bluuebunny/crossref_metadata_2025 huggingface dataset:
Projected changes in days with zero-crossings for Norway
Authors: Nilsen Irene Brox , Hanssen-Bauer Inger , Tveito Ole Einar , Wong Wai Kwok
Published: March 2021

This presentation describes projected changes in the number of days with zero-crossings (DZCs) for Norway, that is, a day where the maximum temperature exceeds 0 °C and the minimum temperature drops below 0 °C, as an example of how the Norwegian Centre for Climate Services disseminates climate information to various user groups. Changes in DZCs have been requested by several user groups in Norway, for instance by agriculture and the transport sector. 
A cold bias was detected in the regional climate model ensemble for Norway (here: EURO-CORDEX), which highlighted the need for bias-adjusting temperature fields before analyses. This is important for any index that is dependent on a fixed temperature threshold, not only the given index DZCs.
Gridded projections of changes in DZCs were produced for the period 2071–2100 relative to 1971–2000 under RCP4.5 and RCP8.5, at a 1 × 1 km resolution. The projections have been made publicly available at the Norwegian Centre for Climate Services' website https://klimaservicesenter.no. Results show that in regions and seasons that are mild, the number of DZCs is thus projected to decrease. This decrease was found for lowland regions in spring and coastal regions in winter. In regions and seasons that are cold, the number of DZCs is projected to give more frequent crossings of the 0 °C threshold. This increase was found for inland regions in winter and the northernmost county, Finnmark, in spring. Thus, more frequent icing of the snowpack is expected in Finnmark. This information can be used by the transport sector (e.g. winter road maintenance) and agriculture (e.g. reindeer herders) in the relevant regions. The Norwegian Centre for Climate Services disseminates information through fact-sheets, web-based maps and downloadable files.
Impact of mesoscale eddies on salinity and CO2 ocean parameters in the western tropical Atlantic in February 2020
Authors: Olivier Léa , Boutin Jacqueline , Lefèvre Nathalie , Reverdin Gilles , Landschützer Peter , Speich Sabrina , Karstensen Johannes
Published: March 2021

Large oceanic eddies are formed by the retroflection of the North Brazil Current (NBC) near 8°N in the western tropical Atlantic. The EUREC4A-OA/Atomic cruise took place in January - February 2020, and extensively documented two NBC rings. The NBC flows northward across the Equator and pass the mouth of the Amazon River, entraining fresh and nutrient-rich water along its nearshore edge. From December to March, the Amazon river discharge is low but a freshwater filament stirred by a NBC ring was nevertheless observed. The strong salinity gradient can be used to delineate the NBC ring during its initial phase and its westward propagation. Using satellite sea surface salinity and ocean color associated to in-situ measurements of salinity, temperature, dissolved inorganic carbon, alkalinity and fugacity of CO2 we characterize the salinity and biogeochemical signature of NBC rings.
 The Climate Response to Emissions Reductions due to COVID-19
Authors: Jones Chris ,   Covid-MIP analysis
Published: March 2021

Many nations responded to the COVID-19 pandemic by restricting travel and other activities during 2020, resulting in temporarily reduced emissions of CO2, other greenhouse gases and ozone and aerosol precursors. We perform a coordinated Intercomparison, CovidMIP, of Earth System model simulations to assess the impact on climate of these emissions reductions. Eleven models performed multiple initial-condition ensembles to produce over 280 simulations spanning both initial condition and model structural uncertainty. We find model consensus on reduced aerosol amounts (particularly over East Asia) and associated increases in surface shortwave radiation levels. However, any impact on near-surface temperature or rainfall during 2020-2024 is extremely small and is not detectable in this initial analysis. Regional analyses on a finer scale, and closer attention to extremes (especially linked to changes in atmospheric composition and air quality) are required to test the impact of COVID-19-related emission reductions on near-term climate.

This first-look at results has focussed on surface climate, but future analysis will include attribution of drivers of climate signals; longer term implications of emissions reductions and options for economic recovery; quantifying changes in extremes; influence on atmospheric circulation and the carbon cycle.
Amphibole CPO in retrograded gabbro from the Lyngen Magmatic Complex (Northern Scandinavian Caledonides, Norway).
Authors: Galindos Alfarache Marina , Stünitz Holger , Konopásek Jiří , Lee Amicia
Published: March 2021

