bluuebunny/crossref_metadata_2025 huggingface dataset:
Freeze-thaw dynamics in synthetic permafrost soil columns with variable organic carbon content
Authors: de Bruin Jelte , Bense Victor , van der Ploeg Martine
Published: March 2020

Cold-regions hold a pool of organic carbon that has accumulated over many thousands to millions of years and which is currently kept immobile by permafrost. However, in a warming climate, a deepening of the active layer results in the release of greenhouse gasses CO2 and CH4 into the atmosphere from this carbon pool. Additionally, due to the degradation of deeper permafost, soil hydraulic properties and associated groundwater flow paths are shifting rapidly as a result of which also organic carbon in deeper permafrost is being dissolved into groundwater, which can then reach the surface environment via groundwater flow.  This provides an additional mechanism by which permafrost carbon can be mobilized in  a warming climate, and one which is likely increasingly important for progressive surface warming.

Although the process of carbon leaching from thawing organic rich permafrost layers into the groundwater is an increasingly important part of the carbon cycle of cold-regions, it is notoriously difficult to measure in situ or incorporate into numerical model assessments due to the highly heterogeneous properties of the permafrost, and lack of process knowledge. In particular, the crucial understanding of the influence of different soil physical properties such as soil grain size and organic matter content on permafrost thawing processes is missing, as well the precise release mechanisms  of organic matter into pore waters in thawing soils.

This study employs lab soil column experiments to investigate the interplay between soil physical properties and thawing dynamics of permafrost. One meter high soil columns are frozen to create controlled permafrost conditions. A range of sand grain sizes (0.1 to 0.8mm) and organic matter contents (1 to 10 wt%) representative for sedimentary permafrost are used. The column is thermally insulated on the sides and top, exposing only one face to ambient temperature in the climate chamber. In this way one-dimensional heat flow conditions are created. So far, the columns are equipped with arrays of temperature sensors. Experiments consist of a cycle of freezing and thawing. Our initial data and analysis illustrate how a fast evolving thawing front develops through the frozen soil column  including the effects of latent heat at the thawing front. Numerical modeling allows to infer the soil thermal properties relevant to model the permafrost thawing process.
The Role of Restricted Basins in Global Biogeochemical Cycles
Authors: Turchyn Alexandra
Published: March 2020

The formation of restricted basins isolates seawater from the global ocean and allows the formation of salt deposits, often because restricted basins can have minor connectivity to the global ocean and thus can fill and evaporate many times over. The formation of salts removes ions from the global ocean, potentially decreasing their concentration elsewhere and leading to an alteration of their biogeochemical cycle.  The subsequent exposure and chemical weathering of these salt deposits changes the source of these elements back into the global ocean and can influence their biogeochemical cycles for a long time after the formation of the restricted basin.   Sediment biogeochemistry in restricted basins also differs from most global continental shelf, slope, and deep-sea sediments. The formation of sedimentary minerals and their subsequent diagenesis means that the amount and isotopic composition of deposited minerals in restricted basins can differ greatly from those in the global ocean. In this talk I am going to explore how the formation of restricted basins, including epicontinental seas and isolated seas, has influenced the biogeochemical cycle of carbon and sulfur over the course of the last 65 million years.  I am going to use a combination of new measurements on the carbon and sulfur isotopic composition of the ocean over this time to explore how different types of restricted basins influence global biogeochemical cycles in the rest of the ocean. I will argue that the formation of restricted basins has been important in driving changes in the carbon and sulfur isotopic composition of the ocean over time, linking changes in ocean chemistry to tectonics.
The impact of perturbations to tropical aerosols and their precursors on local and remote climates
Authors: Wells Chris , Voulgarakis Apostolos , Kasoar Matt
Published: March 2020

