important element of energy meteorology is to characterize both the evolving wind and wave fields during severe storms as both elements contribute to turbine loads and potential damage.

The present conference contribution presents a literature review of the major events during Storm Xaver and impacts on energy infrastructure.  Tide gauge records are reanalyzed to trace the progress of the storm surge wave around the North Sea.  A spectral analysis is used to separate the long period storm surge component, diurnal/semidiurnal tide, and short period components in the original water level record.  The short period component of the tide gauge record is important as it may be linked with infragravity waves that have been implicated in certain cases of offshore infrastructure damage in addition to coastal erosion.  Discussion is made of offshore wave records during the storm.  Storm Xaver is compared with two damaging offshore storms in 2006 and 2007.
Differences in inner magnetospheric wave activity, outer Van Allen belt electron dynamics and atmospheric precipitation during CME sheaths and flux ropes
Authors: Kilpua Emilia , Kalliokoski Milla , Juusola Liisa , Grandin Maxime , Kero Antti , Turner Drew , Jaynes Allison , Asikainen Timo , Dubyagin Stepan , George Harriet , Hietala Heli , Koskinen Hannu , Osmane Adnane , Palmroth Minna , Partamies Noora , Pulkkinen Tuija , Raita Tero , Turc Lucile , Vainio Rami
Published: March 2020

Coronal mass ejection (CME) driven sheath regions are one of the key structures driving strong magnetospheric disturbances, in particular at high latitudes. Sheaths are turbulent and compressed regions that exhibit large-amplitude magnetic field variations and high and variable dynamic pressure. They thus put the magnetosphere under particularly strong solar wind forcing. We show here the results of our recent studies that have investigated the response of inner magnetosphere plasma waves, energy and L-shell resolved outer belt electron variations and precipitation of high-energy electrons to the upper atmosphere during sheath regions. The data come primarily from Van Allen Probes and ground-based riometers. Our results reveal that sheaths drive intense “wave storms” in the inner magnetosphere (ULF, EMIC, chorus, hiss). Lower-energy electron fluxes (source and seed populations) are typically enhanced due to frequent and strong substorms injecting fresh electrons, while relativistic electrons are effectively depleted at wide L-ranges due to scattering by wave-particle interactions and magnetopause shadowing playing in concert. We found that even non-geoeffective sheaths can drive significant wave activity and dramatic changes in the outer belt electron fluxes. The “complex ejecta”, however, that consist of multiple sheaths and distorted CME ejecta can lead to sustained chorus and ULF waves, and as a consequence, effective electron acceleration to high energies. We also report some distinct characteristics in the intensity and Magnetic Local Time distribution of precipitation during sheaths when compared to other large-scale solar wind driver structures. The different precipitation responses likely stem from driver specific characteristics in their ability to excite inner magnetosphere plasma waves.

 
Volcano Ambient Noise Interferometry in the Caribbean (VANIC)
Authors: Sleeman Reinoud
Published: March 2020

The hazardous stratovolcanoes in the Lesser Antilles island arc are monitored with sparse seismic networks. The application of ambient noise interferometry to monitor seismic velocity variations (dv/v) on data from such a sparse instrumented volcanic environment often is a challenge. For the purpose of monitoring it is important a) to analyse the applicability of, and differences between, cross- and single-station cross-correlations, b) to estimate the base level of seismic velocity variations during quiet times and c) to understand the characteristics. Within the EUROVOLC instrument “Transnational Access (TA)” a proposal called VANIC was supported to a) use and evaluate different types of ambient noise cross correlations (single stations vs. multiple stations; auto, cross and cross-component correlations) to be applied on seismic recordings from the Guadeloupe seismic network on La Soufriere, b) compare the results with dv/v base level estimates from the sparse Netherlands Caribbean network on The Quill and Mt. Scenery and c) start collaboration between OVSG and KNMI on both monitoring and research levels with a focus on volcano seismology. This presentation will focus is on the results obtained during the TA visit to OVGS.
Microgravity Methods to Characterize the karst structures in north-western Algeria
Authors: Khaldaoui Fatma , Abtout Abdesslam ABTOUT , Bouguerra Hayet , Hedjazi Ibtissem
Published: March 2020