Deformation of natural mafic rocks by viscous deformation mechanisms can occur even at low temperature conditions. In such instances, crystal plastic mechanisms are not operative, as their activity is restricted to very high temperatures for amphiboles, pyroxenes, and plagioclase. Instead, simultaneous mineral reactions may facilitate deformation at low temperature conditions. The gabbro from the Lyngen Magmatic Complex (LMC) constitutes a good example of such processes, because it has experienced deformation at low temperatures of greenschist to lower amphibolite-facies conditions, and the rock has been transformed from gabbro to greenschist. This study focuses on detailed analysis of deformation processes, metamorphic reactions and fabric development in the LMC gabbro. Most samples are overprinted by epidote amphibolite and greenschist-facies mineral assemblages. Preliminary observations distinguish two different types of amphiboles, which have been interpreted as different generations. The predominant type defines the stretching lineation and shows long prismatic habits whereas the less abundant type crystallized in a sub- to anhedral manner. The metamorphic conditions of growth for each amphibole type is yet not well constrained. However, we initially interpret the former to grow during epidote amphibolite- or greenschist facies-conditions, whereas the latter could represent relict grains from the original magmatic assemblage or products generated at amphibolite- or epidote amphibolite-facies conditions. Further analysis will determine the orientation, geochemistry and metamorphic conditions during growth for both amphibole types. A recent model proposed for eclogites suggests that simultaneous mineral growth and deformation can result in new products growing in a preferred direction. Such preferential growth can generate a shape preferred orientation parallel to the lineation, which results in the formation of crystal preferred orientations (CPO). We aim to test if similar microstructural observations can be translated to the amphiboles of the LMC gabbro. In such case, amphibole CPO’s would not be the product of crystal plasticity but of preferential growth. The large scale deformation of the LMC emphasizes the relevance of these results, as it would demonstrate that the interaction between mineral reactions and deformation can play a major role on regional deformation of large mafic bodies, such as the ocean floor.
Impact of variability in measured and simulated tundra snowpack properties on heat transfer metrics
Authors: Dutch Victoria , Rutter Nick , Wake Leanne , Sandells Mel , Derksen Chris , Hould Gosselin Gabriel , Sonnentag Oliver , Essery Richard , Marsh Phillip
Published: March 2021

Tundra snowpack properties are highly heterogenous over a variety of spatial scales and evolve over the course of the winter. Variations in snowpack properties such as snow density and microstructure control the transfer of heat through the snowpack. Thermal properties of the snowpack impact the subnivean environment; snow insulates the underlying soil, allowing films of liquid water to remain unfrozen, enabling biological processes to take place. In this study, field measurements from four field campaigns across two different winters (March and November 2018, January and March 2019) are used to capture and constrain the spatial variability of the snowpack. These include 1050 spatially distributed Snow MicroPenetrometer (SMP) profiles throughout the Trail Valley Creek catchment in the Northwest Territories, Canada. Bespoke coefficients for tundra snowpacks were calculated (based on the work of King et al., 2020) to convert raw SMP force measurements to densities. This allowed density changes of vertical profiles to be assessed and spatial variability in the thickness and properties of three snowpack layers (wind slab, indurated hoar and depth hoar) to be quantified. 105 needleprobe measurements from 37 snowpits were used to contrast the density and thermal conductivity of snowpack layers, as well as thermal conductivities estimated from recalibrated SMP density profiles. These in-situ measurements will be compared to 1-D simulations of snowpack properties from the Community Land Model (PTCLM 5.0) over the two winter seasons. The impact of snowpack layering on snow heat transfer metrics will be investigated using both 2-layer (wind slab: depth hoar) and 3-layer (wind slab: indurated hoar: depth hoar) snowpack configurations. The spatial variability of heat transfer metrics across the Trail Valley Creek catchment will also be considered.
Interrogating Tomographic Uncertainties for Subsurface Structural Information
Authors: Curtis Andrew , Zhao Xuebin , Zhang Xin
Published: March 2021

The ultimate goal of a geophysical investigation is usually to find answers to scientific (often low-dimensional) questions: how large is a subsurface body? How deeply does lithosphere subduct? Does a certain subsurface feature exist? Background research reviews existing information, an experiment is designed and performed to acquire new data, and the most likely answer is estimated. Typically the answer is interpreted from geophysical inversions, but is usually biased because only one particular forward function (model-data relationship) is considered, one inversion method is used, and because human interpretation is a biased process. Interrogation theory provides a systematic way to answer specific questions. Answers balance information from multiple forward models, inverse methods and model parametrizations probabilistically, and optimal answers are found using decision theory.

Two examples illustrate interrogation of the Earth’s subsurface. In a synthetic test, we estimate the cross-sectional area of a subsurface low velocity anomaly by interrogating Bayesian probabilistic tomographic maps. By combining the results of four different nonlinear inversion algorithms, the optimal answer is very close to the true answer. In a field data application, we evaluate the extent of the Irish Sea Sedimentary Basin based on the uncertainties in velocity structure derived from Love wave tomography. This example shows that the computational expense of estimating uncertainties adds explicit value to answers.

This study demonstrates that interrogation theory answers realistic questions about the Earth’s subsurface. The same theory can be used to solve different types of scientific problem - experimental design, interpreting models, expert elicitation and risk estimation - and can be applied in any field of science. One of its most important contributions is to show that fully nonlinear estimates of uncertainty are critical for decision-making in real-world geoscientific problems, potentially justifying their computational expense.

 
New MESSy scavenging subroutine to treat aerosol particles gas-phase partitioning in convective clouds
Authors: Taverna Giorgio , Barra Marc , Tost Holger
Published: March 2021

The Modular Earth Submodel System (MESSy) has been proven to be successful in the understanding of several processes which characterize the terrestrial atmosphere and climate.

