bluuebunny/crossref_metadata_2025 huggingface dataset:
Interactions between soil conversation service and land cover changes in the Three Gorges Reservoir Area after returning farmland to forest
Authors: Huang Yue , Huang Zhilin , Ma Liang
Published: March 2020

Intensification of returning farmland to forest has led to success in ecological construction and improvement. Returning farmland to forest project has been implemented at the Three Gorges Reservoir Area (TGRA) since 2000. We aimed to access the soil conservation service variation in the Lanlingxi watershed of TGRA using land cover change as a proxy indicator. Lanlingxi watershed is a representative pilot of TGRA, which included specialized in the national demonstration of returning farmland to forest project. The multi-stage methodology included; (i) land cover analysis in phased process using and GIS (ii) assessing soil conservation service values using InVEST model. The results showed that during 1999-2017, significant land cover transformations occurred in the study area, increase of economic forests land, tea, citrus in exchange of cultivated land. Langlingxi watershed covered an area of 1527.43 hm2, cultivated land occupied 32.58% of the 497.65 hm2 in 1999, and reduced to 4.16% in 2017. Tea land occupied 19.41% of the total land in 2017, which was under 1% in 1999. Land cover conversion was from cultivated land to tea, citrus and bush. Land cover change happened within at lower altitude of protection and economic forest, no significant change at ecological welfare forest. The value of soil conversation was 415.08 t/hm2 in 1999, while the land was cover by tea, citrus and bush in 2017, the value of soil conversation was higher than 490 t/hm2. Total soil conversation increased 28.56% at lowest attitude and 19.82% at intermediate altitude area in 2017 as a result of land cover change. The ability and capacity of soil conversation were higher by returning farmland to forest. Such changes contributed to the increase of soil conservation service, mainly as a result of a better capacity in soil and water conservation by forests. The results of this study emphasized the importance of land management and forests restored for better ecosystem services and conservation.
How global dryland vegetation dynamics relate to changing climatic conditions and anthropogenic dynamics
Authors: Abel Christin , Horion Stéphanie , Tagesson Torbern , De Keersmaecker Wanda , Seddon Alistair W.R. , Abdi Abdulhakim M. , Fensholt Rasmus
Published: March 2020

Monitoring ecosystem dynamics is fundamental to understanding and eventually forecasting ecosystem states. To achieve this, it is crucial to identify and understand potential negative/ positive effects from a changing world on the system. As one key aspect of every ecosystem are the living organisms it involves, our research focuses on vegetation, since it has major implications for both the climate, because plants absorb carbon dioxide, and human well-being, because people depend on the products of plants. Specifically addressing global drylands, where vegetation productivity is tightly linked to the availability of water (mainly through rainfall), we quantify changes in vegetation functioning by analyzing the slopes of a sequential linear regression (SeRGS) over a time series of remote sensing data (NDVI and rainfall), as introduced in Abel et al., 2019. Further, we apply a data-driven, empirical approach to estimate the relative importance of potential drivers of identified changes, as in Abel et al., 2020 (in revision). We show that there are substantial regional and continental differences in vegetation functioning and that these trends can be linked to global trends of population expansion, large-scale agriculture intensification/ expansion and changing climatic conditions. Results from these studies, follow-up research and perspectives will be presented and discussed at EGU.

References:

Abel, C., Horion, S., Tagesson, T., Brandt, M., Fensholt, R. (2019). Towards improved remote sensing based monitoring of dryland ecosystem functioning using sequential linear regression slopes (SeRGS). Remote Sens. Environ. 224, 317–332.

Abel, C., Horion, S., Tagesson, T., De Keersmaecker, W., Seddon, A. W. R., Abdi A. M., Fensholt, R. (2020). How the human-environment nexus changes global dryland vegetation functioning, in revision.
Zn isotopes in deep sea corals: a useful palaeoceanographic archive?
Authors: Little Susan , van De Flierdt Tina , Wilson David , Rehkämper Mark , Adkins Jess , Robinson Laura
Published: March 2020

Zinc (Zn) is an important bioessential trace element. Its distribution in the modern oceans reflects a combination of biological uptake, remineralization and the physical ocean circulation. Furthermore, the partitioning behaviour of Zn (DZn) and its isotopes (δ66Zn) in carbonates has been linked to ambient seawater carbonate chemistry [1-3].

Development of Zn isotopes in carbonates as a palaeoceanographic tool has been hampered by the high concentrations of Zn in contaminating material, such as lithogenic or authigenic (e.g. Fe-Mn oxide) phases. However, deep-sea corals are large enough to be subjected to aggressive physical and chemical cleaning, enabling effective removal of contaminating phases. They also have several other advantages over traditional palaeoclimate archives, including the ability to assign precise absolute ages to individual specimens based on uranium-series dating [4].