A gravimetric study was conducted on a site located at Tlemcen, a city of western Algeria, where it was intended to build residential buildings. During the excavation for the preparation of foundations, cavities were discovered. This is confirmed by visual inspection. The study area is geologically composed of dolomitic limestone jurrassique, characterized by strong pérméabilité caused by cracking and karstic formation.

The geophysical method more appropriate in this case is the microgravimetric. The gravimetric campaign which lasted 15 days is composed of more than 1000 stations measures and was realized on several zones at the site with a step of 2.5 m. All these stations have been identified topographically.

            The Bouguer anomaly map presents a short-wavelength gravity low which reaches a minimum value up of - 33.190 mGal. A qualitative analysis of this map showed that the relative gravity lows is related to the mass deficit. Some of the anomalies detected by microgravimetric are well correlated with cavities observed on the surface. Mass deficits have been assimilated as underground cavities and that can present a danger to the stability of buildings.

The 3D modelling has been realized using software based on the algorithm of Talwani (Talwani & all 1960), it has allowed us to determinate location and dimensions of the cavities detected.

Key words: Cavities, karst, Microgravimetic, Anomalies, Talwani, Tlemcen, Algeria.
Temporal Variability of the Meridional Overturning Cells in the South Atlantic
Authors: Kersalé Marion , Meinen Christopher , Perez Renellys , Le Hénaff Matthieu , Valla Daniel , Lamont Tarron , Sato Olga , Dong Shenfu , Terre Thierry , van Caspel Mathias , Chidichimo Maria Paz , van den Berg Marcel , Speich Sabrina , Piola Alberto , Campos Edmo , Ansorge Isabelle , Volkov Denis , Lumpkin Rick , Garzoli Silvia
Published: March 2020

Variations in the Meridional Overturning Circulation (MOC) are known to have important impacts on global scale climate phenomena including precipitation patterns, surface air temperatures, coastal sea level, and extreme weather. The MOC flow structure in the South Atlantic is thought to control the stability of the entire global MOC system. Given this importance, significant resources have been invested on observing the MOC in the South Atlantic over the past decade. Multiple years of full-depth daily observations from moored instruments at 34.5°S are used to calculate the meridional transports near the western and eastern boundaries, as well as the basin-wide interior transports, via geostrophic methods. These transport estimates are combined with Ekman transports derived from satellite wind products to yield daily estimates of the total meridional transports. Analysis of the MOC volume transport using all available moored instruments from 2013 to 2017 allows us to quantify for the first time the daily volume transport of both the upper and abyssal overturning cells at 34.5°S. The structure of these flows is characterized in unprecedented detail; no statistically significant trend is detectable in either cell. Abyssal-cell transport variability is largely independent of the transport variability in the upper-cell. Analysis of this new data set is crucial for improving our understanding of the temporal and spatial scales of variability that governs MOC related flows, and for disentangling their respective roles in modulating its overall variability.
Can stationary cnoidal waves explain periodic deformation bands in porous sandstone?
Authors: Elphick Liz , Schrank Christoph , Lv Adelina , Regenauer-Lieb Klaus
Published: March 2020

Deformation bands are sub-seismic brittle structures found in granular materials. These structures exhibit two spatial distributions: [1] non-linear decay of spacing associated with the damage zone of a fault, and [2] periodic, constant spacing not associated with faults. Periodically spaced deformation bands are of interest as they can be pervasive through porous (>5% φ) formations and are known to impact fluid flow. Bands can act as conduits or barriers to fluid flow and are commonly identified in petroleum reservoirs. An understanding of the factors controlling their distribution is therefore of great importance.