Aerosols are a major climate forcer, but their historical effect has the largest uncertainty of any forcing, and so their mechanisms and impacts must be better understood. Due to their short lifetime, aerosols have large impacts near their emission region, but they also have effects on the climate in remote locations. In recent years, studies have investigated the influences of regional aerosols on global and regional climate, and the mechanisms that lead to remote responses to their inhomogeneous forcing. However, there has been little work on the influence of emissions from the tropics, as the aforementioned studies typically focused only on northern mid-latitude pollution effects. This work uses the new UK Earth System Model (UKESM1) to investigate the atmospheric composition and climate effects of tropical aerosols and aerosol precursor emissions. We performed three idealised perturbation experiments in which a) tropical SO2 emissions were multiplied by a factor of 10; b) tropical biomass burning carbonaceous aerosol emissions were multiplied by 10; and c) tropical biomass burning carbonaceous aerosol emissions were entirely removed. Impacts on radiation fluxes, temperature, circulation and precipitation are investigated, both over the emission regions, where microphysical effects dominate, and remotely, where dynamical influences become more relevant. Increasing tropical SO2 emissions causes a global cooling, and the asymmetric forcing (stronger negative forcing in the Northern Hemisphere Tropics) drives a southward shift of the intertropical convergence zone (ITCZ). The experiment with the large increase in tropical biomass burning organic carbon (OC) and black carbon (BC) features a net warming globally, and a local cooling in locations where the aerosol load increases the most, since OC and BC reduce radiation at the surface locally, causing cooling. However, whereas OC scatters radiation with a negative forcing, BC has a warming effect since it reduces the planetary albedo, and this warming wins out on the global scale. The forcing is asymmetric, but changes sign between seasons as biomass burning in Africa shifts across the Equator, driving a more complex response of the ITCZ. The removal of biomass burning OC and BC leads to opposite effects to the 10x increase, but with a smaller magnitude, and with dynamical changes playing a more important role than microphysical ones, relative to the larger perturbations. Using the Shared Socioeconomic Pathway scenarios (SSPs), transient future experiments have also been performed, testing the effect of Africa following a relatively more polluting route (SSP3-RCP7.0) to the rest of the world (SSP1-RCP1.9), relative to a global SSP1-RCP1.9 control. Preliminary results from this analysis will also be presented.
Dynamics of Pliocene East Antarctic Ice Sheet from depositional signatures of the Prydz Bay shelf and Trough Mouth Fan
Authors: Huang Xiaoxia , Leitchenkov German , Bernhardt Anne , Eagles Graeme , Gohl Karsten , Gao Jinyao
Published: March 2020

The Pliocene saw multiple advances and retreats of the ice-sheet margin in East Antarctica. Amery Ice Shelf (AIS) is the largest ice shelf in East Antarctica and also the largest single ice stream draining from the Antarctic Plateau. It buttresses the Lambert Glacier drainage system, and accounts for 14% of the outflow from the East Antarctic Ice Sheet (EAIS). However, evidence for the state of the EAIS during the Pliocene is sparse and difficult to interpret unequivocally. Marine geological-geophysical data collected from the continental shelf in Prydz Bay, Antarctica, including seismic-reflection data, bathymetry, core records from ODP drilling and gravity coring sites, reveal a complex paleo-subglacial drainage system linked to an offshore depositional regime dominated on a trough mouth fan (TMF). Detailed seismic stratigraphic and facies analysis reveals the glacial evolution of Prydz Bay shelf and its TMF, including several glacial expansions across the shelf indicated by erosional surfaces and stratal bodies with chaotic acoustic character. The geometry of seismic sequences suggests that the glaciers and their associated TMF developed after a major episode of shelf and slope erosion during the Pliocene-Pleistocene.

 The shelf in Prydz Bay is dominated by a wide, south-north trending glacially-eroded trough (the Prydz Channel: -500~-1000 m depth) and shallower banks (-500~0 m depth). Well preserved grounding zone wedges areevidenced by prograding foreset deposits. Evidence for erosion of the wedges and/or lineations that extend across their upper surfaces indifferent water depths ranging from 200 m to 800 m imply their formation during multiple glacial stages or cycles.  Stacked erosional surfaces reveal major cross-shelf glacial expansions and the development of deep channel systems (up to -500 m depth) associated with extensive subglacial meltwater in Prydz Bay. These glacial related features provide good constraints for reconstructing the stability of the Pliocene EAIS.
Simulating compound weather extremes responsible for critical crop failure with stochastic weather generators
Authors: Yiou Pascal , Pfleiderer Peter , Jézéquel Aglaé , Legrand Juliette , Legrix Natacha , Markantonis Jason , Vignotto Edoardo
Published: March 2020

In 2016, northern France experienced an unprecedented wheat crop loss. This extreme event was likely due to particular meteorological conditions, i.e.  too few cold days in late autumn and an abnormally high precipitation during the spring season. The cause of this event is not fully understood yet and none of the most used crop forecast models were able to predict the event (Ben-Ari et al, 2018).  

This work is motivated by two main questions: were the 2016 meteorological conditions the most extreme we could imagine under current climate? and what would be the worst case scenario we could expect that could lead to even worst crop loss? To answer these questions, instead of relying on computationally intensive climate model simulations, we use an analogue based importance sampling algorithm that was recently introduced into this field of research (Yiou and Jézéquel, 2019). This algorithm is a modification of a stochastic weather generator (SWG), which gives more weight to trajectories with more extreme meteorological conditions (here temperature and precipitation). This data driven technique constructs artificial weather events by combining daily observations in a dynamically realistic manner and in a relatively fast way.

This is the first application of SWGs to simulate warm winters and wet springs. We show that with some adjustments both (new) weather events can be adequately simulated with SWGs, highlighting the wide applicability of the method. 