Here we present Zn/Ca and δ66Zn data for a suite of modern and recent (<1000 yr) deep sea corals from six ocean regions spanning the far North Atlantic to the Tasman Sea. We observe what appears to be species-specific Zn partitioning behaviour, but no clear links between DZn or coral δ66Zn and ambient seawater carbonate chemistry. Overall, there is good agreement between measured or best-guess modern seawater δ66Zn and coral aragonite δ66Zn values, suggesting that corals of species Desmophyllum dianthus and genus Caryophyllia do not significantly fractionate Zn isotopes during calcification. Deep sea corals may thus provide a useful archive of the past ocean Zn isotope composition and its spatial variability.

[1] Marchitto T. M., Curry W. B. and Oppo D. W. (2000). Paleoceanography 15, 299–306. 
[2] van Dijk, I., de Nooijer, L. J., Wolthers, M., & Reichart, G. J. (2017). Geochimica et Cosmochimica Acta 197, 263-277. 
[3] Mavromatis, V., González, A. G., Dietzel, M., & Schott, J. (2019). Geochimica et Cosmochimica Acta 244, 99-112. 
[4] Robinson, L. F., Adkins, J. F., Frank, N..., & van de Flierdt, T. (2014), DSR Part II 99, 184-198.

 
Pan-Eurasian Experiment (PEEX) Programme – Overview on the recent results
Authors: Lappalainen Hanna , Kerminen Veli-Matti , Altimir Nuria , Mahura Alexander , Ezhova Ekataterina , Vihma Timo , Uuotila Petteri , Chalov Sergey , Konstantinov Pavel , Archinov Michael , Qui Yubao , Ezau Igor , Kukkonen Ilmo , Melnikov Vladimir , Ding Aijun , Baklanov Alexander , Kasimov Nikolai , Guo Hudong , Bondur Varely , Petäjä Tuukka ,   Hanna Lappalainen
Published: March 2020

Pan-Eurasian Experiment (PEEX) Programme (www.atm.helsinki.fi/peex) initiated in 2012 is an asset for INAR at the University of Helsinki and its co-partners to have high international visibility, to attract further research collaboration and to upscale the scientific impact in various arenas. The PEEX is interested in the northern high latitudes (Arctic, boreal) and on China and the new Silk Road Economic Belt regions. The PEEX scientific focus is on understanding of large-scale feedbacks and interactions between the land -atmosphere - ocean continuum under the changing climate of the Northern high latitudes and at the Arctic (Kulmala et al. 2015, Lappalainen et al. 2014; 2015; 2016; 2018, Vihma et al. 2019, Alekseychik et al. 2019, Kasimov et al. 2018) and on the transport and transformation of air pollution in China. PEEX research results have been published the PEEX Special Issue in J. Atmospheric Chemistry and Physics (www.atmos-chem-phys.net/special_issue395.html), in the Journal “Geography, Environment, Sustainability” (ges.rgo.ru/jour) and in the J. Big Data (journalofbigdata.springeropen.com).  In 2019 PEEX started comprehensive analysis on the first results over last five years based on the published peer review papers and results attained from the PEEX geographical domain.  The aim of the analysis is to study the state-of-the-art research outcome versus the PEEX large-scale research questions addressed by the Science Plan (Lappalainen et al. 2015). To facilitate the direct input from the research community, we have asked researchers to answer to a form where they could list their main scientific results and activities considered relevant to PEEX region and also include ancillary information such as type of activity or geographical extend. The preliminary metadata database covers information from over 400 scientific papers and the analysis is in progress. The key gaps of current understanding and future research needs will be discussed from the system point of view, from the land ecosystems, atmosphere, ocean & river systems and society perspectives and preliminary results will be introduced at EGU PEEX session.
Plume-induced subduction initiation: single- or multi-slab subduction?
Authors: Baes Marzieh , Sobolev Stephan , Gerya Taras , Brune Sascha
Published: March 2020

The formation of new subduction zones is a key component of global plate tectonics. Initiation of subduction following the impingement of a hot buoyant mantle plume is one of the few scenarios that allow breaking the lithosphere and recycling a stagnant lid without requiring any pre-existing weak zones. According to this scenario, upon arrival of a hot and buoyant mantle plume beneath the lithosphere, the lithosphere breaks apart and the hot mantle plume materials flow atop of the broken parts of the lithosphere. This leads to bending of the lithosphere and eventually initiation of subduction. Plume-lithosphere interaction can lead to subduction initiation provided that the plume causes a critical local weakening of the lithospheric material above it, which depends on the plume volume, its buoyancy, and the thickness of the lithosphere. Previous modeling studies showed that plume-lithosphere interaction can result in initiation of multi- or single-slab subduction zones around the newly formed plateau. However, they did not explore the parameters playing key roles in discriminating between the single- and multi-slab subduction scenarios. Here, we investigate factors controlling the number and shape of retreating subducting slabs formed by plume-lithosphere interaction. Using 3d thermo-mechanical models we show that the response of the lithosphere to arrival of a mantle plume beneath it depends on several parameters such as age of oceanic lithosphere, thickness of the crust, large-scale lithospheric extension rate, relative location of plume head and plateau edge and mantle temperature. The numerical experiments reveal that plume-lithosphere interaction in present day Earth can result in three different deformation regimes: (a) multi-slab subduction initiation, (b) single-slab subduction initiation and (c) plateau formation without subduction initiation. On early Earth (in Archean times) plume-lithosphere interaction could result in formation of either multi-slab subduction zones, very efficient in production of new crust, or episodic short-lived circular subduction. Extension eases subduction initiation caused by plume-lithosphere interaction. Plume-induced subduction initiation of old oceanic lithosphere with a plateau with thick crust is only possible if the lithosphere is subjected to extension.
Energy management in dry canopy starts with efficient leaf-scale heat exchange
Authors: Müller Jonathan D. , Rotenberg Eyal , Tatarinov Fedor , Oz Itay , Schwartz Efrat , Yakir Dan
Published: March 2020