Here, we test a novel mathematical theory postulating that material instabilities in solids with internal mass transfer associated with volumetric deformation are due to elastoviscoplastic p-waves termed cnoidal waves. The stationary cnoidal wave model for periodic compaction bands predicts that their spacing is controlled by important material properties: the permeability of the weak phase in the pores, the viscosity of the weak phase, and the inelastic volumetric viscosity (strength) of the solid grains. A semi-analytical parametric study of the dimensional non-linear governing equations yields a surprisingly simple scaling relationship, which requires testing in the field. Stronger units with higher permeability are predicted to exhibit a wider spacing between deformation bands.

We test the cnoidal-wave model on natural deformation bands from Castlepoint, North Island, New Zealand. These bands are hosted by Miocene turbidites of the Whakataki formation, which formed in tectonically controlled trench-slope basins associated with the onset of subduction of the Pacific plate beneath the Zealandian plate along the Hikurangi subduction margin. Adjacent sand- and siltstone beds exhibit significant differences in deformation band spacing. Spacing statistics derived from field mapping and laboratory measurements of host-rock permeability and strength are employed to test the scaling relation predicted by the cnoidal wave model. Inconsistencies between theoretical and observed spacing are discussed critically.
Timescale-dependent AMOC-AMO relationship
Authors: Kim Hyojeong , An Soon-Il
Published: March 2020

Previous studies showed that both AMOC and AMO work in different ways in interdecadal and multidecadal timescales. Although their relationship has also been covered in many studies, the possibility that overlapping between multiple timescales may have diluted their inherent relation has not been considered. To understand their physical relation correctly, it is necessary to consider interdecadal and multidecadal timescales, separately.

Here, we apply a band-pass filter to the AMO and AMOC indices obtained from a present-day climate simulation, to separate interdecadal and multidecadal variability. The results show that strong AMOC induces a warm phase of AMO by the northward heat transport in both timescales, but with a different time lag. This is because, in the interdecadal timescale, the southward propagation of AMOC anomaly gradually warms up the Atlantic basin from the high to low latitudes, resulting in a lag of seven years. As the delayed AMO peak provides negative feedback to AMOC by surface density modulation, the AMOC-AMO relationship can be described as an oscillatory system. On the other hand, AMOC in the multidecadal timescale matures at once in the entire basin, simultaneously warming the surface. The synchronous maturity of AMOC and AMO indicates that AMO-related density changes cannot account for the AMOC phase transition, and AMO remains a relatively passive component in their relationship. This study implies that overlooking timescale-dependency in physical processes may obscure our understanding of interactions between climate components.
Air-Sea seasonal CO2 fluxes in a fast warming oligotrophic region – the Eastern Mediterranean case study
Authors: Yu Juntao
Published: March 2020

In a recent study, it was suggested based on the apparent correlation between multi-annual measurements of summertime maxima and wintertime minima temperature and calculated pCO2 in the most eastern region of the Mediterranean Sea surface waters that they are a net source of atmospheric CO2. Furthermore, it was predicted that the magnitude of this source would increase substantially in this region and that adjacent regions in the Eastern Mediterranean as well would turn into net sources of atmospheric CO2 due to the fast warming of these waters. In order to confirm the underlying assumption that seasonal variations in pCO2 in Eastern Mediterranean surface waters are primarily a strong function of seasonal variations in temperature, water samples were collected for the analysis of total alkalinity and pH during 12 monthly cruises from February 2018 to January 2019 at the shallow (THEMO1) and the deep (THEMO2) open water stations that are ca.10 and 20 NM off the Mediterranean coast of Israel. The data from all the cruises show that surface (< 30m depth) seawater pCO2 has a strong positive linear relationship with temperature in both stations (n=56, r2=0.94, p<0.001). The calculated annual net flux of CO2 from the surface to the atmosphere based on these measurements is ca.1.13 Tg C y−1, which is ca.15% higher than the previously estimated flux, but within its range of uncertainty (± 30%). These results clearly demonstrate that surface water pCO2 levels are indeed a strong positive function of the seasonal variations in sea-surface temperature and that the open water of the most eastern Mediterranean Sea is a net source of atmospheric CO2. These results are also in agreement with the conclusions of observational and modelling studies of air-sea CO2 fluxes in the centers of subtropical gyres and therefore globally relevant.
In-Situ Calibration of Differential Pressure Gauges on OBSIP Ocean Bottom Seismometers
Authors: Laske Gabi , Doran Adrian
Published: March 2020