While the number of cold days in late autumn 2015 was close to the plausible maximum, our simulations of extreme spring precipitation show that considerably wetter springs than what was observed in 2016 are possible. Although the crop loss of 2016 is not fully understood yet, these results indicate that similar events with higher impacts could be possible.
Assessing the operational value of short-term forecast information under climate change
Authors: Moreno Dumont Goulart Henrique , Giuliani Matteo , Herman Jonathan , Steinschneider Scott , Castelletti Andrea
Published: March 2020

Climate change is expected to increase the variability of hydrological regimes, generating more recurrent and intense floods and droughts. This trend will very likely diminish the resilience of reservoir systems in supplying water, controlling floods, and generating energy. While forecast information has proven valuable for improving water systems operations under stationary hydroclimatic conditions, little is known about its potential value in more variable regimes and its capacity in mitigating the increased risks. In this work, we propose a framework to quantify the future operational value of forecast information under different climate change projections. Specifically, a stochastic model replicating observed forecast error is calibrated over a hindcast dataset from the Subseasonal to Seasonal (S2S) prediction project and used to generate synthetic forecasts for future hydrologic scenarios. Then, a policy search routine is used to design optimal operating policies informed by the forecast information. The forecast operational value is quantified by comparing the performance of these policies against a baseline solution not informed by any forecast and an upper bound solution which uses perfect knowledge of the future. This experiment is performed on a case study of Folsom Reservoir, California. Results indicate that the use of forecasts can improve future operations both in terms of water supply and flood control. We assess the forecast value in two distinct forms: the absolute value, which is the total gain generated by the use of forecast information and aligns with the provider point of view, and the relative value, which measures the gain with respect to the no-forecast case and relates to the reservoir operator perspective. The absolute value of forecasts is projected to increase for all selected scenarios. Conversely, projected relative forecast value depends on the nature of the climate scenario, increasing in wet scenarios while decreasing in dry scenarios. This experiment suggests that risks associated with increasing precipitation variability on seasonal to interannual timescales can be at least partially mitigated by the use of short-term forecasts. Future work will consider the potential for the forecast error structure to change over time as a result of climate change and improved weather models.
Wildfires risk and spatio-temporal dynamic in the Chiquitania region (Bolivia)
Authors: Bustillo Sanchez Marcela , Poffet Baptiste , Tonini Marj , Fiorucci Paolo
Published: March 2020

Wildfires risk in the Amazonian forest will probably increases in the future as a consequence of the predicted increased frequency of droughts combined with the growing rate of deforestation. The main cause of fire ignition in the Amazon tropical rainforest is anthropogenic (human-made). Indeed, burning is the easiest and cheaper way to clear the land, especially in the absence of transport or roads. This practice, known as slash-and-burn, consist on cutting trees and low vegetation/agricultural residuals and finally burning the biomass. The purpose is to make way for agriculture, livestock, logging, or simply to clear the agricultural land for new cultivations. In Bolivia this centuries-old practice of burning portions of tropical forest to prepare fields for the next year’s crop is called chaqueo. This practice can get out of control and initiate large fires, burning hectares and hectares of forest. Moreover, in September 2019 a controversial national decree, allowed the use of chaqueo in forestry areas to promote the expansion of the agricultural frontier, triggered an unprecedented situation. Although it is evident that fires in Bolivia, mainly cause by the practice of chaqueo, and land use and land cover change (LULCC), mainly the deforestation, are related, the spatio-temporal association among these two elements has not been deeply investigated jet.

The present study aims at investigating the spatio-temporal evolution of wildfires in the Chiquitania region, Bolivia, and its relationship with LULCC, particularly with regards to the deforestation, in the last three decades. The investigated region is located in the Department of Santa Cruz and is part of the Chiquitano dry forest ecoregion - spreading over Bolivia, Brazil and Paraguay - connecting the Gran Chaco shrublands to the south with the Amazon rainforests to the north. The characteristic tropical forest biome combined with the the near future drier and more seasonally extreme climatic conditions will increase the risk of wildfires in the Chiquitania region. Changes are also driven by the actual policies supporting the settlement of new farming communities and the expansion of the agricultural frontier and the road network in the region.

The investigation methods are based on a geospatial statistical approaches allowing to: 1) explore LULCC within the entire the study period and elaborate the map of changes showing the transitions among different classes; 2) quantify gained and lost areas for the classes forest, urban and croplands; 3) investigate the evolution in space and in time of fires and map local over-densities; 4) asses the main drivers for fire risk in the region.
Evolution of tear faults in subduction zones: an analogue modelling perspective
Authors: Bertone Nicolò , Bonini Lorenzo , Basili Roberto , Del Ben Anna , Maesano Francesco Emanuele , Tiberti Mara Monica , Pini Gian Andrea
Published: March 2020

Tear faults are common structures in subduction zones, especially at slab edges, where they origin from differential forces applied to a subducting slab in areas close to the trench. Presence and geometry of tears have been sometimes inferred from bathymetric features, suggesting the abrupt lateral termination of the subduction zone.

Differential forces acting at the subduction boundaries can be related to different mechanisms, such as slab retreat, differential velocities along plate margins, complex mantle flow, differential lateral rheology. As a result, plates down-warp and tear in a scissor-like motion, with both strike-slip and dip-slip kinematics.