Dry forests are expected to heat up considerably more than adjacent shrubland areas due to lower albedo and reduced latent heat flux. Paradoxically, the forest surface at our research site was observed to be cooler than the non-forested neighbouring areas during drought. This reflected the control over canopy temperature through the sensible heat flux, i.e. a 'convector effect'. Our objective was to examine how the efficient non-evaporative energy management, critical to protect the biological functioning of dryland ecosystems, develops at the small, leaf scale. 

We developed a novel system to continuously measure the energy balance and heat dissipation mechanisms on a leaf scale under field conditions. It allows the measurement of emitted leaf and background longwave radiation, and estimating the incoming, absorbed and reflected shortwave radiation using PAR measurements and full spectrum models.  Latent heat exchange and photosynthetic activity were measured with branch chambers. The system was deployed during the long summer drought (>8 months) in drought-exposed and irrigated plots in our semi-arid research Aleppo Pine forest site in southern Israel (mean daytime temperature of >30°C).

Preliminary results showed that in spite of a x10 higher transpiration rate in the irrigated plot compared with the control plots, leaf temperature remains within 1-2°C of air temperature on average in both plots during direct exposure to sunlight at midday. These results suggest an effective leaf to air heat transfer which prevents overheating independent of the latent heat flux. Under the high radiation load, the midday summer value of incoming shortwave radiation was >800 W·m-2 (mostly absorbed by the low albedo leaves), and background longwave radiation was >500 W·m-2. In turn, the energy dissipation in the drought-exposed trees was dominated by sensible heat flux of >500 W·m-2, while the long-wave radiation balance was near neutral (~50 W m-2), and the residual latent heat flux was <50 W·m-2. We demonstrated a system that provided new insights to leaf and canopy energy management under drought, which is a basis for the evolution of the convector effect.
Multidisciplinary studies of the Puigcercós historical landslide in the Catalan Pyrenees
Authors: Khazaradze Giorgi , Guinau Marta , Blanch Xabier , Abellán Antonio , Tapia Mar , Furdada Gloria , Suriñach Emma
Published: March 2020

More than a century ago, the Puigcercós village located in the region of Pallars Jussà (Catalonia, Spain), suffered a large-scale landslide that occurred on January 13th, 1881. More than 5 million m3 of sediments and rocks were displaced and a 200 m long and 25 m high rock scarp was formed. Luckily, during the main event, the nearby village was not affected, and due to a prompt evacuation and re-location of the entire village, no casualties were reported. Nevertheless, consequent retreat of the main scarp did destroy the big part of the old village, which confirmed not only the necessity for its relocation, but also gave one of the first clearly described and confirmed examples of a successful geologic risk prevention.

During the last decade, the members of the RISKNAT-UB group have chosen this site to conduct pilot studies of rockfalls and landslides using a multidisciplinary approach. The utilized observational techniques include Terrestrial Laser Scanner (TLS), photogrammetry, GPS, seismic monitoring and geophysical prospecting techniques. The work presented here is an overview of these activities, including the main milestones of the ongoing research. Special emphasis will be given to the use of geodetic techniques for investigating changes on the depositional area of the landslide and around the crown cracks at the upper level of the main scarp. As a result of the GPS observations, for the first time, 130 years after the occurrence of the event, it was possible to observe a continuing geomorphological activity of the depositional zone of this historical landslide, Currently, the RISKNAT-UB group operates cost-effective, high-resolution and low-cost photogrammetric instruments and seismic continuous records at the site, in order to monitor the evolution of the Puigcercós rock scarp. The correlation of the seismic and the photogrammetric data and intermittently obtained LiDAR images enables us to monitor and characterize frequent rockfalls and premonitory deformations occurring at the site. These observations have allowed quantifying the rate of retreat of the rock scarp at a rate of 10 to 11 cm/yr and a slow motion of the depositional zone up to 6 mm/yr. Since the geologic risk at the study area is not significant, due to the absence of population and/or infrastructures, this site is an ideal natural laboratory for developing new observational techniques, which can be used to develop early warning systems for rockfalls and landslides.