A standard ocean bottom seismometer (OBS) package of the U.S. OBS Instrument Pool (OBSIP) carries a seismometer and a pressure sensor. For broadband applications, the seismometer typically is a wide-band or broad-band three-components seismometer, and the pressure sensor is a differential pressure gauge (DPG). The purpose of the pressure sensor is manifold and includes the capture of pressure signals not picked up by a ground motion sensor (e.g. the passage of tsunami), but also for purposes of correcting the seismograms for unwanted signals generated in the water column (e.g. p-wave reverberations).
Unfortunately, the instrument response of the widely used Cox-Webb DPG remains somewhat poorly known, and can vary by individual sensor, and even by deployment of the same sensor.

Efforts have been under way to construct and test DPG responses in the laboratory. But the sensitivity and long‐period response are difficult to calibrate as they  vary with temperature and pressure, and perhaps by hardware of the same mechanical specifications.  Here, we present a way to test the response for each individual sensor and deployment in situ in the ocean. This test requires a relatively minimal and inexpensive modification to the OBS instrument frame and a release mechanism that allows a drop of the DPG by 3 inches after the OBS package settled and the DPG equilibrated on the seafloor. The seismic signal generated by this drop is then analyzed in the laboratory upon retrieval of the data. 

The results compare favorably with calibrations estimated independently through post‐deployment data analyses of other signals such as Earth tides and the signals from large teleseismic earthquakes. Our study demonstrates that observed response functions can deviate from the nominal response by a factor of two or greater with regards to both the sensitivity and the time constant. Given the fact that sensor calibrations of DPGs in the lab require very specific and stable environments and are time consuming, the use of in-situ DPG calibration frames pose a reliable and inexpensive alternative. 
Effect of mesoscale eddies on subtropical mode water formation and ocean heat storage
Authors: Chen Yanxu , Speich Sabrina , Bopp Laurent
Published: March 2020

Mode water formation results from air-sea exchange processes in association with the dynamics and thermodynamics of ocean currents or fronts in every ocean basin. Here, a new algorithm is applied to the Argo global array to define surface mixed layer depths and to detect mode waters with homogeneous properties underneath. Specifically, we revisit the spatial and temporal evolution of South Atlantic subtropical mode water (SASTMW) using this new algorithm and find that our set of criteria is more precise than previous detections of mode water. With satellite altimetry measurements and eddy tracking algorithms (Laxenaire et al., 2018), the colocalization between mesoscale eddies and mode waters can be achieved. We then test how much the profiles indicative of mode water are matched with locations of mesoscale eddies and to what extent these eddies influence mode water variability. In addition, we investigate the relationship between the temporal integral of surface heat flux with the heat stored within the layers of the SASTMWs during the formation periods. Nearly all Argo profiles indicate that mode water formation occurs at the time and within the region where loss of latent heat flux from ocean to the atmosphere is significant. Anticyclonic eddies, specifically, play a crucial role in heat redistribution associated with mode waters advected by the subtropical gyre.
MUSICA - Modeling for Chemistry, Weather and Climate
Authors: Pfister Gabriele , Conley Andrew , Barth Mary , Emmons Louisa , Lacey Forrest , Schwantes Rebecca
Published: March 2020