The goal of this work is to gain insights into the evolution of tear faults by adopting an analogue modelling approach and comparing the results with natural cases. In particular, we focus on the bathymetric observation made in subduction zones where the upper plate accretionary wedge is not well developed. Two scenarios were considered: 1) tear faults nucleating and evolving in a homogeneous setting, i.e. without large mechanical discontinuities (e.g., Tonga subduction zone); and 2) tear faults reactivating pre-existing strike-slip faults as an analogue of transform faults (e.g., South Sandwich subduction zone).

The experimental apparatus was designed to reproduce the lateral propagation of a tear fault using two blocks: one entirely flat and the other with an inclined plane. Wet kaolin acts as the analogue of the intact rocks above a propagating tear fault.

Our results revealed different evolutionary processes: in the homogeneous setting, the tear fault generates a symmetric subsidence zone with an axis perpendicular to the fault zone and a depocenter located in the centre; in the second case, the depocenter is located in front of the fault plane and the subsidence zone is asymmetric. Both cases depict a symmetrical Gaussian shape of the displacement profile, with the maximum displacement located at the centre of the fault. However, the maximum slip (Dmax) and the fault length (L)  are both larger in the experiment involving a strong re-activation of the strike-slip fault than those in the case of the homogeneous setting.
Determination of geochemical backgroud of waters of Kola Peninsula in order to decrease anthropogenic pollution in analysed area
Authors: Moroniak-Wawryszuk Dorota , Wawryszuk Mateusz , Chmiel Stanisław , Huber Miłosz , Kramarz Paweł , Lata Lesia , Skupiński Sebastian
Published: March 2020

In this study the geochemical background of waters of Kola Peninsula in the context of decreasing the athropogenic pollution in that region was indicated. The study was conducted on 14 water samples from different phases of hydrological cycle- precipitation water, snow-melting water, ground water, river water, lake water, sea water; also 12 samples of rocks and soils were used. pH of waters, conductivity, isotopic ratio of δ18O i δD, concentration of ions (anions and cations) along with metal ions were analysed. For conductivity measure InoLab 1 (WTW) was used, cations and anions were indicated by ions chromatograph (Metrohm MIC 3), metal ions were indicated by spectrometer ICP-MS (Thermo Xseries2). Laser analyzer PICARRO L2130 was used for defining the isotopic ratio of δ18O i δD. Soils and rocks samples were analysed using scanning electrone microscope (Hitachi SU6600) with EDS add-on and spectroscope XRF Epsilon 3 (Pananalytical).

The study showed significant impact of bedrock and soils on ion composition of waters in different locations in Kola Peninsula in example on several geogenical metal ions of P, F, Cl, Fe, Mn, Cu, Ni, S. Chemical composition of water backround is strictly related to polymetalic rocks and metal ores of the Baltic Shield which build analysed area. The waters' richness in alkali minerals is due to alkaline bedrock occuring in numerous areas of Kola Peninsula. The content of metal ions like Zn, Pb, Cr, Cd in numerous water samples indicates severe anthropogenic influence on water composition which can be especially noticed in the composition of surface water affected by the nearby heavy industry plants thus pollution of surface water.

Analisys of water samples proves significant impact of geological structure on chemical composition of water and should be considered in reclamation of natural environment of Kola Peninsula from anthropogenic pollution.
On the effect of surface roughness on velocity profiles and runout lengths of dry granular flows
Authors: Reider Lukas , Kaitna Roland
Published: March 2020

Gravitational mass flows like debris flows are often physically modelled as an assembly of particles flowing in simplified flume configurations. There is indication that natural flows exhibit a combined movement of sliding and internal deformation, which is not well understood and underrepresented in scaled laboratory experiments. In this study we investigate the effect of the surface roughness on the velocity profile and the runout of small-scale, dry granular avalanches. The experimental set-up is a 0.17 m wide flume with an inclination of 34° for the first 1.5 m, following an 0.8 m curved transition zone with a radius of 1.7 m, and ending in a runout zone with an angle of 4°. The tested material consisted of non-perfect spherical ceramic beads with a diameter of 2.8 to 4.3 mm. We tested four different types of surface roughness ranging from 0 to 6 mm height and additionally one macro roughness, which was higher than the maximum flow height. To also get information about the influence of the relative roughness experiments with three different starting volumes were undertaken. All fourteen experimental variations were repeated three times. Flow heights were measured with laser sensors at four different positions along the channel. Three of them were used to calculate the mean front velocity of the flowing mass in two cross sections. Furthermore, the experiments were recorded with a high-speed camera through one sidewall out of acrylic glass. The recordings were analysed using a PIV (Particle Image Velocimetry) software to derive velocity profiles in 1/1500 second time steps. Results show that the velocity profiles changed from the head to the tail of the flow and that the profiles of the two roughest surfaces are more alike than the smooth roughness configurations. The fraction of sliding on the total movement varied between 0 and close to unity. The runout length decreased the higher the roughness was and increased with higher starting volume. The shape of the velocity profiles at the deepest sections of the flows changed with surface roughness and with starting volumes. Only the velocity profiles for the two roughest surfaces show an inflection point. Our experiments highlight the importance of surface roughness as well as relative roughness for granular mass flows and provide data for model testing.
Assessment of biogenous load on the Gulf of Finland exerted from the Russian territory
Authors: Voronov Nikolai , Victorova Nataly , Shilov Dmitry
Published: March 2020