However, the complexity of aerosol particles/gas phase partitioning of species in deep convective clouds together with the inherent problems of modelling sub-grid scale processes, make MESSy results significant underestimated, especially in case of SO2, when compared with available flight observations. For this reason, the subroutine which reproduce the scavenging of these species has been updated to include a more realistic treatment of liquid/phase partitioning of aerosol induced species in high level clouds.

Results obtained are shown in this poster.
Distinct particle modes in the lower stratosphere constrain secondary aerosol chemistry and gas-phase concentrations
Authors: Murphy Daniel , Froyd Karl , Schill Greg , Brock Charles , Kupc Agnieszka , Williamson Christina
Published: March 2021

There are distinct types of aerosol particles in the lower stratosphere. Stratospheric sulfuric acid particles with and without meteoric metals coexist with mixed organic-sulfate particles that originated in the troposphere. That these particles remain distinct has important implications for aerosol chemistry and the concentrations of several gas-phase species. Neither semi-volatile organics nor ammonia can be in equilibrium with the gas phase. The gas-phase concentrations of semi-volatile organics and ammonia must be very low, or else the sulfuric acid particles would not stay so pure. The upper concentration limits are around a pptv. Yet the sulfuric acid particles in the Northern Hemisphere show a very small but measurable uptake of organics and ammonia, indicating non-zero gas-phase concentrations of those species. Finally, the organic-sulfate particles must be resistant to photochemical loss, or else they would no longer retain their organic content.
Net-zero greenhouse gas targets: pathway and when reached equally important
Authors: Ocko Ilissa , Sun Tianyi , Hamburg Steven
Published: March 2021

The concept of net zero emissions is now a central element of government and business commitments to addressing climate change, with more net zero policies and pledges being rolled out on an almost daily basis. However, of major concern is the limited awareness of how critical the emissions reduction pathway is in achieving desired climate outcomes. The focus of the climate policy community remains on the target date rather than the path to get there, and net zero "by 2050" is considered by many as the required policy characteristic in achieving temperature targets. Ultimately, the rate and magnitude of future warming relies on the amount, type, and timing of greenhouse gas emissions. Based on different combinations of these factors, it is both possible to succeed or fail in achieving temperature goals even if the global community reaches net zero by 2050. For similar reasons, it is also possible to miss the net zero by 2050 target and still succeed in meeting temperature goals. Therefore, it is important to clarify the role of the decarbonization pathway taken and offer recommendations to ensure that net zero pathways succeed in achieving global climate goals. In this analysis, we show how different net zero paths can lead to a range of temperature outcomes, and how we can strengthen the probability of meeting globally agreed upon climate goals by establishing complementary near-term targets. Key components of ensuring success in achieving temperature targets include incorporating a carbon dioxide budget and acting early to reduce methane emissions. Not only do these actions make achieving our goals more likely, but they also make the path forward more affordable and less dependent on technology not yet available at scale. Overall, improved understanding of the role of the path to net zero would create greater flexibility in effectively fulfilling commitments; open opportunities for trading across groups of greenhouse gases with no loss in climate benefits; and make it easier and cheaper to accomplish corporate and government goals.
A Rainfall Erosivity database for Brazil from MSWEP rainfall dataset
Authors: Petry Ingrid , Mainardi Fan Fernando
Published: March 2021

In erosion studies the behavior of rainfall is primordial, since rain is responsible for the first stage of the erosion process: the detachment of soil particles. The erosive potential of rainfall, erosivity, is considered in the universal soil loss equations (R)USLE family through the parameter R, or R factor. This factor is calculated from the rainfall erosivity index, which is the product of kinetic energy of the rain by the maximum intensity of the rain of 30 minutes of duration. As sub-hour rainfall data is not always available, there are in the literature a series of equations obtained from regression, which use monthly and annual rainfall and present a good estimate of erosivity for your study site. In Brazil, in addition to limitations regarding the temporal resolution of rainfall data, there are also spatial limitations. Monitoring stations are concentrated mostly in urbanized areas, usually near the coast. The other regions, such as agricultural and forest areas, are poorly monitored, and these areas are of great interest for monitoring erosion, not only because they are periodically exposed soil areas, but also because of the high rainfall rates that humid forests like Amazon have. MSWEP is a rainfall database that combines observed, satellite and reanalysis data. It has global coverage, temporal resolution of 3 hours, spatial 0.1º and data from 1979 to 2016. Databases like this have great potential to be used in areas such as Brazil, due to its spatial and temporal resolution. In this context, considering the relevance that the soil loss equations still present today, this work developed a rainfall erosivity database entitled REDB-BR (Rainfall Erosivity Database for Brazil). It provides the R factor in a 0.1º resolution grid, developed with 37 years of rainfall data from the MSWEP dataset. The R factor was calculated trough 73 erosivity index regression equations, which mostly uses the Modified Fournier Index (MFI), a relation between monthly precipitation and annual precipitation. Thiessen polygons were used in order to spatialize and define the areas of each equation. Over the Brazilian territory, the R factor ranges from 1.200 to 20.000 MJ mm ha-1 h-1 year-1, with the higher values in the North region, and the lowest values in the Northeast. The spatial patterns of erosivity are very similar to the climatic zones of Brazil. The R factor map takes advantage of MSWEP dataset and presents a spatial resolution very detailed to a country with continental scale such as Brazil. The database includes the equations shapefile and table, Thiessen Polygons shapefile and the R factor map in raster format, which allows more possibilities of application. The database can be accessed at . We identified sudden changes in behavior between the delimited areas, which suggests a need for more regression equations in order to better represent the behavior of the erosivity in the Brazilian territory.
Insolation-paced sea level during the Early Pleistocene, Taiwan
Authors: Vaucher Romain , Dashtgard Shahin E. , Horng Chorng-Shern , Zeeden Christian , Dillinger Antoine , Pan Yu-Yen , Setiaji Romy Ari , Chi Wen-Rong , Löwemark Ludvig
Published: March 2021

