bluuebunny/crossref_metadata_2025 huggingface dataset:
The impact of solar variability on climatic parameters
Authors: Tzanis Chris G. , Benetatos Charilaos , Philippopoulos Kostas
Published: March 2021

Natural climate variability is partially attributed to the solar radiative forcing. The scope of this work is to increase the scientific understanding of the relative role of solar variations on the terrestrial climate. The applied methodology examines initially the variation of multiple climatic parameters (temperature, zonal wind, relative and specific humidity, sensible and latent surface heat flux, cloud cover, precipitation) in response to the 11-year solar cycle. An additional goal is to estimate the response of the climate system’s parameters to the solar forcing in multiple forecasting horizons and to evaluate the behavior of the climate system in shorter time scales. The adopted methodology includes the development of linear regression models which calculate the dependency of the climatic parameters to solar variations for each grid point of the global dataset on a monthly time scale. The solar indicator used in this study is the 10.7-cm solar radio flux (F10.7) provided by NOAA, while the climate data are extracted from the NCEP/NCAR Reanalysis 1 project with a spatial resolution of 2.5o X 2.5o for 67 years. Regarding the climate system’s response forecasting, an Artificial Neural Network has been trained for modeling and forecasting the solar indicator time series for a few time steps in advance and the effect on climatic parameters is estimated using the established regression equations. The results exhibit that the variation of the climatic parameters can be partially attributed to the 11-year solar cycle. Statistically significant areas with relatively high solar cycle signal were found in multiple pressure levels and geographical regions. Furthermore, the results indicate that the identification of a clear solar signal in the climatic data is a difficult task due to the climate system’s complexity; advanced non-linear methods could be applied in order to obtain a more accurate understanding of this research field.
Effect of different soil textures and saturation levels on the equilibration time of oxygen isotopes using the direct liquid-vapor equilibration method
Authors: Vadibeler Devakunjari , Stockinger Michael , Stumpp Christine
Published: March 2021

Stable water isotopes of oxygen (d18O) are used as tracers to study soil pore water. One method to measure d18O of soil samples is the direct liquid-vapor equilibration (DLVE) method. In this method, test samples are stored in Ziploc bags and equilibrated for three days. After equilibration, the headspace gas is measured using laser spectrometry. The DLVE method requires minimum sample handling, enables direct isotopic measurements without the need of extracting the water, and is highly reliable and comparatively cheaper than other measurement methods. However, the influence of different soil textures and saturation levels on the δ18O isotope when using the DLVE method is not well understood yet. In this study, three different soil textures (sand, organic carbon rich silt and kaolinite) were oven-dried for three days at 105°C and saturated to different saturation levels (100%, 80%, 60% and 40%) in laboratory cylinders for a week. The samples were saturated using tap water of known isotopic value and stored in Ziploc bags for different amounts of time. The samples were analyzed after 1, 2, 3, 4 and 7 days using cavity ring down spectroscopy (CRDS), and the isotopic ratios recorded after storage were compared with the isotopic measurements obtained before the sample equilibration. The resulting isotopic deviations were less than the CRDS measurement precision after one day of sample storage for sandy soil regardless of their saturation levels. Likewise, one day was also adequate for 100%, 80% and 40% saturated kaolinite, with 100% saturation allowing for up to seven days of sample storage with only small isotopic deviations (±0.43‰). Contrary to this, for organic-silty soil the required equilibration time depended on the saturation level. The findings from this laboratory-based analysis enhance the understanding of the impact of soil texture and saturation level on the DLVE method.
Speleothem records of interannual variability in the tropics during the Holocene
Authors: Parker Sarah , Harrison Sandy , Comas-Bru Laia
Published: March 2021

Reconstruction of changes in interannual variability through the Holocene period can provide valuable insight into the sensitivity of internal modes of variability (e.g. ENSO, PDO) to external forcing. Coral and bivalve records are widely used examine past changes in short-term variability, however, far fewer reconstructions exist in the terrestrial realm. Here, we use the SISAL (Speleothem Isotopes Synthesis and AnaLysis) database to examine changes in the amplitude of interannual/short-term variability across the monsoon regions, recorded by speleothem δ18O standard deviation (δ18O s.d.). First, we identified and corrected for any confounding factors that may obscure interannual climate signals in the speleothem records, such as variable growth rate. We used a multiple linear regression model to constrain relationships between δ18O s.d. and growth rate and mean climate (represented by mean δ18O), then used these relationships to apply a correction. Second, corrected δ18O s.d. trends were combined into regional monsoon composites, representing changes in short-term variability across the Holocene. Trends are very similar between raw and corrected δ18O s.d., suggesting that confounding factors have a minimal effect. Trends differ amongst regions: the Indian monsoon shows gradually increasing δ18O s.d. through the Holocene, whilst the East Asian monsoon shows no significant changes through this period. The Indonesian-Australian monsoon shows higher than present δ18O s.d. during the mid- to early Holocene and the South American monsoon shows multi-centennial scale fluctuations between higher and lower δ18O s.d.
Polar  Stratospheric Clouds detection at Belgrano II Antarctic station from DOAS measurements
Authors: Gómez Martín Laura , Toledo Daniel , Yela Margarita , Prados-Román Cristina , Adame José Antonio , Ochoa Héctor
Published: March 2021