The authors would like to acknowledge a financial support from CHARMA (CGL2013-40828-R) and PROMONTEC (CGL2017-84720-R AEI/FEDER, UE) projects, financed by the Spanish MINEICO. We are also thankful to UNESCO Global Geopark Conca de Tremp-Montsec for their support.
Sensitivity of trends to estimation methods and quantification of subsampling effects in global radiosounding temperature and humidity time series
Authors: Sy Souleymane , Madonna Fabio , Tramutola Emanuele , Rosoldi Marco , Proto Monica , Pappalardo Gelsomina
Published: March 2020

Inaccurate climate trend detections may lead to incorrect conclusions about the current state and future evolution of the climate. Trend estimation based on the use of radiosonde historical time series may be significantly affected by the choice of the estimation method. In addition, the dataset subsampling both in time (due to gaps in the data records) and in space (due to need of selecting the most reliable subset of stations for each specific application) can further increase the trend uncertainty. 

Uncertainties of trend estimations have been quantified in few past investigations, considering the difference between pairs of regression methods, although limited to datasets affected by several inhomogeneities and characterized by smaller trend rates than those observed over the last two decades.

This work, carried out in the frame of the Copernicus Climate Change Service (C3S), aims to examine the sensitivity of trend estimations to linear estimation methods and to subsampling effects. The analysis is carried out using about 600 historical radiosounding time series for the period 1978-2018 available within version 2 of the Integrated Global Radiosonde Archive (IGRA).

The sensitivity of linear trends to the choice regression methods and the subsampling effects have been quantified through the comparison of four regression methods (parametric and non-parametric). The uncertainties introduced by missing data in each time series has been also quantified using a new approach, selecting different samples of stations with different amounts of missing monthly data equivalent to 0, 5, 10 and 20 years from 1978 to present. Instead, the spatial subsampling effects are quantified artificially reducing the size of the IGRA stations.

The presented work will shortly discuss results obtained for temperature and relative humidity for both night and day times  (at 0000 and 1200 UTC, respectively) at different pressure levels and latitudes.
Floodplain forest carbon exchange – a micrometeorological point of view
Authors: Kowalska Natalia , Jocher Georg , Šigut Ladislav , Pavelka Marian
Published: March 2020

Since the eddy covariance (EC) method became a key method for measurements of the energy and greenhouse gas exchange between ecosystems and the atmosphere, a large number of studies was conducted to understand the mechanisms driving the carbon exchange in forest ecosystems. In recent years, case studies further focused on testing and validating the applicability of the EC technique above forest ecosystems, also assessing the spatial and temporal variability of sub canopy fluxes. These studies led to the conclusion that there is a high probability of overestimating the forest carbon sink strength with EC measurements above the forest canopy only, as these measurements may miss respiration components from within and below the canopy due to insufficient mixing across the canopy. Additional below canopy EC measurements were suggested to tackle this problem and to get information about potential decoupling between below and above forest canopy air masses as well as potentially missing respiration components in the above canopy derived signal.

The overall goal of the study here is to derive an as detailed as possible understanding of the carbon exchange in Lanžhot floodplain forest with the help of concurrent EC measurements below and above the forest canopy. Lanžhot floodplain forest is situated 6.5 km north of the confluence of the Morava and Thaya rivers in Czech Republic (48.6815483 N, 16.9463317 E). The long-term average annual precipitation at this site is around 517 mm and the mean annual temperature is 9.5 °C. The average groundwater level is -2.7 m. Since a long time flooding occurs here very rarely, the last flooding event was in 2013. In addition, the site is hydrologically managed. Consequently, the water regime of the site changed over the years and represents nowadays relatively dry conditions for such type of ecosystem.

To reach our research goal we evaluate different single- and two-level filtering strategies of the above canopy derived carbon exchange values and the impact of these filterings on the annual ecosystem carbon exchange rates. Our hypothesis is that conventional single-level EC flux filtering strategies like the u*-filtering might not be sufficient to fully capture the carbon exchange of the studied floodplain forest ecosystem. We further hypothesize that additional below canopy EC measurements are mandatory to achieve unbiased forest carbon exchange values with the EC technique.
Growth and evolution of continental lithosphere by cycles of oceanic subductions – Evidence from seismic anisotropy supported by petrologic and geochemical findings
Authors: Babuška Vladislav , Plomerová Jaroslava , Vecsey Luděk , Žlebčíková Helena
Published: March 2020

Formation and evolution of the continental lithosphere, one of the ILP research themes, still belongs to fundamental questions often debated within different geoscience disciplines. We emphasize the role of mantle lithosphere that forms the biggest volume of continents, but is often overlooked, particularly in geologic interpretations of tectonic processes. Investigation of seismic anisotropy from propagation of teleseismic P and S waves in three dimensions (3D) provides a unique constraint on tectonic fabrics and character of past and present-day deformations. We collect independent findings from seismology, petrology and geochemistry to support our 3D anisotropic model of mantle lithosphere with tilted symmetry axes, derived from data of passive seismic experiments organised in tectonically different domains of Archean, Proterozoic and Phanerozoic provinces of Europe. We delimit the extent of lithosphere domains and their boundaries according to changes in orientation of the large-scale anisotropy, associated with a systematic preferred orientation of olivine, originally formed by mantle convection in the oceanic mantle lithosphere and “frozen” deep in continents.