The Pleistocene was a phase of global cooling of the Earth through which glacial-interglacial cycles occurred, and the growth and decay of the ice-sheets resulted in quasi-cyclic sea-level fluctuations driven by orbital forcing. Despite that summer insolation is mostly controlled by precession, the records of the glacial cycles showcase a significant periodicity of ~41 kyrs during the Early Pleistocene forced by Earth’s obliquity (tilt) that varies the latitudinal distribution of insolation especially in high latitudes. The dominance of obliquity over precession in marine archives is commonly attributed to the in-phase effect of obliquity-related insolation versus the opposite-phased influence of precession, which may cancel out the summer insolation signal received by the southern and northern hemispheres.

Here, we present a clastic shallow marine record from the Cholan Formation (Early Pleistocene; Taiwan). Facies analysis indicates that quasi-cyclic deposition occurred in shoreface to offshore environments in the paleo-Taiwan Strait. The magnetobiostratigraphic framework indicates that the studied section occurs in the lower part of the Matuyama subchron (1.925 - 2.595 Ma) close to the lower limit of the Olduvai (1.925 Ma) normal polarity subchron. Comparison of the stratigraphy to a d18O isotope record of benthic foraminifera and orbital curves of precession and obliquity at the time of sediment accumulation reveals a good correlation between depositional cycles and the Northern Hemisphere summer insolation, demonstrating precession dominated sea-level fluctuations during the Early Pleistocene. These results underpin recent findings suggesting that d18O isotope records of benthic foraminifera have a more significant precession signal than previously described. This study also demonstrates that shallow-marine stratigraphic successions in high-accommodation and high-sedimentation basins can be outstanding climate archives, possibly even preserving sediment flux responding to half-precession cycles.
Three Dimensional Numerical Simulations of Internal Tides in the Angolan Upwelling Region
Authors: Zeng Zhi , Brandt Peter , Lamb Kevin , Greatbatch Richard , Dengler Marcus , Claus Martin , Chen Xueen
Published: March 2021

In austral winter, biological productivity at the Angolan shelf reaches its maximum. The alongshore winds, however, reach their seasonal minimum suggesting that processes other than local wind-driven upwelling contribute to near-coastal cooling and upward nutrient supply, one possibility being mixing induced by internal tides (ITs). Here, we apply a three-dimensional ocean model to simulate the generation, propagation and dissipation of ITs at the Angolan continental slope and shelf. Model results are validated against moored acoustic Doppler current profiler and other observations. Simulated ITs are mainly generated in regions with a critical/supercritical slope typically between the 200- and 500-m isobaths. Mixing induced by ITs is found to be strongest close to the coast and gradually decreases offshore thereby contributing to the establishment of cross-shore temperature gradients. The available seasonal coverage of hydrographic data is used to design simulations to investigate the influence of seasonally varying stratification characterized by low stratification in austral winter and high stratification in austral summer. The results show that IT characteristics, such as their wavelengths, sea surface convergence patterns and baroclinic structure, have substantial seasonal variations and additionally strong spatial inhomogeneities. However, seasonal variations in the spatially-averaged generation, onshore flux and dissipation of IT energy are weak. By evaluating the change of potential energy, it is shown, nevertheless, that mixing due to ITs is more effective during austral winter. We argue this is because the weaker background stratification in austral winter than in austral summer acts as a preconditioning for IT mixing.
Developing Equatorial Plasma Bubbles Observed by Multi-Instrument at Dawn
Authors: Wu Kun , Xu Jiyao , Yue Xinan , Xiong Chao , Wang Wenbin , Yuan Wei , Wang Chi , Zhu Yajun , luo Ji
Published: March 2021