Ground-based zenith DOAS (Differential Optical Absorption Spectroscopy) measurements have been used to detect and estimate the altitude of PSCs over Belgrano II Antarctic station during the polar sunrise seasons of 2018 and 2019. The method used in this work studies the evolution of the color index (CI) during twilights. The CI has been defined here as the ratio of the recorded signal at 520 and 420 nm. In the presence of PSCs, the CI shows a maximum at a given solar zenith angle (SZA). The value of such SZA depends on the altitude of the PSC. By using a spherical Monte Carlo radiative transfer model (RTM), the method has been validated and a function relating the SZA of the CI maximum and the PSC altitude has been calculated. Model simulations also show that PSCs can be detected and their altitude can be estimated even in presence of optically thin tropospheric clouds or aerosols. Our results are in good agreement with the stratospheric temperature evolution obtained through the ERA5 data reanalysis from the global meteorological model ECMWF (European Centre for Medium Range Weather Forecasts) and the PSCs observations from CALIPSO (Cloud-Aerosol-Lidar and Infrared Pathfinder Satellite Observations).

The methodology used in this work could also be applied to foreseen and/or historical measurements obtained with ground-based spectrometers such e. g. the DOAS instruments dedicated to trace gas observation in Arctic and Antarctic sites. This would also allow to investigate the presence and long-term evolution of PSCs.

Keywords: Polar stratospheric clouds; color index; radiative transfer model; visible spectroscopy.
Detection of absorbing aerosols from ground based observations of scattered sun light
Authors: Wagner Thomas , Dörner Steffen , Donner Sebastian , Beirle Steffen , Puķīte Janis , Kinne Stefan
Published: March 2021

Absorption of solar radiation by atmospheric aerosols is an important heat source in the atmosphere. The absorption potential by aerosols (usually quantified by the co single scattering albedo) can vary strongly, depending on the aerosol composition. The absorption potential can be captured by in-situ sample analyses or retrieved by remote sensing techniques (e.g. by sun/sky photometry). For a global view, advanced satellite sensors with polarization and especially multi-viewing would be required (e.g. 3MI). However, sensor data at different UV wavelengths (e.g. TOMS) already inform qualitatively on the presence of (elevated) absorbing aerosol (i.e. from mineral dust, wildfires) via the so-called UV absorbing aerosol index (UVAI).

In this study, we propose an UVAI similar approach for ground-based observations of scattered sun light. We first performed radiative transfer simulations. Based on these simulations we found that absorbing aerosols can indeed be identified from ground-based measurements. We could in particular show that the detection of absorbing aerosols is possible in the presence of clouds (except optical very thick clouds), which will be of special importance, because existing remote sensing measurements of the aerosol absorption are only possible for clear sky conditions.

We also derived the UVAI from ground based measurements during a ship cruise in April and May 2019 over the tropical Atlantic. Clearly enhanced values of the UVAI could be detected when the ship crossed air masses which were contaminated by desert dust aerosols from the Sahara.

We present these early results and discuss possible future improvements.
Assessment of land use and land cover datasets for Brazil and impact on C emissions
Authors: Rosan Thais M. , Goldewijk Kees Klein , Ganzenmüller Raphael , O'Sullivan Michael , Pongratz Julia , Mercado Lina M. , Aragao Luiz E. O. C. , Heinrich Viola , Von Randow Celso , Wiltshire Andrew , Tubiello Francesco N. , Bastos Ana , Friedlingstein Pierre , Sitch Stephen
Published: March 2021

Brazil is responsible for about one third of the global land use and land cover change (LULCC) carbon dioxide emissions. However, there is a disagreement among different methodologies on the magnitude and trends in emissions and their geographic distribution. One of the main uncertainties is associated with different LULCC datatasets used as input in the different approaches. In this work we perform an evaluation of LULCC datasets for Brazil, including the global dataset (HYDE 3.2) used in the annual Global Carbon Budget (GCB), and national Brazilian dataset (MapBiomas) over the period 2000-2018. We also analyze the latest global HYDE 3.3 dataset based on new FAO inventory estimates and multi-annual ESA CCI satellite-based land cover maps. Results show that the new HYDE 3.3 can represent well the observed spatial variation in cropland and pastures areas over the last decades compared to national data (MapBiomas) and shows an improvement compared to HYDE 3.2 used in GCB. However, the magnitude of LULCC assessed with HYDE 3.3 is lower than national estimates from MapBiomas. Finally, we used HYDE 3.3 as input to two different approaches included in GCB, a global bookkeeping model (BLUE) and a process-based Dynamic Global Vegetation Model (JULES-ES) to determine the impact of the new version of HYDE dataset on Brazil’s land-use emissions trends over the period 2000-2017. Both JULES-ES and BLUE now simulate a negative land-use emissions trend for the last two decades. This negative trend is in agreement with Brazilian INPE-EM, global H&N bookkeeping models, FAO and as reported in National GHG inventories (NGHGI), although magnitudes differ among approaches. Overall, the inclusion of the multi-annual ESA CCI Land Cover dataset to allocate spatially the FAO statistical data has improved spatial representation of agricultural area change in Brazil in the last two decades, contributing to improve global model capability to simulate Brazil’s LULCC emissions in agreement with national trends estimates and spatial distribution.
Phosphorus in Aeolian desert dust deposits can be captured, dissolved, and absorbed by plant leaves
Authors: Erel Ran , Tiwari Sudeep , Shtein Ilana , Gross Avner
Published: March 2021