Current chemical transport models inadequately account for the two-way coupling of atmospheric chemistry with other Earth System components over the range of urban/local to regional to global scales and from the surface up to the top of the atmosphere.  To meet future challenges, future modeling systems need to have the ability to (1) change spatial scales in a consistent manner, (2) resolve multiple spatial scales in a single simulation, (3) couple model components which represent different Earth system processes, and (4) easily mix-and-match model components. This is the motivation behind MUSICA - the Multi-Scale Infrastructure for Chemistry and Aerosols, which we develop together with the atmospheric chemistry community. MUSICA will allow simulation of large-scale atmospheric phenomena while still resolving chemistry at scales relevant for representing societal and scientific critical phenomena (e.g. urban air quality, or convection in monsoon regions) and also enable connections to other components of the earth system by fully coupling to land and ocean models. MUSICA objectives will be achieved through development of a global modeling system capable of regional refinement and the new Model Independent Chemistry Module (MICM). We will discuss the infrastructure and show preliminary results of atmospheric chemistry simulations being conducted in a global model with regional refinement: the Community Atmosphere Model with chemistry using spectral element grids that refine from one-degree resolution to ~14 km resolution over the conterminous United States. These early results confirm that model resolution does matter for representing regional air quality and that the two-way feedback between the local and global scale can play an important role.
Cambium production pattern in Q. ilex growing at a dry site in Southern Italy
Authors: De Micco Veronica , Cufar Katarina , Balzano Angela
Published: March 2020

Survival of forest tree species in semi-arid environments such as the Mediterranean area is threatened by the increase in harsh drought conditions. Therefore, better knowledge of the eco-physiology of Mediterranean species and their growth responses to climatic factors is needed to develop strategies for sustainable management.

The studies of cambial activity and wood formation can provide information on tree growth and physiological responses to variations in intra-annual climatic parameters, helping to answer questions related to tree performance and plasticity under changing environmental conditions.

Our aim was to investigate cambium production in holm oak (Quercus ilex L.) as one of the most widespread evergreen oaks in Southern Italy. We studied the response of cambium activity throughout the particularly dry year 2017. We collected tissues from tree stems every two weeks by sampling microcores containing phloem, cambium and xylem. For the analyses, thin cross sections of the microcores were analysed under a light microscope to identify the timing of cambial production, xylogenesis and phloem formation. We detected the period in which the cambium was active, as well as the period in which the cambium was not productive. We interpreted the cambial response to climatic conditions at the site during the period of observation.

The observed pattern of xylogenesis differed from the expected bi-modal pattern typical for Mediterranean species which usually results in Intra-annual Density Fluctuations (IADFs) in tree-rings. In Q. ilex we observed only one peak of cambial activity, likely due to the low water availability during the year 2017.

The obtained results provide useful information supporting the forecasting of the wood-growth responses to expected climate change. Moreover, we gained technical experience on optimal preparation of thin sections of problematic tissues, which is especially challenging in Q.ilex due to high hardness of the peculiar wood structure making the investigations of xylogenesis very challenging in this species.
Experimental determination of magnesite solubility in water and silicate saturated saline solutions under high temperature and pressure
Authors: Li Wan-Cai , Wang Qinxia , Ni Huaiwei
Published: March 2020