We explain the oriented dipping fabrics in the continental mantle lithosphere by successive subductions of ancient oceanic plates and their accretions enlarging a primordial continent core, consequent supercontinent break-ups and assemblages of wandering micro-plates to create the patchwork structure of the present-day continents. Supporting arguments for such model arise from petrologic and geochemical studies indicating that continental peridotites formed in oceanic environments and became “continental” after significant thickening or underthrusting. Combining seismological, petrologic and geochemical findings can help to bridge the gap between the different viewpoints and evoke further discussions on growth mechanisms and evolution of the continental lithosphere. Data gathered during new large-scale passive seismic experiments, like AlpArray, AdriaArray, PACASE and related projects, including CoLiBrI - Continental Lithosphere: a Broadscale Investigation, will provide new exciting materials for studies of formation and evolution of the continental lithosphere.
The French network of magnetic observatories
Authors: Lesur Vincent , Chambodut Aude
Published: March 2020

In magnetic observatories the Earth’s magnetic field is continuously recorded and the acquired data are calibrated so that the evolution of the field can be studied on time scales ranging from seconds to decades. The French network (the so called BCMT) includes 18 observatories around the world and the different types of data produced are freely accessible on several data centres. We will describe a typical infrastructure of a magnetic observatory, the measurement techniques, the instruments used, the general processing applied to obtain calibrated data and finally the environmental constraints that have to be respected in order to acquire suitable data. If magnetic observatories were originally set to monitor the slow variations of the Earth’s main magnetic field, they are more and more often used for space-weather monitoring and to study signal generated in the ionosphere and magnetosphere. This new range of applications implies an evolution of the network, of the acquisition and distribution techniques. The strategy we developed to respond to these new challenges will be also presented.
First measurements of the Mesospheric Magnetic Field in the Auroral Zone by means of laser
Authors: Johnsen Magnar G. , Gulbrandsen Njål , Hillman Paul , Denman Craig , Matzka Jürgen , Schultze Volkmar , Hoppe Ulf-Peter
Published: March 2020

In December 2019, for the first time, we were able to remotely measure the magnetic field in the mesospheric sodium layer, in the auroral zone.

By means of laser optical pumping and Larmor-resonance detection, it is possible to use the naturally occurring sodium layer in the mesosphere to measure Earth’s magnetic field magnitude at 90 km above ground. This is an altitude otherwise only accessible by rockets, which only will provide point measurements of very short time scales.

During the winter of 2019-20 we have applied a cw sum-frequency fasor/laser for probing the sodium-atom Larmor resonance at the Artic Lidar Observatory for Mesospheric Research (ALOMAR) at Andøya in northern Norway in order to measure and monitor the magnetic field in situ in the high latitude mesosphere over longer time scales.

The technique, which has been proved earlier at mid-latitudes, has now been confirmed and applied to high latitudes in the auroral zone during disturbed auroral and geomagnetic conditions. The magnetic field in the auroral zone is close to vertical making our measurements a notable achievement since the beam is closer to parallel with the magnetic field, contary to earlier measurements being closer to perpendicular as shown as best by theory.

This opens up for a completely new domain of measurements of externally generated geomagnetic variations related to currents in the magnetosphere-ionosphere system.

Here we report on the instrumental setup, and discuss our measurements of the mesospheric magnetic field.
Mapping the Moho in the Bohemian Massif with P-receiver functions
Authors: Kampfová Exnerová Hana , Plomerová Jaroslava , Kvapil Jiří , Babuška Vladislav , Vecsey Luděk , Working Group the AlpArray-EASI , Working Group the AlpArray
Published: March 2020

We present a new detailed map of the Moho in the Bohemian Massif (BM) derived from P-to-S conversions calculated from broad-band waveforms of teleseismic events recorded at 325 temporary and permanent stations operating in a region framed in 10–19º E and 48–52º N during last two decades. We processed data collected from running AlpArray Seismic Network (2015 – 2019) (http://www.alparray.ethz.ch/) and its complementary experiment AlpArray-EASI (2014 – 2015), as well as from previous passive seismic experiments in the region – BOHEMA I-IV (2001 – 2014), PASSEQ (2006 – 2008) and EgerRift (2007 – 2013). The study aims at upgrading the current knowledge of structure of the BM crust and providing a homogeneous estimate of Moho depths, particularly for the use in deep Earth studies, e.g., the upper mantle tomography. Different velocity models, including the new one retrieved from the ambient-noise study (see Kvapil et al., EGU2020_SM4.3), are tested in the time-depth migration procedures. Regional variations of the Moho depth correlate with main tectonic units of the BM. The crust thickens significantly in the Moldanubian part of the BM and thins along the Eger Rift in the western part of the massif. Detailed variations of the Moho depth from the receiver functions along several profiles are compared with crustal sections retrieved from the ambient noise tomography.
Contribution of climatic changes in means and variability to temperature and precipitation extremes
Authors: van der Wiel Karin , Bintanja Richard
Published: March 2020