Phosphorus (P) limitation is prevalent around the world,primarily because most soil P have low bioavailability. In P poor ecosystems, deposition of P-rich desert dust is recognized as a major component of the P cycle. The acknowledged paradigm is that plants acquire P deposited in soil primarily via their roots. We tested whether, and to what extent, plants acquire P directly from dust deposited on their leaves and what are the underlining uptake mechanisms of insoluble P. P-rich dust was applied to P sufficient and P deficient chickpea, maize and wheat plants and was compared to plants which received inert silica powder. Foliar application of dust doubled the growth of P stressed chickpea and wheat, two crops originating near the Syrian Desert. P deficiency enhanced the acquisition of insoluble P through series of leaf modifications that increased foliar dust capture, acidified the leaf surface and, in chickpea, enhanced exudation of P-solubilizing organic acids. In in-situ trials, we demonstrated that the modifications of leaf pH and exudation of oxalic and malic acids substantially promoted P solubilisation from dust.  Foliar responses did not occur in maize and in P sufficient plants which displayed only a marginal response to dust. Our results demonstrate that foliar uptake of P from dust can be an alternative P acquisition pathway in P-deficient plants. Interestingly, the abovementioned foliar responses are comparable to known P uptake root responses. Given that P limitation is almost universal, foliar P uptake pathway will have significant ecological and agricultural implications.
Trends, variability and predictive skill of the ocean heat content in North Atlantic: An analysis with the EC-Earth3 model
Authors: Carmo-Costa Teresa , Bilbao Roberto , Ortega Pablo , Teles-Machado Ana , Dutra Emanuel
Published: March 2021

As the global climate is warming, with important regional differences, there is a growing need to (i) better understand whether and how internal variability controls the regional warming trends, and (ii) to identify the regions in which both the trends and the superimposed interannual variability are predictable. In this study we investigate trends, variability and predictive skill of the upper ocean heat content in the North Atlantic basin. This region is a source of decadal variability, in which internal ocean processes can locally modulate the global warming trends and add additional prediction skill. The analysis is focused on the period 1970-2014, and combines the study of an ensemble of ocean reanalyses, with two sets of CMIP6 experiments performed with the Earth system model EC-Earth3: (i) a 10-member historical ensemble; and (ii) an initialized 10-member retrospective decadal prediction system. External forcings are found to be important for the development of the regional trends, but on their own are unable to reproduce the exact geographical pattern. Our results also show that not all regions in the North Atlantic are equally predictable, which is explained by different contributions of the forcings and internal climate variability. While high levels of predictive skill in regions like the Eastern Subpolar North Atlantic, or the Irminger and Iceland Seas are clearly enabled by initialization, with a negligible influence of the external forcings, skill in others areas like the Subtropical North Atlantic, or the Gulf Stream extension mostly comes from the externally forced trends. The Labrador Sea is a particular case where predictive skill has both an external and internal origin. Large observational and modeling uncertainties affect the Central Subpolar North Atlantic, the only region exhibiting a cooling during the study period, uncertainties that might explain its very poor predictive skill. We would like to acknowledge the financial support from FCT through projects FCT-UIDB/50019/2020 and PD/BD/142785/2018.
Structural evolution of a crustal-scale seismogenic fault in a magmatic arc: The Bolfin Fault Zone (Atacama Fault System)
Authors: Masoch Simone , Gomila Rodrigo , Fondriest Michele , Jensen Erik , Mitchell Tom , Pennacchioni Giorgio , Cembrano José , Di Toro Giulio
Published: March 2021

The nucleation and evolution of major crustal-scale seismogenic faults in the crystalline basement as well as the process of strain localization represent a long-standing, but poorly understood, issue in structural geology and fault mechanics. Here, we addressed the spatio-temporal evolution of the Bolfin Fault Zone (BFZ), a >40-km-long exhumed seismogenic splay fault of the 1000-km-long strike-slip Atacama Fault System. The BFZ has a sinuous fault trace across the Mesozoic magmatic arc of the Coastal Cordillera (Northern Chile). Seismic faulting occurred at 5-7 km depth and ≤ 270 °C in a fluid-rich environment as recorded by extensive propylitic alteration and epidote-chlorite veining. The ancient (125-118 Ma) seismicity is attested by the widespread occurrence of pseudotachylytes both in the fault core and in the damage zone. Field geological surveys indicate nucleation of the BFZ on precursory geometrical anisotropies represented by magmatic foliation of plutons (northern and central segments) and andesitic dyke swarms (southern segment) within the heterogeneous crystalline basement. Faulting exploited the segments of precursory anisotropies that were favorably oriented with respect to the long-term stress field associated with the oblique ancient subduction. The large-scale sinuous geometry of the BFZ may result from linkage of these anisotropy-pinned segments during fault growth. This evolution may provide a model to explain the complex fault pattern of the crustal-scale Atacama Fault System.
Effects of flood timing on vegetated riparian and coastal habitats in a changing climate
Authors: Balke Thorsten , Vovides Alejandra , Ladd Cai , Basyuni Mohammad , Nilsson Christer
Published: March 2021