The purpose of the essay was analysis and evaluation of the load generated by pollutants in the Russian part of the catchment area directly entering the Baltic Sea, as well as consideration of pro-rata contribution of all sources in the formation of factual biogenous load at the catchment areas of rivers flowing into the Gulf of Finland.

The assessment of biogenous load was made on the basis of observation data, statistical reporting data, mathematical modelling data and additional monitoring data for bodies of water in previously uncontrolled areas. To assess the amount of biogenous input from uncontrolled tributaries of the Gulf of Finland, field observations of the discharge and concentration of pollutants over a number of past years were analyzed and generalized.

It is noted that there has been a tendency towards reduction of pollutants for a number of substances in the last decade, as shown by the analysis. It is demonstrated that a significant decrease is due to reduced load from point sources that discharge pollutants directly to the Baltic Sea and its bays. Some proposals are presented for improving the Russian system of monitoring the load exerted on water bodies.
PECASUS - ICAO Designated Space Weather Service Network for Aviation
Authors: Haukka Harri , Harri Ari-Matti , Kauristie Kirsti , Andries Jesse , Gibbs Mark , Beck Peter , Berdermann Jens , Perrone Loredana , van den Oord Bert , Berghmans David , Bergeot Nicolas , De Donder Erwin , Latocha Martin , Dierckxsens Mark , Haralambous Haris , Stanislawska Iwona M , Wilken Volker , Romano Vincenzo , Kriegel Martin , Österberg Kari
Published: March 2020

The PECASUS Consortium (European Consortium for Aviation Space weather User Services) provides targeted space weather services focusing on the dissemination of warning messages, called 'advisories', towards aviation actors. PECASUS services corresponds to extreme space weather events with impact on aviation GNSS systems, HF communication and radiation levels at flight altitudes. In November 2018 ICAO (International Civil Aviation Organization) designated three global space weather service centers. These centers acre operated by the European PECASUS consortium, by United States and by the consortium of Australia, Canada, France and Japan.

PECASUS was set-up as a consortium bringing together a number of European partners with proven space weather service capabilities. The PECASUS consortium is coordinated by FMI (Finland) who is also the ultimate responsible for communications towards the aviation sector. The Advisory Messages are produced by STCE (Belgium) on the basis of expert interpretation and data streams produced by DLR (Germany), INGV (Italy), Seibersdorf Laboratories (Austria), STCE (Belgium), SRC (Poland) and FU (Cyprus). In addition, the MetOffice (UK) will act as a resilience node in case of a major failure in the network, while the KNMI (The Netherlands) will take care of user liaison and monitor the PECASUS performance.

The PECASUS Consortium was audited in February 2018 by space weather and operational management experts, nominated by the World Meteorological Organisation (WMO). The audit addressed a broad spectrum of criteria under Institutional, Operational, Technical and Communication/ Dissemination categories. PECASUS was declared fully compliant in all ICAO/WMO criteria with no areas for improvement identified.

Our presentation we will describe the coordinated actions of three ICAO Space Weather Centers, PECASUS network and its operations, and the vision of the PECASUS team to move forward. User interactions such as education and training, user feedback at ESWW, product and performance verification are part of PECASUS operations.
Supporting reduction of risks of tailings dams using earth observation data
Authors: Davison Mark , Roca Marta , Petkovsek Gregor
Published: March 2020

Tailings dams are earth embankments used to store toxic mine waste and effluent. Their failure, as already seen in January 2019 with the fatal failure of Brumadinho dam in Brazil, can cause loss of life, irreversible damage to ecosystems and large economic damages. In countries with limited resources, it is challenging for the authorities to be able to assess the risk and effectively monitor this type of infrastructure, especially when located in remote areas.

We are developing DAMSAT (Dam Monitoring from SATellites), a web-based system for a sustainable and cost effective way of remotely monitor tailings and water retention dams to support early decision making and reduce the social, economic and environmental impacts downstream of potential failures.

DAMSAT monitors the displacement of the structures using earth observation technologies such as Interferometric Synthetic Aperture Radar (InSAR) and Global Navigation Satellite System (GNSS) technologies, combined with real-time in-situ devices. These observations combined with weather forecasting tools allow the issue of alerts for unusual behaviour or weather conditions that could lead to dam failure. These alerts are part of the Disaster Risk Management cycle to trigger the implementation of mitigation measures to reduce the likelihood of failure of the dam or the potential consequences downstream.  