Weather or climate extreme events disproportionately affect societies and ecosystems. Physical understanding of the impact of global climate change on the occurrence of such extreme events is therefore crucial. Here we separate changes in the occurrence of high-temperature and heavy-precipitation events in a part caused by climatic changes of the mean state and a part caused by climatic changes in variability. We extend the frequently used Probability Ratio (PR) framework, used to quantify changes in the occurrence of extreme events, such that it produces a 'PRmean' value for changes due to a change in mean climate and a 'PRvar' value for changes due to changes in climate variability. Large ensemble climate model simulations are used to quantify changes in extreme events in a 2C warmer world. It is found that the increased occurrence of high-temperature extremes is predominantly caused by the increase of mean temperatures, with a much smaller role for changes in variability (PRmean >> PRvar). The spatial differences are considerable, however, with the polar regions standing out as regions where changes in temperature variability do have a considerable limiting effect on extreme event occurrence. Changes in heavy-precipitation extremes are generally due to changes in both mean climate and variability (PRvar ≈ PRmean). Despite complex feedbacks in the global climate system, the ratio of PRmean to PRvar is largely independent of the event threshold and the climate scenario. These results help to quantify robustness of projected changes in climate extremes, given that projections of changes in the mean state are in many cases much better constrained than projections of changes in variability.
Influence of Alfvénic characteristics on calibration of satellite magnetometer
Authors: Pan Zonghao , Wang Guoqiang , Meng LiFei , Zhang Tielong
Published: March 2020

The zero offset of the fluxgate magnetometer in satellite orbit will be changed due to several factors. For this reason, the Davis-Smith method is proposed to calculate the zero compensation of the magnetometer based on the feature that the shear Alfvén waves do not change the total magnetic field strength. In fact, there is no pure Alfvén waves in the interplanetary space. In this paper, numerical simulation is used to analyze the influence of the amplitude, period and phase of the Alfvén waves and the time length of the data window on the zero offset of the magnetometer calculated by the Davis-Smith method in the presence of weak compressional waves. We find that Alfvén waves can produce a non-negligible error in the calculation of zero compensation only when its period is the same as the period of the compressional wave. The greater the amplitude of Alfvén waves, the smaller the error of the zero offset. The error of the zero offset is also affected by the initial phase of the Alfvén wave. In addition, the error of the zero offset tends to decrease to its true value for the longer the data window length.
Crustal structures of the Anatolian Plate from receiver function analysis
Authors: Zhou Zhipeng , Thybo Hans , Kusky Timothy , Tang Chi-Chia
Published: March 2020

The crustal structure of the Anatolian plateau in Turkey is investigated using receiver functions obtained from the teleseismic recordings of the Kandilli Observatory array (KOERI; KO) and the available IRIS data (e.g., Eastern Turkey Seismic Experiment (ETSE), Northern Anatolian Fault experiment (YL), Continental Dynamics–Central Anatolian Tectonics (CD-CAT) project). The following steps are included for studying the crustal structures in Anatolia Plate: 1) high-resolution crustal structures inferred from Receiver Function (RF) inversion algorithm using multiple-taper correlation (MTC) estimates, we try to distinguish interfaces including Moho, bottom of partial melting and other interfaces by the Ps phase; 2) we calculate RFs by Time Domain Interactive Deconvolution and transform the time domain RFs into the H-Vp/Vs (H-k) domain to find the best fit Moho and Vp/Vs, we classify the quality of the H-k stacking results and record all the possible H-k couples; 3) we determine the H-k values for the stations with low quality by comparing the RF H-k stacking results with nearby stations with good quality. With the dense stations, we present high-quality Moho variations and crustal structures in the Anatolia Plate.
Comparison study for different approaches in applying High-Resolution Atmospheric Transport Modelling based on validation with Xe-133 observations in Europe
Authors: Philipp Anne , Schoeppner Michael , Kusmierczyk-Michulec Jolanta , Bourgouin Pierre , Kalinowski Martin
Published: March 2020

The International Data Centre (IDC) of the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO) investigates the best method to add the utilisation of High-Resolution Atmospheric Transport Modelling (HRATM) in their operational and automatised pipeline. Supporting the decision process, the IDC accomplished a comparison study with different approaches for applying HRATM. An initial validation study with the HRATM Flexpart-WRF, which is a Lagrangian particle dispersion model (LPDM), showed a performance which is dependent on the scenario and delivered results comparable to the conventional Flexpart model. The approach uses the Weather Research and Forecasting model (WRF) to generate high-resolution meteorological input data for Flexpart-WRF and WRF was driven by the National Centers for Environmental Prediction (NCEP) data having a horizontal resolution of 0.5 degrees and time resolution of 1h. Based on this initial study, an extended study was conducted to compare the results to FLEXPART-WRF using input data from the European Centre for Medium-Range Weather Forecasts  (ECMWF) for WRF and to results from the conventional Flexpart model using high-resolution ECMWF input data. Furthermore, a sensitivity study was performed to optimize the physical and computational parameters of WRF to test possible meteorological improvements prior to the comparison study.