Ecosystem functioning of habitats at land-water interfaces, such as riparian forests and intertidal salt marshes or mangroves is predominantly driven by inundation. Whereas seasonality of ecological processes (i.e. phenology) and of hydrological extremes/events have been relatively well studied independently from each other their interdependence remains largely unknown. Filling this knowledge gap may become especially important in a changing climate as the timing of ecological and abiotic processes is already changing, often independently from each other. As these ecosystems are increasingly praised as Nature-based Solutions, predicting the ecosystem functioning of riparian forests and coastal wetlands under future climate change is crucial.

Here, we will highlight the importance of match and mismatch of ecological and hydrological processes through a range of experiments and field observations in coastal wetlands from the single seedling to the ecosystem level. For riparian floodplains of Europe, we will show how the temporal relationships between flooding and thermal growing season have already changed in past decades, with currently unknown consequences. Finally, we will showcase methodological advances in field monitoring to better study these timing effects and offer conceptual insights to identify tipping points of ecosystem change along land-water interfaces.

This presentation will focus on UPH ‘interfaces’ and ‘variability’.
The Source Locations of Major Flares and CMEs in the Emerging Active Regions
Authors: Liu Lijuan , Wang Yuming , Zhou Zhenjuan , Cui Jun
Published: March 2021

Major flares and coronal mass ejections (CMEs) tend to originate from the compact polarity inversion lines (PILs) in the solar active regions (ARs). Recently, a scenario named as “collisional shearing” is proposed by Chintzoglou et al. (2019) to explain the phenomenon, which suggests that the collision between different emerging bipoles is able to form the compact PIL, driving the shearing and flux cancellation that are responsible to the subsequent large activities. In this work, through tracking the evolution of 19 emerging ARs from their birth until they produce the first major flares or CMEs, we investigated the source PILs of the activities, i.e., the active PILs, to explore the generality of “collisional shearing”. We find that none of the active PILs is the self PIL (sPIL) of a single bipole. We further find that 11 eruptions originate from the collisional PILs (cPILs) formed due to the collision between different bipoles, 6 from the conjoined systems of sPIL and cPIL, and 2 from the conjoined systems of sPIL and ePIL (external  PIL between the AR and the nearby preexisting polarities). Collision accompanied by shearing and flux cancellation is found developing at all PILs prior to the eruptions, with 84% (16/19) cases having collisional length longer than 18 Mm. Moreover, we find that the magnitude of the flares is positively correlated with the collisional length of the active PILs, indicating that the intenser activities tend to originate from the PILs with severer collision. The results suggest that the “collisional shearing”, i.e., bipole-bipole interaction during the flux emergence is a common process in driving the major activities in emerging ARs.
Coronal dimmings associated with coronal mass ejections on the solar limb
Authors: Chikunova Galina , Dissauer Karin , Podladchikova Tatiana , Veronig Astrid
Published: March 2021

We studied 43 coronal dimming events associated with Earth-directed coronal mass ejections (CMEs) that were observed in quasi-quadrature by the SDO and STEREO satellites. We derived the properties of the dimmings as observed above the limb by STEREO EUVI, and compared them with the mass and speed of the associated CMEs. The unique satellite constellation allowed us to compare our ﬁndings with the results from Dissauer et al. (2018, 2019), who studied these events observed against the solar disk by SDO AIA. Such statistics is done for the ﬁrst time and confirms the close relation between characteristic dimming and CME parameters for the off-limb viewpoint. We ﬁnd that the dimming areas are typically larger for off-limb observations (mean value of 1.24±1.23×1011 km2 against 3.51±0.71×1010 km2 for on-disk), while the decrease in the total extreme ultraviolet intensity is similar (c=0.60±0.14). The off-limb dimming areas and brightnesses are strongly correlated with the CME mass (c=0.82±0.06 and 0.75±0.08), whereas the dimming area and brightness change rate correlate with the CME speed (c∼0.6). Our ﬁndings suggest that coronal dimmings have the potential to provide early estimates of the Earth-directed CMEs parameters, relevant for space weather forecasts, for satellite locations at both L1 and L5.
The magnetic properties of natural pigments: preliminary analyses for their identification in Fine Arts
Authors: Anselmi Chiara , Sgamellotti Antonio , Vagnini Manuela , Winkler Aldo
Published: March 2021

A multidisciplinary approach, including compositional, spectroscopic and microscopic methodologies, is often used for the analysis and identification of pigments in Fine Arts. Although a large part of widely used natural and synthetic pigments contain Fe-oxides and hydroxides, their magnetic characterization is still poorly explored. The application of rock magnetism analyses through fast, cheap and non-destructive measurements, can be instead useful for the identification and discrimination of pigments through their distinctive magnetic properties.