Previous studies have shown that equatorial plasma bubbles (EPBs) usually occur after sunset, and they usually drift eastward. Observations from an all-sky imager and the Global Navigation Satellite Systems (GNSS) network in southern China showed a special EPB event. Observational results show that the EPBs appeared near dawn and continued to develop after sunrise. They disappeared about one hour after sunrise which the life time of those EPBs exceeds 3 hours. The result provided an evidence that the EPB could develop around sunrise in optical observation. Meanwhile, those observation showed that the EPBs drifted westward, which was different from the usually eastward drifts of EPBs. The simulation from TIE-GCM model suggest that the westward drift of EPBs should be related to the enhanced westward winds at storm time. Besides, increasing in the ionospheric F region peak height was also observed near sunrise. We suggest enhance upward vertical plasma drift during geomagnetic storm plays a major role in triggering the EPBs near sunrise.
Depth-dependent inversion of normal faults: Structural analysis of the Penobscot 3D seismic volume, offshore Nova Scotia
Authors: Peace Alexander , Schiffer Christian , Jess Scott , Phethean Jordan
Published: March 2021

The inversion of rift-related faults on passive margins through kinematic reactivation is documented globally. Such structures form an integral part in petroleum systems, provide essential constraints on the kinematic and structural evolution of rifts and passive margins, and can be used as global markers for far-field stresses. Despite the importance of inverted normal faults, the controls on their kinematic evolution, as well as existence and interactions within fault populations are often poorly constrained. Here, we present new structural interpretation and kinematic modelling of an inverted relay ramp structure located offshore Nova Scotia, Canada. This structure is imaged on the Penobscot 3D seismic reflection survey down to ~3.5 s TWTT, and is constrained by two exploration wells. We map two major normal faults that display evidence for inversion in their lower portions (reverse faulting and low-amplitude folding), below ~2.5 s TWTT, though retain a normal offset in upper sections. The wider fault population is dominated by ~ENE-WSW striking normal faults that dip both north and south, while both of the two major faults dip approximately south and are associated with antithetic and synthetic faults. This kinematic dichotomy along the major faults is important as inversion such as this may go unrecognised if seismic data does not image the full depth of a structure. To accommodate such depth-dependent inversion, if both horizons co-existed during inversion, a reduction in volume of the sedimentary package is required between the normal and reverse segments of the fault. In this study, we explore possible kinematic mechanisms to explain inversion structure and the mechanisms accommodating the volumetric changes/ or mass movements required using fault restoration and strain modelling. Our results favour a poly-phase deformation history that can be reconciled with other inversion structures on related passive-margin segments, suggesting these could be widespread processes.
Drought spatiotemporal propagation via land feedbacks
Authors: Miralles Diego G. , Schumacher Dominik L. , Keune Jessica , Dirmeyer Paul A.
Published: March 2021

The predicted increase in drought occurrence and intensity will pose serious threats to global future water and food security. This was hinted by several historically unprecedented droughts over the last two decades, taking place in Europe, Australia, Amazonia or the USA. It has been hypothesised that the strength of these events responded to self-reinforcement processes related to land–atmospheric feedbacks: as rainfall deficits dry out soil and vegetation, the evaporation of land water is reduced, then the local air becomes too dry to yield rainfall, which further enhances drought conditions. Despite the 'local' nature of these feedbacks, their consequences can be remote, as downwind regions may rely on evaporated water transported by winds from drought-affected locations. Following this rationale, droughts may not only self-reinforce locally, due to land atmospheric feedbacks, but self-propagate in the downwind direction, always conditioned on atmospheric circulation. This propagation is not only meteorological but relies on soil moisture drought, and may lead to a downwind cascading of impacts on water resources. However, a global capacity to observe these processes is lacking, and thus our knowledge of how droughts start and evolve, and how this may change as climate changes, remains limited. Furthermore, climate and forecast models are still immature when it comes to representing the influences of land on rainfall.

Here, the largest global drought events are studied to unravel the role of land–atmosphere feedbacks during the spatiotemporal propagation of these events. We based our study on satellite and reanalysis records of soil moisture, evaporation, air humidity, winds and precipitation, in combination with a Lagrangian framework that can map water vapor trajectories and explore multi-dimensional feedbacks. We estimate the reduction in precipitation in the direction of drought propagation that is caused by the upwind soil moisture drought, and isolate this effect from the influence of potential evaporation and circulation changes. By doing so, the downwind lack of precipitation caused by upwind soil drought via water vapor deficits, and hence the impact of drought self-propagation, is determined. We show that droughts occurring in dryland regions are particularly prone to self-propagate, as evaporation there tends to respond strongly to enhanced soil stress and precipitation is frequently convective. This kind of knowledge may be used to improve climate and forecast models and can be exploited to develop geo-engineering mitigation strategies to help prevent drought events from aggravating during their early stages.
Water Masses in the Black Sea as Seen by Profiling Floats. A revisit of the role of winter, slope and geothermal convectio.
Authors: Stanev Emil , Chtirkova Boriana , Peneva Elisaveta
Published: March 2021