The performance of the different approaches is evaluated by using observational data and includes statistical metrics which were established during the first ATM challenge in 2016. Observational data of seven episodes of elevated Xe-133 concentrations were selected from the IMS (International Monitoring System) noble gas system DEX33 located in Germany. Each episode consists of 6 to 11 subsequent samples with each sample being taken over 24 hours. Both Flexpart models were using the source terms from a medical isotope production facility in Belgium to simulate the resulting concentration time series at the DEX33 station for different output resolutions. Backward simulations for each sample were conducted, and in the case of Flexpart-WRF nested input of increased resolution around the source and receptor was used.

The simulated concentrations, as well as the measurements, are also compared to the simulated results produced by the conventional Flexpart model to guide the decision-making process.
Cross-border co-operation as a baseline for management of natural and man-made hazards
Authors: Kupila Juho
Published: March 2020

In January 2019, with the support of the project partners, Geological Survey of Finland launched a co-operation project “HazArctic – Geo-Bio Hazards in the Arctic Region”. It approaches both natural and man-made environmental hazards and risks in the Arctic and Subarctic areas, in Northern parts of Scandinavia and Russia.

Project studies, among others, the areal extension of harmful acid sulfate soils (ASS) and the role of microbes in the geo-bio interaction in possible hazardous environments. In addition, studies related to the mine environments, the stability of closed and open mines and mine tailings reuse, will be carried out. Project will also focus on training as well as analyzing and sharing of the best practices. Results will give a good background knowledge for participant organizations, local stakeholders and actors, authorities and public. Lessons learnt will guide actions in the future, for example farming in areas of ASS and in safety issues of the active and closed mines. Results will be available in public and can be adapted for use everywhere with similar conditions in natural or man-made environments.

The first year of the project produced new data about the areal extension of ASS in Finland, Sweden and Norway. Also the studies related to the geomicrobiology were started as well as the studies of the safety of the active open pit in Russia. Co-operation between project partners also created new networks in the field of research of the natural hazards. In 2020, started actions will continue and some new ones will start, for example the training related to the mine environments.

“HazArctic” is a co-operation project between Geological Surveys from Finland, Sweden and Norway, Natural Resources Institute Finland as well as Geological Institute and Mining Institute from the Federal Research Centre “Kola Science Centre of the Russian Academy of Sciences”. It is funded by Kolarctic CBC 2014-2020 program, EU, Russia, Norway, Sweden and Finland with the contribution from the project partners. Total budget is approx. 1.29 M€ and implementation period is 2019-2021.
Controls on copper and gold endowments of porphyry deposits
Authors: Chiaradia Massimo
Published: March 2020

Porphyry deposits are the major natural source of copper and a significant natural source of gold, which are essential metals for our society. Porphyry deposits form at convergent margins both during subduction (syn-subduction, Andean-type deposits) and in post-subduction to post-collision and extensional geodynamic settings (post-subduction deposits). Syn-subduction porphyry deposits are typically associated with calc-alkaline magmas often characterized by high Sr/Y values (~50-150). In contrast, post-subduction deposits are mostly associated with variably alkaline magmas having lower Sr/Y values (~25-75). The reasons of the association of porphyry deposits with magmas having different geochemical affinities and of their widely variable Cu and Au endowments (from <1 to >100 Mt for Cu and from few tens to >2500 tons for gold) remain unconstrained.

Porphyry Cu-Au deposits define two distinct trends in plots of Au versus Cu endowments and Au endowment versus duration of the ore process (Chiaradia, 2020): one trend (Cu-rich) is characterized by steep Cu/Au endowment values (Cu/Au~250000) and an average low rate of Au deposition (~100 tons Au/Ma); the other trend (Au-rich) is characterized by low Cu/Au endowment values (Cu/Au~12500) and an average high rate of gold deposition (~4500 tons Au/Ma). The Au-rich trend is defined to the greatest extent by seven, alkaline magma-related, porphyry gold systems (>1100 tons Au) and subordinately by numerous calc-alkaline systems (<1300 tons Au). The Cu-rich trend is defined only by calc-alkaline magma-related porphyry systems.

Modelling of petrological and metal precipitation processes using a Monte Carlo approach suggests that, whereas Cu-rich porphyries are formed by large volumes of magma, Au-rich porphyries result from a better precipitation efficiency of Au. The specific association of the largest Au-rich porphyry deposits with variably alkaline magmas also points out that alkaline magma chemistry favours an upgrade of Au endowments.