In order to have a better understanding of these potential consequences and provide all the information necessary for asset managers to take decisions, DAMSAT also assesses the hazard component of disaster risk due to dam failure using a set of modelling tools. A dam breach simulation model (EMBREA) is combined with a mud flow model to spread the flood hazard downstream of the dam if a failure occurs.  The consequences of the flood are assessed in terms of loss of life using an evacuation model, the Life Safety Model. Different flood warning scenarios and evacuation strategies are mapped to inform emergency planning.

DAMSAT is currently being piloted in two mining regions in Peru with the involvement of government organisations and other relevant stakeholders. 
Rapid Global Finite-Frequency Ambient Noise Source Inversion
Authors: Igel Jonas , Ermert Laura , Fichtner Andreas
Published: March 2020

Common assumptions in ambient noise seismology such as Green’s function retrieval and equipartitioned wavefields are often not met in the Earth. Full waveform ambient noise tomography methods are free of such assumptions, as they implement knowledge of the time- and space-dependent ambient noise source distribution, whilst also taking finite-frequency effects into account. Such methods would greatly simplify near real-time monitoring of the sub-surface. Additionally, the distribution of the secondary microseisms could act as a new observable of the ocean state since its mechanism is well understood (e.g. Ardhuin et al., 2011).

To efficiently forward-model global noise cross-correlations we implement (1) pre-computed high-frequency wavefields obtained using, for example, AxiSEM (Nissen-Meyer et al., 2014), and (2) spatially variable grids, both of which greatly reduce the computational cost. Global cross-correlations for any source distribution can be computed within a few seconds in the microseismic frequency range (up to 0.2 Hz). Similarly, we can compute the finite-frequency sensitivity kernels which are then used to perform a gradient-based iterative inversion of the power-spectral density of the noise source distribution. We take a windowed logarithmic energy ratio of the causal and acausal branches of the cross-correlations as measurement, which is largely insensitive to unknown 3D Earth structures.

Due to its parallelisation on a cluster, our inversion tool is able to rapidly invert for the global microseismic noise source distribution with minimal required user interaction. Synthetic and real data inversions show promising results for noise sources in the North Atlantic with the structure and spatial distribution resolved at scales of a few hundred kilometres. Finally, daily noise sources maps could be computed by combining our inversion tool with a daily data download and processing toolkit.
Using PRIMAVERA high-resolution global climate models for European windstorm risk assessment in present and future climates for the (re)insurance industry
Authors: Lockwood Julia , Palin Erika , Guentchev Galina , Roberts Malcolm
Published: March 2020

PRIMAVERA is a European Union Horizon2020 project about creating a new generation of advanced and well-evaluated high-resolution global climate models, for the beneﬁt of governments, business and society in general. The project has been engaging with several sectors, including ﬁnance, transport, and energy, to understand the extent to which any improved process understanding arising from high-resolution global climate modelling can – in turn – help with using climate model output to address user needs.

In this talk we will outline our work for the ﬁnance and (re)insurance industries.  Following consultation with members of the industry, we are using PRIMAVERA climate models to generate a European windstorm event set for use in catastrophe modelling and risk analysis.  The event set is generated from five different climate models, each run at a selection of resolutions ranging from 18-140km, covering the period 1950-2050, giving approximately 1700 years of climate model data in total.  High-resolution climate models tend to have reduced biases in storm track position (which is too zonal in low-resolution climate models) and windstorm intensity.  We will compare the properties of the windstorm footprints and associated risk across the different models and resolutions, to assess whether the high-resolution models lead to improved estimation of European windstorm risk.  We will also compare windstorm risk in present and future climates, to see if a consistent picture emerges between models.  Finally we will address the question of whether the event sets from each PRIMAVERA model can be combined to form a multi-model event set ensemble covering thousands of years of windstorm data.
Southern Chilean continent-ocean interaction over the last glacial cycle
Authors: Hagemann Julia Rieke , Lamy Frank , Nagashima Kana , Harada Naomi , Iwasaki Shinya , Martínez-Garcia Alfredo , Kaiser Jérôme , Arz Helge W. , Nowaczyk Norbert , Lange Carina , Tiedemann Ralf
Published: March 2020

Available sea surface temperature (SST) records from the subantarctic SE Pacific reveal large amplitude changes at orbital time-scales. High sedimentation rates along the southern Chilean margin provided higher resolution records back to ~70 ka showing millennial-scale SST variations paralleling temperatures reconstructed in Antarctic ice-cores.

Here we present high-resolution millennial-scale SST and subsurface temperature records based on core MR16-09 PC03 covering a complete glacial/interglacial cycle back to Marine Isotope Stage 6, including a high-resolution record of the Eemian. Located on the Chilean margin at the bifurcation of the Antarctic Circumpolar Current into the Peru-Chile Current to the North and the Cape Horn Current to the South, core MR16-09 PC03 is in an ideal position to study the continent-ocean interactions, including changes in water masses, ice sheet formation, precipitation and vegetation.