Aqueous fluid derived from the dehydration of subducting slab can dissolve and transfer carbon to mantle wedge, and thus plays an important role in the globe deep carbon cycle. Carbonates are major phases of carbon in the subducting slab, however their solubilities in the subduction zone fluid are poorly constrained. This heavily hinder our understanding of the  deep carbon cycle. Magnesite is one of the carbonates in the subducting slab, and can be stabilized to sub-arc depth. We determined the solubility of magnesite in pure water and saline fluids buffered by silicate by in situ observation of quantitative magnesite totally dissolved in quantitative fluid under high temperature and pressure in Hydrothermal Diamond Anvil Cell (HDAC). The results demonstrated that the solubility of magnesite in pure water is 0.010-0.026 mol/kg H2O at 1.0-3.3 GPa and 600-900 ℃, and that it increases as increasing temperature, but has no obvious pressure effect. This data is close to the experimental measurement of calcite solubility in literature, but slightly higher than the theoretical results calculated using DEW model. The solubility of magnesite in 5 wt % NaCl solution equilibrium with quartz is 0.22 mol/ kg, at 700 ℃ and 1.5 GPa，an order of magnitudes higher than that in the pure water. Since the formation of new silicate minerals, such as olivine or talc, depends on silicon activity in the fluid, the dissolution of silicate would boost the solubility of magnesite. This mechanism has been previously reported in the Alps metasedimentary rocks. Therefore, the aqueous fluid, rich in saline and silicon in fore-arc and sub-arc depths, has the ability to dissolve and transfer almost all the carbonates in the subducting slab to the overlying mantle wedge.
An updated crustal thickness map of central South America based on receiver function measurements
Authors: Rivadeneyra-Vera Julia Carolina , Bianchi Marcelo , Assumpção Marcelo
Published: March 2020

Determining the seismic properties of continental crust is essential in tectonic studies to understand the geological evolution, as well as elaborating velocity models to better monitoring the regional and global seismicity. Since the early 90s many seismic studies have focused on the details of the crust and upper mantle in the Andean region. However most of the stable part of the continent remains poorly sampled due to its complexity and lack of seismic stations. In the previous compilation of crustal structure in South America, areas as the thin crust in the Sub-Andean lowlands and Amazon region have been largely estimated by gravity data. A deployment of 35 temporary seismic stations in southwest Brazil and parts of Bolivia, Paraguay, Argentina and Uruguay filled a significant gap in crustal information of the central part of South America. Additionally, restricted seismic stations of Bolivia and the eastern of Peru have been analyzed to better constraint our results in the Sub-Andean region. Crustal thicknesses and Vp/Vs ratios were estimated with a modified H-k method by producing three stacked traces to enhance the three Moho conversions (the direct Ps and the two multiples Ppps and Ppss). This modified method yields lower uncertainties than previous studies and shows more regional consistency between close stations. Using the temporary stations, the Brazilian permanent network (RSBR), and the restricted stations of Peru and Bolivia we have better characterized the crustal structure in the central part of South America, our results shows a belt thin crust (35-40 km) along the Sub-Andean region, which is narrower the previous works, and a normal crustal thickness average of 40 km in the central part of the South America. This study, combined with other published data, provides an updated crustal thickness map of South America that is useful for future regional studies of seismic wave propagation, gravity modeling and inferences of crustal evolution.
Climate services for the development plan of the Yellow River Basin in China
Authors: Xiao Chan , Song Lianchun
Published: March 2020

The Yellow River Basin is the place where Chinese civilization originated, known as the mother river of the Chinese nation. The Yellow River originates from the Bayan Kara Mountain in the Qinghai Tibet Plateau. It flows through Qinghai, Sichuan, Gansu, Ningxia, Inner Mongolia, Shanxi, Shaanxi, Henan and Shandong provinces, with a total length of 5464 kilometers, a drainage area of 795000 square kilometers and a population of 110 million. It has an important position in China's economic development. Now the development plan of the Yellow River Basin has been promoted to the level of national strategy. In order to better serve the economic development planning of the Yellow River Basin, the climate characteristics and climate risks of the upper, middle and lower reaches of the Yellow River Basin were analyzed. The topography of the Yellow River Basin is high in the West and low in the East, with great difference in topography and complex climate. It is sensitive to climate change and prone to drought and flood, extreme drought and rainstorm and flood. With global warming, the upstream tends to warm and humid, which has an important impact on the ecosystem, the middle and lower reaches tend to warm and dry, which has an important impact on pollution control and flood control. The impact of climate change must be considered in the development plan of the Yellow River Basin.