 

References

Chiaradia, M. (2020) Gold endowments of porphyry deposits controlled by precipitation efficiency. Nature Communications 11, 248, https://doi.org/10.1038/s41467-019-14113-1.
The transition between solitary wave and diapir emergence from a high porosity disturbance in two-phase flow
Authors: Dohmen Janik , Schmeling Harro
Published: March 2020

Many processes in the earth involve the melting of rocks and the percolation of the produced melt through the residuum. These processes have been extensively studied but there is still much left what is not completely understood. In this work we focus on the emergence of solitary porosity waves, which can emerge from disturbances in regions where melt is allowed to percolate relatively to the matrix. These waves are regions of higher melt fractions that ascend with a constant velocity while not changing their shape during this ascending process. The size of these waves depends on the compaction length, which depends on just poorly known parameters such as the permeability and the viscosity of the matrix. As they can vary over several orders of magnitudes it might have a strong influence on porosity waves and their emergence from local disturbances with higher porosities than the background.

In this work we start with a 2D Gaussian-bell shaped disturbance with a certain porosity amplitude and vary the initial radius which is non-dimensionized by the characteristic compaction length. For some cases this disturbance results in an ascending solitary wave and for others it rises upwards as a diapir. For a few cases a kind of fingering can be observed which  looks like a small emerging porosity wave which is just slightly faster than the following melt of the initial larger disturbance. This leads to a melt ascent with a strongly focused front.

Comparison of porosity wave dispersion curves with analytical ascent rates of a Stokes sphere helps explaining this transition of diapirs to solitary waves via a melt ascent with a strongly focused front.
Operational infrastructure to ensure the long-term sustainability of the IHRS/IHRF
Authors: Barzaghi Riccardo , Sanchez Laura , Vergos George
Published: March 2020

An objective of the International Height Reference System (IHRS) and its realization (the IHRF) is to support the monitoring and analysis of Earth’s system changes. The more accurate the IHRS/IHRF is, the more phenomena can be identified and modelled. Thus, the IHRS/IHRF must provide vertical coordinates and their changes with time as accurately as possible. As many global change phenomena occur at different scales, the global frame should be extended to regional and local levels to guarantee consistency in the observation, detection, and modelling of their effects. From this perspective, an operational infrastructure is needed to ensure the long-term sustainability of the IHRS/IHRF. In this contribution, we discuss the possibility of establishing such as infrastructure within the International Association of Geodesy (IAG) and its International Gravity Field Service (IGFS). Some aspects to be considered are:

- Improvements in the IHRS definition and realization following future developments in geodetic theory, observations and modelling.

- Refinement of the IHRS/IHRF standards/conventions based on the unification of the standards/conventions used by the geometric and gravity IAG Services.

- Development of strategies for collocation of IHRF stations with existing gravity and geometrical reference stations at different densification levels.

- Identification of the geodetic products associated with the IHRF and description of the elements to be considered in the corresponding metadata.

- Servicing the vertical datum needs of other geosciences such as, e.g., hydrography and oceanography.

- Implementation of a registry containing the existing local/regional height systems and their connections to the global IHRS/IHRF.
Monitoring volcanic SO2 emissions with the Infrared Atmospheric Sounding Interferometer
Authors: Taylor Isabelle , Carboni Elisa , Mather Tamsin A. , Grainger Roy G.
Published: March 2020

Satellite remote sensing has been widely used to make measurements of sulphur dioxide (SO2) emissions from volcanoes. The Infrared Atmospheric Sounding Interferometer (IASI) is one such instrument that has been used to examine the emissions from large explosive eruptions.  Much less work has been done using IASI to study the emissions from smaller eruptions, non-eruptive degassing or anthropogenic sources, and similarly it is rarely used for examining long term trends in activity.  Now, when there are three IASI instruments in orbit and with over ten years of data, is the perfect opportunity to explore these topics. This study applied a ‘fast’ linear retrieval developed for IASI in Oxford, across the globe for a ten-year period. Global annual averages were dominated by the emissions from large eruptions (e.g. Nabro in 2011) but elevated signals could also be identified from smaller volcanic sources and industrial centres, suggesting the technique has promise for detecting lower level emissions. A systematic approach was then taken, rotating the linear retrieval output for each orbit at over 100 volcanoes worldwide, with the wind direction at the volcano’s vent, or in cases where the plume was emitted at a greater height, using the observed plume direction. This isolates the elevated signal downwind of the volcano. The rotated outputs were then averaged over monthly, annual and multi-annual time periods. Analysis of the upwind and downwind values establishes whether there is an elevated signal and its intensity. An inventory was then constructed from these observations which show how these emissions varied over a ten-year period. Trends in SO2 emission were compared against fluxes generated for the Ozone Monitoring Instrument (OMI) and the number of thermal anomalies detected by the MODVOLC algorithm developed for MODIS.  It was identified for example, that long term trends are more easily identified at high altitude volcanoes such as Popocatepetl, Sabancaya and Nevado del Ruiz. This is consistent with the idea that the instrument performs better in regions with lower levels of water vapour (e.g. above the boundary layer).