More than 6000 profiles from profiling floats in the Black Sea over the 2005-2020 period were used to study the ventilation of this basin from the top to the very bottom. In the upper layers and in the main pycnocline, water masses show a strong interannual variability following intermittent events of cold water formation. The density ratio decreased three times during the last 15 years, revealing the decreasing role of temperature in the vertical layering of the Black Sea halocline. The deep transition layer (DTL) between 700 and 1700 m acts as an interface between the baroclinic layer and the largest bottom convective layer (BCL) of the world oceans. On top of DTL are the warm intermediate layer (WIL) and deep cold intermediate layer (DCIL). They both showed strong trends in the last fifteen years due to warmer climate and intensification of warmer intrusions from Bosporus. A “salinity wave” was detected in 2005-2009 below ~1700 m, which evidenced for the first time the penetration of gravity flow from Bosporus down to the bottom. The layering of water masses was explained as resulting from the different distribution of sources of heat and salt, double duffusion and balances between the geothermal and salinity flows in the BCL.
Quantifying the seismogenic impact on mass movements in the Alps in terms of Arias Intensity
Authors: Domej Gisela , Frattini Paolo , Valbuzzi Elena , Crosta Giovanni B.
Published: March 2021

Earthquakes are – amongst many others – one type of triggering factors for mass movements in mountainous regions such as landslides, deep-seated gravitational slides (DSGSD), rockfalls, mudflows, etc. Hence, the emerging hazard would require an area-wide assessment of seismogenic impact to better apprehend the interplay of different triggering factors contributing to mass movement activity. However, seismicity itself is difficult to assess for several reasons. On the one hand, there are various parameters describing ground motion, and not all of them are suitable for area-wide assessments due to their availability or complexity. On the other hand, phenomena such as attenuation and topographic amplification must be taken into account, especially when the region of interest is an orogen.

Considering the criteria mentioned above and aiming for a mapping approach ascribing one value of seismogenic impact to one geographic location, we developed a strategy based on two empirical laws approximating Arias Intensity: the first law estimates Arias Intensities for a particular location as a function of earthquake magnitudes and focal depths; the second law corrects these estimated Arias Intensities in relation to the height differences to the nearest channel beds. Finally, we sum all corrected Arias Intensities resulting from different earthquakes in one particular location. Values obtained in this last step do not represent a physical entity; nevertheless, they allow for quantitative assessment of seismic exposure with respect to a given earthquake dataset covering a specific time frame, also allowing for color coding and comparative mapping approaches in GIS for other factors triggering mass movements.

In our case study, we assess the seismic exposure of a set of several hundreds of landslides, DSGSD, and rockfalls located in a rectangular area in the Italian Central Alps. In a first step, the area was discretized using a quadratic grid with increments of 1 km in order to assign points of evaluation to the previously mapped polygons representing landslides, DSGSD, and rockfalls. Additionally, to each polygon, a centroid point was attributed to avoiding the loss of polygons smaller than 1x1 km. In a second step, we computed the seismic exposure in each point resulting from two earthquake datasets covering the Alps, including a 500 km wide buffer zone: instrumental earthquake data of the ISC Bulletin covering a period from 1900 to 2019; macro-seismic earthquake data of the SHARE European Earthquake Catalog covering a period from 1000 to 2006.

The study serves as a preliminary test for assessing wider areas across the Alps, which either geologically or geographically belong together. We illustrate our mapping approach in a series of maps discussing the effects of the number of earthquakes, magnitudes, distances, topography, and time frame.
Electron filling and proton loss in radiation belts and SAA during 2018 storm based on ZH-1 satellite observations
Authors: Zhang Zhenxia
Published: March 2021

Based on data from the ZH-1 satellites, companied with Van Allen Probes and NOAA observations, we analyze the high energy particle evolutions in radiation belts, slot region and SAA during August 2018 major geomagnetic storm (minimum Dst ≈ −190 nT). 

  1) Relativistic electron enhancements in extremely low L-shell regions (reaching L ∼ 3) were observed during storm. Contrary to what occurs in the outer belt, such an intense and deep electron penetration event is rare and more interesting. Strong whistler-mode (chorus and hiss) waves, with amplitudes 81–126 pT, were also observed in the extremely low L-shell simultaneously (reaching L ∼ 2.5) where the plasmapause was suppressed. The bounce-averaged diffusion coefficient calculations support that the chorus waves can play a significantly important role in diffusing and accelerating the 1–3 MeV electrons even in such low L-shells during storms.