We used alkenones and GDGTs to determine SST (UK’37) and subsurface temperatures (TEXH86; 0 - 200 m), and integrated these results with XRF core scanner and planktic δ18O data (G. bulloides). During the Eemian, SSTs and subsurface temperatures were ~2° C and ~4° C, higher than during the Holocene, respectively. The high Eemian temperatures at our site are roughly consistent with the few available subantarctic SST records. The large temperature difference in the subsurface water masses between the Eemian and the Holocene could be explained by a deeper thermocline during the Eemian. During the last glacial period, the strongly fluctuating temperatures averaged ~8° C at the surface and ~6° C in the subsurface. The relative amount of C37:4 alkenone (%C37:4) show a drastic increase during the glacial period, especially in Marine Isotope Stage 3 in concentration. High %C37:4 values suggest increased freshwater supply, which could be related to fluctuations of the Patagonian Ice sheet and/ or precipitation on the adjacent land. The sedimentation rate and other terrigenous proxies, e.g. Titanium, BIT, Iron and Alkanes, confirm such increased and highly variable terrestrial inputs.
Electron anisotropy driven by kinetic Alfven waves in the Earth magnetotail
Authors: Lukin Alexander , Artemyev Anton , Panov Evgeny , Petrukovich Anatoly , Nakamura Rumi
Published: March 2020

Thermal and subthermal electron populations in the Earth’s magnetotail is usually characterized by pronounced field-aligned anisotropy that contributes to generation of strong electric currents within the magnetotail current sheet. Formation of this anisotropy requires electron field-aligned acceleration, and thus likely involves field-aligned electric fields. Such fields can be carried by various electromagnetic waves generated by fast plasma flows interacting with ambient magnetotail plasma. In this presentation we consider one of the most intense observed wave emissions, kinetic Alfven waves, that accompany all fast plasma flows in the magnetotail.

Using two tail seasons (2018, 2019) of MMS observations we have collected statistics of 80 fast plasma flows (or BBF) events with distinctive enhancement of intensity of broadband electromagnetic waves sharing properties of kinetic Alfven waves. We show that a direct correlation the intensity of electric fields of kinetic Alfven waves and electron anisotropy distribution: the parallel electron anisotropy significantly increases with magnitude of the wave parallel electric field. The energy range of this electron anisotropic population is well within the range of resonant energies for observed kinetic Alfven waves. Our results show that kinetic Alfven waves can significantly contribute to shaping the magnetotail electron population.
Marine radiocarbon simulations carried out with a global multi-resolution ocean model
Authors: Butzin Martin , Sidorenko Dmitry , Köhler Peter
Published: March 2020

Radiocarbon (14C) is an ideal tracer to study the uptake of carbon dioxide by the seas and the ocean circulation during the past 50,000 years. However, there are various issues impeding a straightforward interpretation of marine 14C records. The spatial and temporal variability of marine 14C records is superimposed by a systematic isotopic depletion of the sea surface with respect to the atmosphere. This effect is frequently expressed as Marine Reservoir Age (MRA), ranging from ~400 years in subtropical oceans to more than 1000 years in polar seas during the late Holocene. Prior to the Holocene, MRAs are poorly constrained through reconstructions. Moreover, the entire database of marine 14C records gets increasingly patchy and sparse the further one steps backwards in time. Model simulations provide a valuable interpretation tool and can help to fill spatial and temporal gaps. However, 14C paleorecords typically originate from continental margins, marginal seas, or tropical lagoons. These regions are not properly resolved by default coarse-resolution ocean models, which may result in regional model and hence interpretation biases. The alternative are marine 14C simulations with high(er) resolution, but the conventional approach involving uniform meshes results in computational costs which are prohibitive in most cases. To overcome these issues, we have implemented 14C into the state-of-the-art ocean model FESOM2 which employs unstructured meshes with variable resolution. This approach permits zooming into certain regions of interest while keeping the model resolution in other areas sufficiently moderate. Here, we present first simulation results considering the Anthropocene, the late Holocene, and the Last Glacial Maximum, focusing on the evolution of Marine Reservoir Ages.
Intensity Prediction Equation for Austria: Applications and analysis
Authors: Papí Isaba María del Puy , Weginger Stefan , Apoloner Maria-Theresia , Jia Yan , Hausmann Helmut , Meurers Rita , Lenhardt Wolfgang
Published: March 2020

We present the results of the intensity prediction equation for Austria as a function of moment magnitude, focal depth and hypocentral distance from the source. This equation aims to be simple and correct to generate shakemaps in near-real-time for crisis management and risk assessment in terms of the impact of an earthquake. Before the model computation, the dataset was carefully selected from the Austrian Earthquake Catalogue (AEC). Then, the model was derived through two Ordinary Least Square Adjustments; the first one was used to calibrate the epicentral intensity, whereas the second one aimed to derive an intensity attenuation law. Additionally, first own-approach to remove local site effects was used to refine the model. In total, the used dataset includes 42 earthquakes befalling in Austria and border regions between 2004 and 2018. Their local magnitude varies between 3.0 and 5.4. In total, 3,214 IDPs with intensity values between III and VII-VIII (EMS-98) were used.