In this preliminary study, the magnetic properties of several iron-based commercial pigments together with paintings models and supports, were analyzed.

In order to investigate the compositional differences of pigments by means of their magnetic behavior, the magnetic susceptibility, the hysteresis properties and the magnetic susceptibility variation at low and high temperature were measured on selected samples.

All the pigments showed different magnetic properties, mainly related to variable proportions of magnetite, hematite and maghemite as the main magnetic carriers.

Further studies will be addressed to define a protocol for applying the magnetic techniques to the characterization of pigments, including tests on samples produced by different brands and different periods, with the final aim of integrating the magnetic measurements with the different spectroscopic techniques commonly employed for the preservation and the analysis of cultural heritage.
Past and future trends in large-scale atmospheric circulations over Europe: Assessment of the Jenkinson-Collison classification with reanalyses and CMIP6
Authors: Herrera-Lormendez Pedro , Matschullat Jörg , Douville Hervé
Published: March 2021

Circulation classifications are a simple tool given their ability to portray aspects of day-to-day weather. As we start facing a dynamical response in general circulation patterns due to anthropogenic global warming, circulation changes can enhance or mitigate regional and local behaviour of extreme weather events.

An automatic weather type (WT) classification, developed by Jenkinson-Collison, is used to evaluate past and future changes in seasonal frequencies of synoptic weather patterns over central and western Europe. A set of three reanalyses and eight Global Climate Models (GCMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6) are used, based on daily Sea Level Pressure (SLP) data.

Discrepancies are found in some of the model outputs as some fall short of capturing interannual variabilities when compared to reanalyses. Cyclonic and westerly circulations tend to be overestimated, whereas anticyclonic are underestimated.

Based on the historical data and Shared Socioeconomic Pathway 5 (SSP5-8.5) scenario, the evaluated trends suggest more robust signals during the summer half-years given their lesser synoptic-scale variability. During this season, increasing frequencies are found for the WT characterized by weak pressure gradients, mostly at the expense of decreasing frequencies of the westerlies. Our findings indicate that the time of emergence of these signals only occurs towards the end of the 21st century, even in such a high-emission scenario.
Added and redistributed heat and carbon in climate model projections for the Southern Ocean
Authors: Roussenov Vassil , Williams Ric , Katavouta Anna
Published: March 2021

Projected changes in ocean heat and carbon storage are assessed in terms of the added and  redistributed tracer using a transport-based framework for 6 CMIP5 Earth system models following an annual 1% rise in atmospheric  CO2. Heat and carbon budgets for the added and redistributed tracer are used to compare the reasons for the relatively-reduced storage of heat and carbon within the Southern Ocean. Here the added tracer takes   account of the net tracer source and the advection of the added tracer, while the redistributed tracer takes account of the time-varying advection of the pre-industrial tracer  distribution. The added heat and carbon are nearly always positive over the Southern Ocean with the net source acting to supply tracer. However, there is a relatively-reduced local storage of heat and carbon in the Southern Ocean due to the passive northward transport of heat and carbon by the overturning, which is augmented by a passive northward carbon transport for the gyre circulation. In contrast, the redistributed heat is usually negative and the redistributed carbon is positive over the Southern Ocean due to the transport effects of a strengthening residual circulation and the opposing gradients in the pre-industrial temperature and  carbon. Hence, climate projections for the Southern Ocean are expected to have heat anomalies of a variable sign and carbon anomalies of a consistently positive  sign, since the effects of added and redistribution heat are opposing in sign, while the effects of added and redistributed  carbon reinforce each other. 

 
Future trends in global water vs. energy-controlled evaporative regimes
Authors: Denissen Jasper , Teuling Adriaan , Li Wantong , Reichstein Markus , Pitman Andy , Orth Rene
Published: March 2021

Water and energy availability govern the exchange of carbon, energy and water between the land surface and the atmosphere and therefore exert influence on near-surface weather. Roughly one can distinguish between two evaporative regimes: One limited by available energy (under wet conditions) and one limited by available soil moisture (under dry conditions). The transition between these evaporative regimes has been studied on local to global scales using observational and modelled datasets. This revealed the complexity of defining this transition, as it varies both in space and time and is sensitive to climate, soil and vegetation characteristics.

In this study, we characterized this transition by comparing the correlations of evaporation anomalies with (i) soil moisture anomalies (proxy for strength of water control) and (ii) temperature anomalies (proxy for strength of energy control). In the first step, we use observation-based data to derive global patterns of evaporative regimes and establish that the regime transition is sensitive to not only long-term average soil moisture, but also long-term average temperature. Analyzing historical and future climate model simulations from the Coupled Model Intercomparison Project (CMIP6), we found that the ensemble mean of the CMIP6 models produces similar global patterns and sensitivities to energy and water availability. However, there is ample disagreement between results of individual models, with the largest spread around the transition zones. Further, the disagreement between individual models on the total area of water-limited regions increases gradually in time from historical to future experiments. In the next step, we attribute trends in evaporative regimes to trends in water and energy availability, CO2 and vapor pressure deficit. This research reveals how global climate change translates into regional-global scale trends in water- vs. energy-controlled evaporative regimes. Our observational results can constrain modelled global evaporative regimes and inform future model development to decrease the substantial spread across the present model ensemble.
Teaching the basics of anti-virus safety in the course "Life Safety"
Authors: Voronov Nikolai , Sapunov Valentin
Published: March 2021

The course "Life Safety" was introduced in higher educational institutions of Russia in the 1990s. It combined information from sanitary medicine, criminology and was aimed at developing self-safety in students. The realities of 2020 required the creation of an anti-virus safety section within the course. The teaching of this problem had experienced in some Russian institutions and universities. This topic is taught to students both through personal contact with the lecturer and on-line. The branch of course is based on the following sections of modern science and practice: 1. Virology, 2. Global ecology, 3. Sanitation and preventive medicine. Teaching contributes to the formation of an objective view of the dangers of viruses in young people, without diminishing or exaggerating the real dangers of infectious diseases. Much attention is paid to the following sections of modern science: 1. The theory of the biosphere by Vladimir Vernadsky, 2. The doctrine of genetic instability and "horizontal transmission", providing informational unity of the biosphere, supported by viruses (Nobel Prize for Barbara McClintoch, 1983). Teaching is combined with practical exercises on the use of personal protective equipment against viral infections. The idea is brought to the students that viruses are a necessary component of the biosphere. They cannot be suffocated and it is impossible to be completely isolated from them. Teaching this course will contribute to improving the health indicators of the population. At the sessions of the European Geosciences Union, it is planned to hold a presentation of programs and teaching textbooks for this course.
Spatially explicit methane emissions from the largest wetland complex in North America: Past, present and future
Authors: Bansal Sheel , Post van der Burg Max , Lo Rachel , McKenna Owen
Published: March 2021

Almost half of all biogenically-produced methane is emitted from small lakes and wetlands. The Prairie Pothole Region (PPR) is the largest wetland complex in North America (10th largest in the world), and contains 5–8 million wetlands and lakes, which can potentially influence continental and global methane budgets. However, there is considerable uncertainty of past, current and future emissions of methane from PPR wetlands due to a lack of landscape-scale models based on PPR-specific data. We used a bottom-up approach to develop a spatially explicit, temporally dynamic model of wetland and lake methane emissions from the PPR. Using a dataset of >20,000 static-chamber flux measurements, we first developed a chamber model to understand functional relationships between methane fluxes and covariates, and then upscaled to the landscape using GIS and remotely sensed proxies for each covariate. Covariates in the chamber model included water-filled pore space (WFPS), hydroperiod, soil temperature, wetland size, land cover, and normalized difference vegetation index (NDVI). Proxies for upscaling included the Dynamic Surface Water Extent (for WFPS, hydroperiod, and area) and NDVI based on Landsat imagery, ClimateNA (for soil temperature), and the North American Land Change Monitoring System (for land cover). Methane emissions increased nonlinearly with increasing WFPS, soil temperature and NDVI, and was greater in wetlands surrounded by grasslands compared to cropland due to low organic carbon substrates in sediment of cropped wetlands. Methane flux had a hump-shaped relationship with area, with the highest emissions in mid-sized wetlands (1-4 ha) that had relatively long hydroperiods and high vegetation cover, whereas methane flux from water bodies >10 ha was negligible due to their relatively high sulfate concentrations. Despite the potential for high total emission from the PPR as would indicate from global models, total emissions were relatively low (~5 and 100 Gg methane) per year during historic dry (1991) and current wet years (2011), respectively, with wetland extent is the primary driver of regional emissions. Future warmer temperature scenarios (under RCP 8.5) indicate that annual methane emissions from the PPR could double.
Brittle-ductile deformation in high-pressure continental units and deep episodic tremor and slip
Authors: Giuntoli Francesco , Viola Giulio
Published: March 2021

The geological record of deep seismic activity in subduction zones is generally limited due to common rock overprinting during exhumation and only a few regions allow studying well-preserved exhumed deep structures. The Northern Apennines (Italy) are one such area, granting access to continental units (Tuscan Metamorphic Units) that were subducted to high-pressure conditions, were affected by brittle-ductile deformation while accommodating deep tremor and slip and then exhumed back to surface, with only minor retrogression.

Our approach is based on detailed fieldwork, microstructural and petrological investigations. Field observations reveal a metamorphosed broken formation composed of boudinaged metaconglomerate levels enveloped by metapelite displaying a pervasive mylonitic foliation. Shear veins occur in both lithologies, but are more common and laterally continuous in the metapelite. They are mostly parallel to the foliation and composed of iso-oriented stretched quartz and Mg-carpholite (XMg>0.5) fibres, which are single-grains up to several centimetres long. These fibres define a stretching direction coherent with that observed in the metaconglomerate and metapelite, which is marked by K-white mica and quartz. Thermodynamic modeling constrains the formation of the high-pressure veins and the mylonitic foliation to ~ 1 GPa and 350°C, corresponding to c. 30-40 km depth in the subduction channel.

Shear veins developed in subducted (meta)sediments are a key indicator of episodic tremor and slip (e.g. 1). We propose that these structures reflect the repeated alternation of localised brittle failure, with shear veins development, and more diffuse viscous deformation. These cycles were probably related to the fluctuation of pore pressure that repeatedly reached lithostatic values. Concluding, these structures can be considered the geological record of episodic tremors and slip occurring at >30 km of depth in the Apenninic subduction channel.

1. Fagereng, Å., Remitti, F. & Sibson, R. H. Incrementally developed slickenfibers — Geological record of repeating low stress-drop seismic events? Tectonophysics 510, 381–386 (2011).

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 839779.
A numerical approach to predict soil bearing potential for isolated footing
Authors: Hinge Gilbert , Kumar Das Jayanta , Bharali Biswadeep
Published: March 2021

The success of any civil engineering structure's foundation design depends upon the accuracy of estimation of soil’s ultimate bearing capacity. Numerous numerical approaches have been proposed to estimate the foundation's bearing capacity value to avoid repetitive and expensive experimental work. All these models have their advantages and disadvantages. In this study, we compiled all the governing equations mentioned in Bureau of Indian standard IS:6403-1981 and modify the equation for Ultimate Bearing Capacity. The equation was modified by considering two new parameters, K1(for general shear) and K2 (for local shear) so that a common governing equation can be used for both general and local shear failure criteria. The program used for running the model was written in MATLAB language code and verified with the observed field data. Results indicate that the proposed model accurately characterized the ultimate, safe, and allowable bearing capacity of a shallow footing at different depths. The correlation coefficients between the observed and model-predicted bearing capacity values for a 2m foundation depth with footing size of 1.5 ×1.5, 2.0 × 2.0, and 2.5 × 2.5 m are 0.95, 0.94, and 0.96. A similar result was noted for the other foundation depth and footing size. Findings show that the model can be used as a reliable tool for predicting the bearing capacity of shallow foundations at any given depth.  Moreover, the formulated model can also be used for the transition zone between general and local shear failure conditions.
Ensemble-based volcanic ash forecasts using satellite retrievals for quantitative verification
Authors: Capponi Antonio , Harvey Natalie J. , Dacre Helen F. , Beven Keith , James Mike R.
Published: March 2021

Volcanic ash poses a significant hazard for aviation. If an ash cloud forms as result of an eruption, it forces a series of flight planning decisions that consider important safety and economic factors. These decisions are made using a combination of satellite retrievals and volcanic ash forecasts issued by Volcanic Ash Advisory Centres.  However, forecasts of ash hazard remain deterministic, and lack quantification of the uncertainty that arises from the estimation of eruption source parameters, meteorology and uncertainties within the dispersion model used to perform the simulations. Quantification of these uncertainties is fundamental and could be achieved by using ensemble simulations. Here, we explore how ensemble-based forecasts — performed using the Met Office dispersion model NAME — together with sequential satellite retrievals of ash column loading, may improve forecast accuracy and uncertainty characterization.

We have developed a new methodology to evaluate each member of the ensemble based on its agreement with the satellite retrievals available at the time. An initial ensemble is passed through a filter of verification metrics and compared with the first available set of satellite observations. Members far from the observations are rejected. The members within a limit of acceptability are used to resample the parameters used in the initial ensemble, and design a new ensemble to compare with the next available set of satellite observations. The filtering process and parameter resampling are applied whenever new satellite observations are available, to create new ensembles propagating forward in time, until all available observations are covered.

Although the method requires the run of many ensemble batches, and it is not yet suited for operational use, it shows how combining ensemble simulations and sequential satellite retrievals can be used to quantify confidence in ash forecasts. We demonstrate the method by applying it to the recent Raikoke (Kurii Islands, Russia) eruption, which occurred on the 22nd July 2019. Each ensemble consists of 1000 members and it is evaluated against 6-hourly HIMAWARI satellite ash retrievals.
A Lithology-based Silicate Weathering Model for Earth-like Planets
Authors: Hakim Kaustubh , Bower Dan J. , Tian Meng , Deitrick Russell , Auclair-Desrotour Pierre , Kitzmann Daniel , Dorn Caroline , Mezger Klaus , Heng Kevin
Published: March 2021

Silicate weathering is a key step in the carbonate-silicate cycle (carbon cycle) that draws down

CO2 from the atmosphere for eventual burial and long-term storage in the planetary interior. This process is thought to provide an essential negative feedback to the carbon cycle to maintain temperate climates on Earth and Earth-like. We implement thermodynamics to determine weathering rates as a function of surface lithology (rock type). These rates provide upper limits that allow estimating the maximum rate of weathering in regulating climate. We model chemical kinetics and thermodynamics to determine weathering rates for three types of rocks inspired by the lithologies of Earth's continental and oceanic crust, and its upper mantle. We find that thermodynamic weathering rates of a continental crust-like lithology are about one to two orders of magnitude lower than those of a lithology characteristic of the oceanic crust. Our results show that the weathering of mineral assemblages in a given rock, rather than individual minerals, is crucial to determine weathering rates at planetary surfaces. We show that when the CO2 partial pressure decreases or surface temperature increases, thermodynamics rather than kinetics exerts a strong control on weathering. The kinetically- and thermodynamically-limited regimes of weathering depend on lithology, whereas, the supply-limited weathering is independent of lithology. Our results imply that the temperature-sensitivity of thermodynamically-limited silicate weathering may instigate positive feedback to the carbon cycle, in which the weathering rate decreases as the surface temperature increases. 
Firn changes at Colle Gnifetti revealed with a high-resolution process-based physical model approach
Authors: Mattea Enrico , Machguth Horst , Kronenberg Marlene , van Pelt Ward , Bassi Manuela , Hoelzle Martin
Published: March 2021

Cold firn is progressively transitioning to a temperate state under a changing climate. This process is expected to affect ice core records and the mass balance of cold and polythermal glaciers. Thus there is a need to gain better understanding of this transition and develop quantitative, physical models, to predict cold firn evolution under a range of climate scenarios.

Here we present the application of a distributed, fully coupled energy balance and sub-surface model, to simulate high-alpine cold firn at Colle Gnifetti over the period 2003–2018. For the first time, we force such a model with high-resolution, long-term, quality-checked meteorological data measured in closest vicinity of the firn site, at the highest weather station in Europe (Capanna Margherita, 4560 m a.s.l.). The model includes the spatial variability of snow accumulation rates, and is calibrated using several, partly unpublished high-altitude measurements from the Monte Rosa area.

Overall, the simulated firn temperature profiles reach a very good agreement in comparison with a large archive of borehole measurements. Our results show a 20 m-depth firn warming rate of 0.44 °C per decade. Moreover, we find that surface melt over the glaciated saddle is increasing by 3–4 mm w.e. yr-2 (+29–36 % in 16 years) depending on the location, although with a large inter-annual variability. The simulation also indicates that atmospheric humidity is a prominent control over melt occurrence, with considerable amounts of sublimation taking place in dry conditions. Hourly-resolution analysis of the melt dynamics reveals a marked tendency towards frequent, small melt events (< 4 mm w.e.): these collectively represent a significant fraction of the total amounts.
Constraining the CME parameters of the spheromak flux rope implemented in EUHFORIA
Authors: Asvestari Eleanna , Pomoell Jens , Kilpua Emilia , Good Simon , Chatzistergos Theodosios , Temmer Manuela , Palmerio Erika , Poedts Stefaan , Magdalenic Jasmina
Published: March 2021

Coronal mass ejections (CMEs) are primary drivers of space weather phenomena. Modelling the evolution of the internal magnetic field configuration of CMEs as they propagate through the interplanetary space is an essential part of space weather forecasting. EUHFORIA (EUropean Heliospheric FORecasting Information Asset) is a data-driven, physics-based model, able to trace the evolution of CMEs and CME-driven shocks through realistic background solar wind conditions. It employs a spheromak-type magnetic flux rope that is initially force-free, providing it with the advantage of modelling CME as magnetised structures. For this work we assessed the spheromak CME model employed in EUHFORIA with a test CME case study. The selected CME eruption occurred on the 6th of January 2013 and was encountered by two spacecraft, Venus Express and STEREO--A, which were radially aligned at the time of the CME passage. Our focus was to constrain the input parameters, with particular interest in: (1) translating the angular widths of the graduated cylindrical shell (GCS) fitting to the spheromak radius, and (2) matching the observed magnetic field topology at the source region. We ran EUHFORIA with three different spheromak radii. The model predicts arrival times from half to a full day ahead of the one observed in situ. We conclude that the choice of spheromak radius affected the modelled magnetic field profiles, their amplitude, arrival times, and sheath region length.
Adaptation of the urban climate model PALM-4U for Wuerzburg, Germany
Authors: Baumann Miriam , Paeth Heiko
Published: March 2021

The European Union-funded research project 'BigData@Geo ­­­­­­­­- Advanced Environmental Technologies using AI on the Web' is dedicated to researching connections and interactions in the natural regional environmental system. This includes the development of a high-resolution regional earth system model for modelling climate change in Northern Bavaria, Germany.

This research aims to run an urban climate model based on the Parallelized Large-Eddy Simulation Model for Urban Applications (PALM-4U) for Lower Franconia and thus to simulate the Main Valley with a focus on Wuerzburg in a high resolution of up to one meter. As part of this, PALM-4U is coupled to the regional climate model REMO to use generated dynamic input data in addition to static data, for example relating to buildings, roads, waterways, bridges, roof greening etc. in the simulation. The effects of variable development and the influence of green spaces and vegetation – especially also of street trees – on the urban climate are thereby considered, taking into account climate change in the 21st century. Furthermore, changes in the boundary conditions, topography and land use are also part of the research and compared using historical, current and future scenarios.

First results of the coupled model, its urban climate components and of applied approaches such as nesting will be shown. Besides possibilities for their evaluation, possible further steps are also presented.

 