2) A robust evidence is clearly demonstrated that the energetic electron flux with energy 30∼600 keV are increased by 2∼3 times in the inner radiation belt near equator and SAA region on dayside during the major geomagnetic storm. This is the first time that the 100s keV electron flux enhancement is reported to be potentially induced by the interaction with magnetosonic waves in extremely low L-shells (L<2) observed by Van Allen Probes. Proton loss in outer boundary of inner radiation belt takes place in energy of 2~220 MeV extensively during the occurrence of this storm but the loss mechanism is energy dependence which is consistent with some previous studies. It is confirmed that the magnetic field line curvature scattering plays a significant role in the proton loss phenomenon in energy 30-100 MeV during this storm. This work provides a beneficial help to comprehensively understand the charged particles trapping and loss in SAA region and inner radiation belt dynamic physics.
Characterising the kinematics of the Joffre Peak landslides using a combined numerical modeling-remote sensing approach
Authors: Fullin Nicola , Ghirotti Monica , Donati Davide , Stead Doug
Published: March 2021

Geological structure and kinematics are often the most important factors controlling the stability of high rock slopes; their characterization can provide insights that are instrumental in understanding the behaviour of a slope in addition to its evolution with time. In this research, we used a combined remote sensing-numerical modelling approach to characterize the Joffre Peak landslides (British Columbia, Canada), two rock avalanche events that occurred on May, 13th and 16th 2019. The May 13th event involved a volume of 2-3million m3, and resulted in a runout distance of 6 km. The May 16th event involved a volume of 2-3 million m3, and a runout distance of 4 km. The failure was likely promoted by permafrost degradation and reduction in shear strength along geological structures (in our simulation checked in dry condition). Using a wide range of techniques, including Structure-from-Motion photogrammetry, virtual outcrop discontinuity mapping, GIS analysis, and 3D distinct element numerical modelling, we investigated the important role that structural geology and slope kinematics played prior to and during the Joffre landslide events. In particular, we demonstrate that i) a very persistent, sub-vertical geological structures formed the lateral and rear release surfaces of the rock mass volume that failed as two discrete landslide events. The landslide blocks were separated by one such sub-vertical structure, which remains visible in the fresh landslide scar; ii) the first block, failed on May 13th 2019, involving planar sliding failure mechanism, possibly promoted by progressive failure and propagation of discontinuities along the basal surface. The detachment of this block enhanced the kinematic freedom of the second landslide block, which, on May 16th, failed as wedge/toppling mechanism; iii) the first landslide block acted as a key block; its displacement and failure provided the kinematic freedom for the occurrence of the second landslide.  In this paper we show that combining remote sensing mapping and 3D numerical modelling allows for the identification of the structural geological features controlling the stability and evolution of high rock slopes in alpine environments. We also show that constraining and validating the numerical modelling results using historical data is of paramount importance to ensure that the correct failure mechanism of the landslides is simulated.

 
Spatial Evaluation of Pore Pressure Variations Related to Rainfall from Seismic Velocity Changes
Authors: Andajani Rezkia Dewi , Tsuji Takeshi , Snieder Roel , Ikeda Tatsunori
Published: March 2021

Crustal pore pressure, which could trigger seismicity and volcanic activity, varies with fluid invasion. Various studies have discussed the potential of using seismic velocity changes from ambient noise to evaluate pore pressure conditions, especially due to rainfall perturbations. Although the influence of rainfall on seismic velocity changes has been reported, consideration of the spatial influence on rainfall towards seismic velocity and its mechanism have not been well understood. We investigated the mechanism of rainfall-induced pore pressure diffusion in southwestern Japan, using seismic velocity change (Vs) inferred from ambient noise. We modeled pore pressure changes from rainfall data based on a diffusion mechanism at the locations where infiltration is indicated. By calculating the correlation between Vs changes and the modeled pore pressure with various hydraulic diffusion parameters, the optimum hydraulic diffusion parameter was obtained. We estimated the diffusion parameters with the highest negative correlation between pore pressure and Vs change because a negative correlation indicates pore pressure increase due to diffusion induced by groundwater load. Furthermore, the spatial variation of the hydraulic diffusivity infers the heterogeneity of the rocks in different locations. This finding suggests that the response of pore pressure induced by rainfall percolation depends on location.  We show that seismic velocity monitoring can be used to evaluate the status of pore pressure at different locations, which is useful for fluid injection, CO2 wellbore storage, and geothermal development.
Lake Tarfala, N-Sweden – first results from a natural observatory mimicking future changes in glacier-fed Arctic lakes
Authors: Kirchner Nina , Schenk Frederik , Kuttenkeuler Jakob , Rosqvist Gunhild , Weckström Jan , Weckström Kaarina , Korhola Atte , Hancke Marnie , Granebeck Annika , Eriksson Pia
Published: March 2021

Lake Tarfala is an up to 50 m deep glacier-proximal Arctic lake in the Kebnekaise Mountains, northern Sweden (~67°55' N, ~18°35' E, 1162 m asl) in direct vicinity to the Tarfala Research Station run by Stockholm University, and to the glacier Storglaciären for which the world’s longest glacier mass balance record is kept since 1946. The neighboring Kebnepakte Glacier drains directly into Lake Tarfala. The site provides a unique an easily accessible natural observatory to study the impacts of climate and environmental change in an Arctic lake linked to a melting glacier.

As other Arctic lakes, Lake Tarfala is exposed to accelerated atmospheric warming in recent decades leading to increasingly shorter periods of lake freeze-over. Recent warming has also led to a widespread mass loss from glaciers with so for unclear implications for glacier-fed lakes which may receive larger amounts of meltwater and sediments from shrinking glaciers.