Applications and analysis of the model will be presented. Furthermore, first results to an Austrian hazard map based on intensities will be introduced.
The Messinian Salinity Crisis (MSC) deposits in the Balearic Promontory: An undeformed analog of the MSC Sicilian basins??
Authors: Raad Fadl , Lofi Johanna , Maillard Agnes , Caruso Antonio , Tzevahirtzian Athina
Published: March 2020

The Messinian Salinity Crisis (MSC) is a prominent and still misunderstood event that influenced the Mediterranean basin in the late Miocene leaving behind a Salt Giant (SG) widespread all over the Mediterranean basin. More than 90% of the Messinian Evaporitic deposits are located offshore with reduced access via boreholes, and thus has been studied mainly by seismic imaging. Onshore-Offshore should be considered a key for a better understanding and answering some of the controversies on the MSC.

The Balearic Promontory (BP) contains a series of small perched basins presently lying at different water depths, stepped from the present-day coastline down to the deep basin. These topographic lows trapped sedimentary series up to 500m thick, interpreted as MSC in age.
The reduced tectonic movements in the BP since the late Miocene (Messinian) till recent days, favored the conservation of the MSC records in this area. Moreover, recent studies revealed the presence of a Salt layer in the Central Mallorca Depression (CMD).

Considering: 1- the bathymetry of the BP, classified as an intermediate perched basin; 2- the distribution of the MSC records accumulated in a series of sub-basins more or less connected between each other; 3- the geometries of the evaporitic formations, provided by how these records appear on the seismic data; this might recall similarities between the BP records (especially the ones in the CMD) and the MSC reference records outcropping in Sicily (especially in the Caltanissetta Basin).

We perform seismic interpretation of a wide seismic reflection dataset in the study area with the aim of refining the mapping of the Messinian evaporites covering the study area. Four seismic units were identified in the BP based on their seismic facies and their seismo-stratigraphic position. We try to match up these units to the consensus Messinian 3-stages chrono-stratigraphic model proposed during the CIESM in 2008.
We also attempt to find similarities in geometries, facies and distribution of the MSC between the sub-basins of the BP and those described in the Sicilian sub-basins.
Fire history in China during the Holocene and its response to the changes in environmental and anthropogenic factors
Authors: Xu Xin , Li Fang , Lin Zhongda , Song Xiang
Published: March 2020

Fire is an intrinsic feature of terrestrial ecosystem, and a key Earth system process that strongly affects ecosystem structure and functioning , carbon and nutrient cycles, climate, air quality and society. Although local and regional paleo-fires in China have been investigated based on one or several fire-proxy records, so far China’s fire history at the country level and its driving forces remain unknown. The present study, for the first time, reconstructs China’s fire history based on charcoal and black carbon records at 107 sites through the Holocene (12 ka BP to the present in this study), and investigates fire historical changes and dominant drivers. Results show that fire activity over China gradually decline from the Early Holocene (12 ka BP) to the Middle Holocene (7.3 ka BP), followed by a sharp rise till the present age. The historical changes are mainly regulated by moisture change through the whole Holocene, and also affected by population growth and agriculture expansion over the past 2 ka.
High sensitivity of seasonal tropical precipitation to local sea-surface temperature
Authors: Chadwick Robin , Good Peter , Holloway Christopher , Kennedy John , Lowe Jason , Roehrig Romain , Rushley Stephanie
Published: March 2020

Seasonal mean tropical precipitation at any location is controlled by a tangle of local and remote effects, including influences from SSTs across the globe. This, along with uncertainty in precipitation observations, and extremely limited observations of atmospheric circulation, makes understanding the relevant physics challenging. Climate model precipitation biases persisting across multiple generations of models point towards stubborn gaps in understanding and reduce confidence in seasonal forecasts and climate projections.  This includes the 'double ITCZ problem': excessive rainfall in the southern tropical Pacific, first reported in 1995.  Model ITCZs also tend to be too wide.

Our study shows that in the real world, the sensitivity of tropical precipitation to local sea surface temperature is high, associated with strong shallow circulations.  This rests on a novel analysis of observations, unpicking local and remote controls on precipitation, and navigating a path through observational uncertainty.  Models with appropriate sensitivity to local sea surface temperature, perform well across many conditions.  Improvements in this sensitivity from the fifth to the sixth model intercomparison project are small, highlighting the need for new understanding.  By further linking model biases to shallow convection, our results highlight a target process for focused research: accelerating improvements in seasonal forecasts through to multi-decadal climate projections.

Wider Met Office work linking precipitation evaluation between climate, seasonal and weather timescales will also be summarised.