General atmospheric warming on the one hand and in response an increased influx of cold glacial meltwater to glacier-fed lakes on the other hand thus cause two competing processes determining the thermal state of a lake. Understanding (changing) lake thermal states and associated lake mixing dynamics is important because it has ramifications for a multitude of lake ecological, biological, and geochemical processes.

Here, we present the first continuous 3-year water temperature record from the deepest part of Lake Tarfala, acquired between 2016 and 2019. The record shows that Lake Tarfala is dimictic with overturning during spring and fall with substantial interannual variability concerning the timing, duration and intensity of mixing processes, as well as of summer and winter stratification. Particularly cold lake winter states appear to be related to elevated influx of cold glacial meltwater.

The projected high mass loss of Scandinavian glaciers with up to more than 80% of their volume under RCP8.5 until 2100 AD relative to 2015 renders Lake Tarfala a natural observatory where changes in processes, inherent timescales and impacts in response to competing drivers can be studied before they occur at other glacial lake sites where glaciers melt at a slower place.
Not essential elements as tracers of geographical provenience of Sorrento PGI lemon juices  
Authors: Ruggiero Luigi , Fontanella Maria Chiara , Amalfitano Carmine , Beone Gian Maria , Adamo Paola
Published: March 2021

The mineral composition of agri-food products is useful to define their provenance for fraud protection. The potential of mineral composition to define the geographical provenance of high-value PGI agri-food products was explored in order to protect them from fraud. The Sorrento lemon (Citrus limon (L.) Burm. f. cv. Ovale di Sorrento), is known for its characteristic cultivation on terraces in the Sorrento peninsula and Capri island of Campania region (South Italy). In this environment, the peculiar soil and climatic features and the traditional cultivation on terraces have contributed not only to high-quality lemon productions but also to protect the landscape. The geographical conformation of the territory leads to different microclimates and habitats even at a very small scale. In this work, the multielement fingerprinting (essential and not essential elements) is proposed for discrimination lemon juices of six different cultivars (Femminello Ovale di Sorrento, Femminello Zagara Bianca, Femminello Siracusano 2KR, Femminello Sfusato Amalfitano, Femminello Adamo, and Femminello Cerza), grown in the PGI area of Sorrento lemon and in other two Campania region areas (no-PGI), according to the cultivars and their geographical origin on regional territory scale in two years (2018 and 2019). The explorative analysis by PCA on the mineral profile of the lemon juices showed natural grouping according to provenance at the expense of different cultivars. This suggests that the juice mineral composition depends slightly on cultivars, but strongly on the features of the cultivation environments. The applied discriminant model S-LDA, according to territorial provenance of lemon juices, showed 97.73% correct classification, 98.48% accuracy, and 93.83% external validation, and Mo, Ba, Rb, Mg, Co, Ca, Fe and Sr as discriminant elements. However, the annual variation of discriminant elements regarding many nutrients, the correlation of lemon juices/soil of some not essential elements (Ba, Rb, and Sr) which also discriminate juices and soils according to areas in both years, suggested the use of not essential elements as stable indicators of lemon juice provenance. In support of this suggestion, we applied S-QDA, more stringent than S-LDA, on only the determined, not essential elements (Ti, Co, Rb, Ba, and Sr). The results were discrimination of lemon juices according to provenance by all not essential elements, with 87.50% correct classification and 83.95% validation, despite the low number of variables. An increasing number of not essential elements is expected to improve the discrimination models. 
Development of a multi-scale greenhouse gas budget estimation system in Japan
Authors: Ito Akihiko , Niwa Yosuke , Hajima Tomohiro , Saigusa Nobuko
Published: March 2021

Achievement of the carbon-neutral society is one of the overarching tasks for the sustainability of humanity. Under the Paris Agreement of the United Nations Framework Convention of Climate Change, it becomes an important task for research community to establish a comprehensive, high-precision, and transparent system of greenhouse gas (GHG) budget estimation. In April 2021, a new task-force project will be launched in Japan to develop a GHG monitoring system, provisionally called the Comprehensive Observation and Modeling for Multi-scale Estimation of Greenhouse Gas budgetS (COMM-EGGS), funded by the Ministry of the Environment, Japan. This is a joint project of National Institute for Environmental Studies, Japan Agency for Marine-Earth Science and Technology, Chiba University, and Meteorological Research Institute. The project is composed of three research components: 1) observation and top-down estimation of GHG budget, 2) evaluation of GHG mitigation with an Earth system model, and 3) bottom-up estimation of GHG budget. These activities cover different spatial scales spanning from major city to national and global emissions, by using ground observatory, aircraft, and satellite observations and fine-mesh atmospheric and surface emission models. In the project, we put emphasis on the Asia-Pacific region, in which a comprehensive GHG monitoring system is deficient to date. Through mutual comparison and validation, we will make attempt to improve confidence of the estimation system for GHG budget verification. Finally, the system aims at contributing to the Global Stocktake of the Paris Agreement by providing scientific evidence for GHG emission